Mosaic Reciprocal Chromosome Translocations in Breeding Swine: Prevalence and Potential Biological Implications.
Acquired chromosome translocations in individuals may either be benign and physiologically asymptomatic or may exert biological consequences and lead to cancer and infertility. In the domestic pig acquired or mosaic translocations are underrepresented, hence their phenotypic and fertility implications are not well understood. This thesis presents the first study of mosaic translocations identified in the domestic pig through routine cytogenetic practices. Routine analysis of the somatic metaphase chromosomes of 5,481 young reproductively unproven boars revealed 32 carriers of mosaic translocations, half of which were carrying a recurrent translocation, mos t(7;9). An additional 7 mosaic translocations were identified through extensive karyotype analysis of relatives of mosaic carriers (n=48) and control animals (n=97). Mosaic translocations in the carriers were phenotypically benign and were recognized to be somatic and confined to hematopoietic cells because mosaicism was not identified in the tissue fibroblast chromosome, fertility of the carriers and pedigree were comparable to breed averages (p>0.05), and cryptic mosaicism was not detected in the pedigree. The results obtained in this study suggest that the incidence of mosaic translocations in Canadian swine is 0.7%, however they impose no observable phenotype or impact on fertility on the carrier animals.