Interestingly, in the recent comprehensive study of germ line mutations in the best characterized genes associated with cancer predisposition syndromes in pediatric cancer patients, 5 patients with relevant mutations (3 patients with TP53 gene mutations, one patients with PMS2 gene mutation, and one patient with RET gene mutation) were identified among 46 (10.8%) patients with Ewing sarcoma, frequency of which was higher than in cases of rhabdomyosarcoma (7%, 3/43) [50]. This evidence concerns the gene PMS2 and Ewing sarcoma.