Figure 5. Canine RD3 coding sequences demonstrating variations among normal and rcd2 affected dogs.

The nucleotide sequence of the wildtype open reading frame is shown with the corresponding translated amino acid sequence underneath, in italics. The start codon and the normal stop codon are bolded. The junction of exons three and four is represented by the backslash (G\G). A hexamer repeat is indicated within square brackets and shaded . Sequence variants with either two or 3 copies of this hexamer are observed from normal dogs; the rcd2-disease allele has 2 copies. This hexamer codes for a pair of amino acids (R P), which are thus predicted to be present twice or 3 times in the translated sequence. The boxed nucleotide represents a SNP (S = C or G), both alleles being observed in normal dogs, that changes the coded amino acid from proline to arginine. The rcd2-disease sequence has the G allele for this SNP. The asterisk (*) marks the site (immediately before the polymorphic nucleotide indicated by ) where a 22 bp sequence ( gcccgcccccgcccccgccccc) is inserted in the rcd2 disease allele.