Effect of GGCX gene polymorphism on the responses of serum undercarboxylated osteocalcin and bone turnover markers after treatment with vitamin K2 (menatetrenone) among postmenopausal Thai women.

The purpose of this study was to evaluate the influence of gamma-glutamyl transferase (GGCX) gene polymorphisms on the response of serum undercarboxylated osteocalcin (ucOC) and bone turnover markers 3 months after treatment with menatetrenone. One hundred and forty postmenopausal Thai women were enrolled and assigned to receive 45 mg/day treatment of menatetrenone (MK-4) concurrently with calcium 1.2 g and vitamin D 400 IU for 3 months. Demographic characteristics, GGCX genotyping, serum bone turnover markers and ucOC levels were obtained from all participants at baseline. We evaluated the reduction of ucOC at 3 months and the reduction of beta-CTx and P1NP at 1 and 3 months. The responses were compared between the different genotypes of GG and GA + AA groups. There was a significant reduction of serum ucOC, beta-CTx and P1NP from the baseline at 3 months (p < 0.001) though there was no significant difference between genotypes (GG vs. GA + AA; p > 0.05). Nonetheless, a subgroup analysis of postmenopausal women who 65 years of age or over (N = 37) revealed a significant difference between the two groups in the reduction of ucOC. Menatetrenone significantly reduced serum ucOC as well as beta-CTX and P1NP from the baseline. GGCX polymorphism appeared to have an influence over the reduction of ucOC especially in older women (age ≥65). Furthermore, the groups which have "A" allele trend to being more efficient in reducing the serum ucOC level than the group which does not have it.