Fetal Alcohol Syndrome (FAS) is the most common cause of preventable mental retardation among children in the world today. Scientists believe that the development of FAS following excessive alcohol exposure is likely influenced by genetic factors in both the mother and child. Mixed-ancestry children in the Western Cape Province of South Africa have the highest frequency of FAS in the world. Knowing that allelic variation influences alcohol metabolising genes, researchers in the December issue of Alcoholism: Clinical & Experimental Research examine what role polymorphisms of the alcohol dehydrogenase (ADH2) gene might have among this population.
"The socioeconomically deprived mixed-ancestry population of the Western Cape has a prevalence of FAS amongst school-entry children of 40 - 70 per thousand," explained Denis Lowe Viljoen, head of the department of human genetics at the National Health Laboratory Service and University of the Witwatersrand Faculty of Health Sciences. Viljoen, also the study's lead author, uses "mixed-ancestry" to refer to descendents of the original Khoisan inhabitants and colonizing Europeans. Some farm laborers in these communities have received part of their wages in the form of alcohol for close to 300 years.
"This prevalence contrasts," he continued, "with approximately 0.33 - 2.2 per thousand for the United States, 8 per thousand amongst birth cohorts for North American Indians between 1970-1980, and 2.29 per thousand for selected inner-city African Americans."