CYP24A1 polymorphisms and its influence on 25(OH)D3 and 1,25(OH)2D3 serum levels in German type 1 diabetes patients

Background: The vitamin D system has been implicated in type 1 diabetes (T1D) by epidemiological and immune intervention studies as well as by polymorphisms of the vitamin D binding protein (DBP) and CYP27B1 genes.

The 25(OH)D₃–24-hydroxylase (CYP24), a cytochrome P450 enzyme, initiates the inactivation or catabolism of the vitamin D metabolites. Thus, CYP24 hydroxyls 1,25(OH)₂D₃ to the less active from 1,24,25(OH)₂D₃.

Thus owing the important role of the vitamin D systems we investigated the rs2248137 and rs2296421 polymorphisms within the CYP24 gene candidates for type 1 diabetes susceptibility and their possible influence on 25(OH)D₃ serum levels.

Materials and methods: Two hundred five simplex type 1 diabetes families (n=609 individuals) were genotyped for the rs2248137 and rs2296421 polymorphisms within the CYP24 gene. Additionally 25(OH)D3 and 1,25(OH)2D3 levels were measured and correlated with CYP24 polymorphisms in 165 type 1 diabetes patients.

Statistic analysis were performed by using Haploview software version 3.2 and Bias Statistical package 7.01. A p value <0.05 was considered as significant.

Results: No association was found between the rs2248137 or rs2296421 polymorphisms in the T1D family analysis (p=0.1859 and p=0.4658, respectively).

There was no correlation between 25(OH)D₃ or 1,25(OH)₂D₃ levels and the rs2248137 and rs2296421 polymorphisms in type 1 diabetic patients.

Conclusion: We conclude that polymorphisms within the CYP24 hydroxylase gene neither are associated with type 1 diabetes nor influence 25(OH)D₃ or 1,25(OH)₂D₃ serum levels. Nevertheless these findings need to be corroborated in larger numbers.