Factors predicting the occurrence of disease-causing variants on next-generation sequencing in children with steroid-resistant nephrotic syndrome - implications for resource-constrained settings.

Abstract

Enhanced availability of high-throughput sequencing (at progressively reducing costs) has revolutionized the identification of monogenic SRNS. However, in resource-poor settings, it may not be possible to perform next-generation sequencing (NGS) in all children wherein monogenic SRNS is suspected. Besides, the optimal strategy of genetic evaluation (in patients with SRNS) in routine clinical practice in resource-limited settings is unknown. Patients with newly diagnosed SRNS were recruited from our center and followed up prospectively. We analyzed the factor(s) independently predicting the occurrence of disease-causing variants in these patients. In our study, 36 children/adolescents with SRNS were included (initial steroid resistance in 53%). On targeted NGS, pathogenic/likely pathogenic variants were identified in 31% (n = 11). These included homozygous or compound heterozygous variants in the following genes: ALOX12B, COL4A3, CRB2, NPHS1, NPHS2, PLCE1, and heterozygous variant in WT1 gene. Overall, 14 variants were identified of which 5 (36%) were novel. Age of < 1 or < 2years and presence of family history of nephrotic syndrome independently predicted the occurrence of monogenic SRNS on multivariate analysis. While NGS-based genetic testing in SRNS is increasingly being incorporated in routine clinical practice the world over, the scenario is far from optimal in resource-limited settings. Our study highlights that resources for genetic testing in SRNS should be prioritized for patients with early age at disease onset and presence of family history. Larger studies composed of diverse multi-ethnic cohorts of patients with SRNS are required to further delineate the optimal strategy of genetic evaluation in resource-poor settings. A higher resolution version of the Graphical abstract is available as Supplementary information.