['The common polymorphism of the apolipoprotein E (APOE) gene is associated with differential risk of atherosclerosis; the gene could be a candidate gene in abdominal aortic aneurysms (AAA).', 'APOE genotypes were determined in 57 men aged 65-73 years with a small AAA (30-50 mm). The patients were included in a population ultrasonographic screening programme and were followed with at least two examinations during an interval of 2-4.5 years. The AAA expansion rates in patients with four different APOE genotypes were studied, with adjustment for initial AAA size and smoking.', 'APOE genotype was a significant determinant of AAA expansion rate (P = 0.001). The adjusted mean (95 per cent confidence interval) rate was 2.1 (1.7-2.6) mm/year in 31 men with genotype E3E3, 1.3 (0.7-1.9) mm/year in 17 men with E3E4, 3.1 (2.0-4. 1) mm/year in six men with E2E3 and 4.2 (2.7-5.6) mm/year in three men with E2E4. The mean expansion rate was 2.2 (1.5-2.8) mm/year in non-smokers and 3.0 (2.5-3.6) mm/year in smokers (P = 0.014).'] Is apolipoprotein E genotype associated with differential expansion rates of small abdominal aortic aneurysms?