Figure 4.

The bm28 mutation cluster’s homology to Q and T region genes demonstrates the nonrandom nature of this mutation event. Using the data from the Southern blot analysis of the cosmid library with the left-half or right-half probes to the mutation cluster, we analyzed the known sequence of the genes. Because there is no published sequence for T12, we isolated the hybridizing BamHI fragment from H6, cloned it, and sequenced across the 5′ region of exon 3. The figure shows the partial nucleotide sequence for the region of interest from each gene, with the candidate donor genes’ nucleotide differences emphasized in lowercase bold letters.