title: Identification of a novel synonymous mutation in the human β -Ureidopropionase Gene UPB1 affecting pre-mRNA splicing.
abstract: β-Ureidopropionase is the third enzyme of the pyrimidine degradation pathway and it catalyzes the conversion of N-carbamyl-β-alanine and N-carbamyl-β-aminoisobutyric acid to β-alanine and β-aminoisobutyric acid, respectively, and ammonia and CO2. To date, only 16 genetically confirmed patients with a complete ß-ureidopropionase deficiency have been reported. Here, we report the clinical, biochemical, and molecular analysis of a newly identified patient with β-ureidopropionase deficiency. Mutation analysis of the UPB1 gene showed that the patient was compound heterozygous for a novel synonymous mutation c.93C >T (p.Gly31Gly) in exon 1 and a previously described missense mutation c.977G >A (p.Arg326Gln) in exon 9. The in silico predicted effect of the synonymous mutation p.Gly31Gly on pre-mRNA splicing was investigated using a minigene approach. Wild-type and the mutated minigene constructs, containing the entire exon 1, intron 1, and exon 2 of UPB1, yielded different splicing products after expression in HEK293 cells. The c.93C >T (p.Gly31Gly) mutation resulted in altered pre-mRNA splicing of the UPB1 minigene construct and a deletion of the last 13 nucleotides of exon 1. This deletion (r.92_104delGCAAGGAACTCAG) results in a frame shift and the generation of a premature stop codon (p.Lys32SerfsX31). Using a minigene approach, we have thus identified the first synonymous mutation in the UPB1 gene, creating a cryptic splice-donor site affecting pre-mRNA splicing.
authors: a Laboratory of Genetic Metabolic Diseases , Academic Medical Center , Amsterdam , The Netherlands.
authors: J
authors: J
authors: Meijer
authors: Y
authors: Y
authors: Nakajima
authors: C
authors: C
authors: Zhang
authors: R
authors: R
authors: Meinsma
authors: T
authors: T
authors: Ito
authors: A B P
authors: AB
authors: Van Kuilenburg
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D000581:Amidohydrolases / Q000172:deficiency* / Q000235:genetics; D001927:Brain Diseases / Q000235:genetics*; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D009069:Movement Disorders / Q000235:genetics*; D009154:Mutation; D011686:Purine-Pyrimidine Metabolism, Inborn Errors / Q000235:genetics*; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D055815:Young Adult
chemical_list: D012322:RNA Precursors; D000581:Amidohydrolases; C021590:beta-ureidopropionase