PDE4B and Alzheimer disease: Cross-trait meta-analysis identifies several loci (Pmeta-analysis < 5 × 10−8) shared by AD and GIT disorders (GERD and PUD) including PDE4B, BRINP3, ATG16L1, SEMA3F, HLA-DRA, SCARA3, MTSS2, PHB, and TOMM40. Colocalization and gene-based analyses reinforce these loci.