Huntington’s disease research news. In plain language. Written by scientists. For the global HD community.
Significant news for the Huntington's disease community this week, as the USA's drug regulator, the FDA, has formally approved Austedo, also known as deutetrabenazine, for prescribing in HD. This modified form of tetrabenazine helps control chorea, the jerky movements often found in HD patients, but is taken twice rather than three times a day.
Beyond affecting movement, mood, and thinking, HD involves a complex set of changes to the body that can be difficult to predict in different individuals. Recently, researchers were able to identify consistent early changes in metabolism by studying a group of HD sheep. This large animal model is helping scientists to track altered substances in the blood that could predict HD progression and response to treatment.
Cannabis, or medical marijuana, has been touted as a treatment for lots of conditions, and Huntington’s disease is no exception. Whenever it hits the news there’s a lot of interest, and recently cannabis found the spotlight again with videos claiming it can reverse the nerve cell damage in Huntington’s disease. These are extraordinary assertions that deserve to be explored.
DNA damage is a hot topic in HD – and new research offers an intriguing explanation. Canadian researchers have uncovered a potential role for huntingtin in the repair of DNA. They speculate that the normal protein is recruited to the nucleus to provide a supporting scaffold for a construction crew of DNA repair proteins. Mutant huntingtin can commute to the job, but can’t perform.
Huntingtin, the protein responsible for Huntington’s disease, is fundamentally important for fetuses to develop in the womb, but we don’t know yet exactly what part it plays in this intricate process. Normally, neurons start life deep within the developing brain, migrate out to the surface and then make a network of connections with others, but Sandrine Humbert’s group showed that those without huntingtin get stuck, never making it to where they need to go. Neurons with mutated huntingtin are no better than those that lack it completely. However, reintroducing normal huntingtin, or the proteins through which it acts, allows neurons to migrate normally again, offering tantalising new ways to treat Huntington’s disease.
Researchers have long known that patients with a greater number of CAG repeats in their HD gene tend to display motor symptoms sooner than those with fewer CAG repeats. However, this relationship is not perfect. Sometimes HD patients display symptoms at a drastically different time than expected based on the number of CAG repeats alone, suggesting that maybe other genetic or environmental factors speed up or slow down the progression of HD. A recent study suggests that comparing patients with the most ‘extreme’ motor symptoms may help to uncover exactly what these factors are.
Researchers have long believed that the Huntington's disease gene causes problems by telling cells to make a harmful protein. Intriguing new animal work from researchers in Spain suggests we might want to look at more than one suspect to completely fix the problems caused by the HD mutation.
Pfizer has announced that the first-pass analysis of its 'Amaryllis' trial, testing a PDE-10 inhibitor drug, shows the drug did not meet its target of improving Huntington's disease symptoms. As a result, the open-label extension study will be stopped. This is not the news we'd been hoping for, but we've learned a lot about HD along the way.
Recent days have seen a slew of news emerging regarding the use of something called genome editing as a potential therapy for genetic diseases like Huntington's Disease. These approaches, which include exotic sounding tools like zinc finger nucleases and CRISPR/Cas9, differ from more traditional ways reducing the impact of the HD mutation on cells. What's new in this exciting area of research?