Estudo de polimorfismos no gene receptor da vitamina D em pacientes com a doença de Alzheimer

Abstract

Vitamin D (VD) is a neurosteroid whose function is related to cell regulation, ion homeostasis, growth regulation and protective effect against injuries. Its deficiency may be associated with neurological disorders such as Alzheimer's disease. The effect of VD is exercised by the interaction with VD receptor, the VDR. The presence of the VDR gene is considered highly expressive, especially in the encephalon, hypothalamus and nigra substance, indicating a significant participation in the functioning of the nervous system. The VDR gene is located on the chromosome 12q13.11 and presents 14 exons. Polymorphisms in this gene have been associated with changes in its function and may influence its effects. The polymorphisms FokI (rs2228570) and TaqI (rs731236) are located in exotic regions and the BsmI (rs1544410) is located in the intronic region. Thus, this study aimed to verify the prevalence of BsmI, TaqI and FokI polymorphisms in the VDR gene in individuals with Alzheimer's disease (AD) and healthy control individuals (CS), in a population of the state of Pernambuco. A total of 78 individuals were evaluated, 39 with Alzheimer’s disease and 39 healthy controls treated in the outpatient clinic of the Hospital das Clínicas of UFPE and the characterization of genotypes was performed using the PCR-RFLP technique. The frequencies of FokI genotypes were 48.9% CC, 46.1% CT, 5% TT for the AD group and 43.6% CC, 53.9% CT and 2.5% TT for the CS group. Regarding genotypes BsmI, 15.4% AA, 53.9 AG and 30.8% GG were observed for the group with AD and 10.3% GG, 56.4% AG and 33.3% AA for the CS group. In turn, the frequencies of the TaqI genotypes for the AD group were 51.3% CT and 48.7% CC while for the CS group they were 61.5% CT and 38.5% CC. No significant difference was found when statistical analyses were performed between the groups (AD x CS) [p >0.05 for each analysis performed]. Thus, we can conclude that none of these three polymorphisms in the VDR gene seems to be involved with the susceptibility to AD in the studied population. However, new studies, including a larger number of patients, may elucidate our observed results.