The clinical phenotype and the molecular defect of a patient with a new sub
type of congenital disorders of glycosylation (CDC-lc, formerly designated
as CDGS type V) characterized by a deficiency of Dol-P-Glc:Man(9)GlcNAc(2)-
PP-Dol glucosyltransferase is described. The clinical picture presents with
several features similar to CDC-la (phosphomannomutase 2 deficiency) such
as hypotonia and atactic-dystonic movements. In contrast to CDG-1a, the cou
rse of the disease appears milder. The head growth, the functioning of the
peripheral nerves and the initial cerebellar development were normal. Seque
ncing of the patient's Dol-P-Clc:Man(9)GlcNAc(2)-PP-Dol glucosyltransferase
cDNA revealed an in-frame deletion of three nucleotides leading to the los
s of isoleucine 299.