ALK and neuroblastoma: Molecular events able to promote ALK gene transcription may also have a pathogenetic role but only 3–4% of NB cases were found to bear extensive ALK amplification while 17–23% presented lower levels of ALK gene gain (2≤gene copies ≤4) [3], [21], [26]–[30], therefore most of the ALK over-expression in NB still remains unexplained.