TTN and Duchenne muscular dystrophy: Serum titin levels in patients with DMD were significantly higher than those in patients with BMD in the 3–10, 16–20, and 21–33-year age groups (p < 0.05) (Figure 4B), whereas the 11–15-year age group showed no significant difference between patients with DMD and those with BMD (p = 0.51).