CYP19A1 and endometriosis: Similarly, a significantly decreased risk for endometriosis was found in women who had at least a mutant allele of FSHR (genotype GG+GA, 680Ser/Ser+680Ser/Asn) and CYP19 (genotype TT+TC, 264Cys/Cys+264Cys/Arg) (P = 0.01; OR = 0.66) (Table 4).