Huntington's Disease

 Huntington's Disease/HD is an example of atrinucleotide repeat neurodegenerative disease. It is an autosomal dominant disorder, requiring only one gene from either parent's genotype in order to be expressed in the phenotype. Unlike other inherited diseases, HD begins to express itself later into adulthood (40+). 

Symptoms  The main symptoms of HD include dementia and motor function issues (akin to Parkinsons Disease) , the severity of which increase rapidly as the disease develops.

Treatment

There are no known cures for Huntington's disease for the time being, however there are speculations that excitotoxic drugs or neural transplantation will hold the key to slowing down the course of the illness and treating the dementia symptoms. 

The drugs used to alleviate the motor symptoms includetetrabenazine - which reduces dopamine storage, chlorpromazine - a dopamine antagonist and baclofen - a GABA agonist.

NB - these drugs are essentially the opposite of those used to treat Parkinsons Disease