Sequencing of the human genome and subsequent identification of mutations in ALDH genes associated with loss of ALDH enzyme activity have led to the identification of many disease associations, such as cataracts (ALDH1A1, ALDH3A1, ALDH18A1), seizures (ALDH7A1), hyperprolinaemia (ALDH4A1), heart disease (ALDH2), alcohol sensitivity (ALDH1A1, ALDH1B1, ALDH2), certain cancers (ALDH2) and a broad array of other metabolic and developmental abnormalities [2]. Recently, a role for ALDHs in normal and cancer stem cells has also been identified. For example, ALDH1A1 is differentially expressed in human haematopoietic stem cells (HSCs) and can be used as a stem cell marker for multiple cancers [2]. Similarly, ALDH1B1 is primarily expressed in stem cells in the normal colon and is strongly upregulated in human colonic adenocarcinomas [7,8]. As described by Nelson and colleagues,[9] genomic gene artefact identification becomes very important when using genotyping techniques to identify disease-causing alleles. Gene-duplication events, leading to multiple functional and/or non-functional genetic copies in the genome, can significantly complicate polymerase chain reaction (PCR)-based genotyping assays. Transgenic animal models have permitted the exploration of the functions of ALDHs under in vivo
