Caragh P Stapleton1, Claire Kennedy2, Neil K Fennelly3, Susan L Murray2, Dervla M Connaughton4, Anthony M Dorman3, Brendan Doyle3, Gianpiero L Cavalleri5, Peter J Conlon2,6. 1. School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland. 2. Department of Nephrology and Transplantation, Beaumont Hospital, Dublin, Ireland. 3. Department of Pathology, Beaumont Hospital, Dublin, Ireland. 4. Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA. 5. School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland, gcavalleri@rcsi.ie. 6. Department of Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland.
Abstract
BACKGROUND: Immunoglobulin A nephropathy (IgAN) is a heterogeneous disorder with a strong genetic component. The advent of whole exome sequencing (WES) has accelerated the discovery of genetic risk factors underlying familial disorders. OBJECTIVES: We set out to test whether damaging variants in known kidney disease genes explain a proportion of IgAN cases recruited in Ireland. METHODS: We performed WES in 10 Irish families with multiple affected members having kidney disease where at least one member had biopsy confirmed IgAN. Candidate variants were identified based on being shared between affected family members, minor allele frequency, function and predicted pathogenicity. Pathogenicity of variants was determined according to American College of Medical Genetics and Genomics guidelines. RESULTS: We detected candidate variants in 3 of 10 families. We identified a likely pathogenic variant in COL4A5 in one family and a variant of unknown significance (VUS) in COL4A3 in another. Variants in COL4A5 and COL4A3 are known to cause Alport syndrome. In the third family, we identified a VUS in LMX1B, a gene associated with Nail-patella syndrome. CONCLUSIONS: We identified a number of cases of familial IgAN where the families harbored variants in known kidney disease-related genes indicating that potentially a number of cases of familial IgAN are mistaken for other familial kidney disorders. However, the majority of families studied did not carry a candidate variant in a known kidney disease causing gene indicating that there may be >1 underlying genetic mechanism present in these families.
BACKGROUND: Immunoglobulin A nephropathy (IgAN) is a heterogeneous disorder with a strong genetic component. The advent of whole exome sequencing (WES) has accelerated the discovery of genetic risk factors underlying familial disorders. OBJECTIVES: We set out to test whether damaging variants in known kidney disease genes explain a proportion of IgAN cases recruited in Ireland. METHODS: We performed WES in 10 Irish families with multiple affected members having kidney disease where at least one member had biopsy confirmed IgAN. Candidate variants were identified based on being shared between affected family members, minor allele frequency, function and predicted pathogenicity. Pathogenicity of variants was determined according to American College of Medical Genetics and Genomics guidelines. RESULTS: We detected candidate variants in 3 of 10 families. We identified a likely pathogenic variant in COL4A5 in one family and a variant of unknown significance (VUS) in COL4A3 in another. Variants in COL4A5 and COL4A3 are known to cause Alport syndrome. In the third family, we identified a VUS in LMX1B, a gene associated with Nail-patella syndrome. CONCLUSIONS: We identified a number of cases of familial IgAN where the families harbored variants in known kidney disease-related genes indicating that potentially a number of cases of familial IgAN are mistaken for other familial kidney disorders. However, the majority of families studied did not carry a candidate variant in a known kidney disease causing gene indicating that there may be >1 underlying genetic mechanism present in these families.
Authors: José María García-Aznar; Luis De la Higuera; Lara Besada Cerecedo; Nerea Paz Gandiaga; Ana Isabel Vega; Gema Fernández-Fresnedo; Domingo González-Lamuño Journal: J Clin Med Date: 2022-08-19 Impact factor: 4.964