Patau Sydrome, also known as Trisomy 13 or Trisomy D is a problem with the chromosomes. People who suffer from it have an extra copy of chromosome 13. This is usually because of a problem that occurred during meiosis, but it can also be the result of Robertsonian translocation, a common rearrangement of chromosomes in humans. The risk of getting a problem during meiosis increases when women have babies later in life. The average age for this syndrome is at 31 years.