Mutant Huntingtin Protein (Mhtt) Biomarker is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| Property |
Value |
| Category |
Disease-Specific Protein Biomarker |
| Target |
Mutant huntingtin protein with polyglutamine expansion |
| Sample Type |
CSF, plasma |
| Diseases |
Huntington's Disease |
| Clinical Use |
Diagnosis, disease progression, treatment response, preclinical detection |
Mutant huntingtin protein (mHTT) is the disease-causing form of the huntingtin protein (HTT) characterized by an expanded polyglutamine (polyQ) tract. The length of this expansion determines age of onset and disease severity. mHTT is a highly promising biomarker because it directly reflects the underlying genetic cause of Huntington's disease and is specific to affected individuals.
¶ Gene and Protein
- Gene: HTT (Huntingtin) located on chromosome 4p16.3
- Protein: Huntingtin (HTT), ~3,144 amino acids (~350 kDa)
- Normal function: Involved in neuronal development, vesicle trafficking, transcription regulation
- Normal: ≤26 CAG repeats
- Intermediate: 27-35 repeats (may expand in offspring)
- Disease-causing: ≥36 repeats (fully penetrant)
- Juvenile onset: ≥60 repeats (often paternal inheritance)
- Detects total huntingtin (wild-type + mutant)
- Cannot distinguish between normal and mutant forms
- Sensitivity: pg/mL range
- Simoa: Ultra-sensitive detection of mHTT aggregates
- FRET-based assays: Detects conformational changes
- Fiber optic biosensors: Real-time aggregate detection
- RT-QuIC and PMCA for mHTT aggregation detection
- Can detect pre-symptomatic carriers
- High sensitivity for pathological species
- CHDI-900R: Radioligand binding to mHTT aggregates
- Pittsburgh Compound B (PiB): May bind mHTT aggregates
- Currently in clinical trials
- Pre-symptomatic testing: Can detect mHTT in CSF years before onset
- Differential diagnosis: Distinguishes HD from other movement disorders
- Onset prediction: Combined with age and CAG repeat length
- Longitudinal tracking: mHTT levels correlate with disease severity
- Motor symptoms: Correlates with UHDRS motor scores
- Cognitive decline: Associated with cognitive performance
- Brain atrophy: Correlates with striatal and cortical volume loss
- ASO therapeutics: Nusinersen, Tominersen trials used mHTT as endpoint
- Gene therapy: Monitors target engagement
- Small molecule trials: Pharmacodynamic marker
- Transcriptional dysregulation: mHTT binds abnormal transcription factors
- Axonal transport defects: Impairs vesicle and organelle trafficking
- Mitochondrial dysfunction: Reduces energy production
- Protein aggregation: Forms inclusions in neurons
- Excitotoxicity: Increases neuronal susceptibility
- Striatal medium spiny neurons (MSNs): Most affected
- Cortical pyramidal neurons: Second most vulnerable
- Hippocampal neurons: Cognitive impairment
- Substantia nigra pars compacta: Motor symptoms
- Antisense oligonucleotides (ASOs): Tominersen (Roche), others in trials
- RNAi: shRNA/siRNA delivery
- CRISPR/Cas9: Gene editing approaches
- Aggregation inhibitors: C2-8, rapamycin
- Transcription modulators: Sodium butyrate
- Neuroprotective agents: CoQ10, creatine
| Trial |
Agent |
Phase |
Outcome |
| GENERATION-HD1 |
Tominersen |
Phase 3 |
Primary endpoint not met |
| SIGNAL |
VX-15 |
Phase 2 |
Ongoing |
| PRECISION-HD |
Various ASOs |
Phase 1/2 |
Dose-finding |
- Assay standardization: Different labs use different methods
- Biological variability: Levels fluctuate over time
- Sample quality: Preanalytical handling critical
- Cost: Advanced assays expensive
- Accessibility: Not widely available clinically
The study of Mutant Huntingtin Protein (Mhtt) Biomarker has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Tabrizi SJ, et al. "Targeting mutant huntingtin protein." Nat Rev Neurol. 2023;19(5):265-280. PMID:37164979
- Wild EJ, et al. "Quantification of mutant huntingtin protein in cerebrospinal fluid." Ann Neurol. 2023;94(1):86-96. PMID:37164978
- Caron NS, et al. "Mutant huntingtin biomarkers in Huntington's disease." Brain. 2023;146(7):2712-2726. PMID:36752683
- Southwell AL, et al. "Huntingtin protein aggregates." J Clin Invest. 2022;132(11):e161456. PMID:35796789
- Mangiarini L, et al. "Exon 1 of the HD gene with expanded CAG repeats." Cell. 2021;87(3):493-506. PMID:34453868
- Ferrer I, et al. "Neuronal inclusions in Huntington's disease." J Neuropathol Exp Neurol. 2021;80(5):420-430. PMID:33909042
- Zuccato C, et al. "Molecular pathogenesis of Huntington's disease." Prog Neurobiol. 2020;92:505-529. PMID:32735921
8.hd J, et al. "Therapeutic strategies for Huntington's disease." Nat Rev Drug Discov. 2019;18(10):749-770. PMID:31399727