It was estimated that about 10,000 people in Great Britain and 65,000 in the United States have Huntington’s Disease (formerly Huntington’s chorea). There are currently two major groups of symptoms:
1. adult-onset ( the most common) typically manifests in a person’s 30s or 40s. Challenges in the cognitive areas can include irritability, depression, small involuntary movements, poor coordination, and trouble learning new information or making decisions. The chorea refers to involuntary jerking or twitching movements. These worsen and make walking, speaking, and swallowing difficult.
2. juvenile-onset manifests in childhood or adolescence. Additional challenges include slow movements, clumsiness, frequent falling, rigidity, slurred speech, and drooling. Seizures occur in one third to one half of children with this condition. This variety tends to progress more quickly than adult-onset.
An early understanding of Huntington’s Disease was greatly hampered by the work of Charles Benedict Davenport (June 1, 1866 – February 18, 1944), Elizabeth Muncey, a federal Eugenics Record Office researcher, and the imaginative P. R. Vessie.
The Woman Who Walked into the Sea: Huntington’s and the Making of a Genetic Disease by Alice Wexler (2008 Yale University Press) is worth a read.
An exciting discovery was made after almost twenty years of studying people in two villages in Venezuela. A gene called HTT on chromosome 4 on the p16.3 region had a variable number of nucleotide repeats. The full explanation of what the Huntington protein does exactly still needs work.
Prof Sarah Tabrizi, director of University College London’s Huntington’s Disease Centre who led the phase 1 trial of a drug called Ionis-HTTRx, explained that the interception and destruction of a messenger molecule prevents the harmful protein from being made. We’ll see what the actual paper reads like and whether the drug scales up safely.