First report of two Taiwanese siblings with sialidosis type I: a 10-year follow-up study.
We report the clinical features, electrophysiological findings and genetic characteristics of the first two Taiwanese siblings ever reported with sialidosis type I. We also provide a 10-year follow-up result. Enzymological analysis revealed a primary sialidase deficit. The back-averaged electroencephalography demonstrated myoclonic jerk-related cortical activities and the somatosensory evoked potential studies revealed giant cortical components. During the 10-year follow-up, the brain magnetic resonance images of the younger brother remained normal, whereas they showed mild cerebellar atrophy in the older sister. Macular cherry red spots were absent in both siblings. However, visual evoked potential revealed progressively prolonged latencies of P100 bilaterally, which was consistent with progressive deterioration of the siblings' visions. DNA analysis showed that the siblings had a homozygous missense point mutation c.544A-->G (Ser182Gly) in the exon 3 of the alpha-N-acetyl-neuraminidase (NEU1) gene. The mutation is predicted to cause a decreased sialidase activity but the mutant sialidase can still be targeted to the lysosomes, which may correlate with the mild clinical phenotypes and absent cherry red spots in the siblings.
Chen
Chiung-Mei
CM
Department of Neurology, Chang Gung Memorial Hospital and College of Medicine, Chang-Gung University, Taipei, Taiwan.
Lai
Szu-Chia
SC
Chen
I-Cheng
IC
Hsu
Kai-Cheng
KC
Lyu
Rong-Kuo
RK
Ro
Long-Sun
LS
Chang
Hong-Shiu
HS
D000293:Adolescent; D000328:Adult; D004594:Electrophysiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009081:Mucolipidoses / Q000235:genetics / Q000503:physiopathology*; D009154:Mutation; D009439:Neuraminidase / Q000235:genetics; D035781:Siblings; D013624:Taiwan
C486385:NEU1 protein, human; D009439:Neuraminidase