More importantly, a higher MK level was strongly correlated with poor prognostic factors: over 1 year of age (P=0.0299), MYCN amplification (P<0.0001), low TrkA expression (P=0.0005), nonmass screening, sporadic neuroblastomas (P<0.0001), and diploidy/tetraploidy (P=0.0007). Here, NTRK1 is linked to neuroblastoma.