Chromosome 22q11.2 Deletion
Also known as: chromosome 22q11.2 deletion syndrome, 22q11.2 deletion syndrome, DiGeorge syndrome, Distal Chromosome 22q11.2 Deletion Syndrome.
What is chromosome 22q11.2 deletion?
Chromosome 22q11.2 deletion is a disorder that occurs when a small part of chromosome 22 is missing at birth. It leads to a wide variety of complications in children born with the disorder.
This condition goes by many names including DiGeorge syndrome, Velocardiofacial syndrome, and Shprinzen syndrome. The different names arose initially because different people used their own clinical descriptions for what was later found to represent one condition that can include a large spectrum of clinical findings. Some individuals will have many of the findings and others few. Therefore, the condition is now called “22q11.2 Deletion syndrome.” Approximately 1 in 4000 people has Deletion 22q11.2 syndrome.
What causes chromosome 22q11.2 deletion?
Deletion 22q11 syndrome is caused by a deletion on the long arm of chromosome 22 at 22q11.2. In body cells, each person has 46 chromosomes that come in 23 pairs. Therefore, each person has two copies of chromosome 22, one copy that is inherited from a person’s mother and the other from a person’s father. Each chromosome is divided into two parts, a short arm called the “p” arm and the long arm known as the “q” arm. In the Deletion 22q11 syndrome, the majority of affected individuals have a small piece missing (called a deletion) from the long (“q”) arm of one of their copies of chromosome 22. This missing genetic material causes the clinical findings of this condition.
In approximately 93 percent of affected individuals, the deletion occurs for the first time in the affected person and was not inherited from the person’s mother or father. However, in approximately 6 percent of affected individuals, the deletion was inherited from a parent who also has the deletion. Once a person has a 22q11.2 deletion, the risk for having a child affected with similar problems is 50 percent.
What are the symptoms of chromosome 22q11.2 deletion?
A wide variety of symptoms are related to chromosome 22q11.2 deletion. They include:
Characteristic craniofacial features include:
- Congenital heart defects(approximately 74 percent)
- Palatal abnormalities including cleft palate, submucous cleft palate, and velopharyngeal insufficiency (VPI). VPI results in hypernasal speech. Approximately 64 percent of affected children have palatal abnormalities.
- Immune system deficiency is found in 77 percent of affected children and results in decreased production of T-cells which usually help fight infection.
- Feeding difficulties
- Hearing loss
- Learning and developmental delays
- Low blood calcium
over folded or squared off ear helices, cupped or prominent ears, prominent nasal bridge with a round tip of the nose.
What are chromosome 22q11.2 deletion care options?
With proper management, the prognosis for most children with this condition is positive. With careful attention to speech, cardiac, immune, and learning issues, these children will attend school, have friends, and most of all enjoy life. With close follow-up by a craniofacial team and/or clinical genetics, these children can grow to healthy and happy adults.
Reviewed by: Parul B Jayakar, MD
This page was last updated on: December 18, 2020 05:06 PM
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