By: Débora Palma Maia, MD
The 2013 World Congress on Huntington’s Disease in Rio de Janeiro, Brazil, brought together physicians, scientists, health professionals, patients, family members and support groups to share new knowledge, with the goal of improving the management of HD.
Congress activities began with talks by members of various HD patient organizations. Mr. Rodrigo Osorio, president of Agrupación Chilena de Huntington, described the Red Latinoamericana de Huntington, a network of HD clinics in Latin America (see HD Insights, Vol. 5). It is estimated that 40,000 Latin Americans have HD. This large number of HD patients could help professionals, patients and families to better understand the disease. Mr. Matt Ellison, founder of the HD Youth Organization (HDYO), tackled the challenges faced by young people at risk for HD. He described how the HDYO website may help reduce the stigma of HD by educating young people and families.
In the “Basic Science” session, Dr. Elena Cattaneo described the emergence of huntingtin 800 million years ago, noting that this protein plays a crucial role in the development of brain cells through the formation of structures called rosettes. According to Dr. Marcy MacDonald, the development of HD is a lifelong process, unrelated to prions or prion-like processes. Finally, Dr. Ignacio Muñoz-Sanjuan described how PDE10A inhibitors can reduce the overexcitable properties of medium spiny neurons (see HD Insights, Vol. 5).
The second day of the Congress focused on premanifest HD. Drs. Alexandra Durr and Karl Kieburtz shared their experiences in TRACK-HD and PREDICT-HD, which found that brain imaging is a powerful technique for measuring HD progression. Cognitive tests such as the Symbol Digit Modalities Test are also good measures of progression. Dr. Ralf Reilmann, a movement disorders specialist, reviewed quantitative motor assessment, and argued that movement changes in premanifest subjects can be detected many years before symptoms begin, and are good measures of HD progression (see “Selected by Chance,” p. 1). However, he pointed out that some early movement changes in carriers of the HD mutant gene do not mean that individuals with these movement changes are sick. Prof. Julie Stout reported similar findings for cognitive functions.
Dr. Peggy Nopoulos discussed clinical findings in juvenile HD, and Dr. Francisco Cardoso spoke about the differential diagnosis of HD. He explained that in around 1% of cases, genetic testing does not reveal a CAG expansion. These cases are called HD-like disorders. One of them, HD-like-2, has a phenotype very similar to HD and it is more common in people of African descent. He reminded attendees, however, that these conditions are rare.
Dr. James Gusella presented genetic factors that could influence the age of symptom onset in individuals who are carriers of the HD mutant gene. He believes that understanding the mechanism of the manifestation of symptoms could make it possible to delay their onset. Dr. Laura Jardim discussed the genetic aspects of HD specific to Latin America, a continent with a complex genetic background derived from the population’s Indigenous, European and African genetic ancestries.
Drs. Sarah Camargos and Mônica Haddad presented ENROLL-HD, a global observational study of HD that aims to enroll as many people as possible. They discussed the importance of sharing data, and argued that ENROLL-HD may help to further understanding of the disease, and to educate health professionals around the world about better methods of care for HD patients.
The last Congress session discussed novel therapies. Dr. Douglas MacDonald told the Congress, that there is a “rich pipeline of therapeutics” advancing into the clinic. Dr. MacDonald’s group is working in particular with antisense oligonucelotides to silence the Huntingtin gene, and he told the Congress about emerging gene silencing techniques (see HD Insights, Vol. 3). Dr. Neil Aronin presented his group’s efforts to use deactivated viruses to silence the mutant HD gene. These gene-silencing approaches have shown great promise for the near future. Dr. Bernhard Landwehrmeyer gave an update on clinical trials in HD, while Dr. David Craufurd discussed drug treatment for psychiatric symptoms that is often necessary, and Dr. Binit Shah described deep brain stimulation in HD. At the end of the Congress, Dr. Joaquim Ferreira offered an encouraging reminder that while there is currently no cure for HD, there are a number of treatments that help patients, and many more that show great promise are on the horizon.