An Overview of 22q11.2 Duplication
The 22q11.2 Duplication is about half as common as the 22q11.2 deletion (so found in about 1/4000 newborns). But because there are likely so many individuals who remain undiagnosed, it is hard for doctors to estimate the prevalence of this syndrome.
The duplication has the potential to affect many systems in the body and can cause a wide range of health problems. No two people are ever exactly alike, even when they have the same syndrome, and not every person with the duplication is affected in the same way. Many people with the duplication have no apparent physical or intellectual disabilities. Often times, parents of children with the duplication find out that they also have it only after their child is diagnosed.
Though not always present, the key characteristics of this syndrome include combinations and varying degrees of:
- Heart defects
- Palate differences
- Feeding and gastrointestinal difficulties including reflux
- Immune system defects, including neutropenia
- Growth delays and short stature
- Weak muscle tone or hypotonia
- Hearing loss
- Occasional endocrine issues including low calcium and thyroid differences
- Cognitive, developmental and speech delays
- Frequent upper respitory infections, asthma
- Behavioral and learning differences including ADHD, autism, Asperger Syndrome, etc.
- Seizure disorders
- Macrocephaly or large head
The 22q11.2 Duplication is caused by an extra piece of genetic material on the 22nd chromosome. In most cases, the extra genetic material contains about 40 genes.
22q11.2 Duplication Syndrome is not detectable by routine genetic testing (called karyotyping.) Most individuals with 22q11.2 duplication are identified either by something called array genomic hybridization (array GH) testing or by multiplex ligation-dependent probe amplification (MLPA) testing for 22q11.2 deletion syndrome. Both of these tests are performed with blood work but can be diagnosed in pregnancy using cells from the placenta or the amniotic fluid.
About 70 percent of individuals with the duplication inherit it from one of their parents. In other cases, the duplication is not inherited and occurs as a random event during the formation of the child. Any person with the duplication has a 50% chance of having a child with the same duplication.
Although there is no cure for the 22q11.2 duplication, many therapies and medical interventions are available to help address its associated symptoms. The earlier these symptoms are detected, the more doctors can do to help. That’s why, when diagnosed with this condition, evaluation is recommended in the following areas:
- Child development and psychology
- Cleft palate
- Ear, nose and throat
- Neurology, Urology and Endocrinology, if recommended
Even if a child doesn’t have a known heart defect, a cardiologist’s evaluation is important, although the likelihood of finding a previously unrecognized problem is low. An evaluation usually includes a chest X-ray, an electrocardiogram, and an echocardiogram.
Children with a 22q11.2 duplication may have learning style differences requiring some extra help in school. In addition, young children may have delays in their developmental milestones and might benefit from early intervention, such as physical, occupational, and speech therapy. That’s why it’s important to have developmental testing on a regular basis. If your child is noted to be behind in any areas, appropriate interventions will be recommended.
Children with the duplication should see a plastic surgeon who specializes in cleft palate and velopharyngeal incompetence. In addition, they should see a speech and language pathologist who can also evaluate speech, language and — if they’re young — feeding. Some centers have specialized computer methods of objectively measuring speech to decide if intervention is necessary. Some teams also have growth specialists and dentists who monitor face, jaw, and tooth growth.
This evaluation may be done as part of the cleft palate team work-up. Children with a cleft palate often have trouble with ear infections and can benefit from seeing an ear, nose and throat (ENT) doctor — also called an otolaryngologist. In addition, an ENT can help children who have problems with “noisy” breathing as a result of their disorder. Since some children with a 22q11.2 duplication may also have hearing loss, your child would benefit from a hearing test (audiogram), as well.
Occasionally, children with a chromosome 22q11.2 duplication have problems with low calcium when they’re newborns and may need a calcium supplement. During this time, the cardiologist or pediatrician will handle low calcium problems. If the problem continues, your child may need to see an endocrinologist (hormone doctor). In addition, some older children have problems with growth (called short stature) and may require growth hormone therapy. An endocrinologist can help.
Children with a 22q11.2 duplication often have feeding difficulties, especially when they’re newborns. A pediatrician who specializes in feeding can help. Your child’s healthcare provider will only recommend an evaluation if a problem already exists.
The geneticist is the person who’s most likely to have an overview of your child’s diagnosis. The geneticist stays up-to-date with the latest research about the 22q11.2 duplication. It’s important for a child with the duplication to have a yearly evaluation, so the geneticist can answer questions about his or her general care, as well as the chances that the disorder will recur in future generations of a family.
Some newborns with a 22q11.2 duplication have problems with their immune systems, so they may have trouble with infections or certain vaccines. Most children outgrow this problem by their first birthdays, but some of them continue to have trouble into later childhood and adulthood. A child with the duplication should be evaluated by an immunologist at least once.
Some children with a 22q11.2 duplication have a seizure disorder (unrelated to low calcium) or balance problems which require a neurologist’s services. A child’s healthcare team should determine if an initial evaluation with a neurologist may be helpful.
Most children and adults with the 22q11.2 duplication do quite well both medically and as members of their families and communities at large. As with anything that is unexpected, coming to terms with the diagnosis is often difficult at first but becomes easier as more information becomes available. Families can benefit from the opportunity to meet other children and adults with the 22q11.2 duplication and/or to converse with them through diagnosis-specific internet sites. In addition, attendance at family meetings and picnics; contacting support networks; and sending children to camps specifically designed for those individuals with a 22q11.2 syndromes is often helpful, as families realize they are not alone. Learn more about coping with the diagnosis.