Vitamin D receptor polymorphism among rickets children in Mongolia

Vitamin D receptor gene polymorphisms and the risk of rickets among Asians: a meta-analysis

AIMS

To evaluate the association between vitamin D receptor (VDR) gene polymorphisms and the risk of rickets among Asians.

METHODS

Eligible studies were included in our meta-analysis by searching PubMed, Embase, Cochrane and China National Knowledge Infrastructure databases according to a predefined criteria. A random effects model was used to calculate the combined ORs and its corresponding 95% CI.

RESULTS

16 studies were recruited for the analysis of the association between VDR BsmI (rs1544410), TaqI (rs731236), FokI (rs2228570) and ApaI (rs7975232) gene polymorphisms and the risk of rickets among Asians, most of whom were from China. B allele/BB genotype was associated with the susceptibility of rickets (p=0.017 and 0.044, respectively), and bb genotype was associated with lower risk of rickets (p=0.033). F allele/FF genotype was associated with the susceptibility of rickets (p<10(-4)), and ff genotype was associated with lower risk of rickets (p<10(-4)). AA genotype was associated with the onset of rickets (p=0.044). No significant association was observed between TaqI polymorphism the risk of rickets. A allele/aa genotype was not associated with the risk of rickets. No evidence of publication bias was observed.

CONCLUSIONS

B allele/BB genotype at the BsmI site, F allele/FF genotype at the FokI site and AA genotype at the ApaI site may be risk factors for the onset of rickets among Asians; bb genotype at the BsmI site and ff genotype at the FokI site may be protective factors against the risk of rickets among Asians.

Relationship between polymorphisms in vitamin D metabolism-related genes and the risk of rickets in Han Chinese children

Background

Vitamin D deficiency rickets is common in China. Genetic factors may play an important role in the susceptibility to rickets. Our study aimed to identify the relationship between three vitamin D-related genes (group specific component [GC], cytochrome P450, family 2, subfamily R, polypeptide 1 (CYP2R1), and 7-dehydrocholesterol reductase/nicotinamide-adenine dinucleotide synthetase 1 (DHCR7/NADSYN1) and rickets in Han Chinese children from northeastern China.

Methods

A total of 506 Han children from northeastern China were enrolled in the current study. Twelve SNPs in three candidate genes were genotyped using the SNaPshot assay. Linear regression was used to examine the effect of 12 single-nucleotide polymorphisms (SNPs) on the risk of rickets.

Results

In our case–control cohort, six alleles of the 12 SNPs conferred a significantly increased risk of rickets in GC (rs4588 C, P = 0.003, OR: 0.583, 95% CI: 0.412-0.836; rs222020 C, P = 0.009, OR: 1.526, 95% CI: 1.117-2.0985; rs2282679 A, P = 0.010, OR: 0.636, 95% CI: 0.449-0.900; and rs2298849 C, P = 0.001, OR: 1.709, 95% CI: 1.250-2.338) and in CYP2R1 (rs10741657 G, P = 0.019, OR: 1.467, 95% CI: 1.070-2.011; and rs2060793 G, P = 0.023, OR: 0.689, 95% CI: 0.502-0.944). The results remained significant after adjustment for sex and body mass index. We further analyzed the effect of genotypes under three different genetic models. After using Bonferroni’s method for multiple corrections, rs4588, rs2282679, and rs2298849 of the GC gene were significantly associated with rickets under the dominant (P =0.003 for rs4588, P =0.024 for rs2282679, and P =0.005 for rs2298849) and additive models (P = 0.006 for rs4588, P = 0.024 for rs2282679, and P = 0.005 for rs2298849). Haplotype analysis showed that the CAT haplotype of the GC gene (P = 0.005) and the GAA haplotype of the CYP2R1 gene (P = 0.026) were associated with susceptibility to rickets.

Conclusions

This case–control study confirmed the strong effect of GC and CYP2R1 loci on rickets in Han children from northeastern China.

