Table 3.

Casewise concordance rates by zygosity and heritability estimates of the four traits

	twin type	total pairs	discordant pairs (+/-)	concordant pairs with trait (+/+)	casewise concordance (95% CI)	heritability (95% CI)
HPT	MZ	525	73	29	0.44 (0.34–0.55)	0.64 (0.49–0.79)
	DZ	577	135	23	0.25 (0.17–0.34)
RP	MZ	525	75	18	0.32 (0.21–0.44)	0.46 (0.30–0.63)
	DZ	577	111	10	0.15 (0.07–0.24)
MIG	MZ	525	144	60	0.46 (0.38–0.53)	0.43 (0.30–0.55)
	DZ	577	186	40	0.30 (0.23–0.37)
CAD	MZ	525	55	8	0.23 (0.10–0.35)	0.34 (0.13–0.55)
	DZ	577	72	2	0.05 (0.00–0.12)

Casewise concordance rates (95% confidence intervals, CI) are shown for each trait by zygosity. An estimate of trait heritability (95% CI) is also given.

HPT represents hypertension, RP Raynaud's phenomenon, MIG migraine, CAD coronary artery disease.