Chromosomal analysis can detect a specific translocation or other chromosomal abnormality such as hyperdiploidy or hypodiploidy, and thus help establish the WHO subtype. Hyperdiploidy refers to excess numbers of chromosomes; in ALL we can often see as many as 51-67 chromosomes! Interestingly, this hyperdiploidy is found commonly in childhood ALL, is not associated with substantial genetic abnormality except for the excess chromosomes, and actually renders a good prognosis. Hypodiploidy refers to fewer than 46 chromosomes
The image to the right shows hyperdiploidy in a childhood case of ALL (B cell).
12. Woo, Jennifer S et al. “Childhood B-acute lymphoblastic leukemia: a genetic update.” Experimental hematology & oncology vol. 3 16. 13 Jun. 2014, doi:10.1186/2162-3619-3-16
