JPH3 and fragile X-associated tremor/ataxia syndrome: The present review summarizes the pathogenic gene, epidemiology, and cognitive domains affected in multiple REDs, such as NIID, SCAs, C9FTD, FXTAS, HD, and others (DM1, PME, FRDA, HDL2, and CANVAS), demonstrating a high prevalence of cognitive dysfunction in REDs, and provided a new aspect for differential diagnosis and the disease intervention of these diseases.