Introducing Exome Sequencing as Part of the Diagnostic Algorithm for Pediatric Nephrology Patients in Bulgaria: A Single-Center Experience

Introduction: In pediatric kidney patients, where clinical presentation is often not fully developed, and renal biopsy is too risky or inconclusive, it may be difficult to establish the underlying pathology. In cases such as these, genetic diagnosis may be used to guide treatment, prognosis, and counseling. Given the large number of genes involved in kidney disease, introducing next-generation sequencing with extended gene panels as part of the diagnostic algorithm presents a viable solution. Methods: A cohort of 87 consecutive independent cases (83 children and 4 terminated pregnancies) with renal disease was recruited. Exome sequencing with MiSeq or NovaSeq 6000 (Illumina) platforms and analysis of extended gene panels were used for genetic testing. Results: Depending on the presenting pathology, the cases were grouped as patients with glomerular disease, ciliopathies, congenital anomalies, renal electrolyte imbalances, and chronic/acute kidney disease. The overall diagnostic yield was approximately 42% (37 out of 87), with most disease-causing mutations found in COL4A3, COL4A4, COL4A5, and PKHD1 genes. A change or clarification of preliminary diagnosis or adjustment of initial treatment plan based on the results of the genetic testing was made for approximately one-third of the children with meaningful genetic findings (11 out of 37). Discussion: Our results prove the value of targeted exome sequencing as a non-invasive, versatile, and reliable diagnostic tool for pediatric renal disease patients. Providing genetic diagnosis will help for a better understanding of disease etiology and will give the basis for optimal clinical management and insightful genetic counseling.