Molecular genetic studies propose that these tumors have a somatic missense point mutation (c.402C > G) in the FOXL2 (Forkhead box L2) gene, which is observed in 97% of adult GCT and in 5% of juvenile GCT [123], which represents a key element that distinguishes juvenile from adult GCT. The gene discussed is FOXL2; the disease is granular cell tumor.