RESUMO
OBJECTIVE: Oxidative stress has been suggested as a contributor of Alzheimer disease (AD) neurodegeneration, particularly in those patients with late-onset AD (LOAD). Therefore, the authors studied the effect of glutathione S-transferase (GST) P1-M1-T1 gene polymorphisms and their interactions with the apolipoprotein E (ApoE) epsilon4 allelic variant on the three-year longitudinal course of AD. METHODS: Global cognitive level as measured by the Mini-Mental State Exam, basic activities of daily living (BADLs) as measured by the Physical Self-Maintenance Scale, and behavior as measured by the Neuropsychiatric Inventory, were assessed at baseline and after 1, 2, and 3 years in a sample of 99 LOAD patients. These subjects were drug naive and had undergone the first clinical examination for the diagnosis of AD. RESULTS: A multiple regression analysis indicated that the presence of ApoE epsilon4 allelic variant or GSTT1 null phenotype predicted the faster age at onset of the illness (F = 5.76, df = 2, 96, p = 0.0043). Carriers of GSTP1 *C allelic variant had a faster decline in cognitive functions (repeated measures analysis of variance [ANOVA]: F = 4.00, df = 3, 285, p = 0.008) and in BADLs (repeated measures ANOVA: F = 5.27, df = 3, 285, p = 0.001). This faster decline was independent from ApoE epsilon4 allele possession. No effect of GST P1-M1-T1 polymorphisms was found on behavioral symptom severity. CONCLUSION: These data are in line with the hypotheses that oxidative damage is a prominent feature in the clinical progression and the age at onset of LOAD.
Assuntos
Doença de Alzheimer/genética , Apolipoproteína E4/genética , Glutationa S-Transferase pi/genética , Glutationa Transferase/genética , Polimorfismo Genético/genética , Atividades Cotidianas/classificação , Idade de Início , Idoso , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/epidemiologia , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/epidemiologia , Transtornos Cognitivos/genética , Progressão da Doença , Feminino , Variação Genética/genética , Genótipo , Heterozigoto , Humanos , Estudos Longitudinais , Masculino , Testes Neuropsicológicos/estatística & dados numéricos , Estresse Oxidativo/genética , Estresse Oxidativo/fisiologia , Escalas de Graduação Psiquiátrica/estatística & dados numéricos , Análise de RegressãoRESUMO
BACKGROUND: Oxidative stress and neuronal cell death have been implicated in the pathogenesis of Alzheimer disease (AD). Considering that the glutathione transferase (GST) supergene family encodes isoenzymes that appear to be critical in protection against oxidative stress, we aimed at determining the various GSTP1, GSTM1, and GSTT1 polymorphisms and ApoE genotypes to investigate their role as susceptibility genes for late-onset AD (LOAD). METHODS: We included 210 LOAD patients and 228 healthy controls matched for age, sex, and educational level in our case-control genetic association study. GSTM1 and GSTT1 genotypes were studied by conventional PCR, whereas GSTP1 and ApoE genotypes were determined by real-time PCR on the LightCycler. RESULTS: We found a significant association between LOAD and the GSTP1*C allelic variant [odds ratio (OR) = 1.9; P < 0.05], but no association between the GSTM1 and GSTT1 deleted genotypes and LOAD. In addition, a preliminary result suggested that carriers of both the GSTP1*C and ApoE epsilon4 allelic variants were at increased risk of LOAD (OR = 19.98; P < 0.0001). CONCLUSION: The GSTP1*C allelic variant should be considered a candidate for LOAD, particularly in persons having the ApoE epsilon4 allelic variant, because the GSTP1 and ApoE gene products are implicated in oxidative stress and apoptosis processes leading to beta-amyloid-mediated neurodegeneration.
