While an early report suggested that parity may increase risk for early onset (<40 years) breast cancer in BRCA1 carriers (Narod, 2002a), a larger retrospective study of 1260 carrier pairs by the same group did not confirm this finding, and even observed decreased breast cancer risk in BRCA1 carriers with ⩾four children (OR=0.62, 95% CI 0.41–0.94, vs nulliparous carriers) (Cullinane et al, 2005). Here, BRCA1 is linked to breast cancer.