[Two sibling patients with late-onset familial amyloidotic polyneuropathy and atypical clinical manifestations].

Brothers (case 1 and case 2) had familial amyloidotic polyneuropathy type 1 (FAP type 1) confirmed with sural nerve biopsy and DNA analysis. Both patients were unique in that their ages at onset were 56 and 52, and that their only manifestation was sensori-motor polyneuropathy, without clinically apparent autonomic involvements such as orthostatic hypotension, sweat dysfunction and sphincter dysfunction, or severe organ involvement such as gastrointestinal features and myocardial involvement after the onset. They are also unique in that their parents were healthy. The initial manifestation was sensori-motor polyneuropathy starting in the lower extremities. These atypical manifestations made the diagnosis of FAP type 1 difficult in the present cases. Based on reports in the literature and the present cases, there might be a tendency that in patients with late-onset FAP type 1 the clinical manifestations are generally mild and autonomic involvement and organ disturbance are absent or mild. In the etiological diagnosis of polyneuropathy, FAP type 1 should be considered especially in steadily progressive patients.