IVD & Molecular Diagnostics Glossary

The quality of nearness to the truth or the true value.

Acetylation involves the covalent linkage of an acetyl group into an organic molecule.

The goodness of fit statistic for the terminal elimination phase, adjusted for the number of time points used in the estimation of Lambda z.

The adhesion of a gas, liquid or dissolved solid chemical of interest onto a solid surface.

The strength of noncovalent chemical binding between two substances as measured by the dissociation constant of the complex.

A volatile liquid prepared by fermentation of certain carbohydrates. Alcohol acts as a central nervous system (CNS) depressant, a diuretic, and a disinfectant. Although the exact mechanism of CNS depression is unknown, alcohol may act by inhibiting the opening of calcium channels, mediated by the binding of the inhibitory neurotransmitter gamma-amino butyric acid (GABA) to GABA-A receptors, or through inhibitory actions at N-methyl-D-aspartate (NMDA)-type glutamate receptors. Alcohol inhibits the production of antidiuretic hormone, thereby producing diuresis that may lead to dehydration. This agent kills organisms by denaturing their proteins.

Pertaining to a portion of the whole; any one of two or more samples of something, of the same volume or weight.

Mutually exclusive alternative forms of the same gene occupying the same locus on homologous chromosomes, differing in nucleotide sequence and governing the same biochemical and developmental process.

Alternate Splicing is a process in which multiple protein isoforms or products are generated from a single gene as a result of splicing together different nonconsecutive exons during the processing of initially identical nascent transcripts of a gene into mature mRNA transcripts. An exon may be connected to any one of several alternative exons to form the mRNA and generate related proteins, often in a tissue or developmental stage specific manner.

A statistical technique which helps in making inference whether three or more samples might come from populations having the same mean; specifically, whether the differences among the samples might be caused by chance variation.

A type of protein made by B lymphocytes in response to a foreign substance (antigen). Each antibody only binds to a specific antigen, helping to destroy the antigen directly or by assisting white blood cells to destroy the antigen.

Any substance, generally a protein, that stimulates the immune system and elicits an immune response. Recognition by the immune system elicits either a T-lymphocyte response, recognizing processed antigens, or a B-lymphocyte response, producing antibodies that bind to unprocessed antigens.

The area between the x-axis and the curve given by the integrand. It is equal to the definite integral of a function. In the field of pharmacokinetics, the area under the curve (AUC) is the area under the curve in a plot of concentration of a drug in plasma against time. AUC is usually given for the time interval zero to infinity, and other time intervals are indicated.

The sum of a set of values divided by the number of values in the set.

A methodical examination or review of a condition or situation.

A chromosome not involved in sex determination. The diploid human genome consists of a total of 46 chromosomes which includes 22 pairs of autosomes.

Strength of binding, usually of a small molecule with multiple binding sites by a larger, particularly the binding of a complex antigen by an antibody.

Existing conditions, especially those that would be confused with the phenomenon to be observed or measured.

Initiation of DNA base excision repair (BER) involves a DNA glycosylase that binds the altered deoxynucleoside in an extrahelical position and catalyzes cleavage of the base-sugar bond. Subsequently, an AP endonuclease or AP lyase activity incises the abasic site, followed by short-patch gap-filling, excision of the base-free sugar-phosphate residue, and ligation.

A starting point to which things may be compared.

The paired nucleotides in a DNA or RNA sequence.

A sequential p-value procedure that controls expected false discovery rate.

Any deviation of results or inferences from the truth, or processes leading to such deviation.

A family of discrete probability density functions, which models systems that meet the following requirements: 1) the number of trials (n) is fixed; 2) there are only two outcomes for each trial, success or failure; 3) the outcome of each trial is independent; and 4) all trials have the same probability (p) of success. Binomial distributions show the likelihood of the number of successful trials versus the total number of trials.

A biological or chemical substance that exerts toxic or pathologic effects on living entities.

A storage facility of biospecimens that includes tissue samples, fluids, and molecular derivatives such as DNA, RNA, and proteins. The biorepository has stringent guidelines regarding the standardized collection, handling, storage, and documentation of biological specimens.

A characteristic of experiment design in which one or more groups involved (receiving, administering, or evaluating intervention) are unaware of which intervention any particular subject is receiving.

An ionic compound that resists changes in its pH.

The act of checking or adjusting (by comparison with a standard) the accuracy of a measuring instrument.

An instrument designed to measure the size of an opening or one used to increase the diameter of an opening; can also refer to a standard or reference material used to set the operating parameters of an instrument.

Enzymatic (e.g. dUTP/UNG) and physical measures that stop amplified DNA from contaminating later runs. Labs with high daily volumes usually require dUTP/UNG chemistry in purchased assays; confirm this when comparing kits from different manufacturers.

A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition. For example, one group may have been exposed to a particular substance that the other was not. Also called retrospective study.

Single-stranded DNA that is complementary to messenger RNA or DNA that has been synthesized from messenger RNA by reverse transcriptase.

