Considering the role of FcγR proteins in modulating autoimmune responses but also the plausibility of a gender-specific effect of estrogens to modulate immune responses, we aimed at analyzing whether the presence of single nucleotide polymorphisms (SNPs) within steroid hormone signaling (ESR1, ESR2, NR1I2, PGR, and SHBG), phase I- and II-metabolizing enzyme (CYP1A1, CYP1A2, CYP1B1, CYP17A1, CYP2C9, CYP2C19, CYP3A4, GSTP1, HSD17B1 and SULT1A1) and Fc gamma receptor (FcγR3A and FCGR2A) genes influence disease progression in RA. The gene discussed is CYP1B1; the disease is rheumatoid arthritis.