Huntington's disease is an inherited disease and affects the brain. You have a 50% of chance of this disease, if one of your parents has this disease. An affected individual inherits one copy of the gene from affected parents. When both parents have Huntington disease, the risk of increases is 75%. The risk will be 100% if either parent has expanded copies. It is caused by mutation in a gene on chromosome four. A blood test will help you in the recognition of this disease. It results from degeneration of neuron nerve cells.This affects the cell in basal ganglia of brain. This portion of brains controls cognitive ability, ability emotion and movement. The symptoms include difficulty in walking, speaking, swallowing, muscle co-ordination and poor memory. It also affects the outer surface of brain.