Chromosomal distribution of recurrent CNVs in twenty-one liver cancers. The 52 recurrent copy number gains (red upward bars) and 99 recurrent copy number losses (red downward bars) were called from the AluScans of 21 liver cancers from Additional file 2: Table S2 using the 23-sample reference template for comparison. Blue bars represent CNVs the frequencies of which did not exceed the green lines marking significant recurrence (p <0.01). The orange columns represent CNVs called from WGS data by Kan et al. .