A manufacturer declaration that an in vitro diagnostic complies with applicable EU legislation (the IVDR since May 2022). CE-IVD indicates regulatory conformance, not a statement of clinical superiority; buyers still review performance claims and intended use.

A process where a rotating machine exposes a specimen to centrifugal force. This process can be used to remove moisture from a specimen, to subject an organism to increased gravitational forces, or to separate the components of heterogeneous mixtures based on density differences.

A machine that uses centrifugal force to separate heavier substances from lighter ones, for removing moisture, or for simulating gravitational effects.

The nonstaining primary constriction of a chromosome which is the point of attachment of the spindle fiber; provides the mechanism of chromosome movement during cell division; the centromere divides the chromosome into two arms, and its position is constant for a specific chromosome: near one end (acrocentric), near the center (metacentric), or between (submetacentric).

The process by which a person demonstrates specific knowledge, skills, or abilities in the view of a certifying body. Similarly, the process by which a product or process can achieve certification indicating its suitability for a specific purpose.

Chi-square test is a statistical test for testing the null hypothesis that the distribution of a discrete random variable coincides with a given distribution. It is one of the most popular goodness-of-fit tests.

The genetic material of the nucleus, consisting of deoxyribonucleoprotein, which occurs in two forms during the phase between mitotic divisions: 1) as heterochromatin, seen as condensed, readily stainable clumps; 2) as euchromatin, dispersed lightly staining or nonstaining material. During mitotic division the chromatin condenses into chromosomes.

A structure found in cells that is comprised of a strand of linearized double-stranded DNA plus proteins that package the DNA in a condensed coil form and regulate chromosomal function.

A sequence of single-stranded RNA that forms a covalently closed continuous loop.

Neoplasm-derived DNA fragments found in the bloodstream or other bodily fluids that have been released from cells.

A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid.

The ratio of standard deviation to mean, expressed as a percentage or fraction.

A research study that compares a particular outcome (such as lung cancer) in groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke compared with those who do not smoke).

A range of values for a parameter that may contain the parameter and the degree of confidence that it is in fact there.

A sequence pattern derived from the alignment of multiple sequences that represents the nucleotide or amino acid most likely to occur at each position in a sequence.

The presence of any substance or organism that makes a preparation impure.

Variation in the number of copies of a particular sequence within the genetic material of an individual. Large-scale copy number polymorphisms are common and widely distributed in the human genome.

The degree to which two or more quantities or events are linearly associated, a statistical relation between two or more variables such that systematic changes in the value of one variable are accompanied by systematic changes in the others.

Problem associated with the degree to which an antibody or antigen participates in cross reactions.

A study in which participants are examined once for a characteristic, such as disease, at a single point in time.

A statistical method of partitioning a sample of data into subsets such that the analysis is initially performed on a single subset, while the other subsets are retained for subsequent use in confirming and validating the initial analysis.

Preservation of cells, tissues, organs, or embryos by storage at low temperatures.

A substance that is used to protect from the effects of freezing, largely by preventing large ice crystals from forming.

Elimination, especially by blotting out, cutting out, or erasing.

Enzymes that catalyze the hydrolytic cleavage of phosphodiester bond linkages in the DNA backbone. Deoxyribonucleases belong to a larger family of nucleases, which cleave DNA bases at various positions in the DNA backbone.

A nucleotide comprised of either a purine or pyrimidine nitrogenous base bound to a deoxyribose sugar esterified with three phosphate groups. These molecules are essential for DNA synthesis.

The proportion of all the observations that have been classified correctly by the diagnostic procedures in given population, or using some diagnostic test, or by some medical institution or professional.

The probability that a test will produce a true negative result when used on non-effected subjects as compared to a reference or "gold standard". The specificity of a test can be determined by calculating: number of true negative results divided by the sum of true negative results plus number of false positive results.

A DNA sequencing technique in which a mixture of deoxynucleosidetriphosphates (dNTPs) and chain-terminating dNTPs, which are radioactively or fluorescently labeled, are combined within the reaction mixture. Once the reaction is complete, the DNA strands are separated by size, and the labeled chain terminating dNTPs can be read in sequence by the investigator or by a machine.

A PCR format that partitions each sample into thousands of sub-reactions and calls each partition positive or negative, giving absolute quantification without a standard curve. Useful for low-level targets, copy-number work, and reference material characterization; throughput and per-test cost differ from qPCR.

A type of polymerase chain reaction technique in which the sample is fractionated, within which individual PCR reactions occur in each fraction.

Any liquid or solid material used to lessen the strength or flavor of a solution or mixture of another ingredient.

To reduce in strength or concentration, especially by the addition of water.

A long linear double-stranded polymer formed from nucleotides attached to a deoxyribose backbone and found in the nucleus of a cell; associated with the transmission of genetic information.

