ALDH3B2 is present as a single distinct gene in human, chimpanzee and macaque, whereas two copies occur in mouse and rat. ALDH3B2 is absent from common marmoset, cow, zebra finch, chicken and zebrafish. Mouse and rat ALDH3B3 share 86.4 per cent and 76.9 per cent AA identity, respectively, with the corresponding parent ALDH3B2 proteins and 83.4 per cent identity with each other. The two ALDH3B3 genes are found on corresponding syntenic chromosomes within their respective genomes. Presently, the protein product of Entrez Gene ID 688778 (R. norvegicus) is annotated as 'ALDH3B1 (predicted)'. Based on a phylogenetic clustering of ALDH3B1 and ALDH3B2 protein sequences (Figure 1), however, we believe it is better to name this protein ALDH3B3; this shows that both mouse and rat ALDH3B3 proteins are in the ALDH3B2 clade and are more similar to each other than to rodent or human ALDH3B2 proteins. The alignment used for phylogenetic clustering can be seen in Supplementary Table S1 (Table 5).
