Endothelial nitric oxide synthase gene variation associated with chronic kidney disease after liver transplant

OBJECTIVE: To identify single nucleotide polymorphisms (SNPs) associated with risk of developing chronic kidney disease (CKD), a prevalent comorbidity, after liver transplant (LT). PATIENTS AND METHODS: This study consists of a cohort of adult (≥18 years) primary-LT recipients who had normal renal function before LT and who survived 1 year or more after LT at a high-volume US LT program between January 1, 1990, and December 31, 2000. Patients with adequate renal function (estimated glomerular filtration rate, ≥40 mL/min per 1.73 m² during follow-up; n=308) and patients with incident CKD (estimated glomerular filtration rate, <40 mL/min per 1.73 m² after LT; n=92) were identified. To investigate the association of 6 candidate genes with post-LT CKD, we selected SNPs that have been associated with renal function in the literature. Hazard ratios were estimated using Cox regression, adjusted for potential confounding variables. RESULTS: The variant allele (298Asp) of the Glu298Asp SNP in the endothelial nitric oxide synthase gene (NOS3) was significantly associated with CKD after LT (P=.05; adjusted for multiple comparisons). The 5-year incidence of CKD was 70% among patients homozygous for the NOS3 variant allele (298Asp) compared with 42% among those not homozygous for the NOS3 variant allele. Specifically, homozygosity for the NOS3 variant allele conferred a 2.5-fold increased risk of developing CKD after LT (P=.005, adjusted for confounding variables). CONCLUSION: Homozygosity for the variant allele of NOS3 (298Asp) is associated with CKD after LT and may be useful for identifying recipients at higher risk of post-LT CKD.