OBJECTIVETo investigate the effect of interleukin-6 (IL-6) and calcium sensing receptor (CASR) gene polymorphisms on bone mass accrual in Chinese adolescent girls.

METHODSA total of 228 premenarche Chinese girls (9-11.5 years) were recruited for a 2-year study. Bone mineral densities (BMD) and Bone mineral contents (BMC) in the total body, total left hip including femoral neck, trochanter, intertrochanter and Ward's triangle area, and lumbar spine (L1-L4) were measured by DEXA. The -634C/G polymorphism of IL-6 gene was detected by PCR-restriction fragment length polymorphism and A986S polymorphism of CASR gene was detected by allele-special mutagenically separated amplication-PCR.

RESULTSThere were 176 available subjects when the 2-year study was completed. The -634C/G polymorphism of IL-6 gene and A986S polymorphism of CASR gene were significantly associated with bone mass accrual after adjusting the potential confounding factors. Girls with CC genotype of IL-6 -634G/C gene had higher percentage of increase in BMD of total body (P= 0.027) and femoral trochanter (P= 0.028) than those with CG+ GG genotypes. Girls with AA genotype of CASR gene had greater percentage of increase in L1-L4 lumbar spine BMC (P= 0.022) and Ward's triangle area BMD (P= 0.049) than their AS+ SS counterparts. Subjects with G allele of IL-6 gene in combination with S allele of CASR gene had less increase in BMC of femoral neck and L1-L4 lumbar spine.

CONCLUSIONAdolescent girls carrying the G allele of IL-6 gene at -634C/G and S allele of CASR gene at A986S could potentially be the risk population of lower bone mass accrual.