Comprehensive Genotyping for Susceptibility to Metabolic Muscle Disease

DESCRIPTION (provided by applicant): The goal of this project is to develop a large-scale genotyping tool for metabolic muscle disease that can be applied to certain high risk groups in order to prevent life-threatening symptoms that are fast becoming a public health problem. The triggering of life-threatening metabolic muscle diseases by environmental factors such as drugs, viral infections, extreme exertion, anesthesia, sleep deprivation, exposure to temperature extremes, and other environmental stresso rs is increasing in the general population. Among those potentially at risk are nearly 20 million Americans taking cholesterol-lowering drugs, known as statins; those submitted to multiple environmental triggers including military, police and fire-fighting recruits, as well as athletes; and more than 15 million Americans who have surgery performed annually under general anesthesia. The recent expansion of newborn screening is also responsible for detecting larger numbers of newborns at risk for developing s erious metabolic disorders for which no comprehensive mutation screen is available. There is a need for a comprehensive genotyping platform that will provide detection of disease-causing mutations and risk-associated genetic variants for all of these high risk groups preferably before symptoms arise. The extent of disease prevention from this screening tool will have a large impact on reducing both mortality and morbidity considering the millions of Americans potentially at risk. For this Phase I study, we propose to develop a large-scale genotyping assay for 384 mutations and genetic variants associated with 10 muscle diseases that, in the long-term, can be applied to screening all 7 risk groups. The platform used will be the GoldenGate Genotyping Assay (Il lumina) which employs cutting edge technology for producing one of the most robust systems for genotyping in the industry. The GoldenGate assay allows for a high degree of multiplexing during extension and amplification steps, thus minimizing time, reagent volumes, and materials required for the process. The assay will be used to screen 960 DNA samples from individuals with severe statin myopathy and 4 control groups. In preliminary studies, 7 mutations causing 3 common metabolic muscle diseases were evalua ted in patients with severe statin myopathy. Ten percent of patients had disease mutations; carrier status alone was increased for certain of these disorders as much as 20-fold. The proposed study will increase the number of mutations and variants evaluate d by 55-fold and increase the number of disorders studied by 2.75-fold, predicting that the number of individuals with disease- causing risk factors will rise to at least 25%. The results of this project are expected to set the stage for the development of a commercially available assay in Phase II that will be expanded to include a wide variety of genetic variants and disorders and will be applied to additional high risk groups. At the present time, there is no comprehensive genetic-based testing for metab olic muscle diseases at the level proposed in this study. The disorders have in common the fact that they can be triggered by environmental exposures that are increasingly prevalent in the general population. Thousands of individuals suffer life-threatenin g episodes of incapacitating muscle damage every year from unexpected triggering of underlying disease ranging from adverse drug reactions (e.g., statin exposure) to extreme exertion during exposure to extraordinary temperatures (e.g., soldiers deployed to Iraq). The proposed development of comprehensive genotyping for hereditary muscle diseases will lead in the long-term to cost-effective screening, reduced morbidity, and lower healthcare costs relevant to adverse outcomes for at least 7 high risk groups r epresenting gt35 million individuals.