Congenital disorders of glycosylation: Prevalence, incidence and mutational spectrum in the Polish population

INTRODUCTION: The incidence and prevalence of congenital disorders of glycosylation (CDG) have not been well established. The aim of the study was to evaluate the prevalence, incidence and genotypes of CDG patients diagnosed during the last 23 years in Poland (1997 – 30th October 2020). MATERIAL AND METHODS: The diagnosis was based on serum Tf IEF which is performed at The Children's Memorial Health Institute (CMHI) in Warsaw. Based on demographic data, the prevalence of CDG among the Polish population in 2020 as well as the birth prevalence of CDG from 1990 to 2020 were estimated. RESULTS: 39 patients (from 35 families) with molecularly confirmed CDG were diagnosed, including 17 (44%) patients (from 16 families) with PMM2-CDG. The c.422G > A, p.Arg141His and c.691G > A, p.Val231Met pathogenic missense variants were the most common identified PMM2 variants. Eleven other patients were diagnosed with CDG based on serum Tf IEF analysis only; the molecular analysis is pending. Ten CDG patients died, including 6 with PMM2-CDG, 1 with PGM1-CDG and 1 with DPAGT1-CDG. The prevalence of CDG in the Polish population was estimated at approximately 1 per million while that of PMM2 at 0.4 per million. The annual incidence of CDG was estimated at 0.013 per 100,000 people in 2020. CONCLUSIONS: A low frequence of CDG in our study could be underestimated.