Irisin released from DM1 myotubes was significantly lower than that released from the DM2 myotubes (0.22 ± 0.07 vs 0.41 ± 0.07 ng/ml; P = 0.03), though they both did not significantly differ from that released from healthy controls myotubes (0.33 ± 0.18 ng/ml; Figure 1B). Here, FNDC5 is linked to myotonic dystrophy type 1.