新研究发现7个遗传标记分子（genetic markers）与女性胸部大小的关联显著，这让人们认识到，乳房的大小可通过基因遗传给下一代。研究人员称，这是首次发现与乳房大小相关联的特定遗传标记。
遗传位点改变女性乳房大小的同时也影响乳腺癌的风险
与乳房大小相关的遗传位点是靠近ZNF703的rs7816345 ，INHBB侧翼的 rs4849887 和 rs17625845，ESR1附近的rs12173570 ，ZNF365中的rs7089814，PTHLH附近的rs12371778，AREG附近的rs62314947 。
领导这项研究的是基因测试公司23andMe 的Nicholas Eriksson 团队，他们分析了欧洲16175个女性，比较她们的胸围、罩杯大小以及相关遗传性。
单核苷酸多态性（SNP）主要是指在基因组水平上由单个核苷酸的变异所引起的DNA序列多态性。它是人类可遗传变异中最常见的一种，可以显示一个人是否处于危险状态，但不表明所有有特殊（SNP）的人都会受到疾病或症状的影响。
研究发现，与乳房较小的女性相比，乳房较大的女性面临乳腺癌的风险也较大。此外，研究人员在这些遗传标记分子中发现2个之前被证实与乳腺癌有关的基因，这说明了乳房的正常发育和乳腺癌之间具有共同的生物学通路。该研究并没有提出足够的证据说明胸部大小与乳腺癌之间有关系，只是为后续乳腺癌研究提供一个新的研究方向。
这项研究发表在在6月30日的BMC Medical Genetics杂志上。
Genetic variants associated with breast size also influence breast cancer risk
Nicholas Eriksson, Geoffrey M Benton, Chuong B Do, Amy K Kiefer, Joanna L Mountain, David A Hinds, Uta Francke and Joyce Y Tung
Background
While some factors of breast morphology, such as density, are directly implicated in breast cancer, the relationship between breast size and cancer is less clear. Breast size is moderately heritable, yet the genetic variants leading to differences in breast size have not been identified.
Methods
To investigate the genetic factors underlying breast size, we conducted a genome-wide association study (GWAS) of self-reported bra cup size, controlling for age, genetic ancestry, breast surgeries, pregnancy history and bra band size, in a cohort of 16,175 women of European ancestry.
Results
We identified seven single-nucleotide polymorphisms (SNPs) significantly associated with breast size (p < 5 . 10-8): rs7816345 near ZNF703, rs4849887 and (independently) rs17625845 flanking INHBB, rs12173570 near ESR1, rs7089814 in ZNF365, rs12371778 near PTHLH, and rs62314947 near AREG. Two of these seven SNPs are in linkage disequilibrium (LD) with SNPs associated with breast cancer (those near 1 ESR1 and PTHLH), and a third (ZNF365) is near, but not in LD with, a breast cancer SNP. The other three loci (ZNF703, INHBB, and AREG) have strong links to breast cancer, estrogen regulation, and breast development.
Conclusions
These results provide insight into the genetic factors underlying normal breast development and show that some of these factors are shared with breast cancer. While these results do not directly support any possible epidemiological relationships between breast size and cancer, this study may contribute to a better understanding of the subtle interactions between breast morphology and breast cancer risk.
文献链接： https://www.biomedcentral.com/1471-2350/13/53/abstract
