[Study on the relationship between some genetic factors and peak bone mineral density in Beijing young women]

To evaluate the relationship between the peak bone mineral density (PBMD) and vitamin D receptor (VDR), estrogen receptor (ER) allelic variants in Beijing young women.

From March, 2000 to July, 2001, one hundred and fifty-nine young healthy women (25 - 37 years old) in Beijing were voluntarily enrolled in the study. (1) BMD were measured by dual energy X-ray absorptiometry (DXEA) at lumbar and hip. (2) The polymorphism of VDR and ER genes were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). (3) The relationship between BMD and polymorphism of VDR and ER genes were examined.

(1) Lumber BMD was positively correlated to height, weight and body mass index (BMI), whereas, the femoral neck BMD only to weight, and the other sites of hip BMD to BMI. (2) Although subjects with the VDR bb genotype had higher BMD than those with Bb genotype at lumber, femoral neck, inter and troch, no significant difference was found (P > 0.05). (3) In Ward triangle, subjects with ER PP genotype had significantly lower BMD than those in ER Pp and pp genotypes (P < 0.05). (4) Women with BbPP genotype combination had lower BMD levels at lumber and hip, and with bbPP and Bbpp genotypes combination significantly higher lumber BMD levels than BbPP genotype (P < 0.05). However, the differences of BMD among subjects with different VDR and ER genotypes became not significant after adjusting the confounder of body weight.

(1) Body weight and BMI play important roles to PBMD of Beijing women. (2) There was no significant difference of BMD levels between VDR genotypes at any site. (3) PvuII polymorphism of ER gene was associated with low Ward triangle BMD. (4) There was significant relationship between the combination of ER and VDR polymorphisms at lumbar and hip BMD. Our data suggest that genetic variation at the ER locus, singly and in relation to the VDR locus, may influence the attainment and maintenance of peak bone mass in young women.