Type I (transthyretin Met30) familial amyloid polyneuropathy in Japan: early- vs late-onset form.
BACKGROUND
Type I (transthyretin Met30) familial amyloid polyneuropathy (FAP TTR Met30) occurs in 2 endemic foci in Japan. We have also reported late-onset Japanese cases unrelated to an endemic focus and showing distinctive clinicopathologic features.


OBJECTIVE
To compare clinical and geographic features of FAP TTR Met30 between patients with onset before and after 50 years of age.


METHODS
Clinical information was obtained through a nationwide survey by the Study Group for Hereditary Neuropathy in Japan.


RESULTS
Families with early-onset disease in this study numbered 82, and those with late onset, 59. In families with late onset, neuropathy showed male preponderance, low penetrance, little relationship to endemic foci, sensorimotor symptoms beginning distally in the lower extremities with disturbance of both superficial and deep sensation, and relatively mild autonomic symptoms. Families with early onset showed higher penetrance, concentration in endemic foci, predominant loss of superficial sensation, severe autonomic dysfunction, and atrioventricular nodal block requiring pacemaker implantation.


CONCLUSIONS
This study confirmed differences in clinical and geographic features between early- and late-onset FAP TTR Met30. Late-onset cases may be more prevalent and widespread than previously believed.
Koike
Haruki
H
Department of Neurology, Nagoya University Graduate School of Medicine, Japan.
Misu
Ken-ichiro
K
Ikeda
Shu-ichi
S
Ando
Yukio
Y
Nakazato
Masamitsu
M
Ando
Eiko
E
Yamamoto
Masahiko
M
Hattori
Naoki
N
Sobue
Gen
G
D000328:Adult; D017668:Age of Onset; D000368:Aged; D019943:Amino Acid Substitution / Q000235:genetics; D028227:Amyloid Neuropathies, Familial / Q000453:epidemiology* / Q000235:genetics / Q000503:physiopathology; D005260:Female; D006306:Health Surveys; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008715:Methionine / Q000235:genetics; D008875:Middle Aged; D011228:Prealbumin / Q000235:genetics*; D012737:Sex Factors
D011228:Prealbumin; D008715:Methionine