Multiple mechanisms ensure genome maintenance including DNA damage repair, suppression of transposition, and telomere length regulation. The mortal germ line (MRT) mutants in C. elegans are defective in maintaining genome integrity and result in a progressive loss of fertility over many generations. Here I show that the
him-15 locus, defined by the deficiency eDf25, is allelic to
rfs-1, the sole
rad-51 paralog group member in C. elegans. The
rfs-1/ eDf25 mutant displays a MRT phenotype and mutant animals exhibit features of chromosome fusions prior to the onset of sterility. Unlike other MRT genes,
rfs-1 manifests fluctuations in telomere lengths and functions independently of telomerase. These data suggest that
rfs-1 is a novel regulator of genome stability.