Patau

Patau syndrome, also known as trisomy 13, is a genetic disorder caused by the presence of an extra copy of chromosome 13 in most or all of the body's cells. The condition is named after Klaus Patau, who described it in the 1960s. It is a rare anomaly, occurring in about 1 in 12,000 to 1 in 20,000 live births, and affects people of all sexes and ethnic backgrounds. Most cases arise from nondisjunction during gamete formation; less commonly, mosaic trisomy 13 or a parental balanced translocation can occur, which has implications for recurrence risk.

Clinical features of Patau syndrome are diverse and severe, reflecting widespread developmental disruption. Common findings include holoprosencephaly (failure of the forebrain to divide properly), midline facial defects such as cleft lip/palate, microphthalmia or anophthalmia, and abnormal ear formation. Other frequent anomalies include polydactyly (extra fingers or toes), congenital heart defects, renal and genital abnormalities, and growth restriction. Intellectual disability is usually profound, and many infants have limited developmental progress.

Diagnosis is typically based on genetic testing. Prenatal diagnosis can be suggested by ultrasound findings and noninvasive prenatal testing, with confirmation by karyotyping or chromosomal microarray from fetal samples obtained through amniocentesis or chorionic villus sampling. Postnatally, a blood karyotype confirms trisomy 13.

Prognosis for Patau syndrome is generally poor. Most affected newborns die within the first year of life, though a small number survive longer with intensive multidisciplinary care. There is no cure, and management focuses on supportive, palliative, and specialized interventions for individual anomalies, along with genetic counseling to discuss recurrence risks, which are typically low for de novo cases but depend on the specific genetic mechanism present.