Loading
Search products, companies, tests, and guides — go from query to quote request in one place.
Glossary Term
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).
Glossary Term
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.
Tests
A blood test done near the end of the first trimester of pregnancy to screen for common chromosomal defects. This test screens for blood levels of both free beta-human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein A (PAPP-A) and can detect trisomies of chromosomes 21 (Down's syndrome), chromosome 18 (Edward's syndrome), and chromosome 13 (Patau's syndrome).
Glossary Term
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.
Glossary Term
A way of denoting the collective genotype of a number of closely linked loci on a chromosome.
Glossary Term
Having two different allelic forms of a gene, one inherited from each parent, on each of the two homologous chromosomes.
Glossary Term
Having two identical allelic forms of a gene, one inherited from each parent, on each of the two homologous chromosomes.
Tests
A karyotype test is a type of genetic testing . It looks at the size, shape, and number of chromosomes in a sample of cells from your body. Chromosomes are tiny "packages" in your cells that contain your genes . Genes carry information, called DNA , that controls what you look like and how your body works.
Glossary Term
A variety of simple di-, tri-, tetra-, and pentanucleotide tandem repeats that are dispersed in the euchromatic arms of most chromosomes.
Glossary Term
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.
Tests
Prenatal cell-free DNA (cfDNA) screening is a blood test given during pregnancy . During pregnancy, some of the fetus's DNA circulates in the mother's bloodstream. A cfDNA screening checks this DNA to find out if the baby is more likely to have certain conditions caused by an abnormal number of chromosomes , such as Down syndrome .
Glossary Term
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.
