BACKGROUND: Many patients suffer from genetically unsolved polycystic liver disease (PLD). Our aim was to explore mutated genes associated with the pathogenesis of PLD. METHODS: First, a family investigation was conducted on probands with a definite diagnosis of PLD and the pedigree was confirmed. Data on the clinical symptoms and biochemical and imaging indicators of family members were collected. Mutation analysis was performed using whole exome sequencing (WES), and Sanger sequencing was used for mutation verification. RESULTS: Nine of the 33 patients from five generations of the proband and their families were diagnosed with PLD/polycystic kidney disease (PKD). Imaging examination of all patients confirmed numerous hepatic and renal cysts. Patients clinically presented with different degrees of abdominal distension and impaired renal function. WES revealed a missense mutation in GANAB c.1118C >
T (p. Thr373Ile) in the proband and her affected son, which resulted in a change from hydrophilic threonine to hydrophobic isoleucine at amino acid 373. The mutation was verified using Sanger sequencing. CONCLUSION: This study identified a novel heterozygous mutation, c.1118C >
T (p. Thr373Ile) in GANAB in patients with PLD/PKD. This mutation has not been reported to date and enriches the phenotype and genotype spectrum of GANAB-related diseases.