In the next step, we looked for hotspot mutations previously observed in the miRNA biogenesis genes, i.e. (i) E969 and E993 in RIIIa and E1147, D1151, Q1187 and E1222 in RIIIb in DROSHA, (ii) p.E518K in the dsRDB1 domain in DGCR8 and (iii) p.R440Ter in XPO5 observed in different pediatric cancers, especially in Wilms’ tumor (56,57,59). This evidence concerns the gene XPO5 and Nephroblastoma.