trisómíur

Trisómíur, known in English as Trisomies, refers to a type of chromosomal abnormality where an individual has three copies of a particular chromosome instead of the usual two. This extra genetic material can lead to a range of developmental issues and health conditions, with the severity depending on which chromosome is affected and the extent of the genetic material involved.

The most common trisomy in live births is Trisomy 21, also known as Down syndrome. This occurs when there is an extra copy of chromosome 21. Other well-known trisomies include Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome). These conditions are generally more severe than Trisomy 21 and are associated with significant intellectual disability and multiple physical abnormalities. Trisomies of the sex chromosomes, such as XXY (Klinefelter syndrome) in males or XXX (Triple X syndrome) in females, can also occur and may have less pronounced physical effects, often impacting fertility or leading to certain developmental differences.

Trisomies typically arise due to an error in cell division called nondisjunction, which occurs during the formation of egg or sperm cells. This error causes a chromosome to fail to separate properly, resulting in a gamete with an extra copy of that chromosome. When this gamete fertilizes an egg, the resulting embryo will have three copies of that chromosome. While the exact causes of nondisjunction are not fully understood, advanced maternal age is a known risk factor for some trisomic conditions. Diagnosis can be made prenatally through screening and diagnostic tests such as amniocentesis or chorionic villus sampling, or postnatally through genetic testing. Management focuses on addressing the specific health concerns and developmental needs associated with each trisomy.