P032: Improving ataxia symptoms in patients with monoallelic DHDDS-CDG using nicotinamide precursor supplements

Congenital disorders of glycosylation are disorders of protein modification. In these disorders, decreased or aberrant surface glycosylation impair protein trafficking and function. Dehydrodolichol diphosphate synthase (encoded by DHDDS) works in complex in the NAD-dependent dolichol cycle to produce dolichol; its derivative dolichol phosphate is a lipid heterozygote and monosaccharide donor of N- & O-glycosylation/GPI anchor formation, respectively. Defective variants in DHDDS lead to typically severe early onset multisystemic autosomal recessive disease; however, inheritance of a single defective variant causes isolated neurological manifestations (ataxia, developmental delay, speech apraxia, and seizures).