NOS1 and essential thrombocythemia: No significant differences were found either in the frequencies of genotypes or in the frequencies of the allelic variants of other SNPs harbored in possible RLS genes loci, including HMOX1, HMOX2, VDR, IL17A, IL1B, NOS1 and ADH1B. Our study did not replicate the previously reported association ofHMOX1 rs2071746 and HMOX2 rs1051308 polymorphisms with ET, which could be due to different ethnic populations or small sample of our study.