A compendium of cytogenetic abnormalities in myelofibrosis: molecular and phenotypic correlates in 826 patients.

Among 826 patients with primary myelofibrosis (PMF) and analysable metaphases on cytogenetic studies, 352 (42·6%) had abnormal karyotype, of which 240 (68·2%) were sole aberrations and 48 (13·6%) were complex; the most frequent abnormalities were 20q- (23·3%), 13q- (18·2%), +8 (11·1%), +9 (9·9%), chromosome 1q+ (9·7%) and -7/7q- (7·1%). Phenotypic correlates included: abnormal karyotype with anaemia (P = 0·02), leucopenia (P < 0·01) and thrombocytopenia (P < 0·01); complex karyotype with younger age (P = 0·04) and thrombocytopenia (P < 0·01); leucopenia with 20q-, +8 and -7/7q- and thrombocytopenia with 20q- and -7/7q-. Cytopenias were less likely to occur with 13q-. 476 patients were annotated for JAK2/CALR/MPL mutations; abnormal karyotype frequencies were 43% in JAK2, 42% CALR, 33% MPL mutated and 34% triple-negative cases (P = 0·3). A proportion of patients were also screened for ASXL1, EZH2, IDH1, IDH2, SRSF2, U2AF1 and SF3B1 mutations; in all instances, mutational frequencies were higher in patients with normal karyotype, reaching significance for ASXL1 (P = 0·02) and U2AF1 (P = 0·01). 13q- was associated with mutant CALR (P = 0·03), +9 with mutant JAK2 (P = 0·02) and 20q- with mutant SRSF2 (P = 0·02). The current PMF study provides detailed cytogenetic information and correlations with mutations and clinical phenotype.