Association of CYP19A1 single-nucleotide polymorphism with digit ratio (2D:4D) in a sample of men and women from Ningxia (China)

Objectives: 2D:4D is an anthropometric indicator that may reflect the level of intrauterine sexual hormone exposure before birth. The aromatase gene (CYP19A1) mainly encodes cytochrome P450 aromatase, a key enzyme that catalyzes the conversion of androgens to estrogens in vivo and affects the development of 2D:4D. Studying the association between six single-nucleotide polymorphisms (SNPs) in CYP19A1 and digit ratios in the normal population of China will provide some basis for the biological basis of digit ratio development and promote the practical application of digit ratios. Methods: In this study, six SNPs (rs10046, rs2414095, rs4646, rs4775936, rs749292 and rs936306) in CYP19A1 were tested in 1949 students (692 males and 1247 females) by TaqMan SNP genotyping in Ningxia, China. The digit ratios (right and left 2D:4D and right-left 2D:4D [Dr-l]) of all participants were collected using a photographic record. Results: The frequencies of the genotypes rs2414095 (P < 0.05), rs10046 (P < 0.01) and rs4775936 (P < 0.05) in the CYP19A1 gene and their allele frequencies were significantly different between the Hui and Han populations, and the frequency of the rs2414095 genotype (P < 0.05) was significantly different between males and females in Ningxia, China. There was a sex difference in right and left 2D:4D and in Dr-l. There was no significant association between the six SNPs of the CYP19A1 gene and right and left 2D:4D, although rs4775936 showed a lower 2D:4D ratio in allele T than in allele C, in both male and female subjects. For Dr-l we found that rs4775936 associated with increased Dr-l in females (t(787) = -2.441, P < 0.05). Conclusions: We found the different frequencies of rs10046, rs2414095 and rs4775936 between Hui and Han populations in China. There was an association between rs4775936 and Dr-l We discuss the implications of this association for links between Dr-l and rs4775936 and prenatal sex steroids and for susceptibility to breast cancer.