BsmI Restriction Fragment Length Polymorphisms Research Articles

Bone mineral status in ambulatory pediatric patients on long-term anti-epileptic drug therapy.

For ambulatory pediatric outpatients,reports of abnormalities of bone metabolism associated with anti-epileptic drugs are inconsistent and may be difficult to interpret. The effects of long-term anti-epileptic therapy (mainly valproic acid and/or carbamazepine) on bone mineral status were evaluated in ambulatory epileptic patients(seven males and 11 females) aged 5.5-15.9 years. Bone mineral density (BMD) at the lumbar spine was measured by dual-energy X-ray absorptiometry and markers of bone and mineral metabolism were determined. The mean BMD was decreased by 9% in our patients relative to the control, and five patients (all males)showed osteopenia, defined as BMD SD scores less than - 1.5. Serum levels of minerals, intact parathyroid hormone and 1alpha,25(OH)2 vitamin D were within the normal ranges. In most patients, serum levels of intact osteocalcin, carboxyterminal propeptide of type I procollagen and pyridinoline cross-linked telopeptide of type I collagen were reduced relative to the corresponding mean control values. The BB genotype by BsmI restriction fragment length polymorphism, associated with low BMD, was not found in our patients. The dietary calcium intake in the osteopenic patients was significantly lower than that of the non-osteopenic patients. Our results indicate that long-term anti-epileptic treatment induces a state of decreased bone turnover in children, resulting in osteopenia preferentially in males. The alterations may be due, at least in part, to direct effects of the drugs on bone cells; and that low calcium intake could be an aggravating factor for anti-epileptic-associated osteopenia.

Relation of BsmI vitamin D receptor gene polymorphism to bone mineral density and occurrence of osteoporosis in postmenopausal Chinese women in Taiwan.

Osteoporosis is a common disorder with a strong genetic component. Our aim was to evaluate the correlation of the vitamin D receptor gene intron 8 BsmI polymorphism with bone mineral density (BMD) and their relationship to osteoporosis. We determined the vitamin D receptor gene intron 8 BsmI polymorphfsm using polymerase chain reaction-based restriction analysis in 171 postmenopausal Chinese women in Taiwan. The polymorphism was detected using the restriction enzyme BsmI, where the B allele indicated absence of the cuttable site and the b allele its presence. BMD of the lumbar spine and proximal femur were measured using dual-energy X-ray absorptiometry. The allelic frequencies for postmenopausal Chinese women in Taiwan were 12.3% for B and 87.7% for b in BsmI restriction fragment length polymorphisms. The prevalence of each genotype in the study population was: 6.4% BB, 11.7% Bb and 81.9% bb. The three genotypic groups differed significantly in BMD at the lumbar spine and the femoral neck. These differences corresponded to significant gene-dose effects at the lumbar spine and femoral neck (p<0.001 for both sites). The relative risk for the development of osteoporosis was about 2-3 times as great as that predicted by the differences between genotypes in BMD, and remained significant even after adjustment for age, height and weight. The vitamin D receptor gene intron 8 BsmI polymorphism is associated with reduced BMD and predisposes women to osteoporosis.

Vitamin D and estrogen receptor polymorphisms and bone mineral changes in postpartum women.

BsmI restriction fragment length polymorphism (RFLP) of the vitamin D receptor (VDR) gene and PvuII RFLPs of the estrogen receptor (ER) gene and their relation to changes in areal bone mineral density (BMD) were examined in 43 healthy postpartum Finnish women aged 31.3 (SD 4.7) years. BMD was measured by dual energy X-ray absorptiometry at lumbar spine, right femoral neck, and dominant distal radius immediately after delivery, 1 month after resumption of menses, and 1 year thereafter. The RFLPs were represented as Bb (BsmI) and Pp (PvuII), the capital letters denoting the absence of and the small letters the presence of the restriction sites. The frequency of VDR alleles was as follows: bb (20.9%), Bb (60.5%), and BB (18.6%), and that of ER alleles was pp (39.5%), Pp (51.2%), and PP (9.3%). Altogether, BMD decreased significantly during postpartum amenorrhea at all sites [the mean bone loss ranging from -1.2 (SD 3.6)% at the distal radius to -3.7 (2.9)% at the femoral neck], and increased after resumption of menses [the 1-year follow-up BMD values ranging from -1.0 (2.4)% at the femoral neck to +3.3 (4.0)% at the lumbar spine as compared with baseline]. No obvious genotype-related differences were found between these changes. These results suggest that the BsmI and PvuII polymorphisms may not have substantial influence on BMD changes postpartum.

Consequences of vitamin D receptor gene polymorphisms for growth inhibition of cultured human peripheral blood mononuclear cells by 1, 25-dihydroxyvitamin D3.

In the vitamin D receptor (VDR) gene a BsmI restriction fragment length polymorphism (RFLP) in intron 8 and a translational start-site polymorphism, identified as a FokI RFLP, have been described. Crucial for a proper interpretation of these polymorphisms in association studies is the knowledge whether they have direct consequences for 1,25-(OH)2D3 action at cellular level. The present study was designed to assess functional significance of the FokI and BsmI VDR gene polymorphisms in peripheral blood mononuclear cells (PBMC) with a natural occurring VDR genotype for cell growth inhibition by 1,25-(OH)2D3. PBMC of women were isolated, VDR genotyped and in vitro inhibition by 1,25-(OH)2D3 of Phytohemagglutinin (PHA)-stimulated growth of PBMC was examined in relation to VDR genotype. PHA-stimulated growth and maximal growth inhibition were independent of VDR genotype. However, the FF genotype had a significant lower ED50 than the Ff genotype corresponding to an allele dose effect of 0.32 nM per f allele copy (P = 0.0036). For BsmI genotypes no differences in ED50 were observed. The present study demonstrates for the first time in cells with a natural VDR genotype a direct functional consequence of the VDR gene translational start-site polymorphism for the action of 1,25-(OH)2D3. Especially under conditions of vitamin D insufficiency these findings might have clinical implications.

