Three full-length ALDH9A1 homologues were identified in zebrafish. The Aldh9a1.2 peptide shares 71.2 per cent and 70.3 per cent identity with Aldh9a1.1 and Aldh9a1.3, respectively. Aldh9a1.3 is 94.9 per cent identical to the parent Aldh9a1.1 peptide, suggesting that this duplication was a relatively recent event when compared with the duplication that gave rise to Aldh9a1.2. Hence, aldh9a1.1, aldh9a1.2 and aldh9a1.3 represent three distinct protein-coding ALDH9 family members. The zebrafish genome also contains two copies of aldh18a1, which are found in very close proximity on Chr 12. Both genes are considered protein coding and would give rise to peptides of the same length which share 100 per cent sequence identity, suggesting a relatively recent duplication event.
