Partington syndrome (PRTS) is an X-linked developmental disorder characterized by impaired intellectual development and variable movement disturbances. Partington syndrome is part of a phenotypic spectrum of disorders caused by mutation in the ARX gene comprising a nearly continuous series of developmental disorders ranging from hydranencephaly and lissencephaly (LISX2; 300215) to Proud syndrome (300004) to infantile spasms without brain malformations (see 308350) to nonsyndromic intellectual disability (300419). Although males with ARX mutations are often more severely affected, female mutation carriers may also be affected (Kato et al., 2004; Wallerstein et al., 2008).

Spinocerebellar ataxia type 14 (SCA14) is characterized by slowly progressive cerebellar ataxia, dysarthria, and nystagmus. Axial myoclonus, cognitive impairment, tremor, and sensory loss may also be observed. Parkinsonian features including rigidity and tremor have been described in some families. Findings seen in other ataxia disorders (e.g., dysphagia, dysphonia) may also occur in SCA14. The average age of onset is in the 30s, with a range from childhood to the seventh decade. Life span is not shortened.

Parkin type of early-onset Parkinson disease (PARK-Parkin) is characterized by the cardinal signs of Parkinson disease (PD): bradykinesia, resting tremor, and rigidity. The median age at onset is 31 years (range: 3-81 years). The disease is slowly progressive: disease duration of more than 50 years has been reported. Clinical findings vary; hyperreflexia is common. Lower-limb dystonia may be a presenting sign and cognitive decline appears to be no more frequent than in the general population. Dyskinesia as a result of treatment with levodopa frequently occurs.

Primary dystonia, DYT17 type is a rare, genetic, isolated dystonia initially presenting as torticollis, and later progressing to segmental or generalized dystonia. Dysphonia and dysarthria also occur later in the disease course.

Adult-onset dystonia-22 (DYT22AO) is an autosomal recessive disorder characterized by focal dystonia or tremor and mild cognitive impairment (Mencacci et al., 2021).