RT Journal A1 Purtilo DT, Sullivan JL T1 IMmunological bases for superior survival of females JF American Journal of Diseases of Children JO American Journal of Diseases of Children YR 1979 FD December 1 VO 133 IS 12 SP 1251 OP 1253 DO 10.1001/archpedi.1979.02130120043008 UL http://dx.doi.org/10.1001/archpedi.1979.02130120043008 AB • Evolutionary selection has equipped females with immunoregulatory genes on the × chromosome for coping with lifethreatening illness. Five immunodeficiency syndromes occur solely in males, suggesting that they arise from mutant immunoregulatory genes located on the × chromosome. These syndromes, although rare, could contribute to poorer survival of males. Females have higher serum IgM concentrations, superior ability to form antibodies to infectious agents, and experience a lower incidence of viral and bacterial infectious diseases. Preponderance of autoimmune disorders in females could arise from modified immune responses owing to estrogens. Clinical and animal studies indicate that male hormones suppress autoantibody production whereas female hormones support their production. Superior immunocompetence and survival of females is based, in part, on their being protected from mutant immunoregulatory genes located on the × chromosome.(Am J Dis Child 133:1251-1253, 1979)