MPDU1 and familial dilated cardiomyopathy: Mannose‐phosphate‐dolichol utilization defect 1 (MPDU1) is involved in the flipping of DPM and dolichol‐phosphate‐glucose (DPG) across the ER membrane and for efficient use of DPM and DPG within the ER lumen.6, 7 MPDU1‐CDG patients have CDG‐I with epilepsy, psychomotor retardation, and skin abnormalities.7, 8, 9 Here, we describe two siblings with a G73E substitution in MPDU1 without skin involvement, but with dilatation of the biliary ducts and dystroglycanopathy symptoms including elevated creatine kinase (CK), dilated cardiomyopathy (DCM), buphthalmos, and glaucoma.