Mutations in a gene that can cause breast fibroadenomas - benign breast tumors - are reported in a study published online this week in Nature Genetics. The results point to a common underlying cause for both breast fibroadenomas and benign tumors of the uterus known as uterine leiomyomas.

Fibroadenomas of the breast are non-cancerous tumors that commonly occur in the breasts of women under the age of 30. The genetic cause of these tumors is not known. Bin Tean Teh and colleagues sequenced the genes of eight fibroadenoma samples and compared them to normal tissue from the same women. They found mutations in the gene MED12 in four of the eight samples. The researchers sequenced the MED12 gene in another 90 fibroadenoma samples and found that 50 carried mutations.

MED12 is one of several genes that interact with estrogen receptors. The only other tumor type that has similar mutations in MED12 is uterine leiomyoma, another female-specific benign tumor.