Association of vitamin D-related gene polymorphisms with manifestation of vitamin D deficiency in children

The prevalence of vitamin D deficiency, presenting as hypocalcemic seizures or rickets in children, is increasing worldwide due to insufficient vitamin D intake and lack of exposure to sunshine. However, considering that relatively few children with low 25-hydroxyvitamin D [25(OH)D] levels manifest symptoms, it is possible that genetic factors may predispose individuals to vitamin D deficiency. Recent twin studies have reported that the level of serum of 25(OH)D is influenced by genetic factors. In addition, genome-wide association studies and candidate gene studies have revealed that several vitamin D-related genes, including VDR, GC, NADSYN1, CYP2R1, CYP24A1, CYP27B1, and C10orf88 contribute to variations in serum 25(OH)D levels. To investigate whether genetic predisposition contributes to vitamin D deficiency, we analyzed polymorphisms in vitamin D-related genes in 30 Japanese patients with vitamin D deficiency presenting at less than 4 years of age, along with 66 controls. A χ(2) test showed that the genotype frequencies of BsmI polymorphism in VDR and rs10898191 in NADSYN1 were significantly different between the two groups. The allele frequencies of BsmI, ApaI, TaqI in VDR, rs10898191 in NADSYN1, and rs705117 in GC were also significantly different. In particular, the frequency of the BAtS haplotype in VDR was significantly increased in the patient group relative to controls (p = 0.0014; odds ratio, 5.61; 95% confidence interval 1.92 - 16.40). Although this is a small study, our findings suggest that VDR, NADSYN1, and GC polymorphisms may be linked to the manifestation of vitamin D deficiency in Japanese children.

Predisposition to vitamin D deficiency osteomalacia and rickets in females is linked to their 25(OH)D and calcium intake rather than vitamin D receptor gene polymorphism

BACKGROUND

Osteomalacia (OSM) and rickets are widely prevalent in developing countries especially in females. The factors associated with such predisposition are not known.

OBJECTIVES

To identify nutritional, endocrine and genetic factors related to calcium and vitamin D metabolism that are associated with OSM/rickets in females.

SUBJECTS AND METHODS

We studied 98 patients with OSM or rickets and their relatives including male and female sibs and parents (n = 221) for the presence of biochemical OSM {low serum 25-hydroxyvitamin D [25(OH)D], raised intact PTH (iPTH) and raised alkaline phosphatase} and associated nutritional and genetic factors. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) was used for genotyping vitamin D receptor (VDR) (BsmI and FokI) and PTH gene (BstBI and DraII) single nucleotide polymorphisms (SNPs) in 74 families. The differences in the factors associated with calcium and vitamin D among the different groups were analysed by analysis of variance (ANOVA). Logistic regression analysis and the transmission disequilibrium test (TDT) were carried out to assess association between nutritional and genetic factors, and the disease, respectively.

RESULTS

Most of the patients were female (91.8%). The mean serum 25(OH)D level of the female patients was comparable to that of the female sibs (14.4 +/- 5.7 vs. 18.3 +/- 9.7 nmol/l). The frequency of biochemical OSM was fivefold higher in female than in male sibs (24.4%vs. 4.9%). Female sibs also had significantly lower 25(OH)D, dietary calcium intake and sunshine exposure than male sibs. The frequency of biochemical OSM was comparable between mothers and fathers. The odds of biochemical OSM in the family members was reduced by 11% per 15-min daily sunshine exposure [odds ratio (OR) = 0.89, 95% confidence interval (CI) = 0.81-0.98, P = 0.02] and decreased by 20% per 100 mg dietary calcium intake (OR = 0.80, 95% CI = 0.67-0.96, P = 0.02). VDR/PTH gene SNPs showed no association with OSM/rickets on TDT analysis.