Drug-, radiation-induced, or spontaneous injuries to DNA that introduce deviations from its normal double-helical conformation. These changes include structural distortions that interfere with replication and transcription, as well as point mutations that disrupt base pairs and exert damaging effects on future generations through changes in DNA sequence. If the damage is minor, it can often be repaired (DNA repair); extensive damage can induce apoptosis.

Any method that extracts and purifies DNA from biological samples, which can include the proper handling of biological samples prior to nucleic acid isolation, the separation of DNA from the rest of the components in the samples, and the storage of the DNA isolates.

A family of enzymes that catalyze the formation of phosphodiester bonds to repair broken strands of DNA.

Enzymatic restoration of DNA structure after chemical, radiation, or spontaneous damage.

An RNA complex consisting of two complementary base-paired strands of RNA.

The largest difference between, or ratio of, an instrument's or method's highest and lowest value in a set, such as pixel (voxel) values in an image.

A WHO procedure that time-limits the listing of diagnostics (and other health products) for use in public-health emergencies when full prequalification is not yet available.

A 50-150bp DNA sequence that increases the rate of transcription of coding sequences. It may be located at various distances and in either orientation upstream from, downstream from or within a structural gene. When bound by a specific transcription factor it increases the levels of expression of the gene, but is not sufficient alone to cause expression. Distinguished from a promoter, that is alone sufficient to cause expression of the gene when bound.

Changes in the regulation of the expression of gene activity without alteration of genetic structure.

The complete set of epigenetic modifications on the genome of a cell.

The simplest form of an antigenic determinant, on a complex antigenic molecule, which can combine with antibody or T cell receptor.

The sequences of a gene that are present in the final, mature, spliced messenger RNA molecule from that gene.

An Exonuclease is a hydrolase (nuclease) that specifically catalyzes the hydrolysis of terminal phosphodiester bonds of deoxyribonucleotide or ribonucleotide chains, releasing mononucleotides.

A statistical method used for multiple testing corrections to control the expected proportion of false positives (Type I error) among rejected tests or hypotheses. It is less stringent than other multiple testing corrections and thereby, will allow a percentage of false positives.

A test result that shows no evidence of a result or condition although it is present.

Problem associated with the device incorrectly reporting that something has not been detected and may mislead the operator into not taking certain actions when action should be taken.

A test result that shows evidence of a result or condition although it is not actually present.

Problem associated with the device incorrectly reporting that something has been detected and may mislead the operator to take certain actions.

A text-based format for storing a biological sequence that encodes the nucleotide calls as well as their quality scores. It is an extension of the FASTA format.

A US pathway in which a device maker demonstrates substantial equivalence to a legally marketed predicate. For IVD test kits, 510(k) clearance documents intended use and analytical/clinical support; it is distinct from CLIA waiver, which concerns point-of-care operation settings.

The chemical preservation of a substance to maintain structural and/or molecular features of that substance as they exist in the living entity.

A compound that preserves tissues and cells for microscopic study.

Fluorescence is a luminescence (i.e., optical phenomenon) in cold bodies, in which a molecule absorbs a high-energy photon, and re-emits it as a lower-energy (longer-wavelength) photon. The energy difference between the absorbed and emitted photons ends up as molecular vibrations (heat).

A class of dyes when excited by light of certain wavelengths, emit photons and become fluorescent. Fluorescence gives fluorochromes imaging characteristics and are used to label or stain biological structures.

Refers to a process where a sample is preserved with formalin and then embedded into a paraffin block for sectioning.

A mutation occurring within the protein-coding region of a gene which results in a shift in the reading frame of the encoded protein. Frameshift mutations often result in the premature truncation of a gene product.

Tissue that is not frozen or embedded in preservatives

A tissue sample that has been frozen prior to analysis.

Any DNA sequence rearrangement that results in the gain of one or more copies of a DNA segment that contains at least one gene.

A deletion that results in the loss of a DNA segment encompassing an entire gene sequence.

Typically involves transcription of genetically encoded information into an intermediary message (messenger RNA) and subsequent translation into a functional protein.

Any hybrid gene formed from two previously separate genes. Such fusions occur as a result of translocation, intersititial deletion or chromosomal inversion, and often result in gene products with functions different from the two fusion partners. Gene fusions are associated frequently with hematological cancers, sarcomas and prostate cancer.

Genetic Variation consists of deviation(s) in the nucleotide sequence of the genetic material of an individual from that typical of the group to which the individual belongs, or deviation(s) in the nucleotide sequence of the genetic material of offspring from that of its parents.

The complete genomic content of an organism, and possibly the full DNA sequence of that organism. It is contained in a set of chromosomes in eukaryotes, a single chromosome in bacteria, or a DNA or RNA molecule in viruses.

The determination of the DNA sequence of an individual.

The n-th root of the multiple products of n values, as contrasted with the normally understood arithmetic mean.

Any mutation that appears in the gametes and which will therefore be transmitted to the progeny with some frequency.

The covalent chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, by glycosyl transferases.

A way of denoting the collective genotype of a number of closely linked loci on a chromosome.

