Nulissomic

Nulissomic refers to a rare chromosomal disorder in which one or more of an individual's chromosomes are deleted, but not identical deleted segments are present on the other two copies of the chromosome.

In a typical individual, most of the time, the same segment of a chromosome is deleted on both copies of the chromosome. However, in the case of nulissomic individuals, the deleted segment of the chromosome is not identical to the deleted segment on the other copy of the chromosome.

This disorder is often caused by errors during the fifth to tenth week of gestation when the chromosomes are being replicated. The error can result in the deletion of a significant portion of a chromosome or multiple small deletions.

Nulissomic individuals may experience a range of symptoms depending on the location and the length of the missing genetic material. Common features include developmental delays, heart defects, feeding difficulties, and other various physical abnormalities.

There are two main types of nulissomic disorders: familial nulissomic deletion syndrome and isolated nulissomic deletion syndrome. Familial nulissomic deletion syndrome affects multiple family members due to a genetic mutation, while isolated nulissomic deletion syndrome occurs in a single child without a family history of the disorder.

Nulissomic disorders are extremely rare, but early identification and diagnosis are crucial in determining the best course of action to help the individual with developmental delays or physical abnormalities. Testing procedures may include examining chromosomes, taking a family history, and performing physical and developmental assessments to diagnose and manage nulissomic disorders.