Neurodegenerative Diseases
Huntington's Disease
Huntington’s disease (HD) is an autosomal nuclear DNA (nDNA) disease caused by a defect in the Huntingtin gene located on chromosome number 4. The disease has a prevalence of 3-7:100,000. Huntington’s disease is caused by a CAG trinucleotide repeat expansion leading to glutamine (Q) insertion in the Huntingtin protein. Individuals with Q-repeat numbers below 36 in the Huntingtin protein are devoid of clinical manifestations. Q-repeat lengths greater than 36, are associated with clinical signs and symptoms of the disease. The Q-repeat number in general correlates with age of onset, i.e., the greater the Q-repeat number, the earlier the age of onset. Defective Huntingtin protein (mHtt) results in degeneration of neurons located within the caudate nucleus and the frontal lobes. The precise mechanism of Htt and mHtt that leads to HD are the subject of considerable investigation, but are unknown today. There are no treatments for HD, and current therapy focuses on symptomatic management. HD is highly debilitating, with a life expectancy of an estimated 15-20 years beyond diagnosis. There are multiple drugs in development for HD.
Parkinson's Disease
Parkinson’s disease (PD) affects an estimated one million Americans with a prevalence placed at approximately 1-2:100. There is no diagnostic test for the majority of Parkinson’s patients. Parkinson’s “disease” is a syndrome comprised of multiple diseases. While the vast majority of individuals suffer from idiopathic Parkinson’s disease for which the cause is unknown, discrete genetic errors have been identified in a small number of individuals. Other causes of Parkinson’s disease include toxin exposure and head trauma. The symptoms of Parkinson’s disease arise from a loss of dopamine producing cells in the substantia nigra region of the brain causing discoordinated regulation of movement. Other cognitive, autonomic and sensorial losses can also be associated with Parkinson’s disease. The majority of drugs used to treat PD are directed at increasing dopamine and symptomatic management of the disease. Stem cell therapy is being explored. PD is not fatal per se, however individuals with PD generally have a shortened life expectancy and suffer increased debilitation. There are multiple drugs in development for PD.