Definitive immunodeficiency was detected in approximately all of children with disseminated BCG infection including: SCID in 7 cases with homozygous mutation and homozygous polymorphism in Rag2 in one patient with heterozygous for the Rag2 mutation and polymorphism in the both parents of him and exclusion of Rag1, Rag2 and Artemis defect in another patients. This evidence concerns the gene RAG2 and Immunodeficiency.