Associations between serum bone-specific alkaline phosphatase activity, biochemical parameters, and functional polymorphisms of the tissue-nonspecific alkaline phosphatase gene in a Japanese population

Introduction: We had demonstrated that single nucleotide polymorphism (787T>C) in the tissue-nonspecific ALP (TNSALP) gene was associated with the bone mineral density (BMD). BMD was the lowest among TNSALP 787T homozygotes (TT-type) and highest among TNSALP 787T>C homozygotes (CC-type) in postmenopausal women. In the present study, we investigated the effects of the TNSALP genotype on associations among serum bone-specific alkaline phosphatase (BAP), serum calcium, and phosphorus in healthy young Japanese subjects. Methods: Young healthy adult subjects (n=193) were genotyped for the polymorphism, and we measured the levels of serum BAP, serum calcium, and phosphorus. Dietary nutrient intakes were calculated based on 3-day food records before the day of blood examinations. Results: Grouped by the TNSALP genotype, a significant negative correlation between serum BAP and phosphorus was observed in 787T>C homozygotes (CC-type), but not in heterozygotes (TC-type), nor in 787T homozygotes (TT-type). Conclusions: In the present study, we revealed that the single nucleotide polymorphism 787T>C in the TNSALP gene had effects on the correlation between serum BAP and phosphorus in young adult subjects. These results suggest that variation in TNSALP may be an important determinant of phosphate metabolism. Our data may be useful for planning strategies to prevent osteoporosis.