CYP27B1 and cryohydrocytosis: Single nucleotide polymorphisms (SNPs) in CYP27B-1260 gene promoter (rs10877012AC) and in vitamin D receptor (VDR) gene rs2228570TC, rs1544410CT, rs7975232AC and rs731236AT were analyzed in a cohort of 238 Caucasian CHC patients treated with pegylated interferon (Peg-IFN) plus ribavirin (RBV).