Further, observations from our study also show that GFAP along with the common AD risk factors (age, sex, and APOE ε4 carriage), and plasma Aβ1–42/Aβ1–40 ratio (a blood-based biomarker associated with brain Aβ status13,15) distinguished between Aβ− and Aβ+ individuals with 90% sensitivity and 80% specificity, wherein GFAP and plasma Aβ1–42/Aβ1–40 ratio were statistically significant additional predictors of brain Aβ load status, over and above the base model. The gene discussed is GFAP; the disease is Alzheimer disease.