Disruption of the integrity of the erythrocyte membrane causing release of hemoglobin.

Having two different allelic forms of a gene, one inherited from each parent, on each of the two homologous chromosomes.

Placeholder definition before migration.

Major protein component of chromatin. Highly conserved basic proteins, originally classified into classes based on the relative amounts of arginine and lysine in each protein. The various classes are now termed H1, H2A, H2B, H3, and H4. In chromatin, they are found in an octamer, containing two each of H2A, H2B, H3, and H4, complexed with DNA in nucleosomes. The histones in the octamer complex are also known as the core histones. The H1 class of histones, termed the linker histones, is loosely associated with the nucleosome.

The process of exchange of genetic material between autonomous replicons, which depends on regions of extensive sequence homology between the participating DNA strands. This process involves double-strand breakage of one participant, resection of the break, and strand invasion, followed by formation, displacement and resolution of the Holliday junction. This process is involved in repairing broken DNA and creating combinations of genes that may be unique from the parent duplexes. Disruptions in this process can result in inviability, premature aging and predisposition to cancers and degenerative diseases.

Having two identical allelic forms of a gene, one inherited from each parent, on each of the two homologous chromosomes.

The X or Y chromosome in human beings that determines the sex of an individual. Females have two X chromosomes in diploid cells; males have an X and a Y chromosome. The sex chromosomes comprise the 23rd chromosome pair in a human karyotype.

The relative frequency of occurrence of something.

Validation evidence that an assay detects the range of variants, genotypes, or serotypes it claims to cover. For evolving targets such as influenza or SARS-CoV-2, inclusivity statements carry a validation date and should be checked against circulating variant lists at procurement time.

A mutation class that includes insertion mutations, deletion mutations and mutation events where both an insertion and a deletion has occurred.

The act of hindering or obstructing or impeding.

A non-target amplification built into a reaction to prove the assay chemistry worked even when the sample is negative. It helps distinguish a true negative from inhibition or setup failure, which matters when interpreting single-target assays on difficult matrices.

The difference between the 3rd and 1st quartiles is called the interquartile range and it is used as a measure of variability (dispersion).

Non-coding, intervening sequences of DNA that are transcribed, but are removed from within the primary gene transcript and rapidly degraded during maturation of messenger RNA.

The act of turning inside out, upside down, or end-for-end.

A reagent, reagent product, calibrator, control material, kit, instrument, apparatus, piece of equipment, software or system, whether used alone or in combination, intended by the manufacturer to be used in vitro for the examination of specimens, including blood and tissue donations, derived from the human body, solely or principally for the purpose of providing information to aid towards a diagnosis.

EU Regulation 2017/746 governing in vitro diagnostics, which replaced the IVDD with stricter evidence, post-market surveillance, and reclassification rules. Products legacy-listed under the IVDD may still carry transitional timelines, so registration status should be verified per product and per market.

The weighted concentration of ions in solutions.

The international quality-management standard for medical device manufacturing. Certification does not certify individual products, but suppliers with ISO 13485-registered production generally support tender documentation more reliably.

An isomer of propyl alcohol with antibacterial properties. Although the exact mechanism of isopropanol's disinfecting action is not known, it might kill cells by denaturing cell proteins and DNA, interfering with cellular metabolism, and dissolving cell lipo-protein membranes. Isopropanol is used in soaps and lotions as an antiseptic.

The chromosomal morphology and number in somatic cells of an individual.

A nonparametric test for finding if three or more independent samples come from populations having the same distribution. It is a nonparametric version of ANOVA.

Major class of enzymes that catalyze the linking together of two molecules (EC class 6) for example DNA ligases that link two fragments of DNA by forming a phosphodiester bond.

The lowest concentration of an analyte that can be quantified with acceptable accuracy and precision under stated conditions — distinct from, and higher than, the limit of detection.

A molecule of RNA 200-17000 nucleotides in length that is transcribed by non-protein coding areas of DNA. These ribonucleotides may play a role in a variety of biological processes.

The formula to calculate body surface area as described by John D. Current. It is mathematically defined as: BSA (m^2) = 1321 + 0.3433 x Weight(g)

A genetic variation where gain, loss, or exchange of DNA results in monoallelic loss of function mutations in a diploid cell. In the context of tumor suppressor genes, where a single copy is sufficient for functionality, loss of function for the second allele is associated with tumorigenesis.

A purification method in which nucleic acids bind to paramagnetic beads and are collected with a magnet through wash steps. It automates well, which is why most high-throughput extraction platforms are bead-based; compare deck footprint and sample capacity when shortlisting systems.

The value which has an equal number of values greater and less than it.

Any physical object that is useful for prevention, diagnosis, monitoring, or treatment of disease or other conditions.

A class of RNA molecule containing protein-coding information in its nucleotide sequence that can be translated into the amino acid sequence of a protein.

The quantity and identity of all of the low molecular weight molecules in a biological entity or sample that are products of or participants in various metabolic processes.

