Late-onset familial amyloid polyneuropathy type I (transthyretin Met30-associated familial amyloid polyneuropathy) unrelated to endemic focus in Japan. Clinicopathological and genetic features.
ABSTRACT Clinicopathological and genetic features were assessed on 35 Japanese families affected by late-onset familial amyloid polyneuropathy type I (transthyretin Met30-associated familial amyloid polyneuropathy, FAP TTR Met30) whose siblings were unrelated to endemic Japanese foci. In these patients (50 years or older), the most common initial symptom was paraesthesias in the legs. Autonomic symptoms were generally mild and did not seriously affect daily activities. The male-to-female ratio was extremely high (10.7 : 1). A family history was evident in only 11 out of 35 families, and other patients were apparently sporadic. The rate of penetrance was very low. Symptomatic siblings of familial cases showed a late age of onset, male preponderance and clinical features similar to those of the probands. Asymptomatic carriers, predominantly female, were detected relatively late in life. The geographical distribution of these late-onset, FAP TTR Met30 cases was scattered throughout Japan. In three autopsy cases and 20 sural nerve biopsy specimens, neurons in sympathetic and sensory ganglia were relatively preserved. Amyloid deposition was seen in the peripheral nervous system, particularly in the sympathetic ganglia, dorsal root ganglia and proximal nerve trunks such as sciatic nerve. These abnormalities were milder than those seen in typical early-onset FAP TTR Met30, as observed in two Japanese endemic foci of this disease. While axonal degeneration was prominent in myelinated fibres, resulting in severe fibre loss, unmyelinated fibres were relatively preserved. Our cases of late-onset FAP TTR Met30 showed features distinct from those of typical early-onset FAP TTR Met30 that occurred in the two Japanese endemic foci. Factors responsible for clinicopathological differences between these two forms of FAP TTR Met30 need to be identified.
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ABSTRACT: Between 1976 and 2003, we diagnosed 144 patients with familial amyloid polyneuropathy (FAP) in the Balearic Islands (Spain). Analysis of genetic epidemiological data from 102 confirmed patients showed 62% were men. Parental transmission was paternal in 38, maternal in 25, and unknown in 39. No family history of FAP was found in 32 patients. TTRVal30Met associated with haplotype I was present in the individuals studied. Mean age-at-onset was 45.7 years which lies between that of Sweden and those of Portugal, Japan and Brazil. Duration of FAP was of 9.7 years. Age-at-onset, age-at-death, duration and fertility were similar between sexes. Twenty-nine intergeneration familial pairs of patients were ascertained. Raw anticipation was positive in twenty-four pairs, zero in one, and negative in four. Differences greater than 9 years between age-at-onset of the first and second member were considered relevant; positive relevant anticipation was found in 76% of the whole pairs. The frequency of positive anticipation of parent-child pairs was not significantly different than those described in the Swedish and Portuguese series. Significant positive correlation in age-at-onset was confirmed in twenty-seven types of pairs supporting the hypothesis that a genetic factor may modulate age-at-onset. The Balearic focus of FAP is expanding and constitutes a public health problem.Amyloid 04/2005; 12(1):54-61. · 2.66 Impact Factor