The Location of the C3 and GLO (Glyoxalase 1) Loci of the Ixth Linkage Group in Mice

Electrophoretic variants of glyoxalase 1 (GLO) and C3 in the mouse were used to define the genetic location of the corresponding genes. Previous work had demonstrated that these two loci are linked to H-2, the major histocompatibility locus of the mouse. The segregation of GLO and H-2 in 880 informative meioses established that the recombination fraction for these two genes is 0.0174 ± 0.005; two intra—H-2 cross-overs position GLO on the K-side of H-2. Similarly, the linkage of C3 to the H-2 locus was confirmed. The recombination fraction is 0.114 ± 0.022. A triple-point cross, involving C3, H-2, and GLO, discloses that the order of these genes is (from the centromere) GLO—H-2—C3. GLO is also linked to the MHC in humans. The data given here show that the position of GLO relative to the MHC is the same in both species, although the recombination frequency is higher in humans. It is speculated that the centromeric end of the MHC may be the more ancient gene of the system, because it has remained in linkage with GLO. It is further speculated that the location of C3 in humans may be on chromosome 6, beyond the distance within which conventional family analysis might reveal linkage to HLA.