P0065DOUBLE MUTATION INHERITANCE IN PATIENTS WITH FOCAL SEGMENTAL GLOMERULOSCLEROSIS AND ALPORT SUNDROME. (6th June 2020)

• Record Type: Journal Article
• Authors: Xie, Jingyuan
• Is Part Of: Nephrology dialysis transplantation. Volume 35(2020)Supplement 3
• Publication Date: 2020-06-06
• Subjects: Nephrology -- Periodicals; Hemodialysis -- Periodicals; Kidneys -- Transplantation -- Periodicals; Hemodialysis; Kidneys -- Transplantation; Nephrology; Periodicals; 616.61
• DOI: 10.1093/ndt/gfaa142.P0065
• Languages: English
• ISSNs: 0931-0509

Abstract

Abstract: Background and Aims: Focal segmental glomerulosclerosis (FSGS) and Alport syndrome (AS) are the leading causes of ESRD globally. FSGS and AS are clinically heterogeneous nephropathies and mainly genetic causes are the mutations in genes expressed in podocytes and glomerular basement membrane (GBM) respectively. A simple Mendelian model fail to explain the genetic control of both nephropathies completely because of the heterogeneous nature and presence of incomplete penetrance. Therefore, here we investigated the possible digenic control of FSGS and AS. Method: To detect the double mutational (mono- or di-genic) cause of FSGS and AS, we conducted whole exome sequencing (WES) and panel sequencing in 67 kidney patients during the period of four years (2015 to June 2019). Inclusion criteria was the proband's clinical symptoms confirming the FSGS or AS based on clinical symptoms and renal biopsy. Clinical and genetic analyses were implemented to correlate the phenotypes with genotypes. Results: Genetic analysis discovered that 35 out of 67 (52.23%) had genetic cause of selected nephropathies and 24 out of 35 (68.57%) had mutations in COL4A (3, 4 & 5) genes and 11 (31.42%) in other genes. Interestingly, we found 7 out of 35 patients (20%) with double mutations (mono- or di-genic) in COL4A3/COL4A4 genes. After the mentioned period, during routine genetic screening, we also found another patient having double mutations in COL4A3 gene. Subsequently, Sanger sequencing confirmed that the identified mutations were co-segregating with the disease(s) in an incomplete penetrance fashion within the family. Lastly, we found 16 mutations in 8 patients having either monogenic or digeneic double mutations in COL4A3 and/or COL4A4 genes. In sum, we found 12 (75%) mutations in COL4A3 and 4 in COL4A4 (25%), and5 probands (62.5%) had compound heterozygous mutations in COL4A3, 1 proband (12.5%) had in COL4A4 and 2 probands (25%) had digenic (COL4A3/COL4A4) mutations. Last of all, among all the mutations, 10 were novel and 6 have been described previously. Conclusion: This genetic analysis provides the first evidence for digenic inheritance of FSGS. The nephrologists and clinical geneticists should keep this possibility in mind for the accuracy in diagnosis, disease management and genetic counseling in future. Additionally, we are also adding 10 novel mutations in COL4A3 and COL4A4 genetic pools.