Monoszómia

Monoszómia is a type of aneuploidy, which is a condition where an individual has an abnormal number of chromosomes. Specifically, monoszómia refers to the absence of one chromosome from a pair. Normally, humans have 23 pairs of chromosomes, meaning they have two copies of each chromosome. In monoszómia, there is only one copy of a particular chromosome.

This condition can occur with any of the autosomal chromosomes (chromosomes 1 through 22) or with the sex chromosomes (X and Y). Monoszómia of autosomal chromosomes is usually not survivable and often results in miscarriage. However, there are rare exceptions. Monoszómia of the sex chromosomes is more common and can lead to certain genetic disorders.

The most well-known example of sex chromosome monoszómia is Turner syndrome, which affects females and is characterized by the presence of only one X chromosome (45,X). Individuals with Turner syndrome may experience a range of symptoms, including short stature, ovarian insufficiency, and heart defects. Monoszómia of the Y chromosome is not observed in live births.

The causes of monoszómia are typically errors during meiosis, the process of cell division that produces gametes (sperm and egg cells). These errors, known as nondisjunction, can lead to a gamete with an incorrect number of chromosomes. If this gamete is involved in fertilization, the resulting zygote will have an abnormal chromosomal makeup, such as monoszómia. Diagnosis is usually made through genetic testing.