Vitamin D receptor polymorphisms in immune thrombocytopenic purpura.

BackgroundVitamin D receptor (VDR) polymorphisms have been studied in immune-mediated disorders, but not yet in immune thrombocytopenic purpura (ITP). We investigated whether VDR variants were associated with ITP in children. MethodsThe study included 44 children with a diagnosis of ITP and 100 healthy controls. Five VDR polymorphisms (Cdx-2, FokI, BsmI, ApaI and TaqI) were genotyped and used to evaluate the association of VDR variants with ITP. ResultsThe distribution of the three Cdx-2 genotype groups (GG, GA, and AA) was significantly different between ITP patients and controls (P = 0.025); the homozygous GG genotype of Cdx-2 was overrepresented in ITP patients. The frequency of the A allele of Cdx-2 was significantly different between patients and controls (P = 0.01). The A allele of Cdx-2 was associated with a decreased risk of ITP (OR, 0.343; 95% CI: 0.150-0.782). No statistically significant difference was found between the ITP group and control group for Fok1, Bsm1, Apa1, and Taq1 polymorphisms (P > 0.5). ConclusionThere appears to be an interaction between the Cdx-2 variant of VDR and childhood immune thrombocytopenia.