RESUMO
Epistasis between interleukin-10 (IL10) and aromatase gene polymorphisms has previously been reported to modify the risk of Alzheimer's disease (AD). However, although the main effects of aromatase variants suggest a sex-specific effect in AD, there has been insufficient power to detect sex-specific epistasis between these genes to date. Here we used the cohort of 1757 AD patients and 6294 controls in the Epistasis Project. We replicated the previously reported main effects of aromatase polymorphisms in AD risk in women, for example, adjusted odds ratio of disease for rs1065778 GG=1.22 (95% confidence interval: 1.01-1.48, P=0.03). We also confirmed a reported epistatic interaction between IL10 rs1800896 and aromatase (CYP19A1) rs1062033, again only in women: adjusted synergy factor=1.94 (1.16-3.25, 0.01). Aromatase, a rate-limiting enzyme in the synthesis of estrogens, is expressed in AD-relevant brain regions ,and is downregulated during the disease. IL-10 is an anti-inflammatory cytokine. Given that estrogens have neuroprotective and anti-inflammatory activities and regulate microglial cytokine production, epistasis is biologically plausible. Diminishing serum estrogen in postmenopausal women, coupled with suboptimal brain estrogen synthesis, may contribute to the inflammatory state, that is a pathological hallmark of AD.
Assuntos
Doença de Alzheimer/genética , Aromatase/genética , Interleucina-10/genética , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/enzimologia , Estudos de Casos e Controles , Epistasia Genética , Feminino , Frequência do Gene , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Desequilíbrio de Ligação , Masculino , Razão de Chances , Polimorfismo de Nucleotídeo Único , Risco , Caracteres SexuaisRESUMO
Associations have been reported of aromatase polymorphisms with Alzheimer's disease (AD). We studied nine polymorphisms in 207 cases of AD, 23 cases of mild cognitive impairment (MCI) and 233 controls, all from the OPTIMA cohort. We replicated two reported associations and found others. Our findings were consistent between AD and MCI. Further, our results were sex-specific, i.e. there were significant interactions between certain polymorphisms and gender, and the associations with AD were almost entirely in women. Aromatase catalyses the conversion of androgens to estrogens. It is expressed in the human brain. In the hippocampus, it is upregulated in postmenopausal women and is lowered in AD. These sex-specific results are therefore plausible. However, our results now need to be replicated in a larger dataset.