Wu CC, et al. - Researchers undertook this prospective observational cohort analysis to determine the impact of common polymorphisms in the dimethylarginine dimethylaminohydrolase 1 (DDAH1) genes on venous intimal hyperplasia in hemodialysis (HD) vascular access in 473 HD patients referred for the angioplasty of vascular access. They genotyped seven single nucleotide polymorphisms (SNPs) in DDAH1 and obtained baseline measurement of asymmetric dimethylarginine (ADMA). Restenosis post-angioplasty was assessed as the primary outcome. A significant variation in plasma ADMA levels, among the 7 SNPs, was seen in DDAH1 rs233112 and rs1498373 genotypes. At 3 months, higher risks of early restenosis were observed in the arteriovenous fistulas (AVF) group with GG + GA genotype of rs233112 and CT + TT genotype of rs1498373. In the arteriovenous grafts (AVG) group, a link with early restenosis was shown only by GG + GA genotype of rs233112. Higher risks were also exhibited by patients with rs233112 GA + GG genotype and rs1498373 CT + TT genotype, as revealed in a combined analysis of AVG and AVF groups. The link of these genotypes with early restenosis did not depend on clinical, access, or biochemical factors, as noted in multivariate analysis. Overall, certain DDAH1 polymorphisms are suggested to be the modulators of circulating ADMA levels and were related to venous intimal hyperplasia.