Single base-pair substitutions in exon–intron junctions of human genes: nature, distribution, and consequences for mRNA splicing

Authors


  • Communicated by Garry R. Cutting

Abstract

Although single base-pair substitutions in splice junctions constitute at least 10% of all mutations causing human inherited disease, the factors that determine their phenotypic consequences at the RNA level remain to be fully elucidated. Employing a neural network for splice-site recognition, we performed a meta-analysis of 478 disease-associated splicing mutations, in 38 different genes, for which detailed laboratory-based mRNA phenotype assessment had been performed. Inspection of the ±50-bp DNA sequence context of the mutations revealed that exon skipping was the preferred phenotype when the immediate vicinity of the affected exon–intron junctions was devoid of alternative splice-sites. By contrast, in the presence of at least one such motif, cryptic splice-site utilization, became more prevalent. This association was, however, confined to donor splice-sites. Outside the obligate dinucleotide, the spatial distribution of pathological mutations was found to differ significantly from that of SNPs. Whereas disease-associated lesions clustered at positions –1 and +3 to +6 for donor sites and –3 for acceptor sites, SNPs were found to be almost evenly distributed over all sequence positions considered. When all putative missense mutations in the vicinity of splice-sites were extracted from the Human Gene Mutation Database for the 38 studied genes, a significantly higher proportion of changes at donor sites (37/152; 24.3%) than at acceptor splice-sites (1/142; 0.7%) was found to reduce the neural network signal emitted by the respective splice-site. Based upon these findings, we estimate that some 1.6% of disease-causing missense substitutions in human genes are likely to affect the mRNA splicing phenotype. Taken together, our results are consistent with correct donor splice-site recognition being a key step in exon recognition. Hum Mutat 28(2), 150–158, 2007. © 2006 Wiley-Liss, Inc.

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