Congenital Disorders of Glycosylation ( CDG ): State of the Art in 2026

Congenital disorders of glycosylation (CDG) are a rapidly expanding group of inherited metabolic diseases affecting glycoconjugate glycan biosynthesis and attachment. This review provides a structured overview of major advances in human CDG reported from 2023 to 2026, including newly recognized CDG, emerging biochemical and pathophysiological insights, advances in diagnostic strategies and biomarkers, and progress in treatment. Recent developments include the recognition of RPN1-CDG, UGGT1-CDG, and DHRSX-CDG, refinement of phenotypes in established disorders, including PMM2-CDG, ALG13-CDG, ALG8-CDG, GMPPA-CDG, TRAPPC11-CDG, and PGAP3-CDG, and increasing use of glycomics, glycoproteomics, cellular models, and multi-omics approaches. Therapeutic progress remains uneven: no FDA/EMA-approved disease-modifying therapy is currently available for any CDG, and most interventions remain off-label, experimental, or supported by limited observational evidence. Despite substantial progress, most CDG still lack disease-modifying treatment, validated biomarkers, and prospective natural history data.