Table 7.

Genetic (ρ_G) and environmental (ρ_E) correlations between absolute dense area and nondense area of breasts, n = 1,140

Breast density		ρ_P^a	ρ_G ± SE	P value (ρ_G = 0)^b	ρ_E ± SE	P value (ρ_E = 0)
Trait 1	Trait 2
Dense area^c	Nondense area^c	−0.33	−0.37 ± 0.07	8.0 × 10⁻⁵	−0.24 ± 0.16	0.16
Dense area + BMI^d	Nondense area + BMI^d	−0.29	−0.32 ± 0.08	0.001	−0.23 ± 0.13	0.10
Multivariate adjusted dense area^e	Multivariate adjusted nondense area^e	−0.29	−0.34 ± 0.08	5.0 × 10⁻⁴	−0.21 ± 0.13	0.13

↵^aPhenotypic correlation between absolute dense area and the nondense area.
↵^bP value for test of null hypothesis of no genetic correlations (ρ_G = 0).
↵^cSquare root–transformed dense and nondense area adjusted for age at mammogram and menopausal status alone.
↵^dSquare root–transformed dense and nondense areas adjusted for age at mammogram, menopausal status and BMI.
↵^eSquare root–transformed dense and nondense areas were adjusted for age at mammogram, HRT use, BMI, WHR, age at first birth, age at menarche, and menopause.