Effects of ACE gene polymorphism on vitamin D therapy according to parathyroid hormone level in patients on hemodialysis

SNP rs11185644 of RXRA gene is identified for dose-response variability to vitamin D3 supplementation: a randomized clinical trial

The level of serum 25-Hydroxyvitamin D [25(OH)D] has high heritability, suggesting that genes may contribute to variations in serum 25(OH)D level and vitamin D dose-response. As vitamin D deficiency has been linked to numerous diseases, understanding how genetic variation contributes to vitamin D dose-response is important for personalized vitamin D treatment and cost-effective disease prevention. To identify genetic variants responsible for vitamin D status and dose-response, we performed two vitamin D3 and calcium clinical supplementation trials in 2,207 postmenopausal Caucasian women. We examined the association of 291 SNPs with baseline serum 25(OH)D levels and 25(OH)D dose-response. Five SNPs, rs10500804 (P = 4.93 × 10⁻⁷), rs2060793 (P = 6.63 × 10⁻⁷), rs10741657 (P = 1.49 × 10⁻⁶), rs10766197 (P = 1.05 × 10⁻⁵) and rs11023380 (P = 7.67 × 10⁻⁵) in the CYP2R1 gene, as well as 6 SNPs, rs4588 (P = 7.86 × 10⁻⁷), rs2298850 (P = 1.94 × 10⁻⁶), rs1155563 (P = 6.39 × 10⁻⁶), rs705119 (P = 2.80 × 10⁻⁵), rs705120 (P = 1.08 × 10⁻⁴) and rs222040 (P = 1.59 × 10⁻⁴) in the GC gene were associated with baseline serum 25(OH)D levels. SNP rs11185644 near the RXRA was significantly associated with 25(OH)D dose-response (P = 1.01 × 10⁻⁴). Our data suggest that polymorphisms in the CYP2R1 and GC gene may contribute to variation in baseline serum 25(OH)D concentration, and that polymorphism rs11185644 may contribute to variation in 25(OH)D dose-response in healthy postmenopausal Caucasian women.

Vitamin D receptor genotypes influence quadriceps strength in chronic obstructive pulmonary disease

BACKGROUND

Quadriceps weakness is an important complication of chronic obstructive pulmonary disease (COPD) and is associated with impaired exercise capacity and greater mortality. Its etiology is multifactorial, and evidence is growing that it is partly determined by genetic susceptibility.

OBJECTIVE

Using an established cohort, we tested whether quadriceps weakness in patients with COPD is influenced by common variations in the gene for the vitamin D receptor.

DESIGN

Vitamin D receptor FokI and BsmI genotypes and the (I/D) angiotensin-converting enzyme (ACE) and bradykinin receptor (+9/-9) genotypes were identified in 107 patients with stable COPD [x +/- SD forced expiratory volume in 1 s (FEV(1)): 34.5 +/- 16.5] and 104 healthy, age-matched control subjects. Quadriceps maximum voluntary contraction force and fat-free mass assessed by bioelectrical impedance analysis were measured.

RESULTS

After adjustment for covariables, both patients and control subjects who were homozygous for the C allele of the FokI polymorphism had less quadriceps strength than did those with > or =1 T allele [41.0 +/- 11.8 compared with 46.0 +/- 13.2 kg (P = 0.01) and 32.5 +/- 11.2 compared with 36.2 +/- 13.1 kg (P = 0.005), respectively]. The b allele of the BsmI polymorphism was associated with greater quadriceps strength in patients-37.0 +/- 13.3, 33.8 +/- 11.6, and 33.8 +/- 11.6 kg for bb, bB, and BB, respectively (P = 0.0005)-but had no effect in healthy control subjects. The effect of BsmI on quadriceps strength was least apparent in patients with the ACE II genotype (P = 0.003).

CONCLUSIONS

The FokI common variants in the VDR gene are associated with skeletal muscle strength in both patients and control subjects, whereas the BsmI polymorphism is associated with strength only in patients.