Cryptosporidium has also been reported in PI3 kinase disease (from GOF mutations in PIK3CD or loss of function mutations in PIK3R1) [71], IL-21 receptor deficiency [72], idiopathic CD4 lymphopaenia [73], DOCK8 deficiency [74] and MHC Class II deficiency [58]. The gene discussed is IL21R; the disease is hyperinsulinemic hypoglycemia, familial, 4.