Figure 1.
Flow chart of participant selection. Qubao village: the suburbs of Xi’an in northwest China. APOE, apolipoprotein E.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.