The Collaborative Center for X-linked Dystonia Parkinsonism (XDP) at Massachusetts General Hospital provides resources and treatment information to patients with XDP.

What is X-linked Dystonia Parkinsonism?

X-linked dystonia parkinsonism (XDP) is an adult-onset, genetic movement disorder which almost entirely affects males who descend from the Philippine Island of Panay. XDP is also known as “Lubag," after the local Filipino term to describe abnormal twisting postures that are a significant feature of the early disease.


Phases of XDP

XDP generally presents in three different clinical phases.

Dystonic Phase

People with dystonia have involuntary, sustained muscle contractions. These involuntary muscle contractions can cause twisting, repetitive movements and abnormal postures. The twisting seen in XDP patients happens because the brain sends signals that tell muscles to tighten and contract involuntarily.

In XDP, dystonia can occur in any part of the body and may spread to other body parts during the course of disease. It can manifest in many different ways, including twisting/dragging a foot, repeated jaw opening and closing, abnormal turning or posture of the neck, tongue protrusion, mouth pursing or excessive eye blinking. Many patients begin showing symptoms in their forties, but the age of onset can vary greatly.  

When one part of the body is affected, it is called focal dystonia.

Over time, more muscles become affected, leading to twisting and uncomfortable postures with muscle spasms. After five years, most patients have developed a generalized dystonia, where many different muscle groups and body parts are affected.

Dystonia and Parkinsonism

The next phase of XDP usually begins 7-15 years after onset of focal dystonia. During this phase, the patient has features of both generalized dystonia as well as parkinsonism.

Parkinsonism involves the development of symptoms that are classically associated with Parkinson's disease, but can also be seen in many other conditions. These involve slowing of movements, shuffling gait, development of a hand tremor and reduction of facial expression. Patients with XDP do not have Parkinson's disease, which is not a genetic condition and is caused by a different mechanism.

Parkinsonism Phase

By 15 years after onset, XDP patients primarily show features of parkinsonism. In 6% of patients, XDP manifests primarily as parkinsonism, without evidence of dystonia.


Prognosis

As XDP progresses, patients become more disabled and are eventually unable to work. In the late stages of disease, patients become dependent on others, immobile and unable to care for themselves. Patients with XDP have a reduced life expectancy due to the complications of the disease.


What causes XDP?

XDP is caused by a genetic mutation that can be passed down from parent to child. The exact mutation has not yet been identified, but researchers have narrowed it down to a stretch of DNA on the X chromosome.

Learn more about genetic mutations

The X chromosome helps determine whether a person is male or female. Since the mutation is found on the X-chromosome, XDP is called a sex-linked or X-linked disease.


The X Chromosome Connection

The X chromosome helps determine whether a person is male or female, therefore XDP is called a sex-linked or X-linked disease. The location of the mutation is significant because it means males will be the ones most often affected by XDP, while females will carry the mutation without exhibiting symptoms.

Women who carry the mutation on one X chromosome have a 50% chance of passing down the mutation to their sons and daughters. The sons will develop XDP, while the daughters will become carriers of the mutation.

Men who carry the mutation and therefore have XDP will produce healthy sons and carrier daughters.

The fact that woman can act as carriers without exhibiting symptoms leads to the mutation persisting in a population.


Where is Panay Island?

Panay is one island in the Philippines, which is located in southeast Asia. The Philippines has a population of roughly 100 million and is made up of over 7,000 islands. Panay is part of a group of islands called the Visayas in the central part of the Philippines. Panay is divided into five provinces; Aklan, Antique, Capiz, Iloilo and Guimaras (a small island off Panay).

These provinces were particularly hard-hit during Typhoon Haiyan in November 2014. There are more than 12 million people of Filipino descent who live overseas in many countries around the world, including the United States.


I am Filipino, why have I not heard of XDP?

The highest concentration of XDP patients is on the island of Panay in the Philippines. XDP patients in the United States or elsewhere can usually trace their maternal ancestry to Panay. How then could someone with family on or from Panay not know about the disease?

Unfortunately, for many years families did not have an understanding of what XDP was. The drastic twisting and jaw opening that many patients exhibited caused families to be ashamed. As a result, patients were often confined to their homes or hidden from the community due to the significant social stigma associated with disease. This may help explain the lack of widespread knowledge about XDP.

Through education and outreach, the Collaborative Center for XDP hopes to further understanding of the disease and ;provide support for XDP patients and their families.


Is Genetic Testing Available?

Clinical genetic testing is not currently available in the US. Please contact our genetic counselor, Trisha Multhaupt-Buell at DystoniaResearch@partners.org for information about testing options outside of the United States.


What are Treatment Options for Patients?


What is Being Done to Help Patients?

The Collaborative Center for XDP was formed to accelerate research into XDP with the goal of providing more effective treatments, and ultimately, a cure.

To that end, the Center has reached out to experts all over the world to bring their talents to the problem of XDP. This includes:

  • Geneticists who are working to find the causative mutation
  • Neuroscientists to identify changes in the brains of XDP patients
  • Cell biologists to determine why neurons in the brain malfunction or die
  • Clinicians working to develop effective treatments for XDP

There is a great need to know the prevalence of XDP in the Philippines. Therefore, the Center also supports local epidemiologists from the XDP Study Group to determine the scope of the disease burden and where the needs are the greatest. This information will empower the Center and collaborators to properly scale and target humanitarian efforts.

Finally, the Center recognizes the devastating toll that XDP takes on a patient and their family.

Men usually start exhibiting symptoms in their early forties after they have had children. At this time in their lives, they are likely the primary source of income for their family. Without this income, families often descend into poverty.

The Center is dedicated to helping such families by providing better access to medicines, clinical care and emotional support. We have employed a network of community advocates to help us understand the daily struggles patients face and the barriers that often prevent access to medical care. Learn more about our Humanitarian Mission


How Can I Help?

The Center supports ongoing efforts at Mass General and in the Philippines to collect, process, and store samples and clinical information from XDP patients and their family members.

These samples are a crucial resource for scientists all over the world to increase our understanding and treatment options for this debilitating disease. For more information please contact Trisha Multhaupt-Buell at DystoniaResearch@partners.org.

If you are considering a monetary donation to the Center to support research or humanitarian efforts, please contact the Mass General development office at 617.726.2200 or mghdevelopment@partners.org.


Resources

Scientific Literature