Life with too much polyprenol: polyprenol reductase deficiency.

Area of Science:

• Biochemistry
• Genetics
• Molecular Biology

Background:

• Congenital disorders of glycosylation (CDG) result from defects in glycoprotein manufacturing.
• Glycosylation is crucial for protein function and cellular processes.

Observation:

• A 6-year-old patient presented with psychomotor retardation, nystagmus, hypotonia, and microcephaly, indicative of a novel CDG-I subtype.
• The patient had a homozygous stop-codon mutation (c.57G>A [W19X]) in the SRD5A3 gene, leading to a non-functional polyprenol reductase.

Findings:

• Despite the absence of functional SRD5A3, approximately 70% of transferrin (Tf) remained correctly glycosylated.
• Fibroblast analysis revealed a high polyprenol/dolichol ratio but normal dolichol levels, suggesting polyprenol may interfere with N-glycan assembly.
• The data implies the existence of an alternative dolichol biosynthesis pathway.

Implications:

• This discovery challenges current understanding of N-glycosylation pathways.
• It opens new avenues for investigating CDG pathogenesis and potential therapeutic targets.
• Further research is needed to elucidate the alternative dolichol biosynthesis pathway.