Also, 27 different genes were associated with those diseases (Figure 2), although there is no biunivocal correspondence between the diseases and the genes (e.g., in STAT3, gain of function variants lead to STAT3 GOF, while loss of function variants are associated with AD-HIES STAT3 deficiency (Job syndrome); also, osteopetrosis appears as a single disease in the classification, but it may be caused by defects in any one of seven different genes). The gene discussed is STAT3; the disease is Alzheimer disease.