Refined localization of H7 and Ctt1 on distal mouse chromosome 9

Genes for more than 40 minor histocompatibility (H) antigens have been mapped as independently segregating loci in the mouse. In many cases, definition of this loci has been accompanied by the creation of congenic strains in which a chromosome segment centered on an allo-H-gene has been introduced into the background of a genetically distinct inbred strain by backcrossing and selection. H7 is one of the more widely studied minor H antigens. It was the object of studies, for example, describing major histocompatibility complex restriction (Bevan 1976) and immunodominance (Wettstein and Bailey 1982; Wettstein 1986). There are two independently derived H7 congenic lines: in the B6.C-H7 super(b) line (HW23), the BALB/c H7 super(b) allele has been introduced into a C57BL/6 (B6) background; in the B10.C-H7 super(b) line (47N), this allele has been introduced into a C57BL/10 (B10) background. H7 maps to distal chromosome (Chr 9), near but recombinationally separable from the point where we recently mapped the gene encoding the CTT1 antigen by typing progeny of a backcross. To better determine the placement of these loci with respect to each other and the simple sequence length polymorphism (SSLP) map of distal Chr 9, we have now typed selected backcross progeny and the CXB recombinant inbred (RI) strains for additional informative SSLP markers.