Although this condition has been initially associated with mutations in Recombination activating gene 1 and 2 (RAG1 and RAG2),62,63 genetic alterations in other genes have also been reported,64, 65, 66, 67, 68, 69, 70, 71, 72 including the ones responsible for ARTEMIS deficiency, ADA deficiency, Cartilage Hair Hypoplasia, CHARGE syndrome, EXTL3 deficiency and atypical complete DiGeorge syndrome. This evidence concerns the gene RAG2 and hyperinsulinemic hypoglycemia, familial, 4.