Causes

Huntington’s Disease is caused by a mutation of one single gene (The Huntington gene). Every human has a Huntingtin gene, but it is only those who have been tested positive for the gene mutation that will develop the disease. It is a genetic disease and therefore hereditary, meaning that it can be passed down from one generation to the next. Children of those with Huntington’s Disease have a 50/50 chance of inheriting the illness.

The Science Explained: The human genome, stored on your DNA, is believed to contain around 20,000 – 25,000 genes. The genome is the entirety of a human’s hereditary information aka the genome and the genes contained are a set of instructions e.g. it tells your hair to be brown or your eyes to be blue.

Every person carries two variations of each gene, one inherited from their mother, the other inherited from their father.

An analogy to the human genome stored on DNA is that of instructions stored in a book:

• The book (genome) would contain 23 chapters (chromosomes);
• Each chapter contains 48 to 250 million letters (A,C,G,T) without spaces;
• Hence, the book contains over 3.2 billion letters total;
• The book fits into a cell nucleus the size of a pinpoint;
• At least one copy of the book (all 23 chapters) is contained in most cells of our body.

DNA is the chemical code that directs the growth and development of the cells in the body. The human body is built of billions and trillions of cells. Within cells, DNA is organized into long structures called chromosomes. During cell division these chromosomes are duplicated in the process of DNA replication, providing each cell its own complete set of chromosomes.

A mutation, such as the Huntington Gene Mutation, is a permanent change in the DNA sequence of a gene. Think of this mutation as being one number of a pin code for a bank card. When one part is wrong it does not work properly.

Changes in DNA caused by mutation can cause errors in protein sequence, creating partially or completely non-functional proteins. Each cell, in order to function correctly, depends on thousands of proteins to function in the right places at the right times. When a mutation alters a protein that plays a critical role in the body, a medical condition can result. A condition caused by mutations in one or more genes is called a genetic disorder.

In Huntington’s Disease this gene mutation causes multiple CAG repeats, these repeats then lead to an imbalance in the brain which cause damage to the neurons in the brain. Subsequently leading to impaired physical ability, mental functioning and emotional.