DLGAP1 and early-onset autosomal dominant Alzheimer disease: DLGAP1, located on chromosome 18p11.31, which is also known as SAP90/PSD‐95‐associated protein (SAPAP) encoding the guanylate kinase‐associated protein (GKAP), was involved in the pathophysiology of several psychiatric disorders, such as obsessive‐compulsive disorder (OCD), schizophrenia (SCZ), major depression disorder (MDD), and Alzheimer's disease (AD; Bertram et al., 2008; Li et al., 2013; Mathias et al., 2016).