Large-scale serum protein biomarker discovery in Duchenne muscular dystrophy

Abstract

Serum biomarkers in Duchenne muscular dystrophy (DMD) may provide deeper insights into disease pathogenesis, suggest new therapeutic approaches, serve as acute read-outs of drug effects, and be useful as surrogate outcome measures to predict later clinical benefit. In this study a large-scale biomarker discovery was performed on serum samples from patients with DMD and age-matched healthy volunteers using a modified aptamer-based proteomics technology. Levels of 1,125 proteins were quantified in serum samples from two independent DMD cohorts: cohort 1 (The Parent Project Muscular Dystrophy-Cincinnati Children's Hospital Medical Center), 42 patients with DMD and 28 age-matched normal volunteers; and cohort 2 (The Cooperative International Neuromuscular Research Group, Duchenne Natural History Study), 51 patients with DMD and 17 age-matched normal volunteers. Forty-four proteins showed significant differences that were consistent in both cohorts when comparing DMD patients and healthy volunteers at a 1% false-discovery rate, a large number of significant protein changes for such a small study. These biomarkers can be classified by known cellular processes and by age-dependent changes in protein concentration. Our findings demonstrate both the utility of this unbiased biomarker discovery approach and suggest potential new diagnostic and therapeutic avenues for ameliorating the burden of DMD and, we hope, other rare and devastating diseases.

Keywords: SOMAmer; SOMAscan; biomarkers; muscular dystrophy; proteomics.

Fig. 1.

Representative CDFs of proteins that are up or down in DMD patients vs. controls from both cohorts. Up proteins: (A) Troponin I, fast skeletal muscle, (B) myoglobin, (C) heat-shock protein 70. Down proteins: (D) RET, (E) gelsolin, (F) bone sialoprotein 2.

Fig. 2.

Example proteins from the four “types” of age-related changes in protein signal levels seen in DMD patients (red) vs. controls (blue) from both cohorts. (A) Group 1, creatine kinase; (B) group 2, RET; (C) group 3, phospholipase A2; (D) group 4, growth-differentiation factor 11.