Author(s):
Barbosa, Mafalda Fernanda Cabral Santos ; Lopes, A. ; Mota, C. ; Martins, E. ; Oliveira, J. ; Alves, S. ; Bonis, P. de ; Mota, M. do Céu ; Dias, C. ; Santos, P. Rodrigues ; Fortuna, A. M. ; Quelhas, D. ; Lacerda, L. ; Biscegliah, L. ; Cardoso, M. L.
Date: 2012
Persistent ID: http://hdl.handle.net/1822/33600
Origin: RepositóriUM - Universidade do Minho
Subject(s): Cystinuria; MLPA analysis; silent mutation; SLC3A1 gene; SLC7A9 gene; Science & Technology
Description
Cystinuria is a rare autosomal inherited disorder characterized by impaired transport of cystine and dibasic aminoacids in the proximal renal tubule. Classically, cystinuria is classified as type I (silent heterozygotes) and non-type I (heterozygotes with urinary hyperexcretion of cystine). Molecularly, cystinuria is classified as type A (mutations on SLC3A1 gene) and type B (mutations on SLC7A9 gene). The goal of this study is to provide a comprehensive clinical, biochemical and molecular characterization of a cohort of 12 Portuguese patients affected with cystinuria in order to provide insight into genotype-phenotype correlations. We describe seven type I and five non-type I patients. Regarding the molecular classification, seven patients were type A and five were type B. In SLC3A1 gene, two large genomic rearrangements and 13 sequence variants, including four new variants c.611-2A>C; c.1136+44G>A; c.1597T (p.Y533N); c.*70A>G, were found. One large genomic rearrangement was found in SLC7A9 gene as well as 24 sequence variants including 3 novel variants: c.216C>T (p.C72C), c.1119G>A (p.S373S) and c.*82C>T. In our cohort the most frequent pathogenic mutations were: large rearrangements (33.3% of mutant alleles) and a missense mutation c.1400T>C (p.M467T) (11.1%). This report expands the spectrum of SLC3A1 and SLC7A9 mutations and provides guidance in the clinical implementation of molecular assays in routine genetic counseling of Portuguese patients affected with cystinuria.