Mis-splicing of the GALNS gene resulting from deep intronic mutations as a cause of Morquio a disease

Caciotti, Anna, Tonin, Rodolfo, Mort, Matthew, Cooper, David N. ORCID: https://orcid.org/0000-0002-8943-8484, Gasperini, Serena, Rigoldi, Miriam, Parini, Rossella, Deodato, Federica, Taurisano, Roberta, Sibilio, Michelina, Parenti, Giancarlo, Guerrini, Renzo and Morrone, Amelia 2018. Mis-splicing of the GALNS gene resulting from deep intronic mutations as a cause of Morquio a disease. BMC Medical Genetics 19 (1) , 183. 10.1186/s12881-018-0694-6

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Abstract

Background Mucopolysaccharidosis-IVA (Morquio A disease) is a lysosomal disorder in which the abnormal accumulation of keratan sulfate and chondroitin-6-sulfate is consequent to mutations in the galactosamine-6-sulfatase (GALNS) gene. Since standard DNA sequencing analysis fails to detect about 16% of GALNS mutant alleles, gross DNA rearrangement screening and uniparental disomy evaluation are required to complete the molecular diagnosis. Despite this, the second pathogenic GALNS allele generally remains unidentified in ~ 5% of Morquio-A disease patients. Methods In an attempt to bridge the residual gap between clinical and molecular diagnosis, we performed an mRNA-based evaluation of three Morquio-A disease patients in whom the second mutant GALNS allele had not been identified. We also performed sequence analysis of the entire GALNS gene in two patients. Results Different aberrant GALNS mRNA transcripts were characterized in each patient. Analysis of these transcripts then allowed the identification, in one patient, of a disease-causing deep intronic GALNS mutation. The aberrant mRNA products identified in the other two individuals resulted in partial exon loss. Despite sequencing the entire GALNS gene region in these patients, the identity of a single underlying pathological lesion could not be unequivocally determined. We postulate that a combination of multiple variants, acting in cis, may synergise in terms of their impact on the splicing machinery. Conclusions We have identified GALNS variants located within deep intronic regions that have the potential to impact splicing. These findings have prompted us to incorporate mRNA analysis into our diagnostic flow procedure for the molecular analysis of Morquio A disease.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Publisher:	BioMed Central
ISSN:	1471-2350
Date of First Compliant Deposit:	16 October 2018
Date of Acceptance:	16 October 2018
Last Modified:	22 Jul 2024 13:58
URI:	https://orca.cardiff.ac.uk/id/eprint/115916

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