DPM2-CDG: A muscular dystrophy-dystroglycanopathy syndrome with severe epilepsy
ANNALS OF NEUROLOGY
Authors: Barone, Rita; Aiello, Chiara; Race, Valerie; Morava, Eva; Foulquier, Francois; Riemersma, Moniek; Passarelli, Chiara; Concolino, Daniela; Carella, Massimo; Santorelli, Filippo; Vleugels, Wendy; Mercuri, Eugenio; Garozzo, Domenico; Sturiale, Luisa; Messina, Sonia; Jaeken, Jaak; Fiumara, Agata; Wevers, Ron A.; Bertini, Enrico; Matthijs, Gert; Lefeber, Dirk J.
Abstract
Objective: Congenital disorders of glycosylation (CDG) are a group of metabolic diseases due to defects in protein and lipid glycosylation. We searched for the primary defect in 3 children from 2 families with a severe neurological phenotype, including profound developmental delay, intractable epilepsy, progressive microcephaly, severe hypotonia with elevated blood creatine kinase levels, and early fatal outcome. There was clinical evidence of a muscular dystrophydystroglycanopathy syndrome, supported by deficient O-mannosylation by muscle immunohistochemistry. Methods: Biochemical and molecular methods were combined to pinpoint the defect in the glycosylation pathway in the endoplasmic reticulum. Results: Metabolic investigations revealed CDG-I, pointing to a defect in protein N-glycosylation in the endoplasmic reticulum. Analysis of lipid-linked oligosaccharides in fibroblasts showed accumulation of Dol-PP-GlcNAc(2)-Man(5). DNA analysis revealed mutations in DPM2, 1 of the subunits of the dolichol-phosphate-mannose (DPM) synthase; the patient in the first family is compound heterozygous for 2 mutations (c.68A>G, predicting a missense mutation p.Y23C and c.4-1G>C, a splice mutation), whereas the patients in the second family are homozygous for the same missense mutation (c.68A>G, p.Y23C). Interpretation: We describe a new CDG, due to a deficiency of DPM2. Hence, mutations have now been described in the genes for the 3 subunits of DPM: DPM1, DPM2, and DPM3, whereby DPM2-CDG links the congenital disorders of glycosylation to the congenital muscular dystrophies. ANN NEUROL 2012;72:550558
CDG-Id in two siblings with partially different phenotypes
AMERICAN JOURNAL OF MEDICAL GENETICS PART A
Authors: Kranz, Christian; Sun, Liangwu; Eklund, Erik A.; Krasnewich, Donna; Casey, Janet R.; Freeze, Hudson H.
Abstract
We present two sibs with congenital disorder of glycosylation (CDG) type Id. Each shows severe global delay, failure to thrive, seizures, microcephaly, axial hypotonia, and disaccharidase deficiency. One sib has more severe digestive issues, while the other is more neurologically impaired. Each is compound heterozygous for a novel point mutation and an already known Mutation in the ALG3 gene that leads to the synthesis of a severely truncated oligosaccharide precursor for N-glycans. The defect is corrected by introduction of a normal ALG3 cDNA. CDG should be ruled out in all patients with severe seizures and failure to thrive. (c) 2007 Wiley-Liss, Inc.