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.
Genetic studies do not support the view that schizophrenia, psychotic mood disorders and schizoaffective disorder are distinct etiological entities, but rather the evidence suggests the existence of common inherited vulnerability that increases the risks for all these syndromes. Some susceptibility pathways may be specific for schizophrenia, others for bipolar disorder, and yet other mechanisms and genes may confer risk for mixed schizophrenic and affective [or mood disorder] psychoses, but there is no support from genetics for the view that these are distinct disorders with distinct etiologies and pathogenesis. Laboratory studies of putative endophenotypes, brain imaging studies, and post mortem studies shed little additional light on the validity of the schizoaffective disorder diagnosis, as most studies combine subjects with different chronic psychoses in comparison to healthy subjects. Viewed broadly then, biological and environmental factors interact with a persons genes in ways which may increase or decrease the risk for developing schizoaffective disorder; exactly how this happens (the biological mechanism) is not yet known. Schizophrenia spectrum disorders, of which schizoaffective disorder is a part, have been increasingly linked to advanced paternal age at the time of conception, a known cause of genetic mutations. The physiology of people diagnosed with schizoaffective disorder appears to be similar, but not identical, to that of those diagnosed with schizophrenia and bipolar disorder; however, human neurophysiological function in normal brain and mental disorder syndromes is not fully understood.While there are various medications and treatment options for those with schizoaffective disorder, this disorder can affect a person for their entire lifespan.