A Common Genetic Variant in the 3′UTR of IRF4/MUM1 Associates with Risk of Disease and Poor Prognosis in Chronic Lymphocytic Leukaemia.

High frequency low penetrance risk alleles for chronic lymphocytic leukaemia (CLL) have been identified at 6p25.3 (rs872071, IRF4/MUM1), 11q24.1 (rs735665, GRAMD1B), 15q23 (rs7176508), 2q37.1 (rs13397985, SP140), 2q13 (rs17483466, ACOXL) and 19q13.32 (rs11083846, PRKD2). Given a role in determining risk of disease it is plausible that these allelic variants also play a role in disease progression and overall survival. In order to test this hypothesis, polymorphic status was determined in a case series of 403 patients diagnosed with CLL recruited via 5 clinical centres in the United Kingdom. Mean follow-up time was 4447 days and 169 patients were deceased at the time of last follow-up. Kaplan-Meier survival analysis and the log-rank test were used to investigate the prognostic significance of constitutional genetic markers. Polymorphic variation at rs735665, rs7176508, rs13397985, rs17483466 and rs11083846 was not significantly association with time from diagnosis to first treatment (p>0.05, log-rank test). However, a genetic variant in the 3′UTR of the interferon regulatory factor 4 (IRF4)/multiple myeloma oncogene 1 (MUM1) gene was significantly associated with poor prognosis. Specifically, carriers of the disease-associated variant at rs872071 had a significantly shorter mean time from diagnosis to first treatment (3983 days), compared to non-carriers (7340 days)(p=0.001), although there was no significant difference in overall survival (p=0.29). The association with time to first treatment remained significant in multivariate Cox regression analysis that included age, gender, immunoglobulin heavy chain variable region mutational status and stage of disease at diagnosis in the model (p=0.021). IRF4 is expressed in germinal centre (GC) and post-GC B-cells, and is important for B-cell maturation and homeostasis. Taken together with the aetiological evidence, these data suggest that common allelic variation in IRF4 not only affects risk of CLL, but also predicts poor prognosis.