Background & aims: Tolvaptan, vasopressin V2-receptor antagonist, has been used for patients with difficult-to-treat ascites in Japan. In this study, we conducted a genome-wide association study (GWAS) in the Japanese population to identify genetic variants associated with tolvaptan's efficacy for patients with hepatic ascites.
Methods: From 2014 through 2018, genomic DNA samples were obtained from 550 patients who were treated with tolvaptan. Of those, 80 cases (non-responder; increase of body weight [BW]) and 333 controls (responder; >1.5 kg decrease of BW) were included in the GWAS and replication study.
Results: Genome-wide association study showed 5 candidate SNPs around the miR818, KIAA1109, and SVEP1 genes. After validation and performing a replication study, an SNP (rs2991364) located in the SVEP1 gene was found to have a significant genome-wide association (OR = 3.55, P = 2.01 × 10-8 ). Multivariate analyses showed that serum sodium (Na), blood urea nitrogen (BUN) and SVEP1 SNP were significantly associated with the response (OR = 0.92, P = .003; OR = 1.02, P = .02 and OR = 3.98, P = .000008, respectively). Based on a prediction model of logistic regression analysis in a population with the rs2991364 risk allele, the failure probability (=exp (score: 22.234 + BUN*0.077 + Na*-0.179) (1 + exp (score)) was determined for the detection of non-responders. Assuming a cutoff of failure probability at 38.6%, sensitivity was 84.4%, specificity was 70% and AUC was 0.774.
Conclusion: SVEP1 rs2991364 was identified as the specific SNP for the tolvaptan response. The prediction score (>38.6%) can identify tolvaptan non-responders and help to avoid a lengthy period of futile treatment.
Keywords: Polydom; blood urine nitrogen (BUN); genome-wide association study (GWAS); hepatic ascites; liver cirrhosis; non-responder.
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