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Genes Can Affect Doping Test Results

Genotype for testosterone glucuronidation enzyme affects accuracy of urine test

TUESDAY, March 25 (HealthDay News) -- The genotype for the UGT2B17 gene can affect the accuracy of testosterone doping test results, according to study findings published online March 11 in the Journal of Clinical Endocrinology & Metabolism.

Jenny Jakobsson Schulze, Ph.D., of Karolinska University Hospital in Stockholm, Sweden, and colleagues conducted a study of 55 healthy males with either two (ins/ins), one (ins/del) or no (del/del) allele of the UGT2B17 gene. The men were given 500-mg testosterone enanthate and were tested for urinary excretion of testosterone glucuronide after dose and testosterone/epitestosterone (T/E) ratio during 15 days.

The rate of increase of testosterone glucuronide was higher by 20-fold in the ins/ins group versus the del/del group, and 40 percent of those in the del/del group never attained the T/E ratio of 4.0, considered suspicious in a doping test, on any of the 15 days. However, when cut-off levels were differentiated according to genotype, at 1.0 for the del/del group and 6.0 for the others, sensitivity was substantially improved for the del/del group and false positives were eliminated in the other groups.

"Consideration of the genetic variation in disposition of androgens will improve the sensitivity and specificity of the testosterone doping test," the authors write. "This is of interest not only for combating androgen doping in sports, but also for detecting and preventing androgen abuse in the society."

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