25-hydroxyvitamin D level and vitamin D gene polymorphisms in Korean youth with type 1 diabetes mellitus

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 796-817-Diabetes Genetics & Epidemiology
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-814
Hyo-Kyoung Nam*1, Joon Woo Baek2, Yeon Joung Oh3, Young Jun Rhie4 and Kee-Hyoung Lee1
1Korea University College of Medicine, Seoul, South Korea, 2Korea University College of Medicine, 3Hallym University Kangnam Sacred Heart Hospital, 4Korea University Ansan Hospital, Korea University College of Medicine, Ansan-si, Gyeonggi-do, South Korea
Objectives: Vitamin D is needed for insulin secretion. A low vitamin D level has been associated with increased risk of diabetes mellitus (DM), but the association has not been evaluated in Asian children and adolescents. The aim of this study was to assess the vitamin D status and to investigate the association of CYP2R1 and CYP27B1 gene polymorphisms in youth with type 1 DM.

Patients and Methods: We measured serum level of 25-hydroxyvitamin D (25-OHD) and 1α,25-dihydroxyvitamin D (1α,25-(OH)2D) in 252 subjects (96 patients with T1DM and 156 controls) and defined vitamin D deficiency as 25-hydroxyvitamin D level below 20 ng/ml. Five single nucleotide polymorphisms (SNPs) in the CYP2R1 gene and three SNPs in the CYP27B1 gene were examined.

Results: Mean value of 25-OHD and 1α,25-(OH)2D was significantly lower in youth with type 1 DM compared to those of normal controls (19.8 ± 7.2 ng/ml vs. 25.1 ± 8.9 ng/ml, p < 0.001 and  32.7 ± 13.0 pg/ml vs. 39.6 ± 17.2 pg/ml, p < 0.01, respectively). Prevalence of vitamin D deficiency was considerably higher in type 1 DM (54.2% vs. 32.1%, p < 0.01) and the serum 25-OHD level was negatively correlated with age. The GG genotype of rs12794714 was significantly more frequent in youth with type 1 DM (45.8% vs. 30.1%, p = 0.040) and patients also had higher frequencies in the allele G of rs12794714 and the allele A of rs10766196 (65.6% vs. 54.8%, p = 0.017 and 64.6% vs. 55.1%, p = 0.036, respectively). In AA genotype of rs12794714 and GG genotype of rs10766196 in patients with type 1 DM, the prevalence of vitamin D deficiency were considerably lower than those lacking them.

Conclusions: Two SNPs of CYP2R1 were identified with significant differences in allele frequencies and the prevalence of vitamin D deficiency were significantly lower in type 1 DM patients with these polymorphisms than patients lacking them. The pathophysiological mechanisms remain unexplained, but vitamin D polymorphisms could be related to susceptibility of type 1 DM in Korean youth.

Nothing to Disclose: HKN, JWB, YJO, YJR, KHL

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