Allotypes close linkage

Further evidence for close linkage of the allotype-determining genes is the occurrence of only a few combinations of determinants (on IgG2a, lgG2b, and IgA) in a large number of inbred strains investigated (Table... 

Eichmann (65) found that in a backcross of Fi (A/J x BALB/c) to BALB/c, individual molecules of antistreptococcal antibody which carry the idiotype characteristic of A/J mice also are of the A/J allotype (present in the Ch region). These results are not proof of close linkage but do not indicate that individual molecules are in general encoded by Vfj and C genes on the same chromosome. A similar finding was made in studies of rabbit V and C region allotypes (Chapter 9). 

The simplest interpretation of the linkage of idiotype and H chain allotype is that genes controlling Vh and Ch regions are in close proximity on the same chromosome but the possibility that there is, instead, a regulatory gene closely linked to the IgCu locus cannot be ruled out... 

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