Hypodiploidy <40 chromosomes is an uncommon genetic feature of acute lymphoblastic leukemia (ALL) in both children and adults. It has long been clear by cytogenetic analyses, and recently confirmed by mutational profiling, that these cases may be further subdivided into 2 subtypes: near-haploid ALL with 24 to 30 chromosomes and low-hypodiploid ALL with 31 to 39 chromosomes. Both groups are associated with a very poor prognosis, and these patients are among those who could benefit most from novel treatments.

Loss of chromosomes is the primary event in near-haploid and low hypodiploid acute lymphoblastic leukemia. Link to publication Citation for published version (APA): Safavi, S., Forestier, E., Golovleva, I., Barbany, G., Hansén Nord, K., Moorman, A. V., ... Paulsson, K. (2013). Loss of chromosomes is the primary event in near-haploid and low hypodiploid acute lymphoblastic leukemia. Leukemia, 27(1), 248-250. DOI: 10.1038/leu.2012 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal The majority of patients with hypodiploid ALL have 45 chromosomes; near-haploidy and HoL are very rare, comprising less than 1% of B-cell precursor (BCP) ALL. 2,4 Near-haploid ALL is seen primarily in children and adolescents, although some adult cases have been reported, whereas HoL occurs at all ages. 4 Cases usually have an early pre-B