Linkage analyses of murine immunoglobulin heavy chain and serum prealbumin genes establish their location on chromosome 12 proximal to the T (5;12) 31H breakpoint in band 12F1.

Analysis of backcross mice carrying the Harwell translocation T(5;12)31H has led to the definitive localization of the immunoglobulin heavy chain gene cluster. Both Igh-1 and Pre-1 loci were found to segregate in tight linkage with the chromosomal markers 5(12) and 12(5), which define the balanced translocation T(5;12)31H. Additional data establish the location of these genes at the telomeric end of chromosome 12. That both loci are proximal to the chromosomal breakpoint in band 12F1 is shown by the phenotypes of segregants aneuploid for the presence or absence of the small marker 5(12). The order of loci inferred from a single recovered recombinant is: centromere-Igh-1-Pre-1-T(5;12)31H.