In cases with an insidious and progressive disease course this may lead to a misdiagnosis of a neurodegenerative condition, such as Lewy body dementia [4, 22, 57] or AD, although in IgLON5-Ab disease the cognitive dysfunction is usually multi-domain and different from the prominent memory impairment typical of AD [58]. The gene discussed is IGLON5; the disease is Alzheimer disease.