APP and Alzheimer disease: Endosomal dysfunction is also observed in neurons of patients with early‐stage AD,8 Additionally, an electron microscopy‐based study found that the number of abnormal endosomes was increased in triploid APP transgenic mice, a commonly used animal model of AD,10 This finding further emphasizes that abnormal APP metabolism resulting from endosomal dysfunction may be involved in the pathogenesis of this disease.