22q11.2 Deletion Syndrome
What is 22q11.2 deletion syndrome?
22q11.2 deletion syndrome is a genetic disorder. In this syndrome, a tiny piece of chromosome 22 is missing. This can cause many health problems. These problems may range from heart defects and developmental delays to seizures. They may also include changes in facial appearance, such as the eyes, nose, or ears. Or the child may have an opening in the roof of the mouth (cleft palate).
The name of the syndrome refers to the missing piece of chromosome. It should be on the long arm of chromosome 22, at a place called q11.2.
Most people with the syndrome don’t have all of the health problems seen with it. In general, any of the health problems can be treated, especially if they are found early.
The signs and symptoms of 22q11.2 deletion syndrome can vary from one person to another. For that reason, several disorders and collections of symptoms caused by this syndrome have had other names in the past. These names include:
Some people with the syndrome had been diagnosed with Opitz G/BBB syndrome or Cayler cardiofacial syndrome in the past. Doctors now know that these disorders all share the same genetic cause as 22q11.2 deletion syndrome.
Who is affected by 22q11.2 deletion syndrome?
About 1 in 4,000 people have 22q11.2 deletion syndrome. Some experts believe this number should be higher. Some people with the chromosome problem may not know they have the syndrome because their symptoms are less severe.
What causes 22q11.2 deletion syndrome?
Most people with 22q11.2 deletion syndrome are missing about 50 genes. The exact function of many of these genes remains a mystery. But missing the gene TBX1 probably causes the syndrome's most common physical symptoms. These include heart problems and cleft palate. Another nearby gene, COMT, may also help explain the higher risk for behavior problems and mental illness in people with the syndrome.
About 9 in 10 cases of 22q11.2 deletion syndrome happen randomly. They occur when the egg is fertilized or early in fetal development. This means that most people with the disorder have no family history of it. But they can pass the condition on to their children. The remaining 10% of cases are inherited from either the mother or the father. When the condition is inherited, other family members could also be affected. Because a person who has this chromosome deletion has a 1 in 2 chance of passing the problem to a child, both parents can have their blood studied to look for the deletion.
What are the signs and symptoms of 22q11.2 deletion syndrome?
The signs and symptoms of 22q11.2 deletion syndrome may vary widely, even among family members. At least 30 signs or symptoms have been seen with this disorder, but most people have only some of the symptoms.
The most common symptoms include:
Heart defects. These are usually present from birth (congenital).
Mouth abnormalities. These include cleft palate and a palate that does not close fully (velopharyngeal insufficiency). These can cause speech problems.
Middle ear infections or hearing loss
Low levels of calcium in the blood. This is caused by problems with the parathyroid glands and can trigger seizures.
Immune system problems that can increase the risk for infections
Spine problems. These include curvature of the spine (scoliosis) and problems with the bones of the neck or upper back.
Learning problems. These include delays in development and speech.
Communication and social interaction problems, including autism
Increased risk for mental illness. This includes anxiety, depression, or schizophrenia in adulthood.
Facial features of children with 22q11.2 deletion syndrome may include:
Small ears with squared upper ear
Cleft lip, cleft palate, or both
Uneven (asymmetric) facial appearance when crying
Small mouth, chin, and side areas of the tip of the nose
The symptoms of 22q11.2 deletion syndrome may look like other health problems. Make sure your child sees his or her healthcare provider for a diagnosis.
How is 22q11.2 deletion syndrome diagnosed?
Your child’s healthcare provider will look at your child’s prenatal history and complete health and family history. He or she will do a physical exam. Your child may need certain tests. These may include:
Blood tests and tests to look for immune system problems
X-ray. This test makes pictures of internal tissues, bones, and organs.
Echocardiography. This test looks at the structure of the heart and how well it is working.
Fluorescent in situ hybridization (FISH) studies. This blood test looks for certain genes that are deleted. If the FISH test doesn’t find any deletion in the 22q11.2 region of the chromosome, but your child has signs of the syndrome, he or she will usually need a full chromosome study. This will look for other chromosome problems.
Chromosomal microarray. This is similar to a FISH test, but it looks at many regions across all the chromosomes, including chromosome 22. This is to find a missing piece in the 22q11.2 location.
If the testing finds a 22q11.2 deletion in your child, you and the child’s other parent can have a FISH test to see if this deletion is inherited. In about 1 in 10 cases of the syndrome, the deletion has been inherited from one of the parents. If you have the 22q11.2 deletion, you have a 1 in 2 chance of passing it on to a child. This is true for every pregnancy.
How is 22q11.2 deletion syndrome treated?
There is no cure for 22q11.2 deletion syndrome. But many of its related health problems can be treated. Parents can help their child by seeking early, competent care.
Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is.
Treatment may include the following:
A cardiologist will look at any heart defects. He or she may correct them with a procedure or surgery.
A plastic surgeon and a speech pathologist will look at any cleft lip or cleft palate defects.
Speech and digestive specialists will look at any feeding problems. Some children with the syndrome have severe feeding problems. They need tube feedings in order to get enough nutrition.
An immune system specialist should look at your child. If your child has a T cell problem, he or she is at risk for infections that keep coming back. Your child should not have any live viral vaccines. Your child should have any blood products for a transfusion irradiated. This is true unless your child’s immune system doctor says that is not needed.
Other common problems that may require treatment include:
Low calcium. This is common in children with the syndrome, especially right after birth. But it can also happen during times of stress, such as during puberty or after surgery. Your child may need to take calcium and vitamin D supplements. Your child may need to see an endocrinologist. This is a doctor who specializes in treating problems of the endocrine system.
Development problems. Young children with 22q11.2 deletion syndrome may be slow to meet developmental milestones. These include sitting, walking, and talking. The International 22q11.2 Deletion Syndrome Foundation recommends that parents consider physical therapy (PT), occupational therapy (OT), and speech therapy for their child. PT strengthens large muscles and helps children meet developmental milestones. OT focuses on small muscles used for tying shoes, buttoning clothes, and other tasks. It can also help with feeding problems. Speech therapy can help your child with language delays.
Long-term outlook for children with 22q11.2 deletion syndrome
A small portion of children with severe heart defects and immune system problems caused by 22q11.2 deletion syndrome will not survive the first year of life. But most children with the syndrome who get proper treatment will survive and grow into adulthood. These children will generally need extra help throughout school. They may also need long-term care for their health needs.
Some children with the syndrome may have behavioral conditions. These include autism, attention deficit disorder, obsessive compulsive disorder, or anxiety.