MS4A4A and Alzheimer disease: In conclusion, we provide evidence that APOE, CLU, and MS4A4A, which have been identified in GWAS to be associated with AD, also significantly affected CSF Aβ1–42. To our knowledge, ours is the first study to report on the correlation between MS4A4A and CSF Aβ1–42. None of the AD risk genes studied showed significant effects on CSF tau.