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Mary E. Fischer, PhD; Mary Ellen Vitek; Don Hedeker, PhD; William G. Henderson, PhD; Steven J. Jacobsen, MD, PhD; Jack Goldberg, PhD

Arch Intern Med. 2004;164:165-168.

Background  The extent of genetic influence on erectile dysfunction (ED) is unknown. This study determines the contribution of heredity to ED in a sample of middle-aged men.

Methods  A classical twin study was conducted in the Vietnam Era Twin Registry, a national sample of male-male pairs (mean birth year, 1949) who served on active duty during the Vietnam era (1965-1975). A 1999 male health survey was completed by 890 monozygotic (MZ) and 619 dizygotic (DZ) pairs. The prevalence and heritability of 2 self-report indicators of ED, difficulty in having an erection and in maintaining an erection, are estimated.

Results  The prevalence of difficulty in having an erection is 23.3% and in maintaining an erection is 26.7%. Twin correlations for dysfunction in having an erection are 0.35 (95% confidence interval [CI], 0.28-0.41) in MZ and 0.17 (95% CI, 0.09-0.27) in DZ pairs. For dysfunction in maintaining an erection, the twin correlations in MZ and DZ pairs are 0.39 (95% CI, 0.32-0.45) and 0.18 (95% CI, 0.09-0.27), respectively. The estimated heritability of liability for dysfunction in having an erection is 35% and in maintaining an erection is 42%. The heritable influence on ED remained significant after adjustment for ED risk factors.

Conclusions  The present study demonstrates an ED-specific genetic component that is independent of genetic influences from numerous ED risk factors. The results suggest that future molecular genetic studies to identify ED-related polymorphisms are warranted.

From the Vietnam Era Twin Registry/Seattle Epidemiologic Research and Information Center, VA Puget Sound Health Care System, Seattle, Wash (Drs Fischer and Goldberg); Cooperative Studies Program Coordinating Center, Hines VA Hospital, Hines, Ill (Ms Vitek and Dr Henderson); Epidemiology-Biostatistics Division, University of Illinois-Chicago (Dr Hedeker); and Division of Epidemiology, Mayo Clinic and Foundation, Rochester, Minn (Dr Jacobsen). The authors have no relevant financial interest in this article.