Objective: Identify the involvement of white matter tracts in HD, using this technique and, thus, evaluate it as a potential biomarker for the disease.

Background: Huntington’s disease (HD) is caused by a mutation with complete penetrance in the huntingtin protein gene. There is still no effective neuroprotective treatment for individuals with the mutation, but there are ongoing trials with new drugs. One of the limitations of clinical trials during pre-symptomatic stage of the disease is the lack of a reliable biological marker for assessing the progression of neurodegeneration. HD occurs in progressive loss of white matter (WM) volume and its integrity. The imaging technique through diffusion tensor imaging (DTI – Diffusion Tensor Imaging) to evaluate the fractional anisotropy (FA – Fractional Anisotropy), is able to study the tracts of WM.

Methods: Thirty four subjects were selected and divided into three groups: 11 patients with Huntington’s disease, 12 pre-symptomatic individuals (positive HD molecular test, without clinical symptoms, pre-symptomatic phase), and 11 control subjects (negative HD molecular test). Study subjects performed Magnetic Resonance Imaging (MRI) of the brain with tractography of white matter using DTI, with measurement of FA.

Results: There was a statistically significant decrease of FA in the cortical spinal tracts, corona radiate, knee, body and splenium of the corpus callosum, external capsule, thalamic radiations, superior and inferior longitudinal fasciculus and inferior frontal-occipital fasciculus WM, when compared DH group to the control and pre-symptomatic groups. This shows decreased congruence/orientation of the fibers in these structures, demonstrating degenerative process and axonal loss in patients with symptomatic HD. There was no statistically significant difference between the pre-symptomatic group and control group. WM is affected in a generalized form and various tracts are involved, demonstrating that the WM appears to have an important role in the pathophysiology of HD.

Conclusions: The tractography seems to be an interesting technique to be applied to patients with DH, but other studies with larger sample are required to assess the possible role in the progression of the neurodegenerative process.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/tractography-study-of-individuals-with-mutation-for-huntingtons-disease-in-symptomatic-and-pre-symptomatic-phases/