In the multivariable analysis, after adjusting for prespecified predictors such as age, sex, hypertension and time to CT, the presence of the APOE ε4 allele (OR 2.020, 95% CI 1.064–3.834, p = 0.032), but not the presence of the APOE ε2 allele (OR 0.734, 95% CI 0.339–1.593, p = 0.435), was associated with the island sign (Table 3). The gene discussed is APOE; the disease is hypertensive disorder.