The weaker signals from subthalamic nuclei thus cause reduced initiation and modulation of movement, resulting in the characteristic movements of the disorder, notably chorea. Huntingtons disease presents itself later in life even though the proteins that cause the disease works towards manifestation from their early stages in the humans affected by the proteins. Along with being a neurodegenerative disorder, HD has links to problems with neurodevelopment.HD is caused by polyglutamine tract expansion in the huntingtin gene, resulting in the mutant huntingtin. Aggregates of mutant huntingtin form as inclusion bodies in neurons, and may be directly toxic. Additionally, they may damage molecular motors and microtubules to interfere with normal axonal transport, leading to impaired transport of important cargoes such as BDNF. Huntingtons disease currently has no effective treatments that would modify the disease. Multiple sclerosis
Multiple sclerosis (MS) is a chronic debilitating demyelinating disease of the central nervous system, caused by an autoimmune attack resulting in the progressive loss of myelin sheath on neuronal axons. The resultant decrease in the speed of signal transduction leads to a loss of functionality that includes both cognitive and motor impairment depending on the location of the lesion. The progression of MS occurs due to episodes of increasing inflammation, which is proposed to be due to the release of antigens such as myelin oligodendrocyte glycoprotein, myelin basic protein, and proteolipid protein, causing an autoimmune response.
Mitochondrial disease leading to neurodegeneration is likely, at least on some level, to involve all of these functions.There is strong evidence that mitochondrial dysfunction and oxidative stress play a causal role in neurodegenerative disease pathogenesis, including in four of the more well known diseases Alzheimers, Parkinsons, Huntingtons, and amyotrophic lateral sclerosis.Neurons are particularly vulnerable to oxidative damage due to their strong metabolic activity associated with high transcription levels, high oxygen consumption, and weak antioxidant defense. DNA damage
The brain metabolizes as much as a fifth of consumed oxygen, and reactive oxygen species produced by oxidative metabolism are a major source of DNA damage in the brain. Damage to a cells DNA is particularly harmful because DNA is the blueprint for protein production and unlike other molecules it cannot simply be replaced by re-synthesis. The vulnerability of post-mitotic neurons to DNA damage (such as oxidative lesions or certain types of DNA strand breaks), coupled with a gradual decline in the activities of repair mechanisms, could lead to accumulation of DNA damage with age and contribute to brain aging and neurodegeneration. DNA single-strand breaks are common and are associated with the neurodegenerative disease ataxia-oculomotor apraxia. Increased oxidative DNA damage in the brain is associated with Alzheimers disease and Parkinsons disease. Defective DNA repair has been linked to neurodegenerative disorders such as Alzheimers disease, amyotrophic lateral sclerosis, ataxia telangiectasia, Cockayne syndrome, Parkinsons disease and xeroderma pigmentosum. Axonal transport
Axonal swelling, and axonal spheroids have been observed in many different neurodegenerative diseases.