Complications

The portions of chromosome 22 deleted in DiGeorge syndrome (22q11.2 deletion syndrome) play a role in the development of a number of body systems. As a result, the disorder can cause several errors during fetal development. Common problems that occur with 22q11.2 deletion syndrome include:

• Heart defects. 22q11.2 deletion syndrome often causes heart defects that could result in an insufficient supply of oxygen-rich blood. For example, defects may include a hole between the lower chambers of the heart (ventricular septal defect); only one large vessel, rather than two vessels, leading out of the heart (truncus arteriosus); or a combination of four abnormal heart structures (tetralogy of Fallot).
• Hypoparathyroidism. The four parathyroid glands in the neck regulate the levels of calcium and phosphorus in the body. 22q11.2 deletion syndrome can cause smaller than normal parathyroid glands that secrete too little parathyroid hormone (PTH), leading to hypoparathyroidism. This condition results in low levels of calcium and high levels of phosphorus in the blood.
• Thymus gland dysfunction. The thymus gland, located beneath the breastbone, is where T cells — a type of white blood cell — mature. Mature T cells are needed to help fight infections. In children with 22q11.2 deletion syndrome, the thymus gland may be small or missing, resulting in poor immune function and frequent, severe infections.
• Cleft palate. A common condition of 22q11.2 deletion syndrome is a cleft palate — an opening (cleft) in the roof of the mouth (palate) — with or without a cleft lip. Other, less visible abnormalities of the palate that may also be present can make it difficult to swallow or produce certain sounds in speech.
• Distinct facial features. A number of particular facial features may be present in some people with 22q11.2 deletion syndrome. These may include small, low-set ears, short width of eye openings (palpebral fissures), hooded eyes, a relatively long face, an enlarged nose tip (bulbous), or a short or flattened groove in the upper lip.
• Learning, behavioral and mental health problems. 22q11.2 deletion may cause problems with development and function of the brain, resulting in learning, social, developmental or behavioral problems. Delays in toddler speech development and learning difficulties are common. Some children develop attention-deficit/hyperactivity disorder (ADHD) or autism spectrum disorder. Later in life, the risk of depression, anxiety disorders and other mental health disorders increases.
• Autoimmune disorders. People who had poor immune function as children, due to a small or missing thymus, may also have an increased risk of autoimmune disorders, such as rheumatoid arthritis or Graves' disease.
• Other problems. A large number of medical conditions may be associated with 22q11.2 deletion syndrome, such as hearing impairment, poor vision, breathing problems, poor kidney function and relatively short stature for one's family.