What is Patau Syndrome?

Patau syndrome, also known as 'Trisomy 13,' is a form of genetic disorder in which all or a portion of the person's chromosome thirteen appears three times instead of twice in the cells of their body. In some people who are affected by the syndrome, only a percentage of the cells may contain the extra thirteenth chromosome, referred to as 'mosaicism'. The extra material interferes with the person's regular process of development, which leads to severe intellectual disability and physical abnormalities in a number of parts of their body.
Patau syndrome is considered as the 3rd commonest autosomal trisomy. This along with Down syndrome (T21) and Edward syndrome (T18) which are the only three trisomies to be compatible with extra-uterine life.

Patau syndrome occurs in approximately one out of every ten-thousand to sixteen-thousand infants. Most conditions of Patau Syndrome cannot be inherited. During the formation of the sperm or egg, a problem with cell division can cause an extra chromosome 13 in the cells. This is not the fault of the parent, but rather a random occurrence. Another type of Patau Syndrome can be inherited. Translocation trisomy 13 can happen when an unaffected parent carries a rearrangement of genetic material from chromosome 13 and another chromosome and passes this material on to the child.Due to the presence of a number of life-threatening medical issues, many babies with Patau syndrome die in the first few days or weeks of their lives. Five to ten-percent of children with Patau syndrome live past their first year of life.
2010-02-16 (Rev. 2015-03-26)
http://www.disabled-world.com/disability/types/patau-syndrome.php