Fluorescence in situ hybridization reveals trisomy 2q by insertion into 9p in hepatoblastoma

Cytogenetics and fluorescence in situ hybridization (FISH) of a hepatoblastoma are presented. The results of standard chromosome analysis were as follows: 47,XY,+2,add(4)(q35),-9,+20[10]. FISH with the use of whole-chromosome paints revealed partial trisomy of the long arm of chromosome 2 by insertion into chromosome 9. Comparison of the G-banded metaphases with metaphase FISH led to a reinterpretation of the karyotype as: 47,XY,add(4)(q35),der(9)ins(9;2)(p22;q?21q?25),+20. This case supports previous observations that the critical region of trisomy 2 lies between 2q21 and 2qter and shows how partial trisomy 2q may evade detection in G-banded metaphases.