At least three mechanisms have been suggested for the etiology of 46,XX male DSD: (i) Translocation of Y chromosome including the SRY gene on the X chromosome or on autosomal chromosomes, (ii) X-linked mutation/overexpression in the genes that cause testis differentiation or mutation/overexpression in autosomal genes [e.g. SRY box-related gene 9 (SOX9)] in SRY negative XX males, and (iii) secret Y mosaicism found only in the gonads (1). The gene discussed is SRY; the disease is disorder of sexual differentiation.