Metabolomics is the study of the biological metabolic profile of a cellular specimen in a specific environment at an isolated timepoint. This discipline depicts the physiological states of cells and organisms by focusing on carbohydrates, lipids, and other metabolites. Several analytical techniques are utilized to quantify the metabolic content of specimens such as mass spectrometry and electrophoretic applications.

The covalent chemical or biochemical addition of a methyl group(s) to a compound. (NCI)

A sequence of single-stranded RNA, that is 20-25 nucleotides in length, which is transcribed from DNA but is not translated into a protein. This nucleic acid may regulate the transcription or translation of other genes.

Genomic instability associated with the presence of hypermutability in specific genetic marker regions resulting from defective DNA mismatch repair.

A variety of simple di-, tri-, tetra-, and pentanucleotide tandem repeats that are dispersed in the euchromatic arms of most chromosomes.

The mismatch repair (MMR) system promotes genomic fidelity by repairing base-base mismatches, insertion-deletion loops and heterologies generated during DNA replication and recombination. This function is critically dependent on the assembly of multimeric complexes involved in mismatch recognition and signal transduction to downstream repair events.

A point mutation occurring within the protein-coding region of a gene, and which codes for a different amino acid than expected.

Required or expected data that is not present, which may be due to non-completion or corruption.

Amplification of several targets in a single reaction using multiple primer pairs, each distinguishable by fluorescent channel or melting profile. Multiplexing raises information per sample but makes channel allocation, dye compatibility, and competition between targets key selection criteria.

Any transmissible change in the genetic material of an organism, which can result from radiation, viral infection, transposition, treatment with mutagenic chemicals and errors during DNA replication or meiosis. The effects of mutation range from single base changes to loss or gain of complete chromosomes. As many of the simpler alterations to DNA may be repaired, such changes are only heritable once the change is fixed in the DNA by the process of replication. Mutations may be associated with genetic diversity or with pathologies including cancer.

A control sample where a negative result is expected, to help correlate a positive result with the variable being tested.

A test result that indicates that a specific disease, condition, or attribute being assessed is not present.

Polymerase chain reaction that uses two sets of primers, in two sequential runs of amplification, with the second set intended to amplify a target within the first run product.

Technologies that facilitate the rapid determination of the nucleotide sequence of large numbers of strands or segments of DNA or RNA.

Any part of a signal that is not the true or original signal but is introduced by the communication mechanism.

In statistical inference procedures (hypothesis tests and confidence intervals), nonparametric procedures are those that are relatively free of assumptions about population parameters.

A point mutation occurring within the protein-coding region of a gene, and which codes for a stop that can truncate the protein.

A family of probability density functions whose mean, median and mode are identical. The function generates a symmetrical curve, whose position and shape is determined by its location and scale parameters, the mean and standard deviation respectively. The standard normal distribution has a location parameter of 0 and a scale parameter of 1.

A reaction that contains all reagents except sample nucleic acid. Amplification in the NTC signals contamination of reagents or the environment, so NTC behavior is one of the first run-validity checks in any qPCR run log.

An organisation designated by an EU member state to assess the conformity of products — including in vitro diagnostics — against applicable regulations before CE marking can be affixed.

Any of various amplification and detection strategies applied to detection of virus contamination in donor blood. Specifically designed to detect recently infected individuals during the latency period before seroconversion.

The sample-preparation stage that lyses cells or virions and purifies DNA/RNA before amplification. Extraction quality (yield, purity, inhibitors removed) often limits assay performance more than the PCR itself, and it defines required instruments and hands-on time in a workflow.

Laboratory procedure in which single stranded nucleic acids are allowed to interact so that complexes, or hybrids, are formed by molecules with sufficiently similar, complementary sequences. By this means the degree of sequence identity can be assessed and specific sequences detected. (From Biology-online)

A subunit of DNA or RNA consisting of a nitrogenous base (adenine, guanine, thymine, or cytosine in DNA; adenine, guanine, uracil, or cytosine in RNA), a phosphate molecule, and a sugar molecule (deoxyribose in DNA and ribose in RNA).

Nucleotide Excision Repair (NER) mends DNA regions that contain chemical adducts, such as UV-induced thymine dimers or carcinogenic adducts, which distort the DNA helix and interfere with replication and transcription. NER is targeted to actively transcribed regions of the genome. During NER in eukaryotes, shape irregularities are detected by protein complexes that slide along the DNA molecule and induce cuts on each side of a lesion several nucleotides away. Removal of the damaged 25-30 nucleotide fragment is followed by repair synthesis and ligation.

A statistical method to test if observations are significant or due to chance. It proposes that no statistical significance exists in a set of given observations and attempts to show that no variation exists between variables or that a single variable is no different than its mean. It is presumed to be true until statistical evidence nullifies it for an alternative hypothesis.

The ratio of the odds of an event occurring in one group to the odds of it occurring in another group, or to a sample-based estimate of that ratio.

A DNA polymer made up of a small number of nucleotides.

