Combined somatic mutation and copy number analysis in the survival of familial CLL

Recurrent large-scale somatic copy number alterations (SCNAs), and somatic point mutations can be analysed to stratify patients with chronic lymphocytic leukaemia (CLL) into distinct prognostic groups. To investigate the relationship between SCNAs and somatic mutations, we performed whole-exome sequencing and single nucleotide polymorphism microarray analyses on 98 CLL patients from 40 families with a high burden of CLL. Overall, 69 somatic mutations in 29 CLL driver genes were detected among 45 subjects (46%), with the most frequently mutated genes being TP53 (8·2%), NOTCH1 (8·2%) and ATM (5·1%). Additionally, 142 SCNAs from 54 subjects (57%) were detected, including losses of chromosome 13q14 (28·9%), 11q (5·6%), 17p (2·1%), and gain of chromosome 12 (4·2%). We found that patients having both an adverse point mutation in a CLL driver gene and an unfavourable SCNA tended to have poorer survival (Hazard ratio [HR] = 3·17, 95% confidence interval [CI] = 0·97-10·35; P = 0·056) than patients having either a point mutation (HR = 1·34, 95%CI = 0·66-2·71; P = 0·42) or SCNAs (HR = 2·65, 95%CI = 0·77-9·13; P = 0·12). TP53 mutation carriers were associated with the poorest overall survival (HR = 4·39, 95%CI = 1·28-15·04; P = 0·018). Our study suggests that combining SCNA and mutational data could contribute to predicting outcome in familial CLL.