Distal 18q deletion syndrome is a chromosomal condition that occurs when a piece of the long (q) arm of chromosome 18 is missing. The term "distal" means that the missing piece occurs near one end of the chromosome. Distal 18q deletion syndrome can lead to a wide variety of signs and symptoms among affected individuals.

Distal 18q deletion syndrome is caused by a deletion of genetic material from one copy of chromosome 18 anywhere between a region called 18q21 and the end of the chromosome. The size of the deletion and where it begins vary among affected individuals. The signs and symptoms of distal 18q deletion syndrome are thought to be related to the loss of multiple genes, some of which have not been identified, from this part of chromosome 18. Certain features of the disorder have been associated with the loss of particular genes in this region. People with deletions that include the TCF4 gene usually have signs and symptoms of another genetic condition known as Pitt-Hopkins syndrome, such as severe intellectual disability and breathing problems, in addition to other features of distal 18q deletion syndrome.

Deletions from the q arm of chromosome 18 occur in an estimated 1 in 55,000 newborns worldwide. Most of these deletions occur in the distal region of the q arm, leading to distal 18q deletion syndrome.

Distal 18q deletion syndrome is considered to be an autosomal dominant condition, which means one copy of the deleted region on chromosome 18 in each cell is sufficient to cause the disorder's characteristic features.

Published Date: November 01, 2018Published By: National Institutes of Health