Common genetic variation and novel loci associated with volumetric mammographic density

Breast Cancer Res. 2018 Apr 17;20(1):30. doi: 10.1186/s13058-018-0954-6.


Background: Mammographic density (MD) is a strong and heritable intermediate phenotype of breast cancer, but much of its genetic variation remains unexplained.

Methods: We conducted a genetic association study of volumetric MD in a Swedish mammography screening cohort (n = 9498) to identify novel MD loci. Associations with volumetric MD phenotypes (percent dense volume, absolute dense volume, and absolute nondense volume) were estimated using linear regression adjusting for age, body mass index, menopausal status, and six principal components. We also estimated the proportion of MD variance explained by additive contributions from single-nucleotide polymorphisms (SNP-based heritability [h2SNP]) in 4948 participants of the cohort.

Results: In total, three novel MD loci were identified (at P < 5 × 10- 8): one for percent dense volume (HABP2) and two for the absolute dense volume (INHBB, LINC01483). INHBB is an established locus for ER-negative breast cancer, and HABP2 and LINC01483 represent putative new breast cancer susceptibility loci, because both loci were associated with breast cancer in available meta-analysis data including 122,977 breast cancer cases and 105,974 control subjects (P < 0.05). h2SNP (SE) estimates for percent dense, absolute dense, and nondense volume were 0.29 (0.07), 0.31 (0.07), and 0.25 (0.07), respectively. Corresponding ratios of h2SNP to previously observed narrow-sense h2 estimates in the same cohort were 0.46, 0.72, and 0.41, respectively.

Conclusions: These findings provide new insights into the genetic basis of MD and biological mechanisms linking MD to breast cancer risk. Apart from identifying three novel loci, we demonstrate that at least 25% of the MD variance is explained by common genetic variation with h2SNP/h2 ratios varying between dense and nondense MD components.

Keywords: Genetic association study; Heritability; Mammographic density.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Breast / diagnostic imaging
  • Breast Density / genetics*
  • Breast Neoplasms / diagnosis
  • Breast Neoplasms / diagnostic imaging
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology
  • DNA Mutational Analysis
  • Estrogen Receptor alpha / genetics
  • Female
  • Genetic Association Studies
  • Genetic Predisposition to Disease
  • Humans
  • Inhibin-beta Subunits / genetics*
  • Mammography
  • Middle Aged
  • Polymorphism, Single Nucleotide / genetics
  • Serine Endopeptidases / genetics*


  • Estrogen Receptor alpha
  • INHBB protein, human
  • Inhibin-beta Subunits
  • HABP2 protein, human
  • Serine Endopeptidases