Introduction Huntington's disease is a monogenic inherited disease, which is a unique model to search for biomarkers of sporadic neurodegenerative diseases. The purpose of this study is to find a new biomarker for Huntington's disease—the linear density of C-fibres in the skin biopsy.

Materials and Methods To evaluate peripheral sensory nerves in Huntington's disease, we studied cutaneous free and encapsulated sensory nerve endings in 30 patients with Huntington's disease, 20 carriers of the mutant Huntington's disease gene and 30 healthy controls using 3-mm punch biopsies from the distal leg and examined the linear density of C-fibres. Skin C-fibres were stained using antibody to protein gene product 9.5 and counted with confocal microscopy.

Results We revealed that the linear density of C-fibres in the skin biopsy was twice less in patients with Huntington's disease as compared with control group patients (8.7±4.0 and 15.87±3.85, respectively) (p<0.01). The decrease of the linear density of C-fibres was also found in carriers of the mutant gene compared with the control group (12.36±2.65 and 15.87±3.85, respectively) (p<0.01). In groups of patients and carriers of Huntington's disease we found such degenerative processes as increased branching, sprouting of nerves and enlargement of the vascular bed.

Conclusion Thus, we have identified a new biomarker for the diagnosis of Huntington's disease, which can serve as a new diagnostic criterion for the identification of other neurodegenerative diseases in the early stage. On the other hand, sensory disturbances are part of the clinical picture of Huntington's disease. We demonstrated a peripheral deafferentation in Huntington's disease that could play a major role in the pathogenesis of the sensory dysfunction.