Figure 1 - Diagram of the results of unequal recombination that produces GH-1 gene deletions. Note that the normal PCR amplification products (A and B) generated by the primers indicated by arrows contain no or two SmaI recognition sites. In contrast, the fusion product (C) associated with 6.7-kb deletions including GH-1 contains a single SmaI recognition site. The corresponding sizes of DNA fragments obtained after digestion of products from normal controls (AB/AB), deletion heterozygotes (AB/C) and deletion homozygotes (C/C) with SmaI are shown below.