The CAG repeat within the androgen receptor gene and benign prostatic hyperplasia

Objectives. Shorter CAG repeat lengths in exon 1 of the androgen receptor ( AR) gene are associated with a stronger transcriptional activity of the AR and with a higher risk of prostate cancer. Because benign prostatic hyperpl asia (BPH) is an androgen-dependent condition, we examined the hypothesis t hat men with shorter AR gene CAG repeat lengths have an increased risk of d eveloping BPH. Methods. Using data from the Health Professionals Follow-up Study (HPFS), w e evaluated the relationship between AR gene CAG repeat length and prevalen t BPH, as defined by BPH surgery, by enlarged prostate gland detected by di gital rectal examination, and by urinary symptoms as determined by the Amer ican Urological Association Symptom Index. Results. The odds ratio for BPH surgery or enlarged prostate gland was 1.92 (95% confidence interval [CI] 1.22 to 3.03; P [trend] = 0.0002), comparing AR gene CAG repeat length of 19 or less to 25 or more. Results were simila r for the end points of BPH surgery (P [trend] = 0.002) and for enlarged pr ostate gland (P [trend] = 0.001), For a six-repeat decrease in CAG repeat l ength, the odds ratio for having moderate or severe urinary obstructive sym ptoms from an enlarged prostate gland was 3.62 (95% CI 1.51 to 8.67; P = 0. 004). Conclusions. Variability in the AR gene CAG repeat influences the developme nt of symptomatic BPH, particularly in predicting obstructive urinary sympt oms. Our findings support further study to establish the appropriate clinic al relevance. UROLOGY 53: 121-125, 1999, (C) 1999, Elsevier Science Inc. Al l rights reserved.