trisómiát

Trisomy is a type of aneuploidy, which is a condition where there is an abnormal number of chromosomes in a cell. Specifically, trisomy means that there are three copies of a particular chromosome instead of the usual two. This can occur with any chromosome in the human genome.

The most common type of trisomy in live births is Trisomy 21, also known as Down syndrome. Individuals with Trisomy 21 have three copies of chromosome 21. Other well-known trisomies include Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome), both of which are associated with severe developmental abnormalities and are often not compatible with long-term survival.

Trisomies usually arise due to an error during meiosis, the process of cell division that produces sperm and egg cells. This error, called nondisjunction, causes a chromosome to fail to separate properly, resulting in a gamete with an extra chromosome. When this gamete fuses with a normal gamete during fertilization, the resulting zygote has three copies of that chromosome.

The presence of an extra chromosome can disrupt normal development and lead to a range of physical and intellectual characteristics, the severity of which depends on the specific chromosome involved and the number of genes it carries. Diagnosis can be made through prenatal testing, such as amniocentesis or chorionic villus sampling, or after birth through genetic analysis. While there is no cure for trisomy, treatments focus on managing the associated health issues and supporting the individual's development.