Scientist at the MRC Laboratory of Molecular Biology, Cambridge, gave diluted alcohol, ethanol, to mice. They then looked at the DNA sequencing and chromosome analysis to identify the genetic damage of acetaldehyde, which is a chemical produced when the body breaks down alcohol. Acetaldehyde was found to break down and damage DNA within blood stem cells leading to rearranged chromosomes and prominent alteration of DNA sequences. Damage of healthy stem cells leads to higher risk of developing cancers. It is important to understand that the body carries an enzyme, aldehyde dehydrogenase, that breaks down acetaldehyde into acetate but many people do not have this enzyme or carry a faulty form of it, particularly those from a South East Asian decent. When the effects of alcohol were monitored with mice lacking the ALDH enzyme were observed, it resulted in four times as much DNA damage in their cells compared to other mice. Obviously, there are also DNA repair mechanisms that can fix and repair DNA damage but these mechanisms and systems can sometimes be faulty. Thus, it will lead to more mutations in the body and eventually these can be harmful and cause cancers.