A genetic taxonomy of hyperkinesis in the dog

Among children who have difficulty inhibiting gross motor activity and focusing on learning tasks requiring them to do this, some are helped by central nervous system stimulants such as amphetamine, while others with identical symptoms are not. Similar variations in response to pharmacological agents are seen in other syndromes, suggesting that multiple biological mechanisms are involved and that these are selectively responsive to pharmacological manipulations. Diagnosis, therefore, involves not only the identification of the condition, but knowledge of the mechanisms by means of which it can be brought about, as well as some means of identify ing these. Since such variations often have a genetic basis, their identification and characterization by genetic and pharmacogenetic approaches permit the investigator to avoid confounding biological variation with statistical error and, ultimately, to suit the treatment to the mechanism when there is no final common path permitting a single intervention specific to a given syndrome. Because such researches are difficult with human patients, we have been attempting to identify animal models with analogous symptoms to human conditions and homologous mechanisms underlying these. The present paper is one in a series describing a dog model for hyperkinesis.