Chromosome 22, microdeletion 22 q11
22q11.2 deletion syndrome (also called DiGeorge syndrome and velocardiofacial syndrome) is a disorder caused by the deletion of a small piece of chromosome 22. The deletion occurs near the middle of the chromosome at a location designated q11.2. more...
The features of this syndrome vary widely, even among members of the same family, and affect many parts of the body. Characteristic signs and symptoms include heart defects that are often present from birth, an opening in the roof of the mouth (a cleft palate or other defect in the palate), learning disabilities, recurrent infections caused by problems with the immune system, and mild differences in facial features. Affected individuals may also have kidney abnormalities, low levels of calcium in the blood (which can result in seizures), significant feeding difficulties, autoimmune disorders such as rheumatoid arthritis, and an increased risk of developing mental illnesses such as schizophrenia and bipolar disorder.
Because the signs and symptoms of 22q11.2 deletion syndrome are so varied, different groupings of features were once described as separate conditions. Doctors named these conditions DiGeorge syndrome, velocardiofacial syndrome (also called Shprintzen syndrome), and conotruncal anomaly face syndrome. In addition, some children with the 22q11.2 deletion were diagnosed with Opitz G/BBB syndrome and Cayler cardiofacial syndrome. Once the genetic basis for these disorders was identified, doctors determined that they were all part of a single syndrome with many possible signs and symptoms. To avoid confusion, this condition is usually called 22q11.2 deletion syndrome, a description based on its underlying genetic cause.
Individuals with a 22q11 deletion have a range of findings, including:
- Congenital heart disease (74% of individuals), particularly conotruncal malformations (tetralogy of Fallot, interrupted aortic arch, ventricular septal defect, and truncus arteriosus)
- palatal abnormalities (69%), particularly velopharyngeal incompetence (VPI), submucosal cleft palate, and cleft palate; characteristic facial features (present in the majority of Caucasian individuals)
- learning difficulties (70-90%)
- an immune deficiency regardless of their clinical presentation (77%)
- hypocalcemia (50%)
- significant feeding problems (30%)
- renal anomalies (37%)
- hearing loss (both conductive and sensorineural)
- laryngotracheoesophageal anomalies
- growth hormone deficiency
- autoimmune disorders
- seizures (without hypocalcemia)
- skeletal abnormalities
Thymus, parathyroid glands and heart derive from the same primitive embryonic structure and that is why these three organs are dysfunctioned together in this disease. Affected patients (usually children) are prone to yeast infections.
The disease is related with genetic deletions (loss of a small part of the genetic material) found on the long arm of the 22nd chromosome. Some patients with similar clinical features may have deletions on the short arm of chromosome 10.
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