Clinical, biochemical and molecular characterization of cystinuria in a cohort of 12 patients.
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.
Unidade de Genética Médica, Centro de Genética Médica Dr. Jacinto Magalhães, Instituto Nacional de Saúde Dr. Ricardo Jorge, Porto, Portugal. mafalda.barbosa@insa.min-saude.pt
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Barbosa
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Lopes
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Mota
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Martins
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Oliveira
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Alves
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De Bonis
M do Céu
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Mota
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Dias
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Rodrigues-Santos
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Fortuna
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Quelhas
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Lacerda
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Bisceglia
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Cardoso
D000293:Adolescent; D000483:Alleles; D026923:Amino Acid Transport Systems, Basic / Q000235:genetics; D026921:Amino Acid Transport Systems, Neutral / Q000235:genetics; D000596:Amino Acids / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D019295:Computational Biology; D003553:Cystine / Q000378:metabolism; D003555:Cystinuria / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D005260:Female; D056726:Genetic Association Studies; D005820:Genetic Testing; D015894:Genome, Human; D056914:Genomic Structural Variation; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D020125:Mutation, Missense; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence
D026923:Amino Acid Transport Systems, Basic; D026921:Amino Acid Transport Systems, Neutral; D000596:Amino Acids; C489857:SLC3A1 protein, human; C499489:SLC7A9 protein, human; D003553:Cystine