restriction enzyme analysis of normal dna derived from individual rats of the national institutes of health outbred osborn-mendel colony revealed that two independent single-copy loci , the igh ( immunoglobulin heavy chain ) locus and the mlvi-2 ( moloney leukemia virus integration 2 ) locus , a putative oncogene , are polymorphic ( i.e. , exhibit allelic variation ) .
C0017351
igh
C0021034
immunoglobulin heavy chain