Identification of a novel Tru9 I polymorphism in the human vitamin D receptor gene.

We found a novel Tru9 I restriction polymorphism in intron 8 of the vitamin D receptor (VDR) gene in healthy French Caucasians. It corresponds to a substitution of A for G at nucleotide +443 bp from the end of exon 8. The allelic frequency of G and A in 151 unrelated subjects was 0.894 and 0.106, respectively. This polymorphism is located in the reverse primer binding site of primers that have been frequently used in the literature to genotype a BsmI restriction polymorphism. The presence of the Tru9I A allele may result in allele drop-out when the BsmI restriction fragment length polymorphism (RFLP) is genotyped with the original set of primers. This novel Tru9I polymorphism may be useful for analysis of the VDR gene.

Early and late postmenopausal bone loss is associated with BsmI vitamin D receptor gene polymorphism in Japanese women.

To determine whether vitamin D receptor (VDR) gene polymorphisms are associated with bone mineral density (BMD) and bone loss in the Japanese population, VDR BsmI RFLPs were analyzed in 191 postmenopausal Japanese women by comparing B allele and b allele DNA sequences, and a point mutation was confirmed. We examined VDR BsmI restriction fragment length polymorphism (RFLP) with an amplification refractory mutation system (ARMS) using this point of mutation. The frequency of VDR BsmI alleles in the Japanese population was significantly different from that in whites. The bb genotype was identified in 79.6%, of the subjects, the Bb genotype in 19.3%, and the BB genotype was in only 1.1%. We find no significant differences in lumbar spine baseline BMD between the bb genotype and the Bb genotype. In both early and late postmenopausal periods, serial measurements of vertebral BMD revealed that subjects with the Bb genotype lost BMD faster than those with the bb genotype (P = 0.001). We conclude that there is a significant relationship between RFLPs of BsmI VDR and the annual rates of bone loss during early and late postmenopausal periods in the Japanese population.

Does Vitamin D Receptor Polymorphism Influence the Response of Bone to Brisk Walking in Postmenopausal Women?

Vitamin D receptor (VDR) polymorphism may be a genetic factor affecting bone mineral density (BMD). This study examined the interaction of VDR genotype with the effect of an exercise intervention on bone measurements in UK postmenopausal women. 33 walkers, who completed 20.4 ± 3.9 (mean ± SD) min day^–1 of brisk walking over 1 year, and 36 controls agreed to give DNA samples. BMD was measured at the lumbar spine, femoral neck and calcaneus by dual energy X-ray absorptiometry and broadband ultrasonic attenuation (BUA) was measured at the calcaneus. VDR genotype was determined by BsmI restriction fragment length polymorphisms and the presence, or absence, of the restriction site was signified by ‘b’ or ‘B’, respectively. At baseline there was no significant difference in BMD between VDR genotypes, but BUA was significantly higher in the BB genotype than in the Bb or bb genotype. Although there was no significant difference in 1-year change (%) in BMD and BUA between the three genotypes, the 1-year changes in spinal BMD and BUA in the bb walkers (0.75 and 2.35%, respectively) were significantly different from those in the bb controls (–1.25 and –6.10%, respectively). These results suggest that in the bb genotype of VDR, bone may be more responsive to exercise than in other VDR genotypes in British postmenopausal women.

Bone mineral density and its change in white women: estrogen and vitamin D receptor genotypes and their interaction.

Low bone mineral density (BMD) is a major risk factor for development of osteoporosis; increasing evidence suggests that attainment and maintenance of peak bone mass as well as bone turnover and bone loss have strong genetic determinants. We examined the association of BMD levels and their change over a 3-year period, and polymorphisms of the estrogen receptor (ER), vitamin D receptor (VDR), type I collagen, osteonectin, osteopontin, and osteocalcin genes in pre- and perimenopausal women who were part of the Michigan Bone Health Study, a population-based longitudinal study of BMD. Body composition measurements, reproductive hormone profiles, bone-related serum protein measurements, and life-style characteristics were also available on each woman. Based on evaluation of women, ER genotypes (identified by PvuII [n = 253] and XbaI [n = 248]) were significantly predictive of both lumbar spine (p < 0.05) and total body BMD level, but not their change over the 3-year period examined. The VDR BsmI restriction fragment length polymorphism was not associated with baseline BMD, change in BMD over time, or any of the bone-related serum and body composition measurements in the 372 women in whom it was evaluated. Likewise, none of the other polymorphic markers was associated with BMD measurements. However, we identified a significant gene x gene interaction effect (p < 0.05) for the VDR locus and PvuII (p < 0.005) and XbaI (p < 0.05) polymorphisms, which impacted BMD levels. Women who had the (-/-) PvuII ER and bb VDR genotype combination had a very high average BMD, while individuals with the (-/-) PvuII ER and BB VDR genotype had significantly lower BMD levels. This contrast was not explained by differences in serum levels of osteocalcin, parathyroid hormone, 1,25-dihydroxyvitamin D, or 25-dihydroxyvitamin D. These data suggest that genetic variation at the ER locus, singly and in relation to the vitamin D receptor gene, influences attainment and maintenance of peak bone mass in younger women, which in turn may render some individuals more susceptible to osteoporosis than others.