Clinical and genetic findings in eight Israeli patients with transthyretin-associated familial amyloid polyneuropathy.

Background: Transthyretin (TTR)-associated familial amyloid polyneuropathy (FAP) is an autosomal dominant multisystem disease with neurological and extra-neurological manifestations. It is caused by various mutations in the TTR gene leading to the formation of insoluble amyloid.
Objectives: To describe the clinical and genetic findings in patients with TTR-associated FAP in Israel.
Methods: We evaluated eight patients clinically and genetically during the years 2006 to 2011.
Results: At onset, all the patients exhibited sensory loss of the lower and upper limbs, five patients experienced muscle pain, and one patient had lower limb weakness. Five patients had autonomic nervous system manifestations, and four demonstrated evidence of amyloid cardiomyopathy. Nerve conduction studies showed sensorimotoraxonal neuropathy in all patients. Sural nerve biopsies were obtained in five patients; only three biopsies revealed amyloid deposit. In four patients of Yemenite descent, genetic analysis of the TTR gene demonstrated ser77tyr mutation. One patient of Tunisian descent and one Ashkenazi patient harbored the val30met mutation. One patient of Iranian descent showed val32ala mutation, and another Ashkenazi patient showed phe33leu mutation.
Conclusions: TTR-associated FAP is a progressive and fatal disease that exists in the Israeli population and is unproportionally common among Yemenite Jews. This disease may be under-diagnosed and should be considered in the differential diagnosis of any patient with rapidly progressive neuropathy, especially with autonomic involvement or extra-neural features. The absence of amyloid in nerve biopsy should not rule out the diagnosis.