Abstract
ALG13-CDG has been recently discovered as a disorder of severe developmental, intellectual and speech disability, microcephaly, visual abnormalities, seizures, hepatomegaly, coagulation abnormalities, and abnormal serumtransferrin isoelectric focusing in serum. A male with seizures, delayed motor, and speech development, but normal cognition carried a hemizygous, predicted pathogenic ALG13 variant (p.E463G). N-glycosylation studies in plasma were normal. ICAM-1 expression was decreased in patient fibroblasts, supporting the variant's pathogenicity. Adding D-galactose to the patient's fibroblast culture increased ICAM-1 expression in vitro, offering a potential treatment option in ALG13-CDG. The present report is a new example for an N-glycosylation disorder, that may present with normal transferrin isoform analysis, and also demonstrates, that CDG type I patients can have normal cognitive development.