Serum titin/Cr ratios in patients with DMD were higher than those with BMD across all age groups (3–10, 11–15, 16–20, and 21–33), but serum CK levels in patients with DMD were significantly higher than those with BMD only in the 11–15 and 21–33-year age groups. The gene discussed is TTN; the disease is Becker muscular dystrophy.