Because the chromosome 22q11.2 deletion can variably affect children, and because it's associated with so many varying symptoms — many of which are associated with other disorders, too — it can be difficult to diagnose. In fact, many parents consult a number of physicians before their child's problem is finally pinpointed.
If your child's physician or specialist suspects your child has a chromosome 22q11.2 deletion, she'll probably refer him for testing to confirm the diagnosis. The FISH (fluorescence in situ hybridization) test — a highly accurate blood test — can help do this.
The FISH test works like a lock and key. The person in the laboratory has the "key" that "lights up" (fluoresces) if it finds the matching "lock" in the chromosome. If the lock is missing from one of the chromosome 22s, only one chromosome will light up in the area in question (q11.2), confirming that your child is missing material on chromosome 22.
Reviewed by: Donna M. McDonald-McGinn, MS, CGC
Date: May 2004