Immunoglobulin heavy chain variable region analysis in dairy goats

Based on the goat genome database, we have annotated the genomic organization of the goat immunoglobulin heavy chain variable region. The goat IgH locus is present on seven genome scaffolds, and contains ten VH, three DH and six JH segments. After the exclusion of three shorter segments, the VH genes were divided into two gene families based on sequence similarity. By analyzing the IgH cDNA sequences, we further identified that VH2 (54.2%), DH1 (61.7%) and JH1 (60.5%) segments were most frequently utilized in the expression of the immunoglobulin variable region, and that point mutations introduced by somatic hypermutation were the major mutation present in these expressed variable region. Compared with human and horses, DH-DH fusion occurred at a higher frequency in goat V(D)J recombination. These results provided variable insights into goat immunoglobulin heavy chain variable region genome loci and repertoire diversity.