Another one...
http://www.medscape.com/viewarticle/852556
"As expected, APOE ε4 was associated with higher rates of amyloid plaque buildup. However, they also identified a novel association between a single nucleotide polymorphism in IL1RAP (rs12053868-G) and higher rates of amyloid accumulation, independent of APOE ε4."
This SNP is tested on 23andme.