Congenital disorders of glycosylation (CDG) represent a newly delineated group of inherited multisystem disorders characterized by defective glycoprotein biosynthesis. In the present study we report and discuss the clinical and neuropathological findings in a newborn with CDG type Ia (CDG-Ia). The patient presented mild dysmorphic facial features, inverted nipples, progressive generalized edema, hypertrophic cardiomyopathy, hepatosplenomegaly, muscular hypotonia and had severe hypoalbuminemia. Deficiency of phosphomannomutase (PMM)-2 activity was detected. Molecular analysis showed V231M/T237R mutations of the PMM2 gene. Muscular biopsy, disclosed myopathic alterations with myofibrillar disarray by electron microscopy. The patient died at 1 month of age of circulatory and respiratory failure. Autopsy showed liver fibrosis and renal abnormalities. Neuropathological abnormalities were mainly confined to the cerebellum. Histological and immunocytochemical examination of cerebellar tissue showed partial atrophy of cerebellar folia with severe loss of Purkinje cells, granular cell depletion and various morphological changes in the remaining Purkinje cells and their dendritic arborization. Autopsy findings confirm the complexity of the CDG-Ia syndrome, and indicate that CDG-Ia is a distinct disease entity, which can be differentiated from other neurological disorders and other types of CDG, not only clinically, but also based on unique pathological findings. The data proved useful in determining the underlying disease process associated with a defective N-glycosylation pathway.