Dr. Madhuri Hegde is currently working on implementing micro-array technology for the CMDs (CMD chip). Improved genetic testing is a must to support the CMD International Registry, which will connect affected people with CMD with a known genetic mutation to future clinical trials.
What is micro-array or “chip” technology?
The micro-array technology is a comprehensive test that relies on DNA sequences placed on a glass slide (chip) to rapidly identify areas of genetic mutations. This type of testing allows for a rapid screen of where a mutation may reside within a variety of genes simultaneously. This is an extremely helpful approach in the CMDs where a person’s presentation can be variable. Traditional DNA sequencing techniques will then confirm the type of genetic mutation.
Stated in a different way:
The chip is a glass slide with all known CMD genes on it. With the chip, one can successfully test for all CMD genes and types of mutations (nonsense, missense, deletion, insertion, duplication, splice site) simultaneously. This test shrinks the wait time and zeros in on areas of genetic variability that could represent a genetic mutation. After hotspot areas are found, traditional DNA sequencing techniques are employed in those limited areas to determine if there is a pathologic mutation.
Has micro-array technology been used in other forms of muscular dystrophy for genetic diagnosis?
Dr. Madhuri Hegde at Emory University designed a chip to speed the diagnosis and accuracy of diagnosis in Duchenne muscular dystrophy. The Duchenne chip has revolutionized the diagnosis of Duchenne, cutting down on turnaround time and greatly increasing the accuracy of diagnosis. She has now turned her attention to developing a “chip” or micro-array technology to diagnose congenital muscular dystrophy, all subtypes.
Will micro-array technology (CMD chip) diagnose everyone’s genetic mutations with CMD?
No, there will still be cases where a genetic mutation cannot be found in the CMDs, because there are still genes that need to be discovered. The “chip” contains only genes and segments of DNA known to already cause or to be associated CMD.
Cure CMD is very excited about Dr. Hegde’s work. We feel that improved diagnostic testing is a high priority to:
a. decrease the diagnostic odyssey
b. provide a higher yield test that will discover new genetic mutations within known CMD genes
c. provide a result with a faster turnaround within 2-3 weeks
d. connect patients with known genetic mutations to future CMD clinical trials.
What does the micro-array test require? The test will require a blood sample and consent forms. Once an affected person’s mutation has been identified, family screening and prenatal diagnosis will be offered. Genetic counselors at Emory Genetic Laboratory will provide additional assistance once the test is launched. The targeted date for test availability is March 2009.