The importance of TTR met 30 in the diagnosis of familial amyloidotic polyneuropathy in the absence of a positive family history

Introduction. Familial amyloidotic polineuropathy type 1 is an hereditary autosomal dominant disease, characterized by having a mutant transthyretin (TTR met 30). For this reason there is a deposition of amyloid in several organs with their subsequent malfunction. The most characteristic clinical presentation is peripheral, sensomotor and autonomic neuropathy. The dysautonomic component is seen early and often dominates the clinical picture. Subsequently, there is cardiac ocular or renal involvement and death generally occurs 10 to 15 years after onset of the disorder. In Portugal one thought the gene was fully penetrant and, thus, a positive family history was an important criterion for the diagnosis. However an increasing number of patients without a positive family history have been identified. Clinical cases. We present the cases of three men and a woman, aged between 36 and 48 years, with clinical sensomotor and autonomic polyneuropathy. There was no known family history of the condition in any case. Nerve biopsy in three of the patients, and biopsy of abdominal fat in the other patient, showed amyloid to be present. Similarly, TTR met 30 analysis was positive in all cases, and allowed the diagnosis to be established Conclusion. It is essential to do TTR met 30 analysis in all patients with peripheral polyneuropathy in whom there is obviously a dysautonomic component and no known family history.