The hippocampus displays a high degree of myelination, which is essential for cognitive function (Abrahám et al., 2010), and myelination has been shown to be disrupted in APP/PS1 mice, which is relevant to AD pathology (Ota et al., 2019; Chao et al., 2018; Dong et al., 2018). The gene discussed is PSEN1; the disease is Alzheimer disease.