What is Trisomy 13?
Trisomy 13 is a chromosomal condition associated with severe intellectual disability and physical abnormalities in many parts of the body. Babies with trisomy 13 often have heart defects, brain or spinal cord abnormalities, very small or poorly developed eyes (microphthalmia), extra fingers or toes, an opening in the lip (a cleft lip) with or without an opening in the roof of the mouth (a cleft palate), and weak muscle tone (hypotonia). Due to the presence of several life-threatening medical problems, many infants with trisomy 13 die within their first days or weeks of life. Only five percent to 10 percent of children with this condition live past their first year.
Babies with trisomy 13 have an extra copy of chromosome 13. Humans typically have 46 chromosomes (23 pairs) in every cell in their body. 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 leads to the serious health problems seen in Trisomy 13.
SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • https://www.thinkgenetic.com/diseases/trisomy-13/overview/9604 • DATE UPDATED: 2016-06-25