BsmI, ApaI and FokI variants of vitamin D receptor gene polymorphism as predictors of response to treatment in immune thrombocytopenia patients.

Vitamin D receptor (VDR) polymorphisms are linked with the incidence and severity of several autoimmune diseases. The current work aimed at evaluating if VDR rs1544410 (BsmI), rs7975232 (ApaI) and rs2228570 (FokI) gene polymorphisms could be predictors of response to steroid treatment in patients with immune thrombocytopenia (ITP). The study involved 75 steroid treatment responders and 75 resistant ITP patients. All participants were subjected to VDR BsmI, ApaI and FokI gene polymorphisms analysis through genotyping by RT-PCR. Carrying the FokI F allele was significantly associated with low vitamin D level and increased risk of developing steroid resistance. Interestingly, the tri-allelic haplotypes BAF and BaF were significantly only present in steroid resistant ITP patients. Thus, the present study suggests that VDR FokI F allele may contribute to ITP pathogenesis and resistance to steroid treatment. Knowing the genetic background of patients helps to individualize treatment to obtain a better outcome.