Splicing Analysis of Exonic OCRL Mutations Causing Lowe Syndrome or Dent-2 Disease

• Published in: Genes Vol. 9; no. 1; p. 15
• Main Authors: Suarez-Artiles, Lorena, Perdomo-Ramirez, Ana, Ramos-Trujillo, Elena, Claverie-Martin, Felix
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 04-01-2018; MDPI
• Subjects: Bioinformatics; Cataracts; Missense mutation; mRNA; Mutation; Phenotypes; Regulatory sequences; Splicing; Dent-2 disease; exon skipping; bioinformatics tools; Lowe syndrome; OCRL gene; splicing mutation; exonic mutation; splice defects; minigene assay; missense mutation
• ISSN: 2073-4425; 2073-4425
• DOI: 10.3390/genes9010015

Mutations in the
gene are associated with both Lowe syndrome and Dent-2 disease. Patients with Lowe syndrome present congenital cataracts, mental disabilities and a renal proximal tubulopathy, whereas patients with Dent-2 disease exhibit similar proximal tubule dysfunction but only mild, or no additional clinical defects. It is not yet understood why some
mutations cause the phenotype of Lowe syndrome, while others develop the milder phenotype of Dent-2 disease. Our goal was to gain new insights into the consequences of
exonic mutations on pre-mRNA splicing. Using predictive bioinformatics tools, we selected thirteen missense mutations and one synonymous mutation based on their potential effects on splicing regulatory elements or splice sites. These mutations were analyzed in a minigene splicing assay. Results of the RNA analysis showed that three presumed missense mutations caused alterations in pre-mRNA splicing. Mutation c.741G>T; p.(Trp247Cys) generated splicing silencer sequences and disrupted splicing enhancer motifs that resulted in skipping of exon 9, while mutations c.2581G>A; p.(Ala861Thr) and c.2581G>C; p.(Ala861Pro) abolished a 5' splice site leading to skipping of exon 23. Mutation c.741G>T represents the first
exonic variant outside the conserved splice site dinucleotides that results in alteration of pre-mRNA splicing. Our results highlight the importance of evaluating the effects of
exonic mutations at the mRNA level.