MAP2K1 and congenital mesoblastic nephroma: Later in 2020, Muthiah S et al. reported MAP2K1 (c.607G > A, p.E203K) in naevus spilus (NS)-type CMN [14].However, it is still unknown whether MAP2K1 mutations are characteristic of CMN, and how MAP2K1 contributes to the pathogenesis of CMN remains to be determined.