The main cause of Huntington’s chorea is the anomaly of the Huntingtin gene, the mutant mHTT. A progressive brain disorder, Huntington’s chorea invariably affects the nerve cells in the brain and causes its gradual degeneration.

It is interesting to note everyone has the Huntingtin gene, but only some have an aberration, a defective gene. Huntington’s chorea can be passed on from the father or mother to the child at the time of conception. It is possible that one generation not exhibit symptoms of Huntington’s chorea and, instead, pass it on because of some other reason. What is clear is that this disease does not skip a generation of people, it is passed on directly only from a parent to the child. Every child of a person with Huntington’s disease has a 50/50 chance of contracting the defective gene. Affecting both men and women in equal numbers, Huntington’s disease normally surfaces in people in the age group of 30-50 years. In subsequent generations, however, the symptoms can start showing up much earlier, even in the 20s.

The huntingtin gene naturally produces what is called the huntingtin protein, but when there is a deviant gene at play, the cytosine, adenine, and guanine (CAG) DNA segment is repeated multiple times, way more than what is normal. Typically, the CAG segment is repeated anywhere between 10-35 times, but this repetition invariably occurs a higher number of times when there is a mutation in the gene. When the number is between 36 and 39, the affected person might not exhibit any symptoms, but the symptoms of brain disease, or Huntington’s chorea, are clearly visible when the recurrence is over 40 times. The presence of a large amount of huntingtin protein affects the brain adversely. It becomes toxic and severely disturbs the normal functions of the basal ganglia and the outer surface of the brain, the cortex.

Inherited in an autosomal dominant format, the mutant huntingtin gene can show up in people at any age. The adult onset of Huntington’s disease shows up a repetition of the CAG DNA segment for 40-50 times, while a juvenile version shows more than 60 repeats. It is important to remember that as the gene is passed on from every parent to their child, the successive generations of children are at increased risk of contracting this brain condition.

Huntington’s disease causes movement disorders, cognitive impairment, and psychiatric ailments. The typical symptoms vary slightly in the case of the adult and juvenile versions of the disease. The duration, severity, and progression of Huntington’s chorea are highly individualized and cannot be generalized. The life expectancy of the patient can differ considerably and can be anywhere between 10 and 30 years after the development of the symptoms. In the later stages of the disease, while there could be awareness and an understanding of the environment, patients of this condition might be bedridden and require round-the-clock nursing care.