trisomy 13

trisomy 13

n.

A syndrome characterized by mental retardation and defects to the central nervous system and heart, caused by having three copies of chromosome 13.

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trisomy 13,

a congenital condition caused by the presence of an extra chromosome in the D group, predominantly chromosome 13, although in rare instances chromosome 14 or 15. It occurs in approximately 1 in 5000 births and is characterized by multiple midline anomalies and central nervous system defects, including holoprosencephaly, microcephaly, myelomeningocele, microphthalmos, and cleft lip and palate. There is also severe mental retardation; polydactyly; deafness; convulsions; and abnormalities of the heart, viscera, and genitalia. Most infants with the condition are severely affected and do not survive beyond the first 6 months of life. The symptom combination of cleft lip and palate, polydactylism, and microcephaly is sometimes identified as the triad. Also called Patau's syndrome, trisomy D syndrome, trisomy 13-15.

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trisomy 13

Patau syndrome, D₁ trisomy syndrome Genetics A congenital defect due to an extra copy of chromosome 13 Clinical Findings in ≥ 50% of Pts: Holoprosencephaly with incomplete development of forebrain and olfactory and optic nerves, accompanied by minor motor seizures, apneic spells, and profound mental defect, microcephaly, deafness, microphthalmia, retinal dysplasia, cleft lip and palate, abnormal helices ± low-set ears, polydactyly, simian crease, pelvic hypoplasia, cardiac defects present in 80% of Pts, including ventricular and/or atrial septal defect, dextroposition of great vessels, cryporchidism, bicornuate uterus, inguinal or umbilical hernias, persistence of embryonic or fetal Hbs Incidence 1:5–15,000 births Prognosis Death usually by age 2