What is 22q11.2 Deletion Syndrome?
The 22q11.2 Deletion Syndrome is an abnormality on the twenty-second chromosome that can cause such health problems as heart defects, immune deficiency, cleft palate, developmental delays, learning disabilities and social/emotional issues. Present in one out of every 2,000-4,000 live births, in 1 in 68 children with congenital heart disease, and in five to eight percent of children born with cleft palate, 22q is almost as common as Down syndrome, a widely recognized chromosomal disorder.
What Causes the 22q11.2 Deletion Syndrome?
22q is a “new deletion†(loss of chromosomal material) that may or may not run in the family. In fact, only about 10 percent of the time does a parent have the deletion as well. So, if it isn’t hereditary what causes it? According to geneticists, the root of the disorder lies within a person’s genetic makeup. You see, most people have 23 pairs of chromosomes (46 total), with one of each pair coming from the mother and the other from the father. Numbered one through 22 (the 23rd pair determines the sex of the baby), chromosomes are divided into two parts called the arms. The top part is the “p†arm and the bottom is the “q†arm. People with a 22q deletion have a small part of the “q†arm missing. When the deletion is not present in a parent, it is new (de novo) in the child. It is nothing that the parents did or didn’t do to make it happen. It just happens.
What are the Signs and Symptoms of 22q11.2 Deletion Syndrome?
While the health effects of 22q vary from patient to patient, the common medical conditions include:
• Cardiovascular Defects
• Feeding Difficulties
• Gastrointestinal Problems
• Immune System Problems
• Growth Problems
• Palatal Anomalies
• Kidney Differences
• Hearing
• Low Calcium
• Autoimmune Disease
• Spine Differences
• Cognitive and Speech Delay
• Behavioral Differences (e.g.ADHD and Autism)
What Are the Treatments for 22q11.2 Deletion Syndrome?
While there is no “cure†for 22q, there are ways to manage its problems. And 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:
• Audiology
• Cardiology
• Child development and psychology
• Cleft palate
• Ear, nose and throat
• Endocrinology
• Feeding/nutrition
• Genetics
• Immunology
• Neurology
• Orthopaedics
• Urology
Even if a child doesn't have a known heart defect, a cardiologist's evaluation is important, although the likelihood of the cardiologist's finding a previously unrecognized problem is low. An evaluation usually includes a chest X-ray, an electrocardiogram and an echocardiogram.
Child development and psychology
Children with a 22q11.2 deletion 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 take your child for developmental testing on a regular basis to determine if he's having any problems and to identify appropriate intervention, when needed.
Cleft palate
Your child should see a plastic surgeon who specializes in cleft palate and velopharyngeal incompetence. In addition, she should see a speech and language pathologist who can also assess speech, language and -- if she's 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.
Ear, nose and throat and audiology
This evaluation may be part of the cleft palate team evaluation. 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 deletion may also have a hearing loss, your child may benefit from a hearing test (audiogram), as well.
Endocrinology
Some children with a chromosome 22q11.2 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.
Feeding/nutritionChildren with a 22q11.2 deletion 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.
GeneticsThe 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 deletion. That's why it's important to take your child for a yearly evaluation, so the geneticist can answer your questions about his general care, as well as the chances that the disorder will recur in any other children you may have.
ImmunologyMany newborns with a 22q11.2 deletion 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. In addition, some children develop autoimmune diseases related to their immune deficiency, such as juvenile rheumatoid arthritis, ideopathic thrombocytopenia, vitiligo and Graves disease. Your child should be evaluated by an immunologist at least once.
NeurologySome children with a 22q11.2 deletion have a seizure disorder (unrelated to low calcium) or balance problems -- which require a neurologist's services. Ask your child's healthcare team if an initial evaluation with a neurologist may be helpful.
UrologySome children have kidney problems -- even a missing kidney -- which a renal (kidney) ultrasound would detect. In addition, some children have urinary tract infections, urinary reflux, bedwetting or urinary frequency. If your child is having these types of problems, he should see a urologist who is a specialist in the chromosome 22q11.2 deletion.
OtherThe problems children with a 22q11.2 deletion have may vary widely, but some other problems include:
• constipation
• leg pain
• differences in the blood vessels in the neck that lead to the brain (carotid arteries) Other, less common, problems include:
• bony abnormalities -- such as extra fingers, extra ribs, a missing forearm bone and spine problems that sometime leads to spine curvature (scoliosis)
• spina bifida
• juvenile rheumatoid arthritis or other autoimmune disorders, such as ideopathic thrombocytopenia, vitiligo and Graves disease
• eye problems, such as colobomas
• premature fusion of the "soft spots" (fontanels) -- called craniosynstosis
• emotional or psychological problems
• intestinal malrotation
• diaphragmatic hernia
• Hirschsprung's disease
• tracheoesophageal fistula
• laryngeal web
• imperforate anus
• absent uterus
If your child has problems in any of these areas, she'll be referred to the specialists who can care for them.
Frequently Asked Questions About the Chromosome 22q11.2 Deletion
What is a genetic disorder, and how does a genetic disorder cause health and learning problems?
A genetic disorder is one that involves a difference in a chromosome or a single gene.
Chromosomes are small structures found in every cell in the body. In human beings, each cell has 23 pairs of chromosomes. Each pair consists of one chromosome from the mother, carried in the ovum or egg, and one chromosome from the father, carried in the sperm that fertilized the egg.
The chromosomes carry even smaller structures called genes. Genes contain the information that determines all of an individual's characteristics -- everything from height and eye color to predisposition to chronic illness.
Occasionally, a baby is conceived with extra or missing chromosomal and genetic material. Since the chromosomes and the genes they contain orchestrate the body's growth and development, a range of physical and behavioral problems may result. In the case of a chromosome 22q11.2 deletion, genetic material is missing (or deleted) from chromosome pair number 22. The "q" in the name of the disorder refers to the precise location of this missing material -- on the q arm (long arm) of the chromosome.
Chromosomes are so small that they can only be examined under the microscope. Genes are even smaller, requiring sophisticated molecular testing.
Does the chromosome 22q11.2 deletion run in families?
Most cases occur at random and aren't inherited or related to any identifiable cause. However, approximately 5 to 10 percent of children with a chromosome 22q11.2 deletion inherit it from a parent who has a mild, usually undiagnosed, form. Because the disorder is so variable, even people from the same family, with the same deletion, may have very different kinds of problems.When one parent has a chromosome 22q11.2 deletion, the chance of passing this disorder on to a child is one in two, or 50 percent, with each pregnancy.