Treatment of transthyretin familial amyloid polyneuropathy with tafamidis: A case report

Abstract

Introduction: Familial amyloid polyneuropathy (FAP) is a rare hereditary disorder caused by mutations in the transthyretin (TTR) gene. Tafamidis is a TTR stabilizer able to prevent TTR tetramer dissociation, and several studies have demonstrated its safety and efficacy at slowing the progression of neuropathy in FAP caused by the TTR Val30Met mutation. However, nerve conduction study (NCS) and electromyography (EMG) results have yet to be reported in relation to FAP progression during tafamidis therapy. Case presentation: A 71-year-old man was admitted to the hospital because of severe numbness and walking difficulties. He did not complain of any autonomic dysfunction or visual disturbance, and he had no family history of neuromuscular disorders. A NCS and EMG indicated length-dependent axonal sensorimotor polyneuropathy. A sural nerve biopsy revealed amyloid deposits, and genetic testing demonstrated a TTR Val30Met mutation. We diagnosed the patient with FAP and treated him using tafamidis therapy. One year later, the patient is still on tafamidis therapy, and his symptoms have shown no significant change. The NCS showed no changes in the compound muscle action potential amplitudes of the left ulnar nerve, while EMG showed the fibrillation/positive sharp wave to have disappeared from the patient’s upper limb. We conclude from these findings a slowing of the neurologic progression. Conclusions: Tafamidis was effective in slowing the neurologic progression over one year in a FAP patient with the TTR Val30 Met mutation, and NCS and EMG were useful for assessing this therapeutic effect.