A spontaneous autosomal recessive mutation in C3H/HeJ mice, gld, results in profound lymphadenopathy and autoantibody production (1, 2) . By 16 wk of age C3H-gld/gld mice of both sexes develop peripheral and mesenteric lymphadenopathy, splenomegaly, antinuclear antibodies including anti-dsDNA, and hypergammaglobulinemia (1) . The lymph nodes of these mice are heavily populated with dull Thy-1+, dull Ly-I',Ly-4-(L3T4-), Ly-2-cells that also express the cell surface antigens Ly-5(B220), Ly-6, Ly-22, Ly-24, and PC-I but are slg -, ThB -, and la-(2) . These unusual cells exhibit polyclonal rearrangements of TCR-0 genes but not Ig heavy chain genes and express full-length TCR-a and TCR-a mRNAs and high levels of the myb protooncogene (2) . The phenotypic manifestations of the gld mutation are very similar to those of the nonallelic lpr mutation (1-3) ; but, unlike the lpr mutation, the gld mutation occurred in a stable inbred mouse strain and has been successfully localized to distal mouse chromosome 1 using a three-point cross analysis (1) .Our group has undertaken a molecular genetic approach to understanding of the pathophysiology of this genetically determined disease in which the mutant or deficient normal gene product(s) remains undefined. We have initiated a large breeding study to obtain mice with chromosome recombination events close to the gld gene. This report represents the results of initial efforts to establish a molecular genetic map of the portion of mouse chromosome 1, including the gld gene . We report the identification ofa restriction fragment length polymorphism (RFLP) closely linked to gld and the definition of a conserved linkage group present on mouse distal chromosome 1 and human chromosome 1 q.
Materials and MethodsMice . C3H/HeJ-gld/gld breeding pairs were obtained from The Jackson Laboratory, Bar Harbor, ME, and subsequently maintained both at our colony at the National Institutes of Health and at Hazleton Laboratory, Rockville, MD, under National Cancer Institute contract NOI-CB94326 . Mus spretus (Spanish) mice and (C3H/HeJ-gld/gld X Mus spretus)F, mice were maintained and bred at the Hazleton Laboratory and the F, x C3H/HeJgld/gld backcross matings were performed at our own colony . All [(C3H/HeJ-gld/gld X 688