Correlation between apolipoprotein E gene polymorphism and the urine level of Alzheimer-associated neuronal thread protein in patients with Alzheimer's disease and mild cognitive impairment / 中华神经科杂志

ABSTRACT

Objective To explore the correlation between apolipoprotein E (ApoE) gene polymorphism and urine Alzheimer-associated neuronal thread protein (AD7c-NTP) level in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI).Methods The cognitive function of 30 AD patients (AD group),30 MCI patients (MCI group) and 30 normal controls (NC group) was evaluated by neuropsychological batteries like MMSE,the Cambridge Cognitive Examination-Chinese Version (CAMCOG-C),etc.ELISA was used to test the urine level of AD7c-NTP.The genotypes of ApoE were analyzed by the high-resolution melting assay in blood samples.Results Compared with the NC group (0.59 (0.40,0.66) ng/ml),the urine level of AD7c-NTP in the AD group (1.03(0.80,1.41) ng/ml) and the MCI group (0.69(0.53,0.91) ng/ml) was increased (Z =33.727,P ＜0.01).The urine level of AD7c-NTP in the AD group was higher than that in the MCI group (Z =8.232,P ＜ 0.05).The level of AD7c-NTP in urine was negatively correlated with MMSE and CAMCOG-C scores (rMMSE =-0.604,P ＜ 0.01;rCAMCOG-C =-0.486,P ＜ 0.01).According to receiver operating characteristic curve,the optimal cutoff point of AD7c-NTP in urine for diagnosis of patients including AD and MCI was 0.70 ng/ml,with sensitivity of 71.7％ and specificity of 83.3％,and area under the curve of 0.82 (95％ CI 0.73-0.90,P ＜0.05).There were four genotypes comprising ε2/3,ε3/3,ε3/4 and ε4/4 for ApoE gene.The frequencies of ε4 carriers were 46.7％ (14/30),23.3％ (7/30) and 23.3％ (7/30) in the AD,MCI and NC groups,respectively.There was a notable increase in urine AD7c-NTP and a significant decrease in CAMCOG-C scores in MCI patients who harbored the ApoE ε4 allele (ZAD7c-NTP =4.857,P ＜ 0.05;ZCAMCOG-C =4.284,P ＜0.05).Conclusions The urine level of AD7c-NTP was significantly increased in AD and MCI patients,the higher the level of AD7c-NTP,the more serious the cognitive impairment.The ε4 carriers exhibited higher urine level of AD7c-NTP,but worse cognitive function compared to ε4 non-carriers in the MCI group.