Characterizing 22q11.2 abnormalities

Duplication of a small region on chromosome 22, resulting in 22q11.2 duplication syndrome, has been associated with autism, but to date there has not been a large-scale cohort study of this association.

Deletion of the identical region, which results in 22q11.2 deletion syndrome, formerly known as DiGeorge syndrome, is also linked to an elevated rate of autism and psychosis, as well as a wide range of birth defects. Children with the duplication have a lower rate of all of these birth defects and no psychosis.

Robert Schultz and his colleagues plan to study children with 22q11.2 duplication syndrome, using the largest cohort of such children at any one center, the 22q and You Center at the Children’s Hospital of Philadelphia. The researchers plan to evaluate how children with 22q11.2 duplication syndrome compare phenotypically with typically developing children, and with those who have 22q11.2 deletion syndrome or idiopathic autism (autism of unknown cause).

In addition, the team plans to evaluate children with atypical deletions or duplications within the 22q11.2 region to narrow in on the regions related to autism. Typically, children with 22q11.2 deletion or duplication syndromes have genetic alterations that affect the same set of about 45 genes. A small proportion of patients, however, have smaller deletions or duplications involving only a subset of these genes.

The 22q and You Center serves dozens of people with smaller atypical deletions or duplications within the 22q11.2 region. By evaluating a large number of individuals, the team hopes to narrow down the list of genes that may influence social and cognitive development in children with 22q11.2 abnormalities.