RAG1 and RAG2 mutations make up the large majority of these whereas DCLRE1C mutations for instance, of which the founder variant was first characterized in Athabascan-speaking Navajo Native Americans, account for only around 20% of T-B-NK+ SCID and thus 3-4% of all SCID cases (9, 30). This evidence concerns the gene RAG2 and severe combined immunodeficiency.