RESUMO
OBJECTIVE: A characteristic feature of spinocerebellar ataxia type 2 (SCA2) is saccadic slowing at early disease stages. We sought to determine whether this sign is detectable before clinical manifestation and quantifies the disease progression throughout life in linear fashion. METHODS: In a specialized ataxia clinic, 54 presymptomatic carriers of SCA2 polyglutamine expansions and 56 relatives without mutation were documented with regard to their maximal saccade velocity (MSV). RESULTS: Among the control individuals, a significant effect of aging on MSV was observed. After elimination of this age influence through a matched-pair approach, a presymptomatic decrease of MSV could be shown. The MSV reduction was stronger in carriers of large expansions. In the years before calculated disease manifestation, the MSV impairment advanced insidiously. CONCLUSION: Saccade velocity is a sensitive SCA2 endophenotype that reflects early pontine degeneration and may be a useful diagnostic parameter before the onset of ataxia. SIGNIFICANCE: Future neuroprotective therapies of polyglutamine neurodegeneration may be assessed by MSV from earliest to prefinal disease stages.
Assuntos
Transtornos da Motilidade Ocular/etiologia , Transtornos da Motilidade Ocular/fisiopatologia , Músculos Oculomotores/fisiopatologia , Movimentos Sacádicos/fisiologia , Ataxias Espinocerebelares/complicações , Ataxias Espinocerebelares/fisiopatologia , Adolescente , Adulto , Idoso , Ataxinas , Cerebelo/fisiopatologia , Progressão da Doença , Diagnóstico Precoce , Feminino , Heterozigoto , Humanos , Masculino , Pessoa de Meia-Idade , Proteínas do Tecido Nervoso/genética , Vias Neurais/fisiopatologia , Transtornos da Motilidade Ocular/diagnóstico , Músculos Oculomotores/inervação , Valor Preditivo dos Testes , Prognóstico , Ataxias Espinocerebelares/diagnóstico , Adulto JovemRESUMO
A characteristic feature of spinocerebellar ataxia type 2 (SCA2) is saccadic slowing at early disease stages. We sought to determine whether this sign is detectable before clinical manifestation and quantifies the disease progression throughout life in linear fashion. In a specialized ataxia clinic, 54 presymptomatic carriers of SCA2 polyglutamine expansions and 56 relatives without mutation were documented with regard to their maximal saccade velocit Spinocerebellar ataxia type 2 Among the control individuals, a significant effect of aging on MSV was observed. After elimination of this age influence through a matched-pair approach, a presymptomatic decrease of MSV could be shown. The MSV reduction was stronger in carriers of large expansions. In the years before calculated disease manifestation, the MSV impairment advanced insidiously.Saccade velocity is a sensitive SCA2 endophenotype that reflects early pontine degenerationPolyglutamine expansion and may be a useful diagnostic parameter before the onset of ataxia. Significance: Future neuroprotective therapies of polyglutamine neurodegeneration may be assessed by MSV from earliest to prefinal disease stages...(AU)
Assuntos
HumanosRESUMO
Spinocerebellar ataxia type 2 (SCA2) is an autosomal-dominant disorder mani-festing with gait, limb, and speech incoordination, and with distinctive symptomssuch as early slowing of horizontal eye movements and early neuropathy.13 Neuro-pathological analysis has demonstrated severe olivopontocerebellar atrophy (OPCA)early in the course of disease, progressing to involve the anterior horn, substantia ni-gra, thalamus, and somatosensory pathways.4,5 Clinical onset is usually in midlife,but has been observed to range from 1 to 65 years of age, depending on the size ofthe underlying mutation, a CAG (cytosine-adenine-guanine)-trinucleotide repeat ex-pansion in exon 1 of the SCA2 gene...(AU)