Classification of particular mature B‐cell neoplasms can be confirmed by their specific SNVs, such as the BRAF V600E somatic mutation in >95% of hairy cell leukaemia (HCL) and the MYD88 L265P mutation in >93%–97% of lymphoplasmacytic lymphoma (LPL) and in primary large B‐cell lymphoma in immune‐privileged sites. The gene discussed is MYD88; the disease is hairy cell leukemia.