Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
22q11.2 deletion syndrome, also known as Velocardiofacial Syndrome, DiGeorge Syndrome, conotruncal anomaly face syndrome, Congenital Thymic Aplasia, and Strong 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 i.e., on the long arm of one of the pair of chromosomes 22. It has a prevalence estimated at 1:4000.[1]
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 may include birth defects such as congenital heart disease, defects in the palate, most commonly related to neuromuscular problems with closure (velo-pharyngeal insufficiency), learning disabilities, mild differences in facial features, and recurrent infections. Infections are common in children due to problems with the immune system’s T-cell mediated response that in a minority of patients is due to an absent or hypoplastic thymus. 22q11.2 deletion syndrome may be first spotted when an affected newborn has convulsions from hypocalcemia due to malfunctioning the parathyroid glands and low levels of parathyroid hormone (parathormone). Affected individuals may also have any other kind of birth defect including kidney abnormalities and significant feeding difficulties as babies. Autoimmune disorders such as hypothyroidism and hyperparathyroidism or thrombocytopenia (low platelet levels), and psychiatric illnesses are common late-occurring features.[2] Microdeletions in chromosomal region 22q11.2 are associated with a 20 to 30-fold increased risk of schizophrenia. [3] Studies provide various rates of 22q11.2 deletion syndrome in schizophrenia, ranging from 0.5 to 2% and averaging about 1%, compared with the overall estimated 0.025% risk of the 22q11.2 deletion syndrome in the general population.[4]Medical students may use the mnemonic CATCH 22 to describe DiGeorge’s syndrome:
Cardiac defects
Abnormal facial features
Thymic aplasia
Cleft palate
Hypocalcemia
and chromosome 22.
Because the signs and symptoms of 22q11.2 deletion syndrome are so varied, different groupings of features were once described as separate conditions. These included the velo-cardio-facial syndrome, Shprintzen syndrome,DiGeorge syndrome, Sedlackova syndrome and conotruncal anomaly face syndrome,
Individuals with a 22q11.2 deletion can suffer from many possible features, ranging in number of associated features and from the mild to the very serious. Symptoms shown to be common include:
The syndrome is caused by genetic deletions (loss of a small part of the genetic material) found on the long arm of one of the two 22nd chromosomes. Very rarely, patients with somewhat similar clinical features may have deletions on the short arm of chromosome 10.
The mechanism that causes all of the associated features of the syndrome is unknown. Some believe that 22q11.2 deletion syndrome may involve migration defects of neural crest-derived tissues, particularly affecting development of the third and fourth branchial pouches (pharyngeal pouches). Also affected is the thymus gland; a mediastinal organ largely responsible for differentiation and induction of tolerance in T-cells. Impaired immune function results principally from this aetiology.
[tubepress mode=’tag’, tagValue=’22q11.2 deletion syndrome’]