The 22q11.2 deletion syndrome is a genetic disorder caused by a missing section (microdeletion) of chromosome 22, which is present from the time a child is conceived. The 22q11.2 deletion is almost as common as Down syndrome. It is present in 1 out of every 1,000 live pregnancies, in 1 in 68 children with congenital heart disease, and in 5 to 8 percent of children born with cleft palate. The deletion has the potential to affect almost every system in the body and can cause a wide range of health problems — although no two people are ever exactly alike or affected in the same way. For more information on the key characteristics of this syndrome, visit the Signs and Symptoms section.
Despite the prevalence of 22q11.2, many physicians are still not familiar with the diagnosis or its extreme variability. Because of this, a family may search for years for an explanation for a child’s problems, as well as for meaningful help. Sometimes patients are in their late teens or even adulthood when the diagnosis is made, and many people never get properly diagnosed at all.
The 22q11.2 deletion is most often a “de novo” event, meaning that it is not inherited from either parent and does not usually run in a family. Only about 10% of children with the 22q11.2 deletion have a parent who is also affected. In the majority of individuals, the deletion happens sporadically without a previous family history of the condition. There is nothing the parents did or failed to do that caused the deletion to occur. For parents who do not have the deletion, the chance that a future child might be affected is very low. For individuals with the 22q11.2 deletion, there is a 50% chance of passing on the deletion to a child with each pregnancy. Individuals within the same family who have the deletion may or may not be similarly affected. For example, a mother could have very mild manifestations of the 22q11.2 deletion, while her child may have a severe heart defect needing surgery immediately after birth.