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What is a rare disease, and how are they treated?

Gene therapy. Blood and marrow transplants. Medical innovation. University of Minnesota Health expert Troy Lund, MD, PhD, discusses the latest in rare disease diagnosis and treatment.
University of Minnesota Health Blood and Marrow Transplant Physician Troy Lund, MD, PhD, conducts rare disease research and treats patients with a rare disease diagnosis.

Rare diseases aren’t as rare as the name seems to imply.

Approximately 25 to 30 million Americans may be living with one of the estimated 7,000 rare diseases in existence, which means that you may know someone who is affected.

Thursday, February 28, is Rare Disease Day. In honor of this event, we asked rare disease expert Troy Lund, MD, PhD, to answer some questions about who is affected, and discuss the diagnoses and treatments available for those with a rare disease. Lund is a University of Minnesota Health blood and marrow transplant physician. He also holds a faculty position at University of Minnesota Medical School.

What is a rare disease? What is an example of a rare disease?

In the United States, the definition of a rare disease is a condition that affects fewer than 200,000 Americans at any point in time. The National Institutes of Health estimates that there around 7,000 rare diseases, and—currently—it’s estimated that the total number of Americans living with a rare disease is between 25 and 30 million people. These numbers demonstrate that even though an individual disease may be considered rare, every family could potentially be touched by one, or at least know someone with one.

I often work with patients with inherited metabolic disorders, like adrenoleukodystrophy (ALD). ALD is a genetic disorder that mainly affects the nervous system and the adrenal glands—the small glands located on top of each kidney. Myelin, the fatty covering that insulates nerves in the brain and spinal cord, deteriorates, reducing the ability of the nerves to relay information to the brain. Children with this genetic disorder—mostly males—experience learning and behavioral problems that usually begin between the ages of 4 and 10 and worsen over time. These symptoms include difficulty reading, writing, understanding speech and comprehending written material. Additional signs and symptoms include aggressive behavior, vision problems, difficulty swallowing and poor coordination. There is no cure for ALD.

What causes a rare disease and how is it diagnosed?

There are many causes of rare diseases. Many are believed to be genetic, which means they are directly caused by changes in genes or chromosomes. In some cases, the genetic changes that cause the disease are passed from one generation to the next. Other times they occur at random.

Approximately 50,000 people in Minnesota have a rare disease, half of whom are children. Many families go through an extensive diagnosis process that can take years. The child may have some symptoms that may not be specific to their disease. This can lead to a child being misdiagnosed at first.

What options are available for rare disease treatment?

While a lot of progress has been made in learning how to diagnose, treat and prevent a variety of rare diseases, there is a lot of work to do because many rare diseases are still without treatments.

A University of Minnesota team conducted the first successful human bone marrow transplant from a matched, related donor in 1968 for a patient who had a rare disease known as severe combined immunodeficiency. At that point, we set the stage both in blood and marrow transplantation and in the treatment of rare diseases. Subsequently, many other patients with rare disease—including immunodeficiency, metabolic storage disease, adrenoleukodystrophy, and a bone disease known as osteopetrosis—have been referred to us from all over the world to be evaluated and receive blood and marrow transplants in hopes of curing their disease.

University of Minnesota Health experts have provided compassionate, comprehensive care to blood and marrow transplant patients for more than 50 years. Learn more about our adult care and pediatric care expertise.

Because the University of Minnesota has been a leader in the rare disease world, many are turning to us to lead the way in gene therapy. Traditional drugs minimize symptoms rather than cure the disease, but gene therapy has the potential to correct underlying genetic defects, which can lead to a cure rather than simply managing symptoms. Sometimes, only a single dose of gene therapy is required for lifelong improvement, as opposed to ongoing treatment.

How does gene therapy help individuals with rare diseases and their families?

Gene therapy uses modified or healthy genetic material to treat or prevent disease. Sometimes we can utilize a gene therapy product to put a normal and functional copy of a gene into a person’s bone marrow stem cells or hematopoietic stem cells, where it replicates and spreads. In other words, we’re using the person’s own cells to deliver the healthy gene. Right now, this is available for just a handful of genes but has been growing by leaps and bounds over the last decade.

What are you doing to advance rare disease research?

I spend a lot of time assessing and evaluating patients from all over the world with rare diseases who can be made better through blood and marrow transplants. I find the appropriate donors and take patients through the transplant process with follow-up care thereafter.

My research focuses on determining better biomarkers for rare diseases and their progression. In the laboratory, I study how these diseases work. I can test new drugs and therapies in hopes of finding low-risk solutions with the fewest side effects to help patients with rare diseases.