Parkinson's disease is a progressive disorder of the nervous system. The disorder affects several regions of the brain, especially an area called the substantia nigra that controls balance and movement.\n\nParkinson's disease can also affect emotions and thinking ability (cognition). Some affected individuals develop psychiatric conditions such as depression and visual hallucinations. People with Parkinson's disease also have an increased risk of developing dementia, which is a decline in intellectual functions including judgment and memory.\n\nOften the first symptom of Parkinson's disease is trembling or shaking (tremor) of a limb, especially when the body is at rest. Typically, the tremor begins on one side of the body, usually in one hand. Tremors can also affect the arms, legs, feet, and face. Other characteristic symptoms of Parkinson's disease include rigidity or stiffness of the limbs and torso, slow movement (bradykinesia) or an inability to move (akinesia), and impaired balance and coordination (postural instability). These symptoms worsen slowly over time.\n\nGenerally, Parkinson's disease that begins after age 50 is called late-onset disease. The condition is described as early-onset disease if signs and symptoms begin before age 50. Early-onset cases that begin before age 20 are sometimes referred to as juvenile-onset Parkinson's disease.

Dystonia-30 (DYT30) is an autosomal dominant neurologic disorder characterized by the onset of symptoms in the first decades of life. Patients present with oromandibular, cervical, bulbar, or upper limb dystonia, and usually show slow progression to generalized dystonia. Some patients may lose ambulation. A subset of patients may also have neurocognitive impairment, including mild intellectual disability or psychiatric manifestations (summary by Steel et al., 2020). In a review of the pathogenesis of disorders with prominent dystonia, Monfrini et al. (2021) classified DYT30 as belonging to a group of neurologic disorders termed 'HOPS-associated neurologic disorders' (HOPSANDs), which are caused by mutations in genes encoding various components of the autophagic/endolysosomal system, including VPS16.

Dystonia-31 (DYT31) is an autosomal recessive progressive neurologic disorder characterized by involuntary muscle twisting movements and postural abnormalities affecting the upper and lower limbs, neck, face, and trunk. Some patients may have orofacial dyskinesia resulting in articulation and swallowing difficulties. The age at onset ranges from childhood to young adulthood. There are usually no additional neurologic symptoms, although late-onset parkinsonism was reported in 1 family (summary by Zech et al., 2022).

Early-onset dystonia-37 with striatal lesions (DYT37) is an autosomal recessive neurologic movement disorder characterized by the onset of progressive dystonia, dysphagia, and choreoathetosis in the first months or years of life. Affected individuals show delayed motor development and may have impaired intellectual development. The disorder is severely disabling; patients lose ambulation and require tube-feeding. Brain imaging shows hyperintense lesions affecting the basal ganglia and striatum (Harrer et al., 2023).

Baraitser-Winter cerebrofrontofacial (BWCFF) syndrome is a multiple congenital anomaly syndrome characterized by typical craniofacial features and intellectual disability. Many (but not all) affected individuals have pachygyria that is predominantly frontal, wasting of the shoulder girdle muscles, and sensory impairment due to iris or retinal coloboma and/or sensorineural deafness. Intellectual disability, which is common but variable, is related to the severity of the brain malformations. Seizures, congenital heart defects, renal malformations, and gastrointestinal dysfunction are also common.