Molecular characterization of the Smyth chicken sublines and their parental controls by RFLP and DNA fingerprint analysis.

The Smyth line (SL) chicken, a model for autoimmune human vitiligo, is characterized by a spontaneous posthatch epidermal pigment loss (vitiligo). Even though the immunological and morphological changes accompanying the vitiligo process have been well studied, the genetics of this phenomenon remains elusive. The SL lines have been maintained by nonpedigreed matings since their inception, and therefore, the inbreeding status is unknown. The present study was designed to provide an estimate of the inbreeding coefficients and the molecular genetic profiles of the SL sublines, each homozygous for a different MHC haplotype and their MHC-matched parental control (BL) sublines. The DNA fingerprint analysis revealed that there is a moderate level of inbreeding within the SL and BL parental sublines. Of the two SL sublines studied, SL101 had the highest level of inbreeding (0.948). Similarly, its parental control line (BL101) was more inbred than the parental subline of SL102 (BL102). The very high level of similarity between the SL sublines and their respective parental control lines is shown further by the similarity index (SI) estimates (SI between SL101 and BL101 was 0.949 and that between SL102 and BL102 was 0.932). Restriction fragment length polymorphism (RFLP) analysis of the endogenous viral genes (avian leukosis virus subgroup E, ALVE) showed that five ALVE-related BamH1 fragments were present in the SL101 and four in SL102 sublines, whereas the parental BL101 and BL102 sublines had five and six fragments, respectively. SL101 and SL102 shared two fragments, but the frequencies were different. Similarly, BL101 and BL102 shared two fragments. SL101 and BL101 shared three fragments, and SL102 and BL102 also shared three fragments.