Association analyses suggest the effects of RANK/RANKL genes on age at menarche in Chinese

Abstract

OBJECTIVE: Age at menarche (AAM), time of first menstrual period, is an important developmental milestone in the female life. In previous studies, RANK (receptor activator of the NF-kB) and RANKL (receptor activator of the NF-kB ligand) were indentified with association of AAM in the Caucasian population. In this study, we conducted association analyses of single nucleotide polymorphisms (SNPs) of RANK and RANKL genes with AAM in Chinese women. METHODS: The total sample consisted of 825women in Changsha, Xi'an and adjacent areas in China. The data of AAM were collected by questionnaire including questions about anthropometric variables, lifestyle, and medical history. Genomic DNA was isolated from leukocytes of peripheral blood using a commercially supplied kit. The SNPs were genotyped using Affymetrix SNP Array 6.0 Set. The association of the SNPs with AAM was analyzed by univariate analysis of variance with Bonferroni correction. The effects of the significant genes on AAM were estimated by linear regression models. The LD patterns of these genes were analyzed using the Haploview program. Then PLINK software was used for analyses of haplotype block association. RESULTS: The mean±SE AAM of the participants was 13.9±0.1 years. In total, 23 SNPs located in or close to RANK and 73 SNPs for RANKL were genotyped. All studied SNPs indicated no deviation from the Hardy–Weinberg equilibrium. Five SNPs in RANK gene showed significant association with AAM: rs7239261 (p=0.006), rs8094884 (p=0.009), rs3826620 (p=0.018), rs8089829 (p=0.034), and rs9956850 (p=0.046). Among these SNPs, rs3826620 was replicated and associated with AAM in our previous study in 306 independent healthy Caucasian females (p=0.022). The contribution of rs7239261, rs8094884, rs3826620, rs8089829, and rs9956850 to the variation ofAAMin Chinesewas 0.5%, 0.7%, 0.2%, 0.3% and 0.1%, respectively. However, no SNPs remained significant after the correction for multiple testing in Chinese. Seven haplotypes of RANK genewere found to be significantly associated with AAM. Three haplotype blocks of RANKL were associated with AAM. An average contribution of each haplotype of RANK and RANKL genes to the variation of AAM in Chinese females was approximately 0.8% and 0.56%, respectively. CONCLUSIONS: This is the first study on RANK and RANKL genes for AAM in Chinese. Our results suggested that RANK and RANKL genes are involved in AAM in different ethnic populations. However, this research warrants the necessity of further more extensive studies.