Objective: The androgen receptor (AR) gene, located on the X chromosome, contains a common polymorphism involving cytosine-adenine-guanine (CAG) repeats, which impacts disease and could contribute to the unequal sex ratio in alcoholism. CAG repeats in the AR gene are known to correlate with impulsivity in males. We report the first preliminary study examining the association between the number of CAG repeats and measures of impulsivity in females with chronic alcoholism.
Methods: A total of 35 women and 85 men with chronic alcoholism were previously recruited for a nutritional clinical trial, and 26 well-characterized females (19 African-American and seven Caucasian) with alcoholism agreed to participate for genetic testing. Genomic deoxyribonucleic acid (DNA) was isolated from peripheral blood and CAG repeats determined by analyzing polymerase chain reaction (PCR)-amplified products, using the polymorphic AR gene assay. CAG repeat length was correlated with raw scores from the Barratt Impulsivity Scale, version 11 and the Alcoholism Severity Scale.
Results: CAG repeat lengths were significantly longer in Caucasian alcoholic women compared with African-Americans, and the average number of CAG repeats were significantly, positively correlated (P<0.05) with impulsivity scores. Women with average CAG repeat length (CAGave) ≥18, representing the upper quartile of the repeat range, showed significantly greater mean raw impulsivity scores. CAG repeat length appeared to have less effect in African-American compared with Caucasian women, possibly due to a shorter average repeat length.
Conclusion: We found an association between the number of CAG repeats and impulsivity in females with chronic alcoholism, specifically in women with CAGave ≥18, seen more commonly in Caucasian compared with African-American women.
Keywords: AR gene; African-American; CAG repeat; Caucasian; behavior.