trisomía

Trisomía is a type of chromosomal abnormality that occurs when an individual has three copies of a particular chromosome instead of the usual two. This condition arises during the formation of reproductive cells (sperm or egg) or very early in embryonic development, a process known as nondisjunction. Nondisjunction means that a pair of chromosomes fails to separate properly.

The most common and well-known example of trisomy in humans is Down syndrome, which is caused by trisomy 21, meaning there are three copies of chromosome 21. Other examples include Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13), both of which are associated with severe developmental abnormalities and often have a poor prognosis. Trisomies can also occur in sex chromosomes, such as Klinefelter syndrome (XXY) in males and Turner syndrome (X0, which is technically monosomy but often discussed in the context of chromosomal number variations).

The effects of trisomy vary greatly depending on which chromosome is affected and the extent of the extra genetic material. Generally, trisomies can lead to a range of physical and intellectual disabilities, characteristic facial features, and an increased risk of certain health problems. Genetic testing, such as karyotyping, can diagnose trisomy by examining the number and structure of chromosomes. While there is no cure for trisomy, medical management focuses on addressing the specific symptoms and health issues associated with the condition.