Oestrogen receptor B-region polymorphism and spontaneous abortion in women with breast cancer.

To examine whether a variant human oestrogen receptor gene, which differs from the wild-type gene in the B region, was associated with spontaneous abortion, obstetric histories of breast cancer patients with this variant were compared with those of breast cancer patients with the wild-type gene. In women with the B-variant, 50% of pregnancies ended in spontaneous abortion, compared with 10% for women homozygous for the wild-type gene. B-variant women also had a higher proportion of spontaneous abortions and a higher number of spontaneous abortions per woman than did those with the wild-type gene.