Figure 4. Sequence analysis of L and M opsin genes in Family 2. Reference sequences of the L and M genes are shown on top of the electropherograms, which were generated from an affected male (individual 1.1) in Family 2. Nucleotides marked with an arrow indicate known differences between the L and M genes. A shows opsin sequence beginning 5′ to the start codon (capital letters) of exon 1. Note the presence of single sequence peaks at positions of known nucleotide variation between L and M gene sequences (arrows), indicating the absence of M exon 1. B shows Exon 3 sequence with single peaks at sites of known variation between L and M opsin gene sequences (arrows) representing the presence of M exon 3 nucleotides and absence of L exon 3 nucleotides. Similarly, absence of an L sequence was noted for exons 4 and 5 (data not shown).