Table 6.

Summary of twin studies on PMS/PMDD.

Authors	Study subjects	Concordance rates	Genetic heritability
Jahanfar et al. (94)	193 subjects [inclusive of same gender twins (n = 176) and females from opposite sex twin sets (n = 17)]	43.0% in monozygotic and 46.8% in dizygotic twins. Proband-wise concordance for PMS was higher in monozygotic (0.81) than in dizygotic twins (0.67), indicating a strong genetic effect	Quantitative genetic modelling found that a model comprising of additive genetic (A) and unique environment (E) factors provided the best fit of A: 95%, E: 5% suggesting 95% genetic heritability
Treloar et al. (95)	720 female twin pairs (454 monozygotic and 266 dizygotic) Australian National Health and Medical Research Council Twin Register	Genetic correlations of 0.62 between reported PMS and neuroticism, and 0.70 with lifetime major depression, 39% of the genetic variance of PMS was not explained by these factors	Indicating weaker genetic effect
Kendler et al. (72)	Virginia Twin Registry two assessments, 72 h apart 314 monozygotic and 181 dizygotic twin pairs	Stability of psychological symptoms of PMS.	A best-fitting twin-measurement model estimated the heritability of the stable component of premenstrual symptoms at 56% and showed no impact of family environment factors
Dalton et al. (97)	31 pairs of twins Prospectively examined premenstrual symptoms	Significantly higher concordance rate in monozygotic pairs (93%, 14 of 15) than in dizygotic pairs (44%, 7 of 16)	Indicating a strong genetic effect
Condon et al. (98)	157 monozygotic and 143 dizygotic female twin pairs Self-report questionnaire on premenstrual syndrome (PMS)	Correlation in global PMS scores nearly twice as great for monozygotic twins (r = 0.55) as for dizygotic (r = 0.28) pairs	Indicating a strong genetic effect