The genes typically code for proteins known to be involved in synaptic transmission, ion channels or ion transporters. The first gene to be identified was the PRRT2 gene on chromosome 16, found in 2011 to be the cause of the disease in some patients. The mutations in this gene included a nonsense mutation identified in the genome of one family and an insertion mutation identified in the genome of another family. Researchers found PRRT2 mutations in 10 of 29 sporadic cases affected with PKD, thus suggests PRRT2 is the gene mutated in a subset of PKD and PKD is genetically heterogeneous. Later reports have identified the genes SCN8A, CHRNA4, and SLC16A2 as further causes of PKD. Pathophysiology
The pathophysiology of PKD is not fully explained. A few mechanisms have been suggested thus far:

GABA dysregulation
Abnormal breakdown of dopamine in the basal ganglia
Dysfunction of the substantia nigra
A form of epilepsyMultiple methods are being used to study the potential brain abnormalities of individuals with PKD compared with “normal” individuals. These methods include SPECT studies, fMRI studies, and diffusion tensor imaging. The main problem with many of the studies concerned with the pathophysiology of the disorder is the small sample size. Because the studies normally only include about 7-10 patients with PKD, the results cannot be generalized to the entire population of patients. However, the studies do bring up possibilities for further study.
Paroxysmal kinesigenic choreoathetosis (PKC) also called paroxysmal kinesigenic dyskinesia (PKD) is a hyperkinetic movement disorder characterized by attacks of involuntary movements, which are triggered by sudden voluntary movements. The number of attacks can increase during puberty and decrease in a persons 20s to 30s. Involuntary movements can take many forms such as ballism, chorea or dystonia and usually only affect one side of the body or one limb in particular. This rare disorder only affects about 1 in 150,000 people, with PKD accounting for 86.8% of all the types of paroxysmal dyskinesias, and occurs more often in males than females. There are two types of PKD, primary and secondary. Primary PKD can be further broken down into familial and sporadic. Familial PKD, which means the individual has a family history of the disorder, is more common, but sporadic cases are also seen. Secondary PKD can be caused by many other medical conditions such as multiple sclerosis (MS), stroke, pseudohypoparathyroidism, hypocalcemia, hypoglycemia, hyperglycemia, central nervous system trauma, or peripheral nervous system trauma. PKD has also been linked with infantile convulsions and choreoathetosis (ICCA) syndrome, in which patients have afebrile seizures during infancy (benign familial infantile epilepsy) and then develop paroxysmal choreoathetosis later in life. This phenomenon is actually quite common, with about 42% of individuals with PKD reporting a history of afebrile seizures as a child. Genetics
Paroxysmal kinesigenic dyskinesias are often inherited in an autosomal dominant fashion and several genes have now been identified where mutations can cause this disease.