Patau syndrome, like Down syndrome, is a trisomy disorder. It is caused by the presence of a whole extra copy (or occasionally partial extra copy) of chromosome 13.
Occurrence in live births is about 1 in 9,500 (in the absence of any prenatal detection programme), and rises with increasing maternal age.
Patau syndrome is associated with a high rate of spontaneous loss of pregnancy (64% loss rate from 2nd trimester onwards) and very poor chances of survival in neonates (median survival is 10 days).
Clinical manifestations involve severe bodily deformities and mental retardation.
Prenatal diagnosis and appropriate counselling is available.