HTRF analysis of soluble huntingtin in PHAROS PBMCs

Neurology. 2013 Sep 24;81(13):1134-40. doi: 10.1212/WNL.0b013e3182a55ede. Epub 2013 Aug 21.


Objective: We measured the levels of mutant huntingtin (mtHtt) and total huntingtin (tHtt) in blood leukocytes from Prospective Huntington At-Risk Observational Study (PHAROS) subjects at 50% risk of carrying the Huntington disease mutation using a homogeneous time-resolved fluorescence (HTRF) assay to assess its potential as a biomarker.

Methods: Peripheral blood mononuclear cells from consenting PHAROS subjects were analyzed by HTRF using antibodies that simultaneously measured mtHtt and tHtt. mtHtt levels were normalized to tHtt, double-stranded DNA, or protein and analyzed according to cytosine-adenine-guanine repeat length (CAGn), demographics, predicted time to clinical onset or known time since clinical onset, and available clinical measures.

Results: From 363 assayed samples, 342 met quality control standards. Levels of mtHtt and mt/tHtt were higher in 114 subjects with expanded CAG repeats (CAG ≥ 37) compared with 228 subjects with nonexpanded CAG repeats (CAG <37) (p < 0.0001). Analysis of relationships to predicted time to onset or to phenoconversion suggested that the HTRF signal could mark changes during the Huntington disease prodrome or after clinical onset.

Conclusions: The HTRF assay can effectively measure mtHtt in multicenter sample sets and may be useful in trials of therapies targeting huntingtin.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Clinical Trials as Topic
  • Double-Blind Method
  • Female
  • Fluorescence Resonance Energy Transfer / methods*
  • Frontal Lobe / metabolism
  • Frontal Lobe / pathology
  • Humans
  • Huntingtin Protein
  • Huntington Disease / blood*
  • Huntington Disease / genetics
  • Huntington Disease / pathology*
  • Leukocytes, Mononuclear / metabolism*
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Mutation / genetics
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Observation*
  • Postmortem Changes
  • Retrospective Studies
  • Trinucleotide Repeat Expansion / genetics


  • HTT protein, human
  • Huntingtin Protein
  • Nerve Tissue Proteins