A stable duplication of the rII region of bacteriophage T4.
D000483:Alleles; D002869:Chromosome Aberrations; D002874:Chromosome Mapping; D003090:Coliphages; D004267:DNA Viruses; D004171:Diploidy; D006579:Heterozygote; D009154:Mutation; D011995:Recombination, Genetic; D012641:Selection, Genetic