Association between apolipoprotein E genotype and Alzheimer disease in African American subjects.
BACKGROUND
The association between Alzheimer disease (AD) and genotypes at the apolipoprotein E (APOE) locus has been confirmed in numerous populations worldwide, but appears to be inconsistent in African American subjects.


OBJECTIVE
To investigate the association between APOE genotypes and AD in elderly African American subjects.


METHODS
Clinic-based, multicenter case-control study and a family study.


METHODS
A total of 338 African American probands meeting criteria for probable or definite AD, 301 cognitively healthy, elderly unrelated control subjects (spouses and community volunteers), and 108 siblings of 88 AD probands.


METHODS
Odds of AD according to APOE genotype.


RESULTS
Compared with individuals with the APOEepsilon3/epsilon3, the odds of having AD were significantly increased among those with 1 or more copies of the epsilon4 allele; the odds ratio (OR) for the epsilon3/epsilon4 genotype was 2.6 (95% confidence interval [CI], 1.8-3.7), and the OR for the epsilon4/epsilon4 genotype was 10.5 (95% CI, 5.1-21.8). These risks decreased substantially after 68 years of age. The risk for AD was lower among individuals with the epsilon2/epsilon3 genotype (OR, 0.41; 95% CI, 0.22-0.79). The patterns of association were similar in men and women. These results obtained from comparisons of unrelated AD patients and controls were bolstered by results of analysis of family data that showed preferential transmission of the epsilon4 allele to demented siblings (P<<.001) and of the epsilon2 allele to nondemented siblings (P=.005).


CONCLUSIONS
The presence of 1 or 2 epsilon4 alleles is a determinant of AD risk in African American subjects. The age-related risk for decline associated with the epsilon4 allele and the apparent protective effect of the epsilon2 allele are similar to patterns observed in white subjects.
Graff-Radford
Neill R
NR
Genetics Program L-320, Boston University School of Medicine, 715 Albany St, Boston, MA 02118, USA. farrer@neugen.bu.edu
Green
Robert C
RC
Go
Rodney C P
RC
Hutton
Michael L
ML
Edeki
Timi
T
Bachman
David
D
Adamson
Jennifer L
JL
Griffith
Patrick
P
Willis
Floyd B
FB
Williams
Mary
M
Hipps
Yvonne
Y
Haines
Jonathan L
JL
Cupples
L Adrienne
LA
Farrer
Lindsay A
LA
D001741:Black or African American / Q000706:statistics & numerical data; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D044383:Black People / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D016017:Odds Ratio; D014481:United States / Q000453:epidemiology
D001057:Apolipoproteins E