Huntington’s Disease (HD) is a genetic disease, which means it can be passed down through families.
The gene that causes HD is normally responsible for the production of a protein called Huntingtin. This is found in cells throughout the human body, but particularly in the brain and spinal cord. The abnormal gene causes the protein to form clumps within the cell, which disrupts the function of cells.
This damage occurs most frequently within the area of the brain called the basal ganglia. The basal ganglia normally control movement, our understanding, problem solving and our emotions. The symptoms of HD therefore relate to problems with movement, problems with thinking and problems with emotions usually observed as changes in behaviour.
HD is a progressive disease which means the condition deteriorates over time. It is divided into 4 stages. The Total Functional Capacity Score (TFC) indicates the level of independence of the person with HD at each stage. The higher the TFC score, the more independent the person is.
Pre manifest: before onset of physical symptoms
Early stage: has physical symptoms with TFC score 11-13
Mid stage: has physical symptoms and a TFC score 7-10 or 3-6
Late stage: has physical symptoms and a TFC score 1-2 or 0 (2)
Symptoms of HD
HD presents with various symptoms which usually appear between the ages of 35 to 40 years.
Early in HD, the damage may result in mild problems with movement, thoughts and behaviour. You may observe unwanted movements of the arms, legs or face. This is termed chorea or dystonia and can result in difficulties with walking. Difficulties with concentrating, planning and organising tasks or sadness, depression; or irritability are also common.