Background
Duchenne Muscular Dystrophy (DMD) is a severe, progressive, neuromuscular disorder of childhood. While a number of serum factors have been identified as potential biomarkers of DMD, none, as yet, are proteins within the dystrophin-associated glycoprotein (DAG) complex.
Conclusions
Our results are the first demonstration of a component of the DAG complex as a potential serum biomarker in DMD. Such a serum measure could be further developed as a tool to help reflect overall muscle DAG complex expression or stability.
Methods
ELISAs of immobilized patient or mouse serum and Western blots were used to assess αDG-N expression.
Objective
We have developed an immobilized serum ELISA assay to measure the expression of a constitutively cleaved and secreted component of the DAG complex, the N-terminal domain of α dystroglycan (αDG-N), and assayed relative expression in serum from muscular dystrophy patients and normal controls.
Results
Immobilization of diluted serum on ELISA plates was important for this assay, as methods to measure serum αDG-N in solution were less robust. αDG-N ELISA signals were significantly reduced in DMD serum (27±3% decrease, n = 9, p < 0.001) relative to serum from otherwise normal controls (n = 38), and calculated serum αDG-N concentrations were reduced in DMD relative to normal (p < 0.01) and Becker Muscular Dystrophy (n = 11, p < 0.05) patient serum. By contrast, ELISA signals from patients with Inclusion Body Myositis were not different than normal (4±3% decrease, n = 8, p = 0.99). αDG-N serum signals were also significantly reduced in utrophin-deficient mdx mice as compared to mdx and wild type mice. Conclusions: Our results are the first demonstration of a component of the DAG complex as a potential serum biomarker in DMD. Such a serum measure could be further developed as a tool to help reflect overall muscle DAG complex expression or stability.