The autosomal recessive IKKα deficiency (IKBKA) and the X-recessive NEMO deficiency, both caused by hypomorphic mutations affecting the canonical NFκB pathway, show a spectrum of phenotypes ranging from fetal death, in complete IKKα deficiency (70), to severe susceptibility to infections and ectodermal dysplasia (EDA-ID phenotype) in newborns (68, 71). Here, NFKB1 is linked to hyperinsulinemic hypoglycemia, familial, 4.