The scientific study of Huntington’s Disease (HD) had began in 1872, by George Huntington who is a family physician that had published a report on the clinical symptoms and peculiar mode of inheritance of the disorder.(1, 2) Huntington’s disease has 3 subtypes according to the age onset, which are infantile, juvenile and the adult-onset.(2) Individuals with Huntington’s disease can become asymptomatic between the ages of 1 and 80 years.(3) The typical mean age of onset is 40 years, with death occurring 15–20 years from onset.(2, 4) The prevalence of HD patients in North America and Europe is 0.005% - 0.01%. It is lowest in Africa and Asian population compared in western European origin population.(5)
The clinical symptoms for HD are divided into 3 categories: psychiatric disorders, movement disorders, and cognitive impairment. Psychiatric disorders can occur at anytime during the disease progress or can …show more content…
(7, 8) Excessive number of repeats in CAG chain results in mutation that leads to the development of HD.(7) The CAG repeat is located within the coding sequence. It is then translated and transcribed with the rest of the gene, giving rise to a polyglutamine array which is a protein known as huntingtin (HTT).(2, 8) The abnormal HTT produced from the mutated gene forms inclusions within neurons leading to their death.(2, 7) HTT consist of repeated units of about 50 amino acids, termed HEAT repeats with a mass of approximately 349 kDa.(4, 8) These repeats comprised of two antiparallel α-helices, forming a superhelix structure with a central hydrophobic core.(4) HTT is a regulatory cytoplasmic protein that has a role in vesicle transport, and can regulate gene transcription. Thus it might also regulate RNA trafficking.(4, 8) However the exact cellular functions of HTT are still not completely