The history of the identification of DMJ must include a description of the three neurological diseases that were identified between 1972 and 1976 by three different groups of researchers in the United States in individuals of Azorean descent. The three new diseases, described in the Machado, Thomas and Joseph families, had common points: the patients observed were of Azorean origin and the way the disease was transmitted in the families was similar. Thus, each group of researchers believed they had discovered a different disease, maintaining their position for several years, and starting what Dr Paula Coutinho referred to as ‘the war of the three diseases’. During a visit to the Azores by Dr Paula Coutinho and Professor Corino de Andrade, these remarkable neurologists described, within the same family, patients as different as those described by the groups of researchers from the USA, thus showing that it was a single disease. In mainland Portugal, the first non-Azorean family with DMJ was described in the 1980s. In 1980, Dr Paula Coutinho and Professor Jorge Sequeiros finally proposed the name ‘Machado-Joseph Disease’, which is currently the most widely used, and which is justified by the fact that the Machado family was the first to be described, and the Joseph family constitutes the largest and best-known group of individuals.
Because DMJ was first described in families of Azorean origin living in the United States of America, it became known as ‘Azorean nervous system disease’. It has been known for a long time that there are cases of DMJ in many parts of the world, with no connection to Portugal or the Azoreans. Thus, DMJ is not an ‘Azorean’ disease, and this fact has already been amply demonstrated in scientific papers, which point to the main origin of the alteration that leads to DMJ being Asian, which occurred several thousand years ago and then spread around the world.
DMJ is a rare disease worldwide; within its group (spinocerebellar ataxias) it is nevertheless the most common, and is present in several countries, including Brazil, the USA, Japan, China, Australia, France, Germany, the UK and the Netherlands.
In Portugal, the prevalence - i.e. the ratio between the number of patients and inhabitants - is highest in the Azores, reaching its highest value on the island of Flores.
