The human GLB1 gene produces two alternatively spliced transcripts that encode the lysosomal enzyme beta-galactosidase (GLB1) and the elastin binding protein (EBP). Mutations at the GLB1 locus, which are responsible for the storage disorder GM1 gangliosidosis, may affect either both proteins or GLB1 only. The EBP, when affected, contributes to specific features of GM1 gangliosidosis patients, such as cardiomyopathy and connective-tissue abnormalities. Here we report the development of reliable and quantitative assays based on real-time PCR for assessing the levels of GLB1 and EBP transcripts in patients' samples. We also report the characterisation of GLB1 gene mutations in nine GM1 gangliosidosis patients in order to correlate the genetic lesions with mRNA levels and phenotypes. Mutation analysis identified four new (c.1835_1836delCC; p.Arg148Cys; c.1068+1G>T; and p.Pro549Leu), five known (p.Arg59His; p.Arg201His; p.Gly123Arg; c.245+1G>A; and c.75+2insT) mutations and one new polymorphism (c.1233+8T>C). Comparative analysis of the patients' phenotypes enabled a more thorough correlation between GLB1 mutations and specific clinical manifestations. GLB1 and EBP mRNA levels were both reduced in three patients carrying the splicing defects. The accurate and fast method for the detection of alternatively spliced transcripts of the GLB1 gene could be applied to other disease-causing lysosomal genes that encode multiple mRNAs.
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http://dx.doi.org/10.1002/humu.9475 | DOI Listing |
Orphanet J Rare Dis
December 2024
Division of Metabolism and Children's Research Center, Reference Center for Inborn Errors of Metabolism, University Children's Hospital of Zurich, University of Zurich, Zurich, Switzerland.
medRxiv
August 2024
Office of the Clinical Director and Medical Genetics Branch, National Human Genome Research Institute, 10 Center Drive, Bethesda MD USA.
GM1 gangliosidosis is an ultra-rare inherited neurodegenerative lysosomal storage disorder caused by biallelic mutations in the gene. GM1 is uniformly fatal and has no approved therapies, although clinical trials investigating gene therapy as a potential treatment for this condition are underway. Novel outcome measures or biomarkers demonstrating the longitudinal effects of GM1 and potential recovery due to therapeutic intervention are urgently needed to establish efficacy of potential therapeutics.
View Article and Find Full Text PDFFront Neuroimaging
September 2024
Image Processing and Analysis Core (iPAC), Department of Radiology, University of Massachusetts Chan Medical School, Worcester, MA, United States.
Stem Cell Res
December 2024
Division of Metabolic Disorders, Children's Hospital of Orange County Specialists, Orange, CA 92868, United States; Department of Pediatrics, University of California-Irvine School of Medicine, Irvine, CA 92697, United States. Electronic address:
Mol Genet Metab
October 2024
Division of Metabolic Disorders, Children's Hospital of Orange County Specialists, Orange, CA 92868, United States; Department of Pediatrics, University of California-Irvine School of Medicine, Irvine, CA 92697, United States. Electronic address:
GM1 gangliosidosis is an autosomal recessive neurodegenerative lysosomal storage disease caused by pathogenic variants in the GLB1 gene, limiting the production of active lysosomal β-galactosidase. Phenotypic heterogeneity is due in part to variant type, location within GLB1, and the amount of residual enzyme activity; in the most severe form, death occurs in infancy. With no FDA approved therapeutics, development of efficacious strategies for the disease is pivotal.
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