What is trisomy 4p?
Trisomy 4p is a rare chromosomal and genetic condition that causes severe mental retardation, distinct facial features, abnormalities of the hands and feet and difficulty breathing.
Chromosomes usually come in pairs. In each pair, one copy comes from the mother and one copy comes from the father. Each pair is numbered 1 through 22 except for the sex chromosomes, which are labeled by “X” and “Y.” Females have two X chromosomes. Males have one X and Y.
Each chromosome has a center or middle section called the centromere. The centromere has two arms coming out of it. There is a long arm and a short arm. The long arm is called the “q” arm. The short arm is called the “p” arm. In trisomy 4p, there is an extra copy of the short "p" arm of chromosome 4 in the body's cells. This is called a "trisomy" because there are three copies instead of the usual two copies of chromosome 4p.
An extra chromosome 4p can cause a range of symptoms, including specific facial features, trouble breathing and eating, abnormal bones, and problems with the hands and feet. Children with trisomy 4p can be born with birth defects, such as problems with the heart, kidney, brain, and genitals. They also have severe intellectual disability and need to be in special classes. Children with trisomy 4p are usually small at birth and stay smaller than other people their age. The symptoms may be more or less severe. This depends on how much of chromosome 4p is added. Usually, having more of the chromosome will result in more serious symptoms.
If you are interested in learning more about trisomy 4p, the UNIQUE support group has a very informative brochure which can be found at Guide to 4p duplications.
SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • https://www.thinkgenetic.com/diseases/trisomy-4p/overview/7582 • DATE UPDATED: 2016-07-04