Although immunodeficiency associated with heterozygosity for a JAK3 mutation has rarely been reported (most of the JAK3 mutations identified to date are homozygous or compound heterozygous)[45], [57], our findings raise the possibility that a spectrum of mild immunodeficiency associated with heterozygote JAK3 mutations may be broader than previously suspected. This evidence concerns the gene JAK3 and Immunodeficiency.