IKZF1 deletions in B precursor ALL is linked to unfavorable outcome, with high frequency in Ph+ and Ph-like ALL. The common deletion types DEL 4-7 and DEL 1-8 have proven prognostic value as single lesions. This is a case control study that looked at other rare variants of IKZF1 deletions to clarify their prognostic role. The study included patients from 9 international study groups, with a total of 134 rare IKZF1 variants and 402 matched controls. Poor EFS was shown in the matched pair analysis in all variant types.
* IKZF1-deletions (including both common and rare variants) may have a role as marker for risk stratification in ALL treatment protocols.