What genetic change causes Trisomy 13?
People with trisomy 13 have an extra copy of chromosome 13. Humans are expected to have 46 chromosomes (23 pairs) in every cell in their body. They are labelled with numbers (chromosome 1, chromosome 2, chromosome 3, etc.) Humans generally have two copies of every chromosome, including chromosome 13. Chromosomes are made up of genes. Duplicating or deleting genes can cause health problems. People with trisomy 13 have three copies of chromosome 13, and have an extra set of all the genes located on this specific chromosome. Having a whole extra chromosome means there are a lot of genes with the wrong dosage (three copies instead of two copies). The extra genetic material typically leads to serious health problems.
Adv Clin Exp Med. 2015 Sep-Oct;24(5):911-21. doi: 10.17219/acem/26324.Medical and Ethical Considerations Related to Viable Fetuses with Trisomy 13 in the 36th Week of Pregnancy--a Review of the Literature.