Expanding the Biomarkers in Familial Amyloid Neuropathy: MRI and Motor Unit Estimation by Electrophysiological Study

Plain-language summary

Familial amyloid neuropathies (FAP) are hereditary disease due to a mutation of the tranthyretin gene (TTR). These neuropathies are severe and life frightening. Asymptomatic carrier of TTR mutation are now detected in large TTR-FAP family. However, it is very hard to detect the moment where a TTR mutation carrier become symptomatic: too early diagnosis exposes the patients to side effect of the treatment and too late diagnosis exposes the patient to disease progression and clinical sequels. Neurological monitoring comprises clinical examination, electrophysiology and imaging. Sensitivity and specificity of these tools are not sufficient and we have to develop new biomarkers sensitive enough to detect modifications under treatment and the moment where a TTR mutation carrier become symptomatic Magnetic resonance imaging (MRI) can well evaluate neuromuscular diseases. Electrophysiological examination is also a good tool to evaluate NAF. MUNIX is a technique that permits to estimate the number of motor unit in one muscl. MUNIX is related to the disability in chronic inflammatory neuropathies and could be more sensitive than clinical scales and other electrophysiological data to detect modification of the disease in TTR-FAP. The objective of this exploratory study is to test the applicability of MUNIX and MRI as early measures for detecting the transition from asymptomatic to symptomatic TTR-FAP. In symptomatic TTR-FAP we will determine if MUNIX and MRI data are related to clinical deficiency and disability of the patients. This is a transversal exploratory study. If we manage to demonstrate that MRI and MUNIX can segregate symptomatic versus asymptomatic TTR mutation gene carriers, we will propose a longitudinal study with a follow up of more asymptomatic gene carriers.

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