The 22q11.2 Deletion Syndrome Clinic at St. Louis Children’s Hospital is the only clinic of its kind in the region and one of just a few in the nation focusing on the care of children with this genetic disorder. The syndrome can produce wide-ranging symptoms, and for that reason the clinic takes a multidisciplinary approach to treatment. Patients are seen by the hospital’s cleft palate team, which encompasses plastic surgery, otolaryngology, audiology, speech therapy, dentistry, orthodontics and developmental psychology. Additional team members are specialists in genetics, allergy and immunology; when needed, patients also are referred to cardiologists and gastroenterologists.
About the disorder
The overall incidence of 22q11.2 deletion syndrome is estimated to occur in approximately one out of every 4,000 live births—a potentially significant population in the United States.
The syndrome occurs when a tiny piece of chromosome 22 is missing at a location called q11.2. While children with the disorder frequently have a cleft palate, there is no unique group of symptoms associated with it. Instead, at least 30 different symptoms have been identified, ranging from heart defects, immune system problems, and spine and kidney abnormalities to learning, communication and social interaction difficulties. Until the chromosome 22q11.2 deletion was identified, specific collections of symptoms were thought to be distinct disorders. These included:
- DiGeorge syndrome
- Velocardiofacial syndrome
- Shprintzen syndrome
- Conotruncal anomaly face syndrome
- Sedlackova syndrome
It is now known that all of these syndromes and others are just one: 22q11.2 deletion syndrome.
Diagnosing the syndrome
Essential to the diagnosis of 22q11.2 deletion syndrome is a prenatal history, complete medical and family history, and a physical examination. Additional diagnostic procedures may include:
- Blood tests and tests to examine for immune system problems.
- X-rays to study internal tissues, bones and organs.
- Echocardiography to evaluate the structure and function of the heart.
- Fluorescent in situ hybridization (FISH) genetic study to look for a deletion in the chromosome 22q11.2 region. Along with a better understanding of the complexities of 22q11.2 deletion syndrome has come quicker recognition that when babies are born with cleft issues, the syndrome should be considered as the cause. When further testing uncovers additional symptoms associated with the syndrome, a definitive diagnosis is made through a FISH study.
The importance of genetic testing
Ninety percent of 22q11.2 deletion syndrome cases occur randomly at conception or early in fetal development. However, babies born with the syndrome then have a 50 percent chance, with each pregnancy, of passing it on to their children.
When a 22q11.2 deletion is detected in a child, both parents are offered the FISH test to see if the deletion is inherited rather than random. In approximately 10 percent of families, the deletion has been inherited from one of the parents.
The 22q11.2 Deletion Syndrome Clinic treats children with the genetic disorder until they reach the age of 21. Referrals then are made to adult specialists. Throughout patients’ childhood and adolescence, the clinic’s specialists work closely with families’ pediatricians to provide the additional expertise and individualized holistic care needed for managing this complex syndrome.