Interestingly, elevated IgE concentrations manifested in only four of seven tested AR STAT5B-deficient patients12,20,41 whereas eight of our nine AD STAT5B-deficient patients presented elevated IgE concentrations with the high penetrance, suggesting strong correlations between dominant actions of our STAT5B mutant proteins and IgE production. The gene discussed is STAT5B; the disease is Alzheimer disease.