Hereditary amyloid polyneuropathy in north west Ireland.

Seven cases of chronic sensorimotor polyneuropathy due to amyloidosis, from 7 different families, are described, in addition to the pathology in a sibling of 1 case. The age of onset ranged from 55 to 72 years. Cardiac involvement, intermittent diarrhoea and syncopal attacks were a frequent occurrence. Motor conduction velocity showed a moderate degree of slowing in 5 of 6 cases studied and marked slowing in 1. Amyloid deposits were seen in nerve biopsy material of all 8 subjects and in rectal mucosa from 1. Immunohistochemical identification revealed AF (transthyretin-derived)--amyloid in all 8 instances, confirming the presence of type 1 familial amyloid neuropathy. The genealogical data supported this analysis. Six of the 8 cases originated in a small area of the north-west coast of County Donegal in Ireland. The remaining cases also originated in the same county.