Alterations in Cerebrospinal Fluid Urea Occur in Late Manifest Huntington's Disease

Area of Science:

• Neuroscience
• Metabolomics
• Genetics

Background:

• Huntington's disease (HD) is a neurodegenerative disorder linked to expanded CAG repeats in the Huntingtin gene.
• Mutant huntingtin proteins (mHTT) are produced, leading to neurodegeneration.
• Previous studies noted elevated urea in HD models and patients, but its timing and mechanisms were unclear.

Purpose of the Study:

• To investigate urea cycle metabolism disturbances in Huntington's disease (HD).
• To determine the timing of urea elevations across different HD stages.
• To explore potential molecular mechanisms behind these metabolic changes.

Main Methods:

• Global metabolomic profiling of cerebrospinal fluid (CSF) was performed.
• Participants included controls and individuals in pre-manifest (PRE), manifest (MAN), and late manifest (LATE) HD stages.
• CSF samples were analyzed for approximately 500 metabolites, including urea and related compounds.

Main Results:

• Around 500 metabolites were altered in pre-manifest HD, but CSF urea levels were unchanged.
• Significantly elevated CSF urea was observed exclusively in late-stage manifest HD patients.
• No significant changes in urea metabolites like citrulline, ornithine, or arginine were detected.

Conclusions:

• Cerebrospinal fluid (CSF) urea elevations in Huntington's disease (HD) manifest late in the disease course.
• These late-stage urea increases may indicate accumulating cellular energy metabolism deficits.
• The findings highlight the dynamic metabolic changes occurring throughout HD progression.