Low bone mineral density and vitamin d deficiency correlated with genetics and other bone markers in female Turkish immigrants in Germany

Abstract

Patients with osteoporosis have a low bone mass resulting in an increased risk for bone fractures, morbidity and mortality. One hundred thirty-one female pre-menopausal participants (98 Turkish immigrants living in Germany in comparison with 33 age-matched healthy Germans) were recruited for this study which explored vitamin D deficiency and specific genetic modifications of bone metabolism. The subjects were investigated for their femoral and lumbar bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) of the right total femur and the lumbar spine. Serum levels of osteologic parameters were determined: parathormone (PTH), calcium (Ca), osteocalcin (OC), phosphate (P), alkaline phosphatase (AP), beta-crossLaps (CL), tartrate-resistant acid phosphatase isoform 5b (TRAP5b), and 25-vitamin D₃ (25-OH D₃). The Bsml- and Fokl-polymorphisms of the vitamin D receptor (VDR) gene and the collagen type I alpha 1 (COLIA1)-gene polymorphism were also genotyped. An extremely high prevalence of vitamin D deficiency could be found in the immigrant cohort (87.8 %). Osteoporosis but not osteopenia was more prevalent in this group. Among immigrants with osteoporosis, TRAP5b was elevated in 42.9 % and beta-CL in 28.6 %. Only the Fokl FF-genotype of the VDR polymorphism was significantly more prevalent among the Turkish women, Ff-genotyped immigrants showed significantly decreased BMD. A significant correlation between the COLIA1-gene polymorphism and BMD could not be identified in the two groups. Vitamin D deficiency and osteoporosis appear to be dominant and unrecognized problem among female Turkish immigrants in Germany. Therefore, in this population, osteologic parameters and BMD should be routinely analyzed and deficiencies be treated immediately.

Keywords: Bone markers; Bone metabolism; Female Turkish immigrants; Genetic modifications; Low bone mineral density.