title: Analysis of aberrant splicing and nonsense-mediated decay of the stop codon mutations c.109G>T and c.504_505delCT in 7 patients with HMG-CoA lyase deficiency.
abstract: Eukaryotic cells can be protected against mutations that generate stop codons by nonsense-mediated mRNA decay (NMD) and/or nonsense-associated altered splicing (NAS). However, the processes are only partially understood and do not always occur. In this work, we study these phenomena in the stop codon mutations c.109G>T (p.Glu37*) and c.504_505delCT; the second and third most frequent mutations in HMG-CoA lyase deficiency (MIM #246450). The deficiency affects the synthesis of ketone bodies and produces severe disorders during early childhood. We used a minigene approach, real-time quantitative PCR and the inhibition of NMD by puromycin treatment, to study the effect of stop codons on splicing (NAS) and NMD in seven patients. Surprisingly, none of the stop codons studied appears to be the direct cause of aberrant splicing. In the mutation c.109G>T, the splicing is due to the base change G>T at position 109, which is critical and cannot be explained by disruption of exonic splicing enhancer (ESE) elements, by the appearance of exonic splicing silencer (ESS) elements which were predicted by bioinformatic tools or by the stop codons. Moreover, the mutation c.504_505delCT produces two mRNA transcripts both with stop codons that generate simultaneous NMD phenomena. The effects of the mutations studied on splicing seemed to be similar in all the patients. Furthermore, we report a Spanish patient with 3-hydroxy-3-methylglutaric aciduria and a novel missense mutation: c.825C>G (p.Asn275Lys).
authors: Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, E-50009 Zaragoza, Spain.
authors: Beatriz
authors: B
authors: Puisac
authors: María Esperanza
authors: ME
authors: Teresa-Rodrigo
authors: María
authors: M
authors: Arnedo
authors: María Concepción
authors: MC
authors: Gil-Rodríguez
authors: Celia
authors: C
authors: Pérez-Cerdá
authors: Antonia
authors: A
authors: Ribes
authors: Angeles
authors: A
authors: Pié
authors: Gloria
authors: G
authors: Bueno
authors: Paulino
authors: P
authors: Gómez-Puertas
authors: Juan
authors: J
authors: Pié
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000172:deficiency / Q000235:genetics; D000592:Amino Acid Metabolism, Inborn Errors / Q000235:genetics*; D001483:Base Sequence; D002675:Child, Preschool; D018389:Codon, Nonsense / Q000235:genetics; D018388:Codon, Terminator / Q000235:genetics; D005260:Female; D006801:Humans; D020125:Mutation, Missense; D059365:Nonsense Mediated mRNA Decay; D012326:RNA Splicing / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D018389:Codon, Nonsense; D018388:Codon, Terminator; D000101:Acetyl-CoA C-Acetyltransferase