Publication Date

5-1-2025

Journal

American Journal of Human Genetics

DOI

10.1016/j.ajhg.2025.03.018

PMID

40267907

PMCID

PMC12120171

PubMedCentral® Posted Date

4-22-2025

PubMedCentral® Full Text Version

Post-print

Abstract

Congenital disorders of glycosylation (CDGs) comprise a large heterogeneous group of metabolic conditions caused by defects in glycoprotein and glycolipid glycan assembly and remodeling, a fundamental molecular process with wide-ranging biological roles. Herein, we describe bi-allelic UGGT1 variants in fifteen individuals from ten unrelated families of various ethnic backgrounds as a cause of a distinctive CDG of variable severity. The cardinal clinical features of UGGT1-CDG involve developmental delay, intellectual disability, seizures, characteristic facial features, and microcephaly in the majority (9/11 affected individuals for whom measurements were available). The more severely affected individuals display congenital heart malformations, variable skeletal abnormalities including scoliosis, and hepatic and renal involvement, including polycystic kidneys mimicking autosomal recessive polycystic kidney disease. Clinical studies defined genotype-phenotype correlations, showing bi-allelic UGGT1 loss-of-function variants associated with increased disease severity, including death in infancy. UGGT1 encodes UDP-glucose:glycoprotein glucosyltransferase 1, an enzyme critical for maintaining quality control of N-linked glycosylation. Molecular studies showed that pathogenic UGGT1 variants impair UGGT1 glucosylation and catalytic activity, disrupt mRNA splicing, or inhibit endoplasmic reticulum (ER) retention. Collectively, our data provide a comprehensive genetic, clinical, and molecular characterization of UGGT1-CDG, broadening the spectrum of N-linked glycosylation disorders.

Keywords

Humans, Congenital Disorders of Glycosylation, Male, Female, Glycosylation, Alleles, Child, Preschool, Glucosyltransferases, Child, Infant, Genetic Association Studies, Adolescent, Endoplasmic Reticulum, Pedigree, Phenotype, Mutation, UGGT1, UDP-glucose:glycoprotein glucosyltransferase 1, MOGS, congential disorder of glycosylation, autosomal recessive, microcephaly, neurodevelopmental disorder, N-linked glycosylation, monogenic disorder

Published Open-Access

yes

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