A Generic Assay to Detect Aberrant Splicing and mRNA Degradation for the Molecular Diagnosis of MPS VI.
Broeders M, Smits K, Goynuk B, Oussoren E, van den Hout HJMP, Bergsma AJ, van der Ploeg AT, Pijnappel WWMP
Molecular therapy. Methods & clinical development, 2020 Dec 11
Abstract
Identification and characterization of disease-associated variants in monogenic disorders is an important aspect of diagnosis, genetic counseling, prediction of disease severity, and development of therapy. However, the effects of disease-associated variants on pre-mRNA splicing and mRNA degradation are difficult to predict and often missed. Here we present a generic assay for unbiased identification and quantification of arylsulfatase B () mRNA for molecular diagnosis of patients with mucopolysaccharidosis VI (MPS VI). We found that healthy control individuals have inefficient splicing because of natural skipping of exon 5 and inclusion of two pseudoexons in introns 5 and 6. Analyses of 12 MPS VI patients with 10 different genotypes resulted in identification of a 151-bp intron inclusion caused by the c.1142+2T>C variant and detection of low expression from alleles with the c.629A>G variant. A special case showed skipping of exon 4 and low expression. Although no disease-associated DNA variant could be identified in this patient, the molecular diagnosis could be made based on RNA. These results highlight the relevance of RNA-based analyses to establish a molecular diagnosis of MPS VI. We speculate that inefficient natural splicing of may be a target for therapy based on promotion of canonical splicing.