title: Lethal deletion of the complement component C4 and steroid 21-hydroxylase genes in the mouse H-2 class III region, caused by meiotic recombination.
abstract: A recombinant H-2 haplotype, designated aw18, was produced that underwent meiotic recombination in the E alpha (I-E alpha chain)--Slp (sex-limited protein) interval of the H-2 class III region between B10.A (H-2a) and wild-derived B10.MOL-SGR (H-2wm7) strains. It appeared that the H-2aw18 haplotype has a single, recessive, lethal mutation, since homozygotes for H-2aw18 were not detected in progeny generated from the intercross of mice that were heterozygous for this H-2 haplotype. Nine newly established recombinant H-2 haplotypes, which arose from the heterozygous mice that resulted from a cross between common inbred H-2 haplotypes and the aw18 haplotype, allowed us to map the lethal gene to the class III region of the H-2 complex. Southern blot analysis indicated that the aw18 haplotype has a deletion of the C4 gene and a deletion of one of the steroid 21-hydroxylase genes. This result was confirmed by an immunodiffusion test that demonstrated the absence of production of the C4 protein in mice of haplotype H-2aw18. All data that were obtained supported the hypothesis that the meiotic, presumably unequal, recombination between homologous chromosomes of the H-2a and H-2wm7 haplotypes caused the deletion of the C4 and the 21-hydroxylase genes.
mesh_terms: D000818:Animals; D002872:Chromosome Deletion; D003181:Complement C4 / Q000235:genetics*; D005796:Genes; D005804:Genes, Lethal; D005838:Genotype; D006183:H-2 Antigens / Q000235:genetics*; D006239:Haplotypes; D008285:Major Histocompatibility Complex; D008540:Meiosis; D051379:Mice; D008815:Mice, Inbred Strains; D013255:Steroid 21-Hydroxylase / Q000235:genetics*; D013250:Steroid Hydroxylases / Q000235:genetics*
chemical_list: D003181:Complement C4; D006183:H-2 Antigens; D013250:Steroid Hydroxylases; D013255:Steroid 21-Hydroxylase