From these higher-order multiple births, we formed a total of 58 additional twin pairs: 3 FF MZ, 3 FF DZ, 13 MM MZ, 12 MM DZ, and 27 MF DZ. In addition, this sample contained a group of 10 triplet sets in which we were able to interview only 2 members of each set a group of 14 triplet sets in which we interviewed all 3 members of each set and 1 set of quadruplets, all of whom we interviewed. From the MM/MF sample, we interviewed both members of 851 MM MZ pairs, 647 MM DZ twins, and 1404 opposite-sex MF DZ pairs. The mean (SD) age of the participating twins in FF3 was 34.6 (7.5) years and ranged from 22 to 59. In FF3, we assessed both members of 854 pairs, 506 of whom were MZ, 345 of whom were DZ, and 3 of whom had unknown zygosity. While the FF sample began with twins who had previously responded to registry contact and our first assessment was by mailed questionnaire (FFQ), the MM/MF sample began with raw registry files and the first wave of contact was by telephone interview ( Figure 1). This article reports results from the third interview wave with the sample of FF twins (FF3) and the first interview wave with the sample of MM and MF twins (MM/MF1). The details of the samples in these 2 projects are outlined in Figure 1. The twins in this article derive from 2 interrelated projects using the population-based Virginia Twin Registry, formed from a systematic review of all birth certificates in the Commonwealth of Virginia, which now constitutes part of the Mid-Atlantic Twin Registry. However, genes may exist that act differently on the risk for MD in men vs women. While we found no evidence to suggest a violation of the equal environment assumption, MD was less common in women from opposite-sex vs same-sex twin pairs.Ĭonclusions Major depression is equally heritable in men and women, and most genetic risk factors influence liability to MD similarly in the 2 sexes. The best-fitting model estimated the genetic correlation in the liability to MD in the 2 sexes to be +0.57. We rejected, with only modest confidence, the hypothesis that the genetic risk factors for MD were the same in men and women. In the best-fitting twin model, the heritability of liability to MD was the same in men and women and equal to 39%, while the remaining 61% of the variance in liability was due to individual-specific environment. Results The odds ratios (plus tetrachoric correlations) for lifetime MD were as follows: (1) male-male monozygotic, 3.29 (+0.37) (2) male-male dizygotic, 1.86 (+0.20) (3) female-female monozygotic, 3.02 (+0.39) (4) female-female dizygotic, 1.59 (+0.18) and (5) male-female dizygotic, 1.39 (+0.11). Results were analyzed using probandwise concordance, odds ratios, and biometrical twin modeling. Methods We obtained, by telephone interview, a lifetime history of MD, defined by the DSM-III-R, from 3790 complete male-male, female-female, and male-female twin pairs, identified through a population-based registry. Although genetic factors play an important etiologic role in MD, we are uncertain whether genetic factors are of equal importance in men and women, and whether the same genetic factors predispose men and women to MD. Shared Decision Making and Communicationīackground Women report higher rates of major depression (MD) than men.Scientific Discovery and the Future of Medicine.Health Care Economics, Insurance, Payment.

Clinical Implications of Basic Neuroscience.Challenges in Clinical Electrocardiography.

Twin models female