MFSD2a has been shown to be critical for maintaining the integrity of the blood–brain barrier by regulating transcytosis and has been implicated in multiple neurological diseases including intracranial hemorrhage, Alzheimer’s disease, sepsis-associated encephalopathy, autosomal recessive primary microcephaly (MCPH) and intracranial tumors [25]. Here, MFSD2A is linked to Alzheimer disease.