Short DNA oligonucleotide chains used to prime DNA (and in some cases RNA) synthesis.

A sequence of nucleotides in that contains no termination codons and so can potentially translate as a polypeptide chain.

The concentration of osmoles of solute per kilogram of solvent present in a sample.

An observation in a data set that is numerically distant from the rest of the data.

A method used to test whether the mean difference between pairs of measurements in a related group are significant.

In statistical inference procedures (hypothesis tests and confidence intervals), parametric procedures are those that incorporate assumptions about population parameters.

How close amplification is to ideal doubling each cycle, reported as a percentage or derived from the standard curve slope. Efficiency near 90–110% with a linear standard curve supports quantification claims; it is a standard checklist item when auditing assay validation dossiers.

A measure of the correlation of two variables X and Y measured on the same object or organism, that is, a measure of the tendency of the variables to increase or decrease together. It is defined as the sum of the products of the standard scores of the two measures divided by the degrees of freedom.

Any of the 99 numbered points that divide an ordered set of scores into 100 parts each of which contains one-hundredth of the total.

Quantity of dimension one used to express on a scale from 0 to 14 the amount-of-substance concentration of hydrogen ion of dilute aqueous solution, calculated as the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter.

The assemblage of traits or outward appearance of an individual. It is the product of interactions between genes and between genes and the environment.

A score reported on a logarithmic scale representing the probability that a nucleotide base was incorrectly called by the base caller.

A small-scale mutation in which a single nucleotide is exchanged for another. Mutagenic chemicals and mistakes in DNA replication may result in point mutations.

A distribution function used to describe the occurrence of rare events or to describe the sampling distribution of isolated counts in a continuum of time or space. This special probability distribution can apply to the number of discrete independent random events occurring in a given interval when knowing their average rate of occurrence over a very long interval.

Encoded by Polymerase Genes, Polymerase enzymes catalyze polymerization reactions, especially of nucleotides to polynucleotides. (NCI)

A control sample that is known to produce a positive result if the test is working as expected.

The enzymatic processing of a polypeptide chain after translation from messenger RNA and after peptide bond formation has occurred. Examples include glycosylation, acylation, limited proteolysis, phosphorylation, isoprenylation.

A quantitative representation of the degree of accuracy necessary for or associated with a particular action.

An expression of the likelihood that a given test result correlates with the presence or absence of disease.

Chemicals that are added to drug products to prolong shelf life and maintain sterility. Protection of formulations, especially aqueous solutions, against microbial growth requires use of either antibacterial or antifungal preservatives. Generally, such agents are active against either bacteria or fungi but a few are active against both. The antimicrobials include but not limited to chlorobutanol, benzyl alcohol, sodium benzoate, sorbic acid, and phenol. The antioxidizing agents include butylated hydroxytoluene, hydroxyanisole, propyl gallate, and sulfites. The necessary addition of preservatives for both safety and economy sometimes has been associated with significant adverse effects in certain patient populations.

The ratio (for a given time period) of the number of occurrences of a disease or event to the number of units at risk in the population.

General term for a piece of DNA or RNA corresponding to a gene or sequence of interest, that has been labelled either radioactively or with some other detectable molecule, such as biotin, digoxygenin or fluorescein. As stretches of DNA or RNA with complementary sequences will hybridize, a probe will label viral plaques, bacterial colonies or bands on a gel that contain the gene of interest.

A program for the determination of laboratory performance where individual labs perform the same test on the same or similar items or materials, with the results from each lab compared and evaluated.

A DNA sequence at which RNA polymerase binds and initiates transcription.

A type of study in which participants are enrolled into the study before they develop the disease or outcome in question.

An enzymatic pre-treatment in nucleic-acid extraction that degrades proteins and nucleases, releasing nucleic acids from clinical material before binding, wash, and elution steps.

Refers to the total protein-encoding capability of an organism's genome. It is also used to refer to the actual total expressed protein complement of an organism or to the identifiable proteins of a single tissue or cell type or subcellular compartment.

The global analysis of cellular proteins. Proteomics uses a combination of sophisticated techniques including two-dimensional (2D) gel electrophoresis, image analysis, mass spectrometry, amino acid sequencing, and bio-informatics to resolve comprehensively, to quantify, and to characterize proteins. The application of proteomics provides major opportunities to elucidate disease mechanisms and to identify new diagnostic markers and therapeutic targets.

Nonfunctional DNA sequences that are very similar to the sequences of known genes. Many seem to have arisen as functional gene duplications that subsequently underwent mutation and loss of function. Others are structurally similar to mRNA and seem to have arisen by a reverse transcription event followed by integration into the genome. Some pseudogenes are transcribed and may play a role in regulation of its homologous gene.

A measure of the probability that a result happened by chance. The lower the p-value, the more likely it is that the result was caused by phenomenon of interest.

Programs of regular assessment of medical and nursing activities to evaluate the quality of medical care including all actions taken to ensure that standards and procedures are adhered to and that delivered products or services meet performance requirements.

