Quantification of mutant huntingtin protein in cerebrospinal fluid from Huntington's disease patients

J Clin Invest. 2015 May;125(5):1979-86. doi: 10.1172/JCI80743. Epub 2015 Apr 6.


Background: Quantification of disease-associated proteins in the cerebrospinal fluid (CSF) has been critical for the study and treatment of several neurodegenerative disorders; however, mutant huntingtin protein (mHTT), the cause of Huntington's disease (HD), is at very low levels in CSF and, to our knowledge, has never been measured previously.

Methods: We developed an ultrasensitive single-molecule counting (SMC) mHTT immunoassay that was used to quantify mHTT levels in CSF samples from individuals bearing the HD mutation and from control individuals in 2 independent cohorts.

Results: This SMC mHTT immunoassay demonstrated high specificity for mHTT, high sensitivity with a femtomolar detection threshold, and a broad dynamic range. Analysis of the CSF samples showed that mHTT was undetectable in CSF from all controls but quantifiable in nearly all mutation carriers. The mHTT concentration in CSF was approximately 3-fold higher in patients with manifest HD than in premanifest mutation carriers. Moreover, mHTT levels increased as the disease progressed and were associated with 5-year onset probability. The mHTT concentration independently predicted cognitive and motor dysfunction. Furthermore, the level of mHTT was associated with the concentrations of tau and neurofilament light chain in the CSF, suggesting a neuronal origin for the detected mHTT.

Conclusions: We have demonstrated that mHTT can be quantified in CSF from HD patients using the described SMC mHTT immunoassay. Moreover, the level of mHTT detected is associated with proximity to disease onset and diminished cognitive and motor function. The ability to quantify CSF mHTT will facilitate the study of HD, and mHTT quantification could potentially serve as a biomarker for the development and testing of experimental mHTT-lowering therapies for HD.

Trial registration: Not applicable.

Funding: CHDI Foundation Inc.; Medical Research Council (MRC) UK; National Institutes for Health Research (NIHR); Rosetrees Trust; Swedish Research Council; and Knut and Alice Wallenberg Foundation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • British Columbia
  • Cohort Studies
  • Disease Progression
  • Female
  • Genetic Carrier Screening
  • Humans
  • Huntingtin Protein
  • Huntington Disease / cerebrospinal fluid*
  • Immunoassay / methods*
  • London
  • Male
  • Middle Aged
  • Nerve Tissue Proteins / cerebrospinal fluid*
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / immunology
  • Neurofilament Proteins / cerebrospinal fluid
  • Recombinant Fusion Proteins / metabolism
  • Sensitivity and Specificity
  • Single-Blind Method
  • Trinucleotide Repeat Expansion
  • tau Proteins / cerebrospinal fluid


  • HTT protein, human
  • Huntingtin Protein
  • MAPT protein, human
  • Nerve Tissue Proteins
  • Neurofilament Proteins
  • Recombinant Fusion Proteins
  • neurofilament protein L
  • tau Proteins