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Higher death rate from liver disease in African Americans may be due to genetic vulnerability, UB study finds
By LOIS BAKER
Contributing Editor
African Americans appear to be genetically more susceptible to the toxic effects of alcohol on the liver than whites, a finding that may help explain their higher rates of death from cirrhosis of the liver despite similar levels of alcohol consumption, UB research shows.
In a study published recently in the Journal of the National Medical Association, UB researchers report finding higher levels of a common marker of liver toxicity in African Americans for all categories of alcohol consumption, including abstainers.
Among current drinkers, the difference in toxicity markers between the two ethnic groups widened as consumption increased. None of the study participants showed any evidence of liver disease at the time of the study.
Saverio Stranges, research scientist in the Department of Social and Preventive Medicine in the School of Public Health and Health Professions and lead author in the study, said the findings highlight the need for more education on the hazards of over-consumption of alcohol.
"These findings indicate a potential need to focus our public health efforts on the prevention of alcohol abuse in African Americans," he said, "as well as on other segments of our population at higher risk of developing health complications in response to alcohol use."
The researchers analyzed fasting blood samples from 241 African American and 3,304 Caucasian residents of Erie and Niagara counties in Western New York. Potential candidates for the study were identified randomly from the New York Department of Motor Vehicles registry and Medicare and Medicaid rolls. Age of participants, both male and female, ranged from 35 to 80 years.
Researchers measured levels of three enzymes, referred to as GGT, AST and ALT, known to be common markers of liver injury. Participants were divided into three groups, based on their reported level of alcohol consumption: lifetime abstainers, current nondrinkers and current drinkers. Current drinkers also reported the total amount and type of alcohol consumed during the past 30 days and the usual ounces consumed per drinking day, an indication of intensity of consumption.
Other studies have suggested that drinking patterns—types of alcohol consumed and how and when it is consumed, as well as the amount consumed—may play a role in the increased incidence of liver disease among African Americans, but are not thought to tell the whole story. Stranges said genetic vulnerability to alcohol-related damage has been speculated as one of the potential main determinants of disparities between ethnic groups.
The current study found that two enzymes that are specific to liver damage—AST and ALT—tended to be higher, though not significantly higher, at the highest levels of consumption in African Americans than Caucasians. Findings were more striking for GGT.
"GGT levels were substantially different between the two groups, with black participants exhibiting significantly elevated mean values, even among lifetime abstainers," said Stranges. "GGT is not a specific marker of alcohol consumption and alcohol-related liver injury, so its elevated average levels in African Americans, even among participants who don't drink, might be due to hepatic vulnerability of this ethnic group."
Additional authors were Jo. L. Freudenheim, Paola Muti, Tom Nochajski and Maurizio Trevisan, all from UB; Eduardo Farinaro from "Frederico II" University of Naples Medical School, Naples, Italy, and Marcia Russell of the Preventive Research Center, Pacific Institute for Research and Evaluation, Berkeley, Calif.
The study was supported in part by a grant from the National Institute of Alcohol Abuse and Alcoholism.