Although, the overall expression of TrkA in MM biopsies correlates with worst prognosis, phosphorylated TrkA is detected in a considerably smaller fraction of metastatic MMs compared to the primary samples [32], suggesting that activation of TrkA signaling might be important for the early onset of the tumor and might undergo down-regulation once the tumor becomes metastatic. The gene discussed is NTRK1; the disease is Miyoshi myopathy.