Genetic diversity has been an accepted reality in the world of science. Different creatures, different genetic make-up: one amazing world. Differences in the human population do exist as well. And while environmental influences play a vital role on each group's lifestyle and survival mechanisms, genetic makeup is also a defining factor in any human being's existence. In some cases though, one's genetic composition could be a blessing.
Luckily for some Latin American women, they may just have that genetic variant that makes them invulnerable to breast cancer.
According to a study conducted by researchers at the University of California, San Francisco, a certain genetic variant protects Latina women from getting breast cancer, which gives the group a lesser incidence of cancer and deaths due to the disease as compared to European or African-American women. The result of the study was published recently in the journal Nature Communications.
The researchers said that the newly identified variant is on Chromosome 6, near a gene coding for an estrogen receptor known as ESR1.
"The variant, a difference in just one of the 3 billion letters in the human genome known as a single-nucleotide polymorphism (SNP), originates from indigenous Americans and confers significant protection from breast cancer, particularly the more aggressive estrogen receptor-negative forms of the disease," the research group said.
The researchers were able to identify the genetic variant after analyzing DNA from 3,140 breast cancer patients in the United States, Mexico and Columbia, and from nearly 8,200 women without breast cancer in those same countries.
Dr. Elad Ziv, professor of medicine and senior author of the study said, "The effect is quite significant. If you have one copy of this variant, which is the case for approximately 20 percent of U.S. Latinas, you are about 40 percent less likely to have breast cancer. If you have two copies, which occurs in approximately 1 percent of the US Latina population, the reduction in risk is on the order of 80 percent."
The findings are supportive of the epidemiological data which indicated that latinas are less susceptible to the disease. Based on the National Cancer Institute data from 2007 to 2009, women of European descent have around 13 per cent lifetime risk of breast cancer while African American women's risk is about 11 per cent. Asians and Pacific Islanders have around 10 per cent risk while Latinas have less than 10 per cent risk. Noteworthy are Hispanics with indigenous American ancestry, who have an even lower lifetime risk of the disease.
The team also found that women with the said genetic variant have breast tissue that appears less dense on mammograms. Breast tissue that appears more dense on a mammogram is said to be a risk factor for breast cancer, according to the study.
Dr. Laura Fejerman, first author and a member of UCSF's Institute of Human Genetics, as well as a latina herself said, "We have detected something that is definitely relevant to the health of Latinas, who represent a large percentage of the population in California, and of other states such as Texas."
The researchers say that the biological basis of the association between the variant and reduced breast cancer risk is still not known, but their preliminary experiments indicate that the variant interferes with the action of transcription factors, proteins that regulate the expression of the ESR1 estrogen receptor.
"Now what we are trying to do is think of how best to incorporate this genetic information with other risk-factor information to better provide a picture of breast cancer risk", Fejerman said.
