Trisomy 18, nonmosaicism (meiotic nondisjunction) Save

Understanding Trisomy 18, Nonmosaicism (Meiotic Nondisjunction)

Trisomy 18, also known as Edwards syndrome, is a chromosomal disorder characterized by the presence of an extra copy of chromosome 18 in each cell. This condition occurs due to a random error during the formation of reproductive cells, called meiotic nondisjunction. Trisomy 18 affects approximately 1 in 5,000 live births, making it a relatively rare genetic disorder.

This condition is referred to as nonmosaicism because the extra copy of chromosome 18 is present in all cells of the body. Unlike mosaic forms of the disorder, where the extra chromosome is present in only some cells, individuals with nonmosaicism have the additional chromosome in every cell.

Trisomy 18 can lead to various physical and developmental abnormalities. Babies born with this condition often have low birth weight, a small head, and distinct facial features such as a small jaw and ears. Other common physical characteristics include clenched fists with overlapping fingers, a prominent back portion of the skull, and clubbed feet. Additionally, individuals with Trisomy 18 commonly experience intellectual disabilities and developmental delays.

Heart defects are present in approximately 90% of individuals with Trisomy 18, contributing to the high mortality rate associated with this condition. Other health complications may include kidney abnormalities, gastrointestinal issues, and problems with the respiratory and nervous systems.

It's important to note that Trisomy 18 is not an inherited condition, but rather a random event that occurs during the formation of reproductive cells. The risk of having a child with Trisomy 18 increases with maternal age, particularly in women over 35 years old.

1. Trisomy 18, also known as Edwards syndrome, affects approximately 1 in 5,000 live births.
2. Nonmosaicism refers to the presence of an extra copy of chromosome 18 in all cells of the body.
3. Physical characteristics of Trisomy 18 include low birth weight, distinct facial features, and clenched fists.
4. Heart defects and other health complications are commonly associated with Trisomy 18.
5. Trisomy 18 is not an inherited condition but occurs randomly during the formation of reproductive cells.

Awareness and understanding of Trisomy 18 are crucial for early diagnosis and intervention. While there is no cure for this condition, early medical support can help manage associated health issues and improve the quality of life for individuals with Trisomy 18.

It's important for expectant parents to consult with healthcare professionals and genetic counselors who can provide accurate information and support during pregnancy and after the birth of a