1723 Genetic landscape of polycystic kidney disease in a Chinese cohort – experience using whole genome sequencing in a tertiary renal unit

Abstract Background and Aims Genetic testing has increasingly been employed to provide definitive diagnoses and prognostic information in patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD). We aim to explore the genetic landscape of ADPKD in a Chinese cohort utilizing whole genome sequencing and study its real-world clinical utility. Method From 1st January 2022 to 31st March 2023, we recruited 50 adult Chinese patients who had the clinical diagnosis of ADPKD followed up at Queen Mary Hospital and consented to the study protocol. The study was approved by the University Institution Review Board and local ethics committees. Genomic DNA was isolated from samples obtained from patients per standard protocol. Whole-genome sequencing was performed and analysed through the germline analysis pipeline. Diagnostic analysis was performed per American College of Medical Genetics (ACMG) guidelines and ClinGen variant curation expert panel specifications. Diagnostic variants were defined as those classified as ‘pathogenic’ or ‘likely pathogenic’. Potential clinical utility of genetic findings were studied case-by-case based on the Kidney Disease Improving Global Outcomes (KDIGO) 2023 Clinical Practice Guideline for the Evaluation, Management and Treatment of ADPKD. Results Among the 50 unrelated probands with ADPKD, half were males and the mean age at presentation was 38. 38% patients had incidental finding of kidney cysts on abdominal imaging performed for unrelated symptoms or health screening, 32% presented for screening due to positive family history and only 30% presented with typical symptoms of ADPKD. Cystic complications were present in 30%, with cyst haemorrhage being the most common, followed by kidney stones, cyst rupture and infection. 80% patients also had liver cysts and none had a history of cerebral aneurysms. The majority of our cohort (72%) had a family history of ADPKD. We identified diagnostic variants in 35 individuals, reaching a diagnostic yield of 70%. Diagnostic variants were identified in PKD1 (20/35), PKD2 (11/35), IFT140 (3/35) and ALG9 (1/35). The majority of diagnostic variants were protein-truncating (32/35), while non-truncating variants consisted of 1 in-frame deletion and 2 missense variants in PKD1. We identified 3 copy number variation:NC_000016.10:g.2110587_2111851del,NC_000016.10:g.2132339_2137621del,NC_000016.10:g.2036427_2101117del. The genetic findings allowed physicians to make definitive diagnosis in 9 patients