Genetics may be to blame for exercise intolerance

This article explains how exercise intolerance may have a genetic component, although does not seem to be a hereditary condition.

Some cases of exercise intolerance have been linked to mutations in a gene found in the mitochondria, the “powerhouses” of the cell, according to a study.

Exercise intolerance is a condition in which a person experiences extreme fatigue, muscle pain or cramps after minimal exercise. Mitochondria provide energy that muscles require to function, so a defect in these could severely limit the ability to exercise.

Mitochondrial DNA — which is separate from DNA found in the nucleus, or control center of the cell — is inherited directly from the mother, so if a child has a disorder linked to the mitochondria, the mother usually also has it.

However, the research team from the Columbia College of Physicians and Surgeons in New York, found that in the patients studied, there was no maternal link to the mutation, and no evidence of the mutation in tissues other than muscles. This suggests that mutation is not inherited but occurs in the embryo, the team suggests. Five patients with exercise intolerance and no family history of the disease enrolled in the study.

Analyses of the patients’ cells revealed that all had defects in respiratory chain enzymes, which are used by mitochondria to make substances that store energy for muscles. Sophisticated techniques narrowed the deficiencies down to mutations in the mitochondrial cytochrome b gene.

The investigators conclude that such mitochondrial gene mutations may be common, and recommend that physicians consider this as a possible diagnosis in patients with “the often elusive symptoms of aches, pain, and cramps.”

No treatments have been developed for this condition, but as a therapeutic course for the patients, researchers suggest “genetic counseling” to explain to the patients that they will not pass their disease onto their children. Also, patients can engage in “appropriate exercise programs,” which might have some benefit, they add.

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The invisible disease that's killing our son - Mitochondrial Disease

Mitochondrial disease is not rare.   Access  a knowledgeable  neurologist to see if this could be causing seizures, muscle weakness, pain, stiffness, movement disorders, autism,  autonomic problems or other conditions. JR

The invisible disease that's killing our son

By Lori Martin, Special to CNN

updated 1:59 PM EDT, Fri September 21, 2012

STORY HIGHLIGHTS

• Every 30 minutes a child is born who will develop mitochondrial disease by age 10
• Mitochondria are responsible for creating more than 90% of our body's energy
• The disease primarily affects children, but adult onset is becoming more common

(CNN) -- On July 5, 2011, my husband and I were told that our 2-year-old son has an invisible killer living inside his body.

Just a few short years ago, I was happily pregnant. Now, suddenly: Why? What? When? All these questions came with so few answers about a disease that few know about or understand.

That invisible killer is called mitochondrial disease. Our son's specific mutation is called Leigh's Disease.

We're one of the lucky ones. It took us only a year to get a diagnosis -- a year filled with anesthesia, a CAT scan, a muscle biopsy, a lumbar puncture, an MRI, an echocardiogram, an EKG, specialists and so on. Most families spend years attempting to find a diagnosis because of the complexities of DNA sequencing.

This silent killer is attacking our nation's children at an appalling rate. According to the United Mitochondrial Disease Foundation, every 30 minutes a child is born who will develop a mitochondrial disease by age 10.

As a first-time mom, I had no idea that I should have been scared of mitochondria. All I knew was some fuzzy science from high school biology about mitochondria being the powerhouse cells of our body.

Mitochondria are responsible for creating more than 90% of the energy needed by the body to sustain life and support growth. When they fail, less and less energy is generated within the cell. Cell injury and even cell death follow.

If this process is repeated throughout the body, whole systems begin to fail, and that person's life is severely compromised. The disease primarily affects children, but adult onset is becoming more common......

....It's National Mitochondrial Disease Awareness week. For us, every day we're deeply aware -- our son is lucky.

Our doctor says he has a mild case of what will one day kill him. We get to hear him say, "I love you" and watch him laugh with friends. So many other "mito" kids can't even roll over, swallow their food or see their favorite "Veggie Tales" character on TV.

There are a lot of days I don't feel so lucky. But then this tow-headed goofball comes barreling at me wanting to give me a bear hug (complete with sound effects) and it snaps me out of my sadness.

My son is my hero. He pushes us to keep going. He is the one enduring endless blood draws, hospital stays and experimental drugs.

There is no cure, but there is hope. Recently, Edison Pharmaceuticals received orphan status for the drug EPI-743. We're one of 128 people in the world who somehow managed to get a spot in their research program.

Essentially, the drug is supposed to help Will's mitochondria function better, giving him increased energy and a chance at a better quality of life.

I often find myself feeling guilty that we're on it when there are so many others who should be. Likely, by the time the Food and Drug Administration approves it, many of these children will perish. It's not a cure, but it is a sign of hope.

http://www.cnn.com/2012/09/21/health/mitochondrial-disease-martin-family/index.html?hpt=hp_c1