Congenital disorders of glycosylation (CDG) type I include variants in the DPM1 gene leading to DPM1-CDG. The nine previously reported patients showed developmental delay, seizures, electroencephalography abnormalities and dysmorphic features with varying disease onset and severity. […] The presented case extends the spectrum of DPM1-CDG to a very young and severely affected child. The deletion of Lys80 in DPM1 results in an impaired helical configuration. This has implications for further understanding the association of structure and function of DPM1.