Gene translocation determines the amino acid sequence of the variable portion of the heavy and light chains that form the Fab of an antibody molecule. The variable portion of the heavy chain is determined after one of the multiple genes of the VH region join with one of the genes of the DH region and one of the genes of the JH region. Likewise, the variable portion of the light chain is determined after one of the multiple genes of the VL region joins with one of the genes of the JL region. Although the exact number of each gene isn't known, there are probably around 85 VH genes; 27 DH genes; 6 JH genes; 35 kappa VL genes; 5 kappa JL genes; 30 lambda VL genes; and 4 lambda JL genes.