What is CATCH-22?

22q11.2 deletion syndrome, which has several presentations including DiGeorge syndrome (DGS), DiGeorge anomaly and velo-cardio-facial syndrome, is a syndrome caused by the deletion of a small piece of chromosome 22. . 


It has a prevalence estimated at 1:4000. The syndrome was described in 1968 by the pediatric endocrinologist Angelo DiGeorge.


Salient features can be summarized using the mnemonic CATCH-22 

Cardiac Abnormality (especially tetralogy of Fallot)
Abnormal facies
Thymic aplasia
Cleft palate
Hypocalcemia/Hypoparathyroidism. 
22 to remind one the chromosomal abnormality is found on the 22 chromosome


DiGeorge syndrome is caused by a large deletion from chromosome 22, produced by an error in recombination at meiosis (the process that creates germ cells and ensures genetic variation in the offspring). This deletion means that several genes from this region are not present in DiGeorge syndrome patients. It appears that the variation in the symptoms of the disease is related to the amount of genetic material lost in the chromosomal deletion. 

There is no cure for 22q11.2 deletion syndrome.The key is to identify each of the associated features and manage each using the best available treatments.

For example, in children it is important that the immune problems are identified early as special precautions are required regarding blood transfusion and immunisation with live vaccines. 

Thymus transplantation can be used to address absence of the thymus in the rare, so-called "complete" DiGeorge syndrome.

 Bacterial infections are treated with antibiotics. 

Cardiac surgery is often required for congenital heart abnormalities. 

Hypoparathyroidism causing hypocalcaemia often requires lifelong vitamin D and calcium supplements.

22q11.2 deletion syndrome is inherited in an autosomal dominant pattern. However, most cases are NOT inherited