Congenital disorder of glycosylation due to DPM1 mutations presenting with dystroglycanopathy-type congenital muscular dystrophy

Autor: Lakshmi Mehta, Kevin P. Campbell, Charles J. Waechter, Tobias Willer, Amy Yang, Bobby G. Ng, Jeffrey S. Rush, Kimiyo Raymond, Hudson H. Freeze, Steven A. Moore
Rok vydání: 2013
Předmět:
Zdroj: Molecular Genetics and Metabolism. 110:345-351
ISSN: 1096-7192
Popis: Congenital disorders of glycosylation (CDG) are rare genetic defects mainly in the post-translational modification of proteins via attachment of carbohydrate chains. We describe an infant with the phenotype of a congenital muscular dystrophy, with borderline microcephaly, hypotonia, camptodactyly, severe motor delay, and elevated creatine kinase. Muscle biopsy showed muscular dystrophy and reduced α-dystroglycan immunostaining with glycoepitope-specific antibodies in a pattern diagnostic of dystroglycanopathy. Carbohydrate deficient transferrin testing showed a pattern pointing to a CDG type I. Sanger sequencing of DPM1 (dolichol-P-mannose synthase subunit 1) revealed a novel Gly > Val change c.455G > T missense mutation resulting in p.Gly152Val) of unknown pathogenicity and deletion/duplication analysis revealed an intragenic deletion from exons 3 to 7 on the other allele. DPM1 activity in fibroblasts was reduced by 80%, while affinity for the substrate was not depressed, suggesting a decrease in the amount of active enzyme. Transfected cells expressing tagged versions of wild type and the p.Gly152Val mutant displayed reduced binding to DPM3, an essential, non-catalytic subunit of the DPM complex, suggesting a mechanism for pathogenicity. The present case is the first individual described with DPM1-CDG (CDG-Ie) to also have clinical and muscle biopsy findings consistent with dystroglycanopathy.
Databáze: OpenAIRE