The spectrum of presentation in individuals with LIG4 deficiency is wide with cases of SCID or atypical SCID [72, 73], Omenn syndrome [74], CID [75, 76], asymptomatic CD4+ T-lymphocytopenia [77], predisposition to malignancy [71], marrow hypoplasia and even asymptomatic individuals [78••], some of whom display microcephaly and growth failure [79]. The gene discussed is LIG4; the disease is hyperinsulinemic hypoglycemia, familial, 4.