The congenital disorder of type 1a glycosylation (CDG-1a) is an autosomal recessive disease that affects the synthesis of glycoproteins. It is characterized by neurological involvement that may be associated with multivisceral involvement and it is estimated that the frequency is 1/50,000-1/100,000.
CDG-1a is characterized by high variability of its clinical manifestations, which may include feeding problems, vomiting and diarrhea, with delayed development in infants, and severe encephalopathy with axial hypotonia, abnormal eye movement, marked psychomotor retardation, peripheral neuropathy, cerebellar hypoplasia, episodes similar to stroke, and retinitis pigmentosa in infancy or in adulthood.
Overall, in the congenital disorder of glycosylation, psychomotor retardation is the most constant sign. The other signs, often present with varying degrees of severity are: lipo-cutaneous anomalies (orange peel), olivopontocerebellar atrophy, skeletal abnormalities, inverted nipples, coagulation disorders, and cytolysis and hepatic fibrosis.
Biological diagnosis is based on the demonstration of abnormal glycosylation of glycoproteins from serum, buffy responsible measure activities and determination of mutations in PMM2 gene.