The ALDH3 family showed the greatest variability among species. ALDH3A1 facilitates cell cycle regulation and scavenging of reactive oxygen species, and acts as a corneal crystallin by filtering UV irradiation in the eye. ALDH3A1 is missing from birds and fish but is present in every mammalian genome analysed in this study, suggesting that the gene evolved some time after 310 MYA. ALDH3A1 is conserved among mammals and shows no apparent duplications. In some species, such as rabbit, it appears that ALDH1A1 is expressed as a corneal crystallin instead of ALDH3A1 [31]. Interestingly, zebrafish is the only species in this study that apparently lacks both ALDH3A1 and ALDH1A1. Studies have suggested that zebrafish use scinla (cytosolic gelsolin) as a corneal crystallin instead [32-34].
