We explore the hypothesis of abnormal Ca<sub>V</sub>2.1 function due to aberrant <i>N</i>-glycosylation as a potential novel pathomechanism of SLE and ataxia in PMM2-CDG by using whole-cell patch-clamp, <i>N</i>-glycosylation blockade and mutagenesis.Nine SLE were identified.Neuroimages showed no signs of stroke.