Objective: Aromatase cytochrome P45019 (CYP19) is a key enzyme in estrogen biosynthesis, and polymorphisms within its gene are associated with an increased risk of estrogen-dependent diseases. Enhanced estrogen stimulation of breast tissue in men may lead to gynecomastia. We assessed whether intron 4 (TTTA)n repeat and TCT deletion/insertion polymorphisms and an exon 10 (3'-UTR) C/T single nucleotide polymorphism of CYP19 are associated with gynecomastia.
Design/methods: We performed a genetic association study of 100 patients referred to the endocrinological outpatient clinic with breast glandular tissue enlargement confirmed by clinical and ultrasound examinations and 99 healthy volunteers without gynecomastia. Microsatellite (TTTA)n and insertion/deletion polymorphisms were studied using capillary electrophoresis, and the C/T polymorphism in the 3'-UTR was analyzed using the TaqMan assay.
Results: Significantly increased risk of gynecomastia was found in subjects carrying a CYP19 exon 10 T allele that was previously related to the high aromatase activity. Frequency of the TT genotype was significantly higher in patients when compared with controls (40.6 vs 26.3%; TT versus CT and CC genotypes; P(c)<0.05). We found strong linkage disequilibrium between the alleles of studied polymorphic loci. T allele in the 3'-UTR was in linkage disequilibrium with the long alleles of the intron 4 polymorphism, mainly (TTTA)11. However, our findings did not show significant correlation of alleles having more than nine TTTA repeats with gynecomastia.
Conclusions: The CYP19 polymorphisms might contribute to the incidence of gynecomastia, but further studies in larger groups are needed to confirm these results.