Two gene variants linked to breast size also linked to breast cancer

Two novel genetic variants linked to breast size may also influence the risk of breast cancer, according to a study carried
out by US genetics company 23andMe.

'The findings in this study show that some of the same
biological pathways underlie both normal breast growth and breast cancer', said
lead author Dr Nicholas Eriksson.

'Some studies have found that larger breast size as a young
woman is associated with a slightly higher risk for breast cancer. The genetic factors we found support this concept that breast size and breast cancer are
related', he said.

Researchers at 23andMe conducted a genome-wide association (GWAS) study, comparing genomic and self-reported data of 16,175 female 23andMe customers
of European ancestry. Self-reported data was collected through online surveys, and
included questions about bra cup size and factors which may affect reported
breast size, including bra band size.

Seven SNPs (single nucleotide polymorphisms) associated with breast size were identified, two
of which were also associated with breast cancer. A third variant of 29 genetic
variations associated with breast cancer was also identified as having a possible
association with breast size, but it did not reach
statistical significance, an article on the NHS Choices website points out.

NHS Choices also lists several caveats to the findings,
stating that the study does not show that larger breast size increases a woman's
risk of developing breast cancer. 'Genome-wide
association studies can provide useful information on the genetic features
underlying certain conditions, but cannot tell us whether people with these
genome variations will go on to develop the condition', it says. 'There are
multiple risk factors for breast cancer, ranging from genetic to environmental
to lifestyle factors. This study cannot tell us how these factors interact to
increase the risk of developing breast cancer'.

The paper notes that more research is needed
before the findings 'could be considered concrete'.

'While these results do not directly support the known
epidemiological relationships between breast size and cancer, this study
contributes to a better understanding of the subtle interactions between breast
morphology and breast cancer risk', Dr Eriksson said.

Customers of 23andMe who participated in study have access
to their raw genetic data and a range of interpretations based on the results
of GWAS.

'The
23andMe research platform is a robust source of new genetic discoveries and
this study demonstrates that important scientific insights can come from the
most unlikely places', stated 23andMe
CEO and co-founder Anne Wojcicki. 'Nearly 90 percent of our more than 150,000
customers participate in our online research', she added.