Set of measurements and inspections taken to verify that performance of equipment and procedures remains within specified limits.

Any of four equal-sized sets of observations in a ranked sample.

The minimum False Discovery Rate (FDR) value required for a test to be considered significant.

A study in which the participants are assigned by chance to separate groups to evaluate treatments. The study also includes a control group, which is undergoing the same rigors of the study with placebo treatment or standard treatment. The trial can also be controlled by the addition of a test group to ensure there are no factors present to skew the results and by the inclusion of peer-review analysis by appropriate government officials. 2005

The difference between the lowest and highest numerical values; the limits or scale of variation.

The number of times a particular locus (site, nucleotide, amplicon, region) was sequenced.

One of the three possible ways of reading a nucleotide sequence. As the genetic code is read in nonoverlapping triplets (codons) there are three possible ways of translating a sequence of nucleotides into a protein, each with a different starting point.

The number of nucleotides successfully ordered from each side of a nucleic acid fragment obtained after the completion of a sequencing process.

Any natural or synthetic substance used in a chemical or biological reaction in order to produce, identify, or measure another substance.

An application of PCR that measures the products generated during each cycle of the polymerase chain reaction process in order to determine the starting amount of template in the reaction.

A PCR method that measures amplification as it happens using fluorescent reporters, so target quantity is estimated from the amplification curve rather than by post-run handling. qPCR is the workhorse format for viral load, pathogen detection, and GMO or food testing workflows.

A set of values of particular type of measurement that is used to interpret corresponding observation results.

Complementary precision measures: repeatability is variation under the same conditions (same operator, equipment, short interval); reproducibility is variation across conditions — different days, operators, lots, or laboratories.

The ability to yield similar results given a set of constraints.

Enzymes that exhibit endonuclease activity at a specific short nucleotide sequence to cleave strands of DNA.

A sequence in DNA that can be recognized by a specific restriction enzyme.

A study in which participants with known outcomes are assessed based on data collected before the study.

An RNA-dependent DNA polymerase that is involved in the replication of retroviruses an in the maintenance of telomeres.

A two-step setup in which RNA is first copied into complementary DNA by a reverse transcriptase and then amplified by PCR. Used for RNA viruses such as influenza, RSV, SARS-CoV-2, and HCV. In procurement documents, confirm whether "RT-PCR" refers to real-time (quantitative) or endpoint (qualitative) reading.

The action of copying RNA into DNA by reverse transcriptase.

Ribonuclease inhibitor (461 aa, ~50 kDa) is encoded by the human RNH1 gene. This protein plays a role in the inhibition of ribonucleases.

Single-stranded long chain of nucleotides containing ribose. It is the end product of DNA transcription by the enzyme RNA polymerase. It is essential in protein synthesis.

An RNA molecule that does not contain protein-coding sequence information and constitutes the majority of the cellular RNA (~80%). This nucleic acid associates with multiple proteins to form ribosomes, which are the organelles that drive mRNA-directed protein synthesis.

Removal of introns from mRNA precursors and the reattachment or annealing of exons.

The goodness of fit statistic for the terminal elimination phase.

Impregnation of one substance by another to the greatest possible extent; that concentration of a dissolved substance that cannot be exceeded.

The act or process of settling particles by mechanical means from a state of suspension in air or water.

Bias encountered due to enrolling study participants that do not reflect the intended target population.

The ability to respond to physical stimuli or to register small physical amounts or differences.

A collection of double stranded DNA fragments flanked by oligonucleotide sequence adapters to enable their analysis by high-throughput sequencing.

Area of repetitive DNA within the genome consisting of multiple, end-to-end copies of a short DNA sequence usually comprised of di-, tri-, or tetranucleotide repeat units.

A detectable physical quantity or impulse (e.g., voltage, current, or magnetic field strength).

The ratio of a measure of useful information from a system to that of a measure of interfering unwanted, often random, information that is also present.

A point mutation occurring within the protein-coding region of a gene, and which codes for the same amino acid as expected.

A purification method that binds nucleic acids to a silica membrane in a spin column through centrifugation or vacuum. It is a common manual and mid-throughput format with well-understood consumable logistics, but is less automation-friendly than magnetic bead approaches.

A natural compound of silicon and oxygen found mostly in sand, Silica has three main crystalline varieties: quartz, tridymite, and cristobalite. Fine particulate silica dust from quartz rock causes over a long-term progressive lung injury, silicosis. (NCI04)

A variation of a single nucleotide at a specific location of the genome due to base substitution, present at an appreciable frequency between individuals of a single interbreeding population.

A variation of a single nucleotide at a specific location of the genome due to base substitution, which is found at any frequency in the population.

A long linear single-stranded polymer formed from nucleotides attached to a deoxyribose backbone.

A 20 to 25-nucleotide double-stranded RNA which is involved in a sequence-specific messenger RNA degradation process known as RNA interference.

The ability of a particular substance to dissolve in a particular solvent (yielding a saturated solution).

