Association of apolipoprotein E genotype and Alzheimer disease in African Americans.
BACKGROUND
Alzheimer disease (AD) is the most frequent cause of dementia. Even though the incidence of AD in the African American population is similar to or higher than that in persons of European descent, AD in African Americans is understudied. Identification of genetic risk factors in African Americans is essential for understanding the etiology of AD.


OBJECTIVE
To determine the effect of apolipoprotein E (APOE) genotype on the risk of AD in elderly African Americans.


METHODS
Population-based longitudinal study of AD.


METHODS
Indianapolis, Ind.


METHODS
African Americans 65 years and older.


METHODS
APOE genotype and diagnosis of AD.


RESULTS
The APOE genotype was determined in 1822 samples. Of these, 690 were clinically evaluated: 318 were normal, and 162 had a diagnosis of AD. The presence of APOE epsilon4 was significantly associated with increased risk of AD (epsilon3/epsilon4: OR, 2.32; 95% confidence interval [CI], 1.41-3.82; and epsilon4/epsilon4: OR, 7.19; 95% CI, 3.00-17.29, compared with the epsilon3/epsilon3 genotype). There was also a significant protective effect with APOE epsilon2 (epsilon2/epsilon2 and epsilon2/epsilon3: OR, 0.42; 95% CI, 0.20-0.89).


CONCLUSIONS
These findings are in marked contrast to the lack of association between APOE and AD in the Ibadan, Nigeria, sample of this project. These results suggest that other genetic factors and different environmental influences may play a role in the risk for AD in individuals of African ancestry.
Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, USA.
Jill R
JR
Murrell
Brandon
B
Price
Kathleen A
KA
Lane
Olusegun
O
Baiyewu
Oye
O
Gureje
Adesola
A
Ogunniyi
Frederick W
FW
Unverzagt
Valerie
V
Smith-Gamble
Sujuan
S
Gao
Hugh C
HC
Hendrie
Kathleen S
KS
Hall
D001741:Black or African American / Q000235:genetics; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D016015:Logistic Models; D008297:Male; D012306:Risk
D001057:Apolipoproteins E