MAN1B1-CDG: novel patients and novel variant

Congenital disorders of glycosylation (CDGs) are a group of genetic disorders due to hypoglycosylation of proteins and lipids. A type I pattern is associated with defects in glycan assembly and transfer (CDG-I; cytosol; and endoplasmic reticulum defects), a type II pattern is seen in processing defects of the Golgi apparatus. MAN1B1-CDG is an autosomal recessive CDG-II due to mutations in the α 1,2-mannosidase gene (MAN1B1), mainly characterized by psychomotor disability, facial dysmorphism, truncal obesity, and hypotonia.

Three patients (two males and one female), with MAN1B1-CDG who had elevated transaminase levels are presented. All patients had presented due to dysmorphic and neurological findings and hypertransaminasemia was remarkable. A type 2 pattern was found on serum transferrin isoelectrofocusing analysis of the presented cases. MAN1B1-CDG was confirmed by genetic analysis.

Although the cause of the increased serum transaminase levels in the present patients is not clear, no evidence for an infection or underlying liver pathology could be identified. In order to know if this is a consistent feature, we suggest measuring serum transaminase levels regularly in MAN1B1-CDG patients.