Concordance rates for benign prostatic disease among twins suggest hereditary influence

Objectives.: The etiology of benign prostatic hyperplasia (BPH) is unknown. Evidence for a hereditary trait would provide new avenues for investigation. Methods.: We compared the concordance for benign prostate disease in monozygotic(MZ) and dizygotic (DZ) twins who served in the United States military in World War II and have been followed by the Medical Follow-up Agency, Institute of Medicine of the National Academy of Sciences. Questionnaires completed in 1985 by 10,000 twins were reviewed for evidence of prostatic disease. Key words indicating benign prostatic disease (prostate, prostatectomy, BPH, TURP, and prostatism) were identified in 533 (5.3%) of the questionnaires. Results.: The average age was 64±3 years (range 56 to 68 in 1985). After eliminatingmen with known prostate cancer, there were 256 twin pairs that were informative for benign prostatic disease: both twins were concordant in 25 instances and discordant in 231, with only one twin mentioning benign prostatic disease. The pairwise concordance for MZ twins was 14.7% (19 of 129) and for DZ pairs it was 4.5% (5 of 112). The relative risk for benign prostatic disease for MZ twins was thus 3.3 (p = 0.008). The probandwise concordance rates, which express the probability of BPH in a cotwin of anaffected twin, were 25.7% for MZ twins and only 8.5% for DZ twins. A covariance analysis estimated that 49% of the observed variance between twins could be attributed to genetic effects. Conclusions.: These data provide preliminary evidence for the heritability of benignprostatic disease.