Array comparative genomic hybridization reveals unbalanced gain of the MYCN region in Wilms tumors

Wilms tumor (WT) is one of the most common solid tumors in childhood. It is characterized by a nonrandom pattern of chromosomal aberrations whose clinical significance is still uncertain. To gain further insight into different genetic events and their corresponding biological role, conventional cytogenetics and array comparative genomic hybridization (array CGH) were performed on 13 tumor samples. In two of these, array CGH revealed, together with other aberrations, a low-level amplification and an unbalanced gain in the region of chromosome bands 2p23∼p24 that encompass the MYCN gene. Both events were confirmed with a MYCN-specific fluorescence in situ hybridization probe, which showed a signal pattern consistent with a small homogenous staining region in one case. In addition, mRNA expression levels for MYCN were determined by quantitative reverse-transcriptase polymerase chain reaction and revealed that gain of chromosomal material was reflected in enhanced levels of MYCN mRNA in both tumors, whereby also additional tumors showed increased MYCN expression. Therefore, our findings suggest that WT is an additional childhood tumor where MYCN gain might play an important role in tumor development.