The gene mutated in adult-onset type II citrullinaemia encodes a putative mitochondrial carrier protein.
Citrullinaemia (CTLN) is an autosomal recessive disease caused by deficiency of argininosuccinate synthetase (ASS). Adult-onset type II citrullinaemia (CTLN2) is characterized by a liver-specific ASS deficiency with no abnormalities in hepatic ASS mRNA or the gene ASS (refs 1-17). CTLN2 patients (1/100,000 in Japan) suffer from a disturbance of consciousness and coma, and most die with cerebral edema within a few years of onset. CTLN2 differs from classical citrullinaemia (CTLN1, OMIM 215700) in that CTLN1 is neonatal or infantile in onset, with ASS enzyme defects (in all tissues) arising due to mutations in ASS on chromosome 9q34 (refs 18-21). We collected 118 CTLN2 families, and localized the CTLN2 locus to chromosome 7q21.3 by homozygosity mapping analysis of individuals from 18 consanguineous unions. Using positional cloning we identified a novel gene, SLC25A13, and found five different DNA sequence alterations that account for mutations in all consanguineous patients examined. SLC25A13 encodes a 3.4-kb transcript expressed most abundantly in liver. The protein encoded by SLC25A13, named citrin, is bipartite in structure, containing a mitochondrial carrier motif and four EF-hand domains, suggesting it is a calcium-dependent mitochondrial solute transporter with a role in urea cycle function.
Kobayashi
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K
Department of Biochemistry, Faculty of Medicine, Kagoshima University, Japan. dodoko12@med2.kufm.kagoshima-u.ac.jp
Sinasac
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Iijima
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Boright
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Begum
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Lee
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JR
Yasuda
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Ikeda
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Hirano
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Terazono
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Crackower
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Kondo
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Tsui
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Scherer
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Saheki
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D000328:Adult; D017668:Age of Onset; D000592:Amino Acid Metabolism, Inborn Errors / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001124:Argininosuccinate Synthase / Q000172:deficiency / Q000235:genetics; D001929:Brain Edema / Q000235:genetics; D017173:Caenorhabditis elegans / Q000235:genetics; D002135:Calcium-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D002874:Chromosome Mapping; D002899:Chromosomes, Human, Pair 9; D002956:Citrulline / Q000097:blood*; D003241:Consanguinity; D017124:Conserved Sequence; D005260:Female; D005808:Genes, Recessive; D005819:Genetic Markers; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D026901:Membrane Transport Proteins; D008930:Mitochondria, Liver / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013577:Syndrome; D014158:Transcription, Genetic; D014508:Urea / Q000378:metabolism
D002135:Calcium-Binding Proteins; D005819:Genetic Markers; D026901:Membrane Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D024101:Mitochondrial Proteins; C119629:SLC25A13 protein, human; D002956:Citrulline; D014508:Urea; D001124:Argininosuccinate Synthase