Prevalence of huntington's disease much higher than estimated

Prevalence of huntington's disease much higher than estimated

Huntington's disease (HD) is much more common in the UK than current estimates suggest, according to a new Comment published in the peer-reviewed medical journal The Lancet. The Comment was

Huntington's disease is an incurable, hereditary brain disorder. It is a devastating brain disorder for which there is no currently 'effective' treatment. Nerve cells become damaged, causing various parts of the brain to deteriorate. The disease affects movement, behavior and cognition - the affected individuals' abilities to walk, think, reason and talk are gradually eroded to such a point that they eventually become entirely reliant on other people for their care. Huntington's disease has a major emotional, mental, social and economic impact on the lives of patients, as well as their families.

It used to be called Huntington's Chorea, because the involuntary movements made by patients with the disease can appear to be like jerky dancing.

The disease is caused by a dominant mutation of either of a person's two copies of the Huntingtin gene, which means any child of an affected parent has a 50% chance of inheriting the disease. In rare situations where both parents have an affected gene, or either parent has two affected copies, this risk is greatly increased.

According to previous studies, which were based on 15 UK locations, there was an estimated prevalence of 6.7 cases per 100,000 population.

However, Professor Rawlins reveals that the Huntington's Disease Association (HDA) - a not-for-profit organisation that provides services for patients with the disease and their families in England and Wales - is currently caring for 6,702 individuals with symptoms.

Professor Rawlings points out:

Specialist neurologists have referred all of them, so their diagnoses can hardly be in doubt. From these numbers alone, the minimum prevalence in England and Wales must therefore be at least 12•4 per 100 000.

Since the Huntington's Disease Association does not cover all England and Wales areas, Professor Rawlins believes that even the 12•4 per 100 000 estimate is most likely too low. He thinks there are numerous factors underlying the difficulty in reaching a true estimate:

  • First, until a genetic test (discovered by Nancy Wexler and colleagues) recently became available, the diagnosis was based totally on clinical features.
  • Second, and probably most significantly, affected individuals might try to hide the true nature of this familial trait, even from their own family doctor.
Professor Rawlins said:

As well as having profound implications for the families with a member who has Huntington's disease, the stigma has negatively affected research, particularly studies that have sought to investigate epidemiology and, most especially, prevalence... Huntington's disease is the only genetic condition for which the insurance industry loads those at risk. The stigma - to the insurance industry's eternal shame - is not only societal but also actuarial.

Professor Rawlins says there are two reasons why reliable estimates are needed:

First, the UK National Health Service (NHS) needs to ensure that there are appropriate services available now - and in the future - to care for those living with the disease and for their families. Second, combining those individuals with symptomatic Huntington's disease with those at risk emphasises the importance of encouraging research that will ultimately lead to treatments that will arrest progression. Such treatments, even if only partly effective, would need to be started long before the appearance of symptomatic disease. By the time symptoms appear, there are already substantial neuropsychiatric changes, and prophylactic therapy in those at risk, and who carry the genetic abnormality, would be essential even though at present we do not know when treatment might best be started.

He concludes:

To promote greater understanding and awareness of Huntington's disease, an All Party Parliamentary Group is being formed, under the chairmanship of Lord Walton of Detchant. With the organisational skills of the former NBC news and war reporter Charles Sabine - who is not only himself at risk but who also carries the abnormal gene - this Group aims to eradicate stigma, promote research, and chivvy the NHS to provide the best possible care.

In a linked Art of Medicine feature, Alice Wexler, sister of Nancy mentioned above, discusses the history of prejudice against HD, and refers to various narratives which undoubtedly played a part in strengthening hostile perceptions of families with HD, within medicine as well as outside it. Wexler currently works at the UCLA Center for the Study of Women, Public Affairs, Los Angeles, USA.

Wexler says:

[Those narratives] helped legitimise the notion that certain classes of people were undesirable as citizens. They bolstered stereotypes of individuals with disabilities as aggressive, violent, criminal, and dangerous, while adding to the stigmas associated with alcoholism, mental illness, and cognitive impairment. They gave a rationale for doctors to endorse sterilisation or even celibacy for people at risk of Huntington's, and encouraged medical indifference toward the care of those with the disease.

Prejudicial representations of Huntington's disease also encouraged flawed biomedical research, such as the 1951 study published in Science claiming (falsely) that those with the mutant Huntington's gene had vastly more children than their siblings without it. Only in the civil rights era of the 1960s and 1970s, with the repudiation of eugenics and the advent of the first lay associations of families affected by Huntington's disease in North America and in Europe, did research priorities and representations begin to change.

(conclusion) Medical histories matter. Whatever the truths of the 17th century, it is clear that some 20th-century scientists and clinicians created historical narratives that deepened the stigmatisation of people with Huntington's disease in their own time - and of other psychiatric and neurological conditions as well. Confronting the eugenic origins and harmful psychological and social legacies of these narratives cannot undo the past, but I believe it can help us change the conditions that perpetuate stigma and shame in the present.

A linked News item in The Lancet Neurology,

Spinney concludes:

In the European Union, a rare disease is defined as one that is life-threatening or chronically debilitating, with a prevalence of 50 or fewer cases per 100 000. Therefore, even if the revised prevalence of Huntington's disease in the UK is twice as high as that with which the UK government is currently working, the disease will continue to be defined as rare. Patients could now begin to see a difference, however, as the new All Party Parliamentary Group strives to ensure that they have access to the health care and political representation that is due to them.

"Huntington's disease out of the closet?"

Michael Rawlins

The Lancet, Early Online Publication, 30 June 2010


" Stigma, history, and Huntington's disease "

Alice Wexler

The Lancet, Early Online Publication, 30 June 2010


"Uncovering the true prevalence of Huntington's disease"

Laura Spinney

The Lancet Neurology, Early Online Publication, 30 June 2010


Huntington's Disease: Stages and Therapies (Video Medical And Professional 2020).

Section Issues On Medicine: Disease