Numerical chromosomal changes and uniparental disomy in pediatric ALL. (A) Frequency of pentasomy/tetrasomy/trisomy affecting each chromosome. For X chromosome, trisomy (105 cases) contains trisosomy X in male pateints (67 cases) and disomy X in female patients (38 cases). All tetrasomy X were female patients. (B) Frequency of uniparental disomy (UPD). Whole: cases with whole chromosome UPD; p arm: cases with UPD of short arm; and q arm: cases with UPD of long arm. Chr: chromosome. UPD involving X chromosome was detected only in female cases. (C) Distribution of whole and partial chromosome UPD in HD and non–HD-ALL. Whole chromosome UPD is frequently detected in HD-ALL. Thirty-four cases with whole chromosome UPD were HD-ALL. Partial UPD is frequently detected in non–HD-ALL. Fifteen of 63 cases with partial UPD were HD-ALL. (D) Frequency of deletion of p16INK4A gene in whole chromosome 9 UPD and 9p UPD. Twenty-three cases showed deletion of p16INK4A, out of a total of 30 cases with 9p UPD. One case had p16INK4A deletion from a total 18 ALL samples with whole chromosome 9 UPD.