Faster test for genetic disease?

January 27, 2010 8:57:24 AM PST
A new lab test called MitoDx is designed to look for genetic mutations linked to mitochondrial disease and other genetic conditions. According to the United Mitochondrial Disease Foundation, every 30 minutes, a child is born who will develop a mitochondrial disease by age 10. Symptoms of mitochondrial disease include loss of motor control, muscle weakness, muscle pain, gastrointestinal problems, swallowing problems, poor growth, cardiac disease, liver disease, diabetes, respiratory complications and more. The wide range of symptoms, experts say, occurs because mitochondria are responsible for creating more than 90 percent of the energy needed by the body. The organs most affected by mitochondrial disease are the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. According to Cleveland Clinic, mitochondrial disease includes more than 40 identified diseases with different genetic features. The common factor is that the mitochondria are unable to completely burn food and oxygen to generate the energy the body needs. For many patients, mitochondrial disease is caused by a genetic mutation that is inherited. Other patients develop symptoms from mitochondrial toxins or medicines that affect the mitochondria.

DIAGNOSIS: The wide range of organs affected and different manifestations of the disease can make diagnosis difficult, experts say. "Because mitochondrial disease can show up as many different things, and because there's not one perfect test for mitochondrial disease, diagnosis becomes very difficult," Richard Boles, M.D., associate professor of the Keck School of Medicine at the University of Southern California, told Ivanhoe.

Doctors often arrive to a diagnosis after a combination of clinical observations, laboratory tests, brain imaging and muscles biopsies. Other tests doctors use include echocardiograms, audiology tests and genetic tests. Once diagnosed, treatment for mitochondrial disease varies from case to case. Since diseases of the mitochondria incurable, the goal of treatment is to alleviate symptoms and slow progression of the disease.

NEW GENETIC TEST FOR MITOCHONDRIAL DISEASE: A new lab test called MitoDx is designed to look for genetic mutations linked to mitochondrial disease and other genetic conditions. The test requires either a blood or saliva sample and uses a type of DNA sequencing technology that searches every base pair in mitochondria. Experts say it's like searching through an entire book looking for "typos," or mutations. "What this test does it is looks at the mitochondrial DNA and sequences or determines the genetic code at each of the over 16,000 base codes within us," Dr. Boles explained. "Not only does it do that, but it looks for small abnormalities ... [and] indicates a mutation or the genetic change that causes the disease." The MitoDx test screens for the mutations with about 30-fold -- or 3,000 percent -- greater sensitivity than comparable traditional tests, and results take about six to eight weeks to be returned, experts say.


Steve Sommer, MD, PhD, FACMG
(626) 804-3645