Histidine decarboxylase gene (HDC) encodes histidine decarboxylase which is the crucial enzyme for the biosynthesis of histidine. Studies have shown that histamine is likely to be involved in the regulation of reproduction system. To find the possible correlation between HDC gene and AANM (age at natural menopause), we selected 265 postmenopausal women from 131 nuclear families and performed a transmission disequilibrium test. Significant within-family associations with AANM for SNP rs854163 and SNP rs854158 of HDC gene were observed (P values = 0.0018 and 0.0197, respectively). After 1000 permutations, SNP rs854163 still remained significant within-family association with AANM. Consistently, we also detected a significant within-family association between haplotype block 2 (defined by SNP rs854163 and rs860526) and AANM in the haplotype analyses (P value = 0.0397). Our results suggest that the HDC gene polymorphisms are significantly associated with AANM in Caucasian women.
KeywordsHDC; Association; Age at natural menopause; SNP Menopause status is one important anthropological variable influencing the overall health of women, especially those in advanced ages. Abnormal low age at natural menopause (AANM) correlates with female infertility due to ovarian aging [1]. Early menopause was also reported to be associated with the increased risks of fracture [2,3], coronary heart disease [4,5], and disorders of the central nervous system [6,7]. In addition, the Caucasian women with menopause ages of about 40-44 years have 4% higher risk of mortality than those with menopause ages of about 50-54 years [8].There is a wide variation in AANM, varying between 40 and 60 years. Extensive studies have been conducted to search for the predictors of AANM. Some lifestyle factors were reported to be associated with AANM, such as obesity, smoking, alcohol consumption, and breastfeeding [9][10][11]. However, these lifestyle factors just accounted for a small part of the large variation in AANM [12]. Additionally, genetic factors were found to play an important role in the variation of AANM. Family study showed that the menopausal ages of daughters were significantly correlated with mothers' [13]. Heritability estimates of AANM ranged from 0.63 to 0.87, suggesting a strong genetic control [14][15][16]. To date, the exact genes involved remain unknown, though some candidate genes underlying AANM have been proposed, such as ESR1 (estrogen receptor alpha), CYP1B1 (cytochrome P450, family 1, subfamily B, poly-peptide 1), Factor V Leiden, and FMR1 (fragile X mental retardation 1) [17][18][19][20].Histidine decarboxylase (HDC) gene encodes histidine decarboxylase, which is the crucial enzyme for synthesis of histamine in human body. As an important bioactive substance, histamine is crucial to various physiological activities [21]. It has been found that histamine directly stimulated the secretion of GnRH (gonadotropin-releasing hormone), which is the key molecule in the regulation of gonadal hormone release [22]. Furthermore, st...