Specifically, among women with age at menarche ≤12 years, there was nearly a 200% increase in breast cancer risk in association with high LUMA methylation levels; in contrast, the LUMA methylation-breast cancer association was only modestly increased by 66% among women with age at menarche >12 years (multiplicative interaction p = 0.05). Here, TMEM43 is linked to breast carcinoma.