trisomy syndrome

trisomy syndrome,

any condition caused by the addition of an extra member to a normal pair of homologous autosomes or to the sex chromosomes or by the translocation of a part of one chromosome to another. Most trisomies occur as a result of complete or partial nondisjunction of the chromosomes during cell division. The more severe conditions are related to trisomies of the autosomes rather than the sex chromosomes. The most common trisomy syndromes with clearly established clinical manifestations are trisomy 8, trisomy 13, trisomy 18, trisomy 21, and trisomy 22. See also trisomy.

---

trisomy (trī´smē),

n an additional chromosome in the normal complement, so that in each nucleus a chromosome is represented three times rather than twice.

trisomy B,

n (trisomy 13-15, Patau's syndrome) Clinical syndrome associated with an autosomal abnormality in which the extra chromosome occurs in the 13 to 15 group. Numerous anatomic defects are present, including hemangiomas, hernia, arrhinencephaly, eye anomalies, cleft lip and palate, and characteristic changes in the footprint and palm print.

trisomy syndrome,

n a congenital condition caused by the addition of an extra member to a normal pair of homologous autosomes or to the sex chromosome or by the translocation of a portion of one chromosome to another. Trisomy 21 results in Down syndrome.