APOE polymorphism and the progression of diabetic nephropathy in Japanese subjects with type 2 diabetes: results of a prospective observational follow-up study.
OBJECTIVE
The aim of this study is to clarify the conflicting results of the epsilon2/epsilon3/epsilon4 APOE polymorphism as a risk factor on diabetic nephropathy by a cohort study.


METHODS
A total of 429 Japanese subjects with type 2 diabetes and with normoalbuminuria (n = 299) or with microalbuminuria (n = 130) were enrolled in a prospective observational follow-up study during 1995-1998 and followed until 2001 (for at least 3 years). The endpoint was the occurrence of a renal event defined as the progression to a higher stage of diabetic nephropathy.


RESULTS
During the study (the mean follow-up period: 4.4 +/- 1.0 years), 31 of 429 subjects progressed: 21 from normoalbuminuria to microalbuminuria and 10 from microalbuminuria to overt proteinuria. The allele frequency of the APOE polymorphism was significantly different between the progressors and the nonprogressors. Eight of 42 epsilon2 carriers (19%) progressed, whereas 23 of 387 noncarriers (6%) progressed with a relative risk of 3.2 (95% CI 1.5-6.7). When subjects were stratified by renal status at baseline, each relative risk for the progression in the epsilon2 carriers was 2.7 (0.99-7.4) in those with normoalbuminuria and 4.2 (1.3-13.3) in those with microalbuminuria. Furthermore, when analyzed only in subjects with normoalbuminuria and short duration of diabetes (<15 years) at baseline, the risk in the epsilon2 carriers became higher to 3.2 (1.2-8.8).


CONCLUSIONS
Our follow-up study indicates that the epsilon2 allele of the APOE polymorphism is a prognostic risk factor for both the onset and the progression of diabetic nephropathy in Japanese type 2 diabetes.
Araki
Shin-Ichi
S
Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan.
Koya
Daisuke
D
Makiishi
Tetsuya
T
Sugimoto
Toshiro
T
Isono
Motohide
M
Kikkawa
Ryuichi
R
Kashiwagi
Atsunori
A
Haneda
Masakazu
M
D000368:Aged; D053329:Apolipoprotein E2; D053318:Apolipoprotein E3; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology* / Q000235:genetics*; D003928:Diabetic Nephropathies / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000453:epidemiology; D005838:Genotype; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors
D053329:Apolipoprotein E2; D053318:Apolipoprotein E3; D053327:Apolipoprotein E4; D001057:Apolipoproteins E