A liquid that dissolves or that is capable of dissolving; the component of a solution that is present in greater amount.

Any mutation with an origin in cells that are not destined to become gametes. As a consequence, such mutations are not transmitted to progeny, though they will be transmitted during any mitosis within the individual. Somatic mutations may contribute to a broad variety of pathologies including cancer.

A part of a thing, or of several things, taken to demonstrate or to determine the character of the whole, e.g. a substance, or portion of material obtained for use in testing, examination, or study; particularly, a preparation of tissue or bodily fluid taken for examination or diagnosis.

Any mutation that occurs within the discrete sequences comprising the 5' or 3' splice sites of a gene that has a spliced message. Splice-site mutation may result in a deletion or insertion of extraneous amino acids in the gene product or a change in the reading frame of the spliced message.

A measure of the range of values in a set of numbers. Standard deviation is a statistic used as a measure of the dispersion or variation in a distribution, equal to the square root of the arithmetic mean of the squares of the deviations from the arithmetic mean.

The standard deviations of the sample in a frequency distribution, obtained by dividing the standard deviation by the square root of the total number of cases in the frequency distribution.

An established procedure to be followed in carrying out a given operation or in a given situation.

The substitution of some value for a missing data point or a missing component of a data point.

A measure of the likelihood that a significance test will detect an effect or difference in a sample if the effect or difference exists in the entire population from which that sample was taken.

A test used to determine the statistical significance of an observation.

The liquid lying above a liquid, solid or semi-solid residue, which is separated by crystallization, precipitation or centrifugation of a biological sample.

A stretch of repetitive nucleotide sequences (TTAGGG repeats in humans) found at both ends of each chromatid arm that plays a role in chromosome stability during replication.

The lowest limit at which something becomes detectable or relevant.

A genetic process in which single-stranded RNA with base sequence complementary to a region of plus strand DNA is synthesized by DNA-dependent RNA polymerases. Following the binding of RNA polymerase on DNA promoter regions, the RNA product is synthesized in a 5' to 3' direction, elongating RNA along the DNA strand as the polymerase proceeds, accompanied by unwinding and rewinding of the DNA template.

The complete set of RNA transcripts that are produced by the genome, under specific circumstances or in a specific cell.

A class of short adaptor RNAs that transfers a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. Each transfer RNA comprises a three-nucleotide sequence that is complementary to the triplet nucleotide coding sequence of an mRNA, conferring specificity to the amino acid being incorporated into the assembling protein.

The act or process of rendering from one language into another.

The movement of a physical object from one place to another. (NCI)

A relatively less common point mutation in which a purine is exchanged for a pyrimidine or a pyrimidine is exchanged for a purine.

A method for converting an individual score into a standard form. While similar to a z-score, t-score is used when the conversion is made without knowledge of the population standard deviation and mean.

A statistical hypothesis test that controls directional errors if rejection of a hypothesis is the result of a directional decision. The two-sided test has less statistical power than the one-sided test.

Ubiquitin is a family of widely distributed proteins found in all eukaryotes that contain a highly conserved sequence of 76 amino acids identical in organisms from humans to insects. It participates in diverse cellular functions by conjugation to other proteins through its carboxy terminus. Ubiquitination is associated with many highly regulated biological events including protein degradation, chromatin remodelling, heat shock, cell cycle progression, differentiation, antigen presentation, retrovirus assembly, apoptosis, signal transduction, transcriptional activation, biological clocks, receptor down regulation, and endocytosis. Protein ubiquitination regulates the half-lives of many proteins by targeting them for degradation. Newly discovered families of ubiquitination and deubiquitination enzymes participate in these processes. Ubiquitination enzymes may provide new therapeutic targets and ways of intervention in many human diseases.

Short random nucleotide sequences that are ligated to each primer molecule during amplification of a nucleotide sample during library preparation to act as a unique tag. Their use helps to identify PCR duplicates in sequencing data.

The product of so-called RNA genes; a functional RNA represents the final product of a gene rather than a transient molecule that will be translated into protein.

The act of validating; finding or testing the truth of something.

A measure of the variability in a sample or population. It is calculated as the mean squared deviation (MSD) of the individual values from their common mean. In calculating the MSD, the divisor n is commonly used for a population variance and the divisor n-1 for a sample variance.

The relative rate of occurrence of a specific variant allele compared to the total number of alleles at that locus in the sample. This measurement may be reported as a ratio or percentage.

An alteration or difference from a norm or standard.

A procedure that can determine the DNA sequence for nearly the entire genome of an individual.

A WHO assessment that confirms a diagnostic meets quality, safety, and performance requirements for procurement by UN agencies and many national programs. WHO PQ status is frequently a tender eligibility criterion for public-health deployment in low- and middle-income countries.

A method for converting an individual score into a standard form. The z-score indicates how far and in what direction an item deviates from its distribution's mean, expressed in units of standard deviation. Calculation of a z-score requires knowledge about the population's standard deviation and mean.