Congenital disorder of glycosylation type Ik (CDG-Ik): a defect of mannosyltransferase I.

This study describes the discovery of a new inherited disorder of glycosylation named "CDG-Ik." CDG-Ik (congenital disorder of glycoslyation type Ik) is based on a defect of human mannosyltransferase I (MT-I [MIM 605907]), an enzyme necessary for the elongation of dolichol-linked chitobiose during N-glycan biosynthesis. Mutations in semiconserved regions in the corresponding gene, HMT-1 (yeast homologue, Alg1), in two patients caused drastically reduced enzyme activity, leading to a severe disease with death in early infancy. One patient had a homozygous point mutation (c.773C-->T, S258L), whereas the other patient was compound heterozygous for the mutations c.773C-->T and c.1025A-->C (E342P). Glycosylation and growth of Alg1-deficient PRY56 yeast cells, showing a temperature-sensitive phenotype, could be restored by the human wild-type allele, whereas only slight restoration was observed after transformation with the patients' alleles.

Citation

Christian Kranz, Jonas Denecke, Ludwig Lehle, Kristina Sohlbach, Stefanie Jeske, Friedhelm Meinhardt, Rainer Rossi, Sonja Gudowius, Thorsten Marquardt. Congenital disorder of glycosylation type Ik (CDG-Ik): a defect of mannosyltransferase I. American journal of human genetics. 2004 Mar;74(3):545-51

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PMID: 14973782

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