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Open Access Research article

Vitamin D receptor initiation codon polymorphism influences genetic susceptibility to type 1 diabetes mellitus in the Japanese population

Yoshiyuki Ban1*, Matsuo Taniyama1, Tatsuo Yanagawa2, Satoru Yamada3, Taro Maruyama4, Akira Kasuga5 and Yoshio Ban1

Author Affiliations

1 Third Department of Internal Medicine, Showa University School of Medicine, Tokyo, Japan

2 Department of Medicine, Nerima General Hospital, Tokyo, Japan

3 Department of Medicine, Saiseikai Central Hospital, Tokyo, Japan

4 Department of Medicine, Saitama Social Insurance Hospital, Saitama, Japan

5 Department of Medicine, Tokyo Denryoku Hospital, Tokyo, Japan

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BMC Medical Genetics 2001, 2:7  doi:10.1186/1471-2350-2-7

Published: 25 June 2001

Abstract

Background

Vitamin D has been shown to exert manifold immunomodulatory effects. Type 1 diabetes mellitus (T1DM) is regarded to be immune-mediated and vitamin D prevents the development of diabetes in the NOD mouse. We studied the association between T1DM and the initiation codon polymorphism in exon 2 of the vitamin D receptor gene in a Japanese population. We also investigated associations between the vitamin D receptor polymorphism and GAD65-antibody (Ab) positivity. We carried out polymerase chain reaction-restriction fragment length polymorphism analysis in 110 Japanese T1DM patients and 250 control subjects. GAD65 antibodies were assessed in 78 patients with T1DM.

Results

We found a significantly higher prevalence of the F allele / the FF genotype in the patients compared to the controls (P = 0.0069 and P = 0.014, respectively). Genotype and allele frequencies differed significantly between GAD65-Ab-positive patients and controls (P = 0.017 and P = 0.012, respectively), but neither between GAD65-Ab-negative patients and controls (P = 0.68 and P = 0.66, respectively) nor between GAD65-Ab-positive and -negative patients (P = 0.19 and P = 0.16, respectively).

Conclusions

Our findings suggest that the vitamin D receptor initiation codon polymorphism influences genetic susceptibility to T1DM among the Japanese. This polymorphism is also associated with GAD65-Ab-positive T1DM, although the absence of a significant difference between GAD65-Ab-negative patients and controls might be simply due to the small sample size of patients tested for GAD65 antibodies.