MedGen

Bethlem myopathy-2 (BTHLM2) is characterized by congenital hypotonia and myopathy. Motor development is delayed, but muscle strength improves with age, and patients are able to achieve ambulation. Proximal joint contractures that improve over time, as well as joint hyperlaxity, are also present. Muscle biopsy shows mild variability in fiber diameter, without degeneration or regeneration (Zou et al., 2014; Hicks et al., 2014). For a discussion of genetic heterogeneity of Bethlem myopathy, see BTHLM1 (158810). [from OMIM]

Childhood-onset parkinsonism-dystonia-3 (PKDYS3) is an autosomal recessive neurodegenerative disorder with onset in infancy or early childhood. Affected individuals present with progressive movement abnormalities, including parkinsonism with tremor, dystonia, myoclonus ataxia, and hyperkinetic movements such as ballismus. The parkinsonism features may be responsive to treatment with levodopa, although many patients develop levodopa-induced dyskinesia. Some patients may have mild cognitive impairment or psychiatric disturbances (summary by Burke et al., 2018 and Skorvanek et al., 2022). For a discussion of genetic heterogeneity of PKDYS, see 613135. [from OMIM]

An infantile-onset neurometabolic disease with characteristics of dystonia, parkinsonism, nonambulation, autonomic dysfunction, developmental delay and mood disturbances. The prevalence is unknown. It has been described in 8 patients from one Saudi Arabian family to date. Caused by a mutation in the SLC18A2 gene (10q25), encoding the vesicular monoamine transporter 2 (VMAT2) which is responsible for the transport of dopamine and serotonin into synaptic vesicles. Mutations in this gene lead to the impairment of VMAT2 and consequently to problems with motor control, autonomic functioning and mood regulation. It is inherited in an autosomal recessive manner. [from SNOMEDCT_US]

Parkinson disease-20 is an autosomal recessive neurodegenerative disorder characterized by young adult-onset of parkinsonism. Additional features may include seizures, cognitive decline, abnormal eye movements, and dystonia (summary by Krebs et al., 2013 and Quadri et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of Parkinson disease, see PD (168600). [from OMIM]

Hypomyelinating leukodystrophy-16 (HLD16) is an autosomal dominant neurologic disorder characterized by onset of hypotonia, nystagmus, and mildly delayed motor development in infancy. Affected individuals have motor disabilities, including ataxic or broad-based gait, hyperreflexia, intention tremor, dysmetria, and a mild pyramidal syndrome. Some patients have cognitive impairment, whereas others may have normal cognition or mild intellectual disability with speech difficulties. Brain imaging typically shows hypomyelination, leukodystrophy, and thin corpus callosum (summary by Simons et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of hypomyelinating leukodystrophy, see 312080. [from OMIM]

Neurodevelopmental disorder with progressive movement abnormalities (NEDPM) is an autosomal recessive complex neurologic disorder characterized by global developmental delay apparent from infancy, moderately to severely impaired intellectual development, poor or absent speech, behavioral abnormalities, and various hyperkinetic movement disorders, including dystonia, spasticity, and cerebellar ataxia, that interfere with gait and cause a stooped posture. The disorder appears to be progressive with age-related deterioration of cognitive and motor function; parkinsonism may develop in older patients. Additional more variable features include seizures, dysmorphic facial features, oculomotor defects, and brain imaging abnormalities (Kaiyrzhanov et al., 2024). [from OMIM]

A habitual positioning of the body with the head and upper back bent forward. [from HPO]