title: Characterization and mRNA expression analysis of a novel ARG1 splicing mutation causing hyperargininemia.
abstract: OBJECTIVE
  Biallelic mutations in the ARG1 gene result in an uncommon autosomal recessive inborn defect of the urea cycle known as hyperargininemia (OMIM #207800). ARG1 splicing mutations are not reported often, and they are probably related to a more severe phenotype than missense mutations. In this article, we describe the results of molecular studies in a young hyperargininemia patient carrying a novel splicing mutation in ARG1.
  
  
  METHODS
  Molecular analyses included PCR amplification and direct nucleotide sequencing of the ARG1 gene. RT-PCR analysis was performed to investigate the effect of the mutation in mRNA splicing and in the expression of ARG1 isoforms.
  
  
  RESULTS
  Mutational analysis identified a novel homozygous ARG1 IVS4-1G>C point mutation in the patient's DNA. Blood leukocyte mRNA was analyzed to demonstrate the splicing defect caused by this mutation. Sequencing of ARG1 RT-PCR products allowed the characterization of a mutated transcript retaining 51-bp from intron 4. In addition, two new, alternatively spliced ARG1 transcripts lacking either exon 4 or exons 4 and 5 were identified in mRNA from the patient and from controls.
  
  
  CONCLUSIONS
  Our results expand the mutational spectrum in hyperargininemia patients and indicate that the novel splicing mutation results in an aberrant transcript retaining intronic sequences. Two novel alternatively spliced ARG1 transcripts were also recognized.
authors.affiliation: Department of Genetics, Institute of Ophthalmology "Conde de Valenciana", Mexico City, Mexico.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Villegas-Ruiz
authors.affiliation: Newborn Screening Laboratory "TamizMas de Quimicos Maldonado", Mérida City, Yucatán, Mexico.
authors.forename: Felix J
authors.initials: FJ
authors.lastname: Campos-Garcia
authors.affiliation: Department of Medical Genetics, General Hospital "Dr. Agustin O'Horan", Mérida City, Yucatán, Mexico.
authors.forename: Silvina
authors.initials: S
authors.lastname: Contreras-Capetillo
authors.affiliation: Newborn Screening Laboratory "TamizMas de Quimicos Maldonado", Mérida City, Yucatán, Mexico.
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Moreno-Graciano
authors.affiliation: Newborn Screening Laboratory "TamizMas de Quimicos Maldonado", Mérida City, Yucatán, Mexico.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Maldonado-Solis
authors.affiliation: Newborn Screening Laboratory "TamizMas de Quimicos Maldonado", Mérida City, Yucatán, Mexico.
authors.forename: Mario A
authors.initials: MA
authors.lastname: Maldonado-Solis
authors.affiliation: Department of Genetics, Institute of Ophthalmology "Conde de Valenciana", Mexico City, Mexico; Biochemistry Department, Faculty of Medicine, UNAM, Mexico City, Mexico. Electronic address: jczenteno@institutodeoftalmologia.org.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Zenteno
mesh_terms: D017398:Alternative Splicing; D001119:Arginase / Q000235:genetics*; D001483:Base Sequence; D005091:Exons; D006720:Homozygote; D006801:Humans; D020162:Hyperargininemia / Q000175:diagnosis* / Q000235:genetics* / Q000473:pathology; D007223:Infant; D007438:Introns; D007527:Isoenzymes / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D001119:Arginase
keywords: ARG1; Hyperargininemia; Splicing mutation; Urea cycle disorders