[Late onset of type I familial amyloid neuropathy: results of biopsy from accessory salivary glands].

Familial amyloidotic polyneuropathy (FAP) type I is usually characterized by onset in the third decade, autonomic nervous system failure, and heart block conduction occurring after the onset of neurological symptoms. A 74-year-old woman, with past medical history of a third degree heart block treated by a pace-maker, was hospitalized because of an axonal sensory-motor polyneuropathy, without autonomic dysfunction. There was no familial history. Because she complained of mouth dryness, biopsies of the labial salivary glands were performed, showing amyloid deposits. Immuno-histochemicals studies confirmed the presence of transthyretin. We analysed the transthyretin gene of the patient and her asymptomatic son, and found in both cases, the point mutation leading to the single amino acid substitution of a methionine for valine at position 30, which is typical of type I FAP. This case revealed the clinical variation of FAP type I and the interest of biopsies of the labial salivary glands in the diagnosis of polyneuropathies.