We report here the molecular study of a t(11;19)(q13;p13) translocation observed in a case of B-cell chronic lymphocytic leukemia. This translocation leads to the juxtaposition of the CCND1 gene on chromosome 11 to a new transcriptional unit on chromosome 19. The cDNA of this new evolutionarily conserved gene (named FLRG for Follistatin-Related Gene) codes for a secreted glycoprotein of the follistatin-module-protein family. FLRG is expressed in a wide range of human and murine adult tissues and its expression seems to be tightly regulated during murine embryogenesis. Its transcripts could not be detected in hematopoietic cells from all lineages and in particular in cells from lymphoid B and T lineage except in the t(11;19)-carrying leukemia described here. A great variability of expression is observed among the other tumoral cell lines analysed. Besides the t(11;19)-carrying leukemia described in this work, structural rearrangements of the FLRG locus have been found in a non-Hodgkin lymphoma, suggesting that it may play a role in leukemogenesis.