However, differential genetic resistance to MD is still possible in the context of fixed MHC haplotype, as demonstrated by the Avian Disease and Oncology Laboratory (ADOL) line 6 and line 7 chickens, which are two highly inbred resistant and susceptible layer chicken lines, respectively, with a shared B2 MHC haplotype; these lines do differ at the independently segregating Rfp-Y locus, which contains non-classical MHC genes and is not associated with MD resistance in these lines [15]. The gene discussed is HLA-C; the disease is bird disease.