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

• We performed diflunisal therapy for late-onset FAP in a Japanese endemic area.
• The treatment resulted in improvement of autonomic symptoms, and maintenance of mBMI.
• Delayed H/M ratios on 123I-MIBG imaging increased significantly.
• Motor and sensory symptoms gradually deteriorated.
• There was no adverse event of diflunisal except reversible hematuria in a patient.

ObjectiveTo evaluate the long-term efficacy and safety of diflunisal in late-onset familial amyloid polyneuropathy (FAP) in a Japanese endemic area.MethodsConsecutive 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 123iodine-metaiodobenzylguanidine (123I-MIBG) myocardial scintigraphy.ResultsOne 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 123I-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.ConclusionDiflunisal might be effective especially for autonomic dysfunction in late-onset FAP with a TTR Val30Met mutation.