Origin and migration of Huntington's chorea in Canada: preliminary report.

This preliminary report is part of a fullscale investigation of Huntington's chorea throughout the world. Data were obtained on some 820 possible cases of Huntington's chorea in Canada, and they were of sufficient quality in 633 cases to enable pedigrees to be drawn up of 104 families. The origin of 75 of these families was traced outside Canada. It was found that 55 of these kinships originally came from the British Isles, contrary to the prevalent feeling that incriminated United States sources. Only 57 of the 633 cases had moved from their first province of residence at the time of reporting. Thus, large and frequent migrations are not the rule, in the Canadian group, as had been previously reported by other authors.