In difficult cases, next generation (targeted) sequencing can be performed including genes frequently mutated or altered in WTs (e.g., WTX, WT1, CTNNB1, SIX1, SIX2, miRNA processing genes) and neuroblastomas (PHOXB2, ALK, ARID1A/B genes) (Table 5). This evidence concerns the gene WT1 and neuroblastoma.