Elevation of fast but not slow troponin I in the circulation of patients with Becker and Duchenne muscular dystrophy

FIGURE 1. Plasma concentrations of CK enzymatic activity (A), TNNI1 (B), and TNNI2 (C) were measured in samples from BMD patients (squares) and DMD patients (triangles), with HV as controls (circles). In each panel, the error bars represent the median +/− the interquartile range. In panels (B) and (C), samples that exhibited no detectable TNNI concentration were assigned values equal to the assay's limit of detection (0.1 ng/mL and 0.001 ng/mL for fast and slow TNNI, respectively) When compared with each other, a significant correlation was found between CK and fast TNNI2 (D), with an R2 of 0.67. There was no significant correlation between CK and slow TNNI1 (E) nor between fast TNNI2 and slow TNNI1 (F) In panels (D) – (F), healthy samples are represented as black triangles, BMD as blue diamonds, and DMD red circles. ****: P < .0001. All other comparisons are non‐significant

FIGURE 2. Concentration of CK enzymatic activity (A), TNNI2 (B), and TNNI1 (C) vs patient age in DMD patient samples. The same comparisons were made for BMD patients in panels (D, E, and F) for CK, TNNI2, and TNNI1, respectively

FIGURE 3. Ambulatory status for DMD was compared against plasma concentrations of CK enzymatic activity (A), TNNI2 (B), and TNNI1 (C). The same comparisons were made for BMD (D, E, and F). A patient was defined as “ambulatory” so long as the patient was not described as wholly dependent upon a wheelchair for mobility. Bars represent the mean +/− the standard error for the population. ****: P < .0001, ns: non‐significant