Summary
Severe combined immune deficiency, [T- B-] is an inherited immune deficiency with autosomal recessive transmission, its incidence is around 1/500,00 live births/year. This deficiency occurs in children from the first months of life, and is manifested by recurrent bacterial or viral (cytomegalovirus, Pneumocystis carinii) infections, sometimes BCGitis (if the child received a BCG vaccination during the neonatal period), severe diarrhoea and failure to thrive. SCID can be treated only in a paediatric unit specialized in immunology and haematology. Subjects suspected of having SCID should never be given live vaccines or transfused with non-irradiated blood products. The only treatment of SCID is a bone-marrow transplantation. Several genetic defects can be responsible for SCID of alymphocytosis type. Two genetic anomalies can account for this disorder: either mutation in the recombination-activating (RAG1 and RAG2) genes or in Artemis gene. SCID antenatal diagnosis essentially relies on the evidence of the absence of lymphocyte populations. It can be performed with fetal blood punctured at 20 weeks of gestation. In families for whom a RAG gene mutation has been identified or a genetic linkage with the chromosome 10p's locus was established, antenatal diagnosis can be performed as early as 11 weeks of amenorrhea on trophoblastic biopsy. Author : *Dr G. de Saint Basile (May 2003)*
