Is 22q11.2 Deletion Syndrome Hereditary?

The short answer is yes, 22q11.2 deletion syndrome can be hereditary, but the vast majority of cases are not passed down from a parent. In about 90% of people diagnosed with the condition, the deletion occurs de novo ^[1]. De novo means “anew” or “from the beginning”—it is a random genetic change that happens by chance in the sperm or egg cell before conception, or very early in the development of the embryo ^[1]. In the remaining 10% or fewer of cases, the deletion is inherited from a parent who also has the condition ^[1].

Because the symptoms of 22q11.2 deletion syndrome can vary dramatically from one person to another, an adult might carry the genetic deletion with such mild symptoms that they never knew they had it until their child was diagnosed ^[2][3]. This is why genetic testing of both parents is an important step when a child receives a diagnosis ^[4]. It also means that if you are diagnosed as an adult, testing may be recommended for your parents, siblings, or existing children to see if the deletion is present elsewhere in your family ^[4].

Chances of Passing the Syndrome to Your Children

Whether you are an adult who has just been diagnosed, or a parent wondering about the risks for your next pregnancy, the chances of the syndrome occurring in future children depend entirely on whether you or your partner carry the deletion.

• If neither parent has the deletion: The chance of having another child with the syndrome is very low, typically estimated at around 1% ^[1]. This small residual risk exists due to a rare phenomenon called germline mosaicism, where a parent might have the genetic deletion only in some of their egg or sperm cells, but not in the blood cells that were tested. For all practical purposes, the recurrence risk is extremely low ^[1].
• If one parent has the deletion: There is a 50% chance in every pregnancy that the baby will inherit the syndrome ^[1]. It is also important to understand that the severity of the syndrome cannot be predicted by how it affects the parent. A parent with very mild symptoms can pass the deletion to a child who may face much more severe medical or developmental challenges ^[2][3].

Grappling with a 50% risk and unpredictable severity can be a heavy emotional burden. The uncertainty of how a child might be affected makes family planning a deeply personal and sometimes difficult process.

Planning for the Future

Because family planning and recurrence risks are major concerns, working with a genetic counselor is highly recommended ^[5][4]. A genetic counselor can help arrange chromosomal testing for you and your partner. Chromosomal Microarray (CMA) is typically the most comprehensive diagnostic test used, while FISH testing might be used for targeted checks if the specific deletion is already known in the family.

A counselor can also explain your specific risks and discuss options for future pregnancies. This includes going over prenatal testing choices, such as chorionic villus sampling (CVS) or amniocentesis, which can test for the deletion during pregnancy if you choose to explore them. Joining a patient advocacy group, such as the 22q Family Foundation, can also provide you with emotional support and community resources as you navigate these decisions.