Characterization of two unusual truncating PMM2 mutations in two CDG-Ia patients.

Congenital disorders of glycosylation type Ia (CDG-Ia) is a recessive metabolic disorder caused by mutations in the PMM2 gene and characterized by a defect in the synthesis of N-glycans. The clinical presentation ranges from very severe multi-organ failure to mild neurological problems. A plethora of PMM2 mutations has been described and the vast majority are missense mutations. This selection reflects the requirement of a minimal phosphomannomutase activity to be compatible with life.