IL-6-174 G/C and ApoE Gene Polymorphisms in Alzheimer's and Vascular Dementia Patients Attending the Cognitive Disorder Clinic of the All India Institute of Medical Sciences, New Delhi

Background: Remarkable improvement in the life expectancy of the Indian population is expected to commensurate with the increase in number of dementia cases. Among various types of dementia, Alzheimer's disease (AD) and vascular dementia (VaD) are common and widely studied. We evaluated the role of apolipoprotein E (ApoE) and interleukin-6 (IL-6)-174 G/C gene polymorphism along with serum IL-6 levels in AD and VaD patients. Methods: The polymorphisms in ApoE and IL-6-174 G/C genes were assessed using RFLP. Serum IL-6 level was measured by ELISA. Results: The allele epsilon 4 of the ApoE gene was found to be associated with AD and VaD patients (p < 0.05). No association of IL-6-174 G/C polymorphism was observed in AD patients, while the IL-6-174 C allele increased the odds of having VaD twofold. Regression analysis to assess possible interaction between ApoE and the IL-6-174 G/C genes revealed that presence of both the epsilon 4 and C alleles increased the odds of having AD 13.75-fold and VaD 14.7-fold. Serum IL-6 levels did not correlate with either presence or severity of disease among AD or VaD patients. Conclusion: The ApoE epsilon 4 allele is an important genetic marker for AD and VaD. Presence of both ApoE epsilon 4 and IL-6 C genes increases the OR of having AD and VaD markedly. Copyright (C) 2011 S. Karger AG, Basel