Early and Systematic Screening in Chronic Neuropathy

Transthyretin familial amyloid polyneuropathy (TTR-FAP) is an autosomal dominant disorder, highly disabling and life-threatening, resulting of transthyretin (TTR) gene mutation. Clinically, TTR FAP is characterized by progressive sensorimotor and dysautonomic neuropathy, usually fatal within a few years. The disease prevalence is highly variable, with a large genotypic and phenotypic heterogeneity. Early and accurate diagnosis remains essential to propose early treatment. New pharmacotherapies have been developed, such as Tafamidis®, and many patients can avoid liver transplant formerly considered as the only therapeutic option. The prevalence of TTR-FAP disease has been previously estimated in series of patients with severe and progressive neuropathy, frequently leading to a delayed diagnosis. TTR-FAP is also easily suspected when neuropathy is associated with cardiac symptoms or dysautonomia.

Currently, genetic testing of TTR-FAP is targeted and is only prescribed to patients in whom the first-line assessment recommended by the High Authority for Health (HAS) did not identify a cause, and on the basis of a worsening of symptoms. An early diagnosis in those cases would allow earlier treatment and monitoring. No data are available about the prevalence of TTR-FAP in populations of patients with from chronic neuropathy of unknown aetiology, through a systematic screening of TTR mutations.

The diagnosis of TTR-FAP will be performed using standard procedures following international recommendations, requiring genetic analysis of the TTR gene.

The patients with a diagnosis of TTR-FAP confirmed during this study will be seen for an additional visit in the Investigating Centre and proposed suitable follow up, treatment and care.

Inclusion criteria

• Patients of both sexes presenting chronically (> 3 months):

• neuropathy confirmed by an electroneuromyography
• without obvious etiology (diabetes, alcohol consumption, renal insufficiency, neurotoxic substances intake, family history of diagnosed hereditary neuropathy)
• without anomaly of the following biological examinations: fasting blood glucose, blood count, gamma-glutamyl transferases, average cell volume, transaminases, serum creatinine clearance, C-reactive protein, TSH
• Aged 18 to 90 years Patients giving their free and informed consent to participate, after research information

Exclusion criteria

• People placed under the protection of justice.
• Patients who are not affiliated or who are not beneficiaries of a social security scheme
• Patients with chronic neuropathy related to a known etiology