1. Collagen type IV-related nephropathies in Portugal: pathogenic COL4A5 mutations and clinical characterization of 22 families
- Author
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Sá, MJ, Storey, H, Flinter, F, Nagel, M, Sampaio, S, Castro, R, Araújo, JA, Gaspar, MA, Soares, C, Oliveira, A, Henriques, AC, Costa, AG, Abreu, CP, Ponce, P, Alves, R, Pinho, L, Silva, SE, Moura, CP, Mendonça, L, and Carvalho, F
- Subjects
Portugal ,urologic and male genital diseases ,Doenças do Rim ,Colágenio Tipo IV - Abstract
Pathogenic mutations in genes COL4A3/COL4A4 are responsible for autosomal Alport syndrome (AS) and thin basement membrane nephropathy (TBMN). We used Sanger sequencing to analyze all exons and splice site regions of COL4A3/COL4A4, in 40 unrelated Portuguese probands with clinical suspicion of AS/TBMN. To assess genotype-phenotype correlations, we compared clinically relevant phenotypes/outcomes between homozygous/compound heterozygous and apparently heterozygous patients. Seventeen novel and four reportedly pathogenic COL4A3/COL4A4 mutations were identified in 62.5% (25/40) of the probands. Regardless of the mutated gene, all patients with ARAS manifested chronic renal failure (CRF) and hearing loss, whereas a minority of the apparently heterozygous patients had CRF or extrarenal symptoms. CRF was diagnosed at a significantly younger age in patients with ARAS. In our families, the occurrence of COL4A3/COL4A4 mutations was higher, while the prevalence of XLAS was lower than expected. Overall, a pathogenic COL4A3/COL4A4/COL4A5 mutation was identified in >50% of patients with fewer than three of the standard diagnostic criteria of AS. With such a population background, simultaneous next-generation sequencing of all three genes may be recommended as the most expedite approach to diagnose collagen IV-related glomerular basement membrane nephropathies.
- Published
- 2014