Sequence chromatographs for imprint analysis in the mammary gland. Direct sequence analysis for insulin (INS) and insulin-like growth factor 2 (IGF2) imprinting in the mammary gland. (A) INS chromatogram traces (viewed in Finch TV version 5.1) for genomic DNA (gDNA) and cDNA. Two polymorphic sites were identified in gDNA, distinguishing the two alleles. In the mammary gland of seven individuals tested, two animals had monoallelic expression at both SNPs (site 1:G/A and site 2: C/T) and five animals had monoallelic expression in a single SNP (one individual at site 1and four individuals at site 2). (B) IGF2 chromatogram traces for gDNA (3′ to 5′) and cDNA (5′ to 3′). A single polymorphic site was identified in gDNA to distinguish the two alleles. Both alleles of IGF2 were monoallelically expressed in four different individuals (three animals expressed the G allele and one animal the A allele).