IGHV gene usage and mutational status in follicular lymphoma: Correlations with prognosis and patient age

Follicular lymphoma (FL) is a heterogeneous disease with some patients developing progressively or transformed disease early, whereas others follow an indolent clinical course. We evaluated the prognostic value of immunoglobulin heavy chain variable (IGHV) gene usage and mutational status in FL patients. One hundred and four IGH sequences were obtained in tumour samples from 99 patients. The IGHV3 subgroup had the highest usage frequency (57.7%) with IGHV3-23 being the most common sequence. Patients with the IGHV5 subgroup or IGHV sequences from more than one subgroup had significantly less favourable prognosis with an estimated 5-year survival of 62.5 and 50.0%, respectively, as compared with a 5-year survival of 95.1% for patients with other IGHV subgroups (P=0.013 and P<0.001, log-rank). The poor survival associated with IGHV5 or >1 IGHV subgroup usage was an independent prognostic factor in Cox multivariate analysis (P=0.005). IGHV genes were unmutated showing >98% homology in 15.2% of cases. Contrasting the situation in chronic lymphocytic leukaemia (CLL), the presence of unmutated sequences did not yield prognostic information, although unmutated sequences were associated with age at diagnosis >60 years (P=0.022, Fisher's exact). In conclusion, our results indicate that analysis of IGHV gene usage might aid in predicting prognosis for FL patients.