ARHGAP18 and bipolar disorder: These are associated with a variety of neurological diseases, such as cognitive defects (ARHGAP15), migraine without aura (ARHGAP28), AD (ARHGAP2), schizophrenia (ARHGAP18), and bipolar disorder (BD; ARHGAP29; Niftullayev and Lamarche-Vane, 2019).