A Generic Assay to Detect Aberrant ARSB Splicing and mRNA Degradation for the Molecular Diagnosis of MPS VI

• Published in: Molecular therapy. Methods & clinical development Vol. 19; pp. 174 - 185
• Main Authors: Broeders, Mike, Smits, Kasper, Goynuk, Busra, Oussoren, Esmee, van den Hout, Hannerieke J.M.P., Bergsma, Atze J., van der Ploeg, Ans T., Pijnappel, W.W.M. Pim
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 11.12.2020; American Society of Gene & Cell Therapy; Elsevier
• Subjects: antisense oligonucleotides; diagnosis; lysosomal disease; nonsense mediated decay; Original; pseudo exon; splicing; diagnosis; nonsense mediated decay; splicing; pseudo exon; lysosomal disease; antisense oligonucleotides
• ISSN: 2329-0501; 2329-0501
• DOI: 10.1016/j.omtm.2020.09.004

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 (ARSB) mRNA for molecular diagnosis of patients with mucopolysaccharidosis VI (MPS VI). We found that healthy control individuals have inefficient ARSB 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 ARSB expression from alleles with the c.629A>G variant. A special case showed skipping of exon 4 and low ARSB 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 ARSB may be a target for therapy based on promotion of canonical splicing. [Display omitted] Broeders et al. present a generic assay for unbiased identification and quantification of arylsulfatase B mRNA for molecular diagnosis of MPS VI. Aberrantly spliced and degraded products were identified in MPS VI patients and healthy control individuals, highlighting the relevance of RNA-based analyses.