Intellectual developmental disorder with language impairment and early-onset dopa-responsive dystonia-parkinsonism (IDLDP) is a neurodevelopmental disorder characterized by global developmental delay affecting motor, cognitive, and speech domains apparent in early childhood or infancy. Some patients may have normal early development in infancy before symptom onset. There is phenotypic heterogeneity and the severity is highly variable; less severely affected individuals have only mild deficits and are able to attend special schools. About half of patients develop various types of seizures that may be refractory or responsive to treatment. Most patients also show movement abnormalities, often hypotonia early in the disease course with later development of dopa-responsive dystonia or parkinsonism (Ramos et al., 2019, Wirth et al., 2020; Singh et al., 2020). [from OMIM]