trisomy 13
a syndrome involving an extra chromosome 13, resulting in the birth of an infant with a variety of problems, including severe intellectual disability; cleft lip and palate; polydactyly (extra fingers or toes); cerebral anomalies; and ocular abnormalities, such as missing or very small eyes, cataracts, and defects in the iris. Many infants with the syndrome die within their first days or weeks of life, and less than 20% of children with this condition live past their first year. Also called D trisomy syndrome; Patau syndrome.