Efficacy of diflunisal on autonomic dysfunction of late-onset familial amyloid polyneuropathy (TTR Val30Met) in a Japanese endemic area.

OBJECTIVE: To evaluate the long-term efficacy and safety of diflunisal in late-onset familial amyloid polyneuropathy (FAP) in a Japanese endemic area. METHODS: Consecutive six FAP patients (mean age: 65.8 ± 7.3 years) with a transthyretin (TTR) Val30Met mutation from an endemic area of late-onset FAP were prospectively recruited to an open label study with oral diflunisal (250 mg twice a day). We evaluated clinical symptoms, Kumamoto FAP score, modified body mass index (mBMI), Medical Research Council sum score, nerve conduction studies (NCS), electrocardiogram (ECG), ECG Holter monitor test, echocardiography, and (123)iodine-metaiodobenzylguanidine ((123)I-MIBG) myocardial scintigraphy. RESULTS: One patient ceased to take diflunisal because of hematuria which was reversible. The other five patients were treated with diflunisal for 3-5 (4.4 ± 0.9 years) years. Autonomic symptoms (orthostatic hypotension and gastrointestinal symptoms) disappeared after treatment in two of the four patients with the symptoms. Delayed heart to mediastinum ratio on (123)I-MIBG imaging, a marker of cardiac postganglionic sympathetic nerve function, increased during the three-year treatment. mBMI was maintained through observation period. While, motor and sensory symptoms, Kumamoto FAP scores, and data on NCS gradually deteriorated. CONCLUSION: Diflunisal might be effective especially for autonomic dysfunction in late-onset FAP with a TTR Val30Met mutation.