Genetic Evaluation in Chronic Kidney Disease: A Canadian Single-Centre Experience from a Multicultural Urban Population

Background: Chronic kidney disease (CKD) affects over 10% of the global population. A genetic diagnosis can be identified in about 30% of pediatric and 10-30% of adults, informing treatment, prognosis, and family-based risk assessment. However, access to renal genetics services remains limited across many healthcare systems. Objectives: To characterize the clinical and genetic landscape of CKD in patients referred for genetic evaluation within a Canadian single-centre nephrology-genetics program, and to evaluate the diagnostic yield and clinical utility of an integrated renal genetics clinic. Methods: We conducted a retrospective study of 206 probands referred for suspected hereditary kidney disease to the McGill University Health Centre Renal Genetics Clinic between 2019 and 2024. Genetic testing was performed in accredited laboratories, predominantly through comprehensive multi-gene panels or phenotype-directed exome sequencing. All reported variants were classified according to the ACMG/AMP criteria, and variants of uncertain significance were reevaluated post hoc using standardized quantitative and evidence-tier frameworks to determine whether they trended toward "likely pathogenic" ("hot") or "likely benign" ("cold"), without implying formal reclassification. Results: A molecular diagnosis was established in 34.5% of probands (71/206), implicating pathogenic or likely pathogenic variants across 35 genes representing diverse monogenic kidney disease etiologies. The highest diagnostic yields were observed in cystic nephropathy (51.9%), tubulopathy (38.5%), and glomerulopathy (35.6%). Genetic results affected clinical management in 23.9% of diagnosed cases, leading to changes in treatment for 16.9%, modification of transplant management in 5.6%, informed living donor risk assessment in 14.1%, and facilitated cascade testing in 66.2% of families. CKD of unknown etiology comprised 28% of the cohort, with a genetic diagnosis reached in 25.9% of these cases. Variants of uncertain significance (VUS) were reported in 39.3% of probands, with higher overall variant burden and lower diagnostic yields among individuals of non-European ancestry. Post hoc internal reassessment stratified 67.4% of VUS as mid or lower confidence ("cold") and 31.4% as higher confidence ("hot") or likely pathogenic. Conclusions: In a diverse urban population, integration of a dedicated renal genetics service within nephrology care achieved high diagnostic yield, substantially influenced management, and facilitated family risk assessment. Structured referral pathways and multidisciplinary variant interpretation optimize the clinical utility of genetic testing in CKD.