Caused by changes in one of several genes involved in brain development and nerve signalling. Changes in one copy of KMT2B or EMC1, often new in the child, cause dominant forms; changes in both copies of ELP2, EMC1 or PSMF1 cause recessive forms.
Signs and symptoms
Developmental delay or intellectual disability with a movement disorder, which may include dystonia, spasticity, ataxia or involuntary movements. KMT2B-related dystonia typically begins in childhood in the legs and spreads to the face, throat and arms. Less often there are seizures or small head size, depending on the gene.
What a diagnosis changes
Care is tailored to the gene and features, with neurology, physiotherapy and developmental support. Deep brain stimulation often helps KMT2B-related dystonia. Genetic counselling guides family testing: parental testing for dominant forms and carrier testing for recessive forms.
Includes 8 related subtypes ↓Hide subtypes ↑
- CACNA1A-related complex neurodevelopmental disorder
- cerebellar atrophy, visual impairment, and psychomotor retardation;
- cerebral palsy, spastic quadriplegic, 3
- complex cortical dysplasia with other brain malformations 5
- developmental and epileptic encephalopathy, 42
- episodic ataxia type 2
- migraine, familial hemiplegic, 1
- spinocerebellar ataxia type 6
