The subsequent reduction of PRRT2 protein may lead to altered synaptic neurotransmitter release and dysregulated neuronal excitability in various regions of the brain, resulting in paroxysmal movement disorders and seizure phenotypes.
The identification of heterozygous mutations in the PRRT2 gene in paroxysmal kinesigenic dyskinesia as well as in benign familial infantile seizures linked episodic movement disorders with epilepsy.
PRRT2 gene mutations have recently been identified as a causative gene of Paroxysmal kinesigenic dyskinesia (PKD), a rare movement disorder characterised by the occurrence of chorea, dystonia or athetosis triggered by sudden action.
Four patients had a deletion of a known movement disorder gene including paroxysmal kinesigenic dyskinesia (PRRT2; n=2), SGCE (myoclonus dystonia, n=1), and TITF1 (benign hereditary chorea, n=1).
Huntington disease (HD) is caused by an expanded HTT CAG repeat that leads in a length-dependent, completely dominant manner to onset of a characteristic movement disorder.
We report the case of a 29 year old woman with a complex movement disorder syndrome due to the combination of coexisting pathological triplet repeat expansions of huntingtin and ATXN8 genes.
The disease results from an expanded sequence of CAG repeats in the huntingtin gene and leads to a movement disorder with associated cognitive and systemic deficits.
In order to examine the effects of CAG block lengths, we have correlated ApoE genotypes with the age of onset in 145 patients symptomatic for HD with psychiatric and somatic symptoms (depression, psychosis, dementia, choreic, and other movement disorders) harbouring only modestly expanded huntingtin alleles (41-45 CAGs).
This case demonstrates that SCN1A mutations may cause movement disorders as an atypical phenotype and the case history of this patient may expand our understanding of the clinical spectrum of SCN1A-associated epileptic encephalopathy.[Published with video sequences].