Using an interspecific cross, gene linkage relationships among members of the 
murine complement receptor-related genes, C4bp, Cfh, Mcry, and Mcr2, were 
analyzed by segregation of RFLP in 200 mice. The human homologues of these genes 
are tightly linked, composing the RCA locus, which maps to human chromosome 
(Chr.)1q32, within a large linkage group conserved between human Chr.1q21-32 and 
mouse Chr.1. RFLP associated with C4bp and Cfh map within this conserved linkage 
group; Cfh is located 9 cM telomeric to C4bp, which is consistent with linkage 
data for their human homologues. Mcry and Mcr2, while tightly linked, are 
located outside the conserved group, 40 cM telomeric to C4bp. These data suggest 
that a translocation or inversion occurred within the RCA family during the 
evolution of the mouse, defining a breakpoint of this large conserved linkage 
group.