SORL1 and Alzheimer disease: The commonly accepted pathology of AD involving SorL1 is that SorL1 mediates retrograde transport of APP from the endosome to the TGN, a process that inhibits APP processing into amyloid plaques.[13, 33] Recent studies have shown that SorL1 deficiency causes early endosomes swelling in human induced pluripotent stem cell‐derived neurons (hiPSC‐Ns)[13] and minipig cortical neurons.[14] However, whether the endosome enlargement of SorL1‐deficient hiPSC‐Ns depends solely on the processing of APP into amyloid plaques in the endosome, especially in individuals, is unclear.