Epidemiology of congenital disorders of glycosylation (CDG)—overview and perspectives

Background and aim Congenital disorders of glycosylation (CDG) are a large heterogeneous group of about 170 rare inherited metabolic disorders due to defective protein and lipid glycosylation. This study aimed to assemble and summarise available data on the epidemiology of CDG. Methods A set of keywords related to epidemiology and CDG was defined. The keywords were combined through a custom Python script, search through the MEDLINE database, using PubMed as the search engine. The script retrieved the correspondent MEDLINE data from each article, and the relevant information was exported. Next, inclusion and exclusion criteria were set and applied during the selection phase. Finally, epidemiology-related information was extracted and compiled. Results One hundred sixty-five papers on CDG epidemiology were included in this literature review. Most of them reported on the frequency of symptoms in CDG patients followed in cohort studies, on pathogenic variant allelic frequency, and on the prevalence of the disorder in populations. According to this review, the most reported CDG was phosphomannomutase-2 deficiency (PMM2-CDG) followed in descending order by FKTN-CDG, EXT1/EXT2-CDG, ALG6-CDG, and PIGA-CDG. Conclusions We provide an overview on epidemiological data regarding 93 CDG by compiling information from the literature. Generating epidemiological data on CDG is important to appropriately target resources for CDG research and drug development and to support public health decision-making.