A C-terminal FMS mutation in a patient with B-cell malignancy.

The FMS proto-oncogene encodes a polypeptide growth factor receptor expressed on the cell surface of monocytes and B lymphocytes within the haematological system. Mutations of the FMS gene at codons 301 and 969 have been detected in a number of haematological disorders. Mutations at these codons are thought to be important in the pathogenesis of leukaemia in cells expressing a mutant receptor. Following our finding that the colony stimulating factor-1 receptor (CSF-1R) was expressed on B cells, we have assessed DNA from 17 patients with B-cell chronic lymphocytic leukaemia (CLL), 15 with acute lymphoblastic leukaemias (ALL), two samples from patients with B-cell non-Hodgkin's lymphoma (B-NHL), and 20 haematologically normal individuals for the presence of C-terminal mutations of the FMS gene. Using single stranded conformational polymorphism analysis (SSCP), a single band shift was detected resulting from a nucleotide insertion at codon 965 in the DNA isolated from a patient with B-NHL. These results indicate that mutations of the FMS gene in this region are rare in B-cell malignancy but may contribute to the pathogenesis of leukaemias and lymphomas in a small subset of patients. However, the presence of other mutations not detected using this type of analysis cannot be excluded.