Number of human V genes

The number of human VK genes was estimated to be quite small in the initial studies of Bentley and Rabbitts [49]. As discussed above (Section 3.4.), these authors suggested that the VKl, III and IV subgroups constitute a single family composed of about 25 germline VK genes. Consistent with this estimate. Bentley [50] found 

Pech et al. [78] have recently reported evidence that most, and perhaps all, of the human k locus is duplicated. Therefore, there may be twice the number of germline VK genes as originally thought that is, there are at least 40 and perhaps 80 human VK genes, depending on the extent of the large duplication within this locus. 

One of the cosmid clusters cloned by Kodaira et al. [40] was examined in great detail. This particular cluster (called cluster 71) contained seven VH genes, five of 

Using mouse-mouse hybrids and Robertsonian translocation markers, Hengart-ner et al. [86] confirmed that the expression of k light chains requires a locus on chromosome 6, whereas the expression of heavy chains required chromosome 12. The formal demonstration that the structural k and Igh loci reside on chromosomes 6 and 12, respectively, was obtained by the analysis of mouse-hamster hybrids using Southern blot hybridization [87,88], A similar approach was used by D Eustachio et al. [89] to assign the A locus to mouse chromosome 16. 

D Hoostelaere et al. [90] have recently mapped the k locus 8 centimorgans from the mouse T-cell receptor beta locus (TcR(3). By setting up a three-point cross, k and TcR/3 were mapped with respect to the morphological marker hypodactyly (Hd) allowing the chromosome order centromere-7cR/3-/c to be determined [90], The chromosomal orientation of VK and CK genes has not been determined. 

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