CONCLUSION

Among the immediate family members of patients with OSM/rickets, female sibs have features of biochemical OSM in up to 24.4%. Female sibs, unlike male sibs, share with patients features of markedly low serum 25(OH)D levels, poor dietary calcium intake and poor exposure to sunshine. Genetic factors such as VDR and PTH gene SNPs were not associated with OSM/rickets.

Bone development in children living on house-boats on a river in Vietnam

Background

With the rapid urbanization of Vietnam, living on boats has come to be associated with underprivileged socioeconomic status, and there are major concerns regarding the health of children living under such conditions. Bone development is a critical concern in children because the foundation for skeletal health is established early in life. We evaluated the bone properties of children living under underprivileged conditions on boats in Hue City, Vietnam, with respect to a number of household factors.

Methods

One hundred and twenty children aged 7-11 years selected randomly from households living on boats in Hue were included in this study. Tibial and radial speed of sound (SOS) were measured by non-invasive quantitative ultrasonometry. Socioeconomic profiles, health promotion proficiency, and nutritional intake of households were assessed by structured interview. The bone properties of 60 children aged 7-11 living on land were also assessed as controls.

Results

The Z-scores of tibial and radial SOS of boat children were -0.16 ± 0.89 and -0.24 ± 0.75 (mean ± SD), respectively. Tibial SOS exhibited a significant correlation with radial SOS (r = 0.39, P < 0.01). Among the household factors examined, the educational level of fathers (P < 0.05) and the health promotion proficiency (P < 0.05) of households exhibited positive associations with the tibial bone properties of the children. The tibial and radial SOS of boat children were lower than those of children living on land (P = 0.001 and P = 0.086, respectively).

Conclusion

The results of the present study revealed the underdevelopment of bone properties in children living on houseboats, which was correlated with their living conditions.

Advances in vitamin D and inflammatory bowel disease

In respect of the comprehensive effect in immunologic regulation (on innate immunity and adaptive immunity) and antibacterial activity, vitamin D is in a high profile position in recent years. Despite the uncertain mechanism, it is a common sense that commensal enteric microbiota initiate and perpetuate immune-mediated bowel inflammation. This suggests that there may be a link between vitamin D's function and pathogenesis of inflammatory bowel disease, and vitamin D-associated agents may be prospective for treatment of inflammatory bowel disease.

Rickets in the Middle East: role of environment and genetic predisposition

CONTEXT

The Middle East has a high incidence of rickets, and it is also common in Europe-dwelling children of Middle Eastern origin.

OBJECTIVE

The objective of the study was to explore the mechanisms leading to rickets in children of the Middle East.

DESIGN AND SETTING

We conducted a prospective study in 98 rachitic and 50 controls (aged 6 months to 4 yr) from university and community outpatient hospitals in Egypt and Turkey.

MAIN OUTCOME MEASURES

We collected epidemiological, maternal, nutritional, radiographic, and biochemical parameters; markers of bone turnover; and vitamin D receptor (VDR) gene polymorphisms.

RESULTS

Epidemiological factors had a key role in pursuit of rickets; Egyptian and Turkish patients had lower (P < 0.01) dietary calcium intake than controls and the recommended dietary intakes, and serum 25-hydroxyvitamin D levels were reduced in patients, the difference with controls being significant (P < 0.001) only in Turkey, although rickets was more severe in Egypt as determined by the x-ray score (P < 0.05). In Turkey, the F VDR allele frequency was significantly (P < 0.05) increased in patients. The BB VDR genotype was associated with lower serum 25-hydroxyvitamin D levels in both patients and controls and with severity of rickets.

CONCLUSIONS

In Turkey most patients had vitamin D deficiency, whereas in Egypt they had mostly calcium insufficiency combined with vitamin D deficiency. In this environ, VDR genotypes may predispose to rickets by increased frequency of the F allele. The unique environs and genetic predisposition have to be accounted for in the design of preventive measures, rather than using European or American recommended dietary intake for calcium and vitamin D.