[3] Of those fetuses that do survive to gestation and birth, common abnormalities may include:[citation needed] Trisomy 13 is the cause of Patau syndrome, which means each cell in the body has three copies of chromosome 13 instead of the usual two.

[citation needed] Most cases of Patau syndrome are not inherited but occur as random events during the formation of reproductive cells (eggs and sperm).

Although they do not have signs of Patau syndrome, people who carry this type of balanced translocation are at an increased risk of having children with the condition.

[citation needed] Unless one of the parents is a carrier of a translocation, the chances of a couple having another trisomy 13 affected child is less than 1%, below that of Down syndrome.

[citation needed] Diagnosis is usually based on clinical findings, although fetal chromosome testing will show trisomy 13.

Many infants have difficulty surviving the first few days or weeks due to severe neurological problems or complex heart defects.

Physical, occupational, and speech therapy will help individuals with Patau syndrome reach their full developmental potential.

[10] Trisomy 13 was first observed by Thomas Bartholin in 1657,[11][12] but the chromosomal nature of the disease was ascertained by Dr. Klaus Patau and Dr. Eeva Therman in 1960.