The most common malignancy in men worldwide is cancer of the prostate. Andr
ogens play a direct role in normal and malignant growth of prostate cells v
ia the androgen receptor (AR). This study analyzed the polymorphic CAG repe
at sequence in exon 1 of the AR gene to determine if the number of repeats
might be an indicator of prostate cancer risk or aggressive disease. DNA wa
s extracted from blood samples of 20 black and 20 white men with well-docum
ented prostate cancer and 40 healthy controls (20 blacks and 20 whites). PC
R amplification was followed by gel electrophoresis and DNA sequencing. Thi
s region normally contains between 9 and 29 repeats. Patients an controls b
oth had minor variations in the number Of repeats, which ranged from 13 to
27 with 21 being the most frequent allele. Black controls and patients both
had a mean of 20 +/- 3 repeats; in whites the mean was significantly lower
in patients than controls (21 +/- 2 versus 23 +/- 2; p = 0.004). Combined
black and white patients also had a lower number than the combined group of
controls (20 +/- 3 versus 22 +/- 3; p = 0.02). Similarly, black and white
patients with aggressive disease had a lower number than patients whose dis
ease was more slowly progressive (19 +/- 2 versus 22 +/- 3; p = 0.02). We c
onclude that the small differences in the number of CAG repeats in both bla
ck and white patients do not appear to be a strong indicator of risk or agg
ressive disease but that this size polymorphism may be one of many genetic
and environmental risk factors involved in prostate cancer.