13trisomiat

13trisomiat, or trisomy 13 (Patau syndrome), is a chromosomal disorder caused by an extra copy of chromosome 13 in cells. Most cases arise from nondisjunction during gamete formation, resulting in three copies in all or most cells. A minority are mosaic trisomy 13, where only some cells carry the extra chromosome. In rare cases the extra chromosome is attached to another chromosome via a translocation. The condition is usually sporadic; maternal age is a risk factor for nondisjunction.

Clinical features are highly variable but commonly include severe developmental delay and multiple congenital malformations. Classic findings include holoprosencephaly, midline facial anomalies, cleft lip/palate, microcephaly, closely spaced eyes, polydactyly, and scalp defects such as cutis aplasia. Cardiac, brain, kidney, and eye anomalies are common. Feeding difficulties and seizures may occur. Mosaic trisomy 13 can be associated with milder features and longer survival.

Diagnosis: Prenatal testing via chorionic villus sampling or amniocentesis can detect trisomy 13; ultrasound may reveal brain and facial anomalies. Noninvasive prenatal testing can indicate increased risk. After birth, diagnosis is confirmed by karyotype or chromosomal microarray.

Incidence and prognosis: Trisomy 13 occurs in about 1 in 8,000 to 1 in 12,000 live births. Many pregnancies are lost before birth. Among live-born infants, survival is limited; many die within the first days to weeks, and only a minority live beyond the first year.

Management: care is multidisciplinary. There is no cure; treatment focuses on managing complications and supporting families, with decisions about surgical interventions based on quality of life and prognosis. Palliative care is an option for extensive disease.