Trisomy 13

 Trisomy 13 is a genetic condition where the indiviual inhereits an extra copy of chromosome 13. It is also known as patau syndrome and affects around 1 in every 10,000 births.  Over 80% of babies born with the condition will die before their first birthday.

The extra genetic material leads to many develeopmental problems. Symptoms can include: cleft lip and palate, seizures, congenital heart disease, decreased muscle tone, severe intellectual disability, low set ears and extra fingers or toes. 

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002625/