Mice with double knockout of FGFR1 and FGFR2 in Pax3-positive cells display severe defect of MM, while mice with either FGFR1 or FGFR2 deficiency have well-developed kidneys.335 These results indicate that FGFR1 and FGFR2 may have a redundant role in establishing and sustaining early MM. The gene discussed is FGFR1; the disease is Miyoshi myopathy.