Genetic map reveals breast cancer-predisposing mutations typical of Asturian valleys | Health & Wellbeing

A team of researchers from the Molecular Oncology Laboratory of the Central University Hospital of Asturias (HUCA) has published a genetic map of familial breast cancer in the principality, which identifies some mutations that are unique in the world and predispose to breast and ovarian tumors. The study, published June 24 in the journal Clinical geneticsemphasizes that between 200 and 400 years ago, a series of hereditary variations occurred in the BRCA1 and BRAC2 genes, which were preserved only in some valleys of Asturias due to the isolation of the population.

The work involves the study and analysis of more than 1,600 families over more than fifteen years and represents an important insight into the incidence of familial breast cancer in Asturias. The investigation revealed that 238 of these families are carriers of genetic variants of the pathogen. One of the main findings of the study is the discovery of several mutations specific to the Asturian population, but which affect more than half of the families with pathogenic variants.

“Some of these mutations have never been described in any other population in the world. They come from Asturias,” says Milagros Balbín, head of the HUCA Molecular Oncology Laboratory. The explanation for this situation lies in the geographical and demographic isolation that the Principality has always had. Thus, the researchers in their work establish that when this variant appeared about 400 years ago, it was easily transmitted from generation to generation until it reached our days. “We are now seeing many families that, although they seem independent, actually have a common ancestor and origin,” explains the researcher, who recalls that the fact that many families with hereditary breast cancer have the same changes prompted them to study its origin.

The genetic studies that made it possible to trace the age of each mutation were carried out by a team led by Balbín and Pilar Blay from the Family Cancer Unit of the Medical Oncology Service of the same hospital. For Blay, although all this may seem very distant, its relevance is very current: “Genetic inheritance is like a coin toss. It’s 50-50%. However, thanks to this work, certain measures can be taken to try to reduce this percentage and avoid, as much as possible, the onset of the disease in the first place, and even by looking for pharmacological solutions later.”

Knowing the changes in these genes has made it possible to develop specific drugs. “For example, there are breast cancers for which drugs have recently been approved if you have any of these mutations,” Balbin emphasizes. These mutations are also necessary to know whether they cause cancer or not. When genetic analysis is performed, there are three possible options: the mutation is hereditary, it is not, or it is unknown, the researchers explain. Both emphasize the complexity that this last option entails, namely variants of uncertain clinical significance, since this uncertainty can affect future generations.

“It’s important for the patient and the rest of her family to know if there’s a mutation that’s causing the disease,” says Bley, citing the example of actress Angelina Jolie, who had a double mastectomy and removal of her ovaries and fallopian tubes after learning she carried the BRCA1 and BRAC2 genetic mutations. “We’ve achieved tie-break “With some of these mutations, it’s not known whether they cause cancer or not,” explains Bley, for whom this achievement is the most important discovery of his recently published study.

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