I don't know a whole lot about genetics, but I remember learning somewhere about how environmental factors can cause genetic mutations. Couldn't poor living conditions lead to it? What about the continued use of DDT in poorer countries? How about access to adequate nutrition? Previous access to health care? These all seem to be issues that could be passed down.

This is just giving me one of those weird feelings that there is more to this than faulty genes.

I would love it if someone who knows more would share. This just doesn't sit well with me.

I don't believe that environmental factors can cause genetic mutations of this kind on this scale. Certainly, nutrition and health care don't affect one's genes.

These women are all Californians--it would be interesting to see the data broken down by class and immigrant status, but none of that would explain why Ashkenazi women, most of whom have been in this country for generations and who span all classes, would have such a radically higher incidence of the gene than the other two groups.

The study isn't actually measuring the rates of breast cancer, from what I can tell--it's measuring the occurrence of the gene, which mean that is down to genes.

I've been told that I "look Latina" and that I "look Jewish." Maybe I have this BRCA1 genetic mutation too?

Ok, I am very interested in this, so I looked it up and according to this: http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/genemutation

Genetic mutations can occur due to environmental factors.

Genetic mutations can occur due to environmental factors.

Yes, but BrCa is a specific gene that causes breast cancer. You can't acquire that specific gene from environmental factors; it's hereditary. If Latinas were discovered to have a series of new genes that cause cancer, that would be due to genetic mutations, caused by any number of things.

Ashkenazic Jews also have higher rates of other genetic diseases, including Tay Sachs. It's probably due to a long history of intermarriage. Without the occasional infusion of fresh blood/genes, you're going to see more genetic disorders.

You're right that your genes don't mutate, but they are talking about change over many generations.

While BRCA gets all the press, the vast majority of breast cancers are unrelated to it, and there are other familial syndromes that can lead to increased breast (and other) cancers -- plus plenty of less well understood, multifactorial influences. Besides age, the biggest risk factor for breast cancer remains family history. If you have a first degree relative who has had breast or other gynecological cancer, especially at an early age, let your doctor know.

And despite all the fancy tests available, the best tool for detecting breast cancer remains yourself. Learn breast self-examination techniques -- google will give you plenty of links!

Actually, the BRCA genes (1 and 2) are not in and of themselves responsible for breast cancer. In fact, you may be surprised to learn that everyone, both men and women, has two copies each of BRCA1 and BRCA2 [we all have two copies of each of our genes, one copy from our mother and one copy from our father].

BRCA genes are actually tumor suppressors, meaning that their normal function is keep tumors from forming in the first place. Humans have a variety of tumor suppressing genes, which regulate cell growth rate, repair DNA mistakes and regulate cell death (i.e. which cells should die and when). So, if you have a mutation in one of these tumor suppressor genes, it can adversely affect these functions, making it more likely that certain cells will be able to grow uncontrollably, thus forming a tumor/causing cancer. However, in order for cancer to occur, you usually have to have at least two or more risk factors (genetic and/or environmental).

That's why it can be useful to know whether or not you carry a mutation in either your BRCA1 or BRCA2 genes, but your status doesn't tell the whole story since other risk factors usually need to be present for cancer to occur.

Anyway, if you have a mutation in the DNA for one of these BRCA tumor suppressor genes, your risk for developing breast cancer increases. The mutation can either be inherited (germline mutation) or it can occur in an individual after birth (somatic mutation). As sassygirl pointed out, of course you can acquire a mutation from environmental factors, but in the case of BRCA genes, I believe that heredity plays a much bigger role in the prevalence of mutations (or something like a mutation caused by an error during DNA synthesis that wasn't caught by DNA repair mechanisms; not say, exposure to a chemical in your drinking water). The point is, you can use this information to inform a group of people if they're carry genetic risk factors that predispose them to cancer.

So sassygirl, you are right in feeling that there is more to it than faulty genes, but don't let the fact that the study separates people into groups leave you feeling uncomfortable. All these labels are telling you is the prevalence of certain mutations in certain populations. Genetic studies have revealed all kinds of disparities between the variations of genes different groups carry, because most people reproduce with others of similar origin (either geographic or racial). This means that genetic risk factors often accumulate in populations of similar origin. Excepting the case of autosomal dominant genetic diseases (like Huntington's), most genetic risk factors are just that: risk factors, not a complete explanation.

Oh, and EG, if you read the link it appears that the study is national. It says the study was based on "more than 3,000 cancer patients in the United States diagnosed before age 65 between 1996 and 2005."

The registry the patient's info was entered into is located in Northern California, not necessarily the patients themselves.

One more thing...for anyone reading all of the comments here, someone mentioned a "series of new genes," which doesn't really happen. People don't typically get brand new genes, and when they do get an additional gene, it's not usually brand new...it's a copy of an already existing gene.

If you have ever wondered how humans can share such a high percentage of genetic material with other animals and yet be so different, it's not so much due to the small percentage of different genes we have. Most of the big differences you see between closely related species has to do with the way genes are *regulated*, not the presence of unique genes.

Wow, Tofurific!

So, could someone have a mutation from exposure and then pass that mutated gene their offspring?

Sassygirl, you cannot pass on a mutation you acquire from environmental factors (unless you are exposed to something that causes a DNA mutation in your sperm or egg cells, like radiation; this is why they put the lead things over your lower body when you're getting an X-ray, they prevent the radiation from the X-ray from reaching the germ cells in your ovaries...the article you linked calls this a "de novo" mutation).

Most environmentally-caused mutations happen to your somatic cells (which are every other cell in your body except sperm and egg cells).

The link you posted from NIH actually explains the different types of mutations pretty well. It give the example of UV exposure, which screws up the DNA in your skin cells by fusing adjacent thymine bases together into "thymine dimers" (remember that DNA contains four different bases, A,G,T & C...the T is thymine). Your cells have enzymes that can repair this UV damage by cutting out the dimers and replacing them with un-fused thymine bases, but excessive UV exposure can lead to more damage than your cells can fix.

This can cause mutations when your DNA is being copied during cell division, because the enzymes that synthesize new DNA strands don't know how to read the thymine dimers and could create a strand with a different base in their place. If this mutation occurs in a gene that has a vital function, it could mess up the vital function and cause problems in the individual. This is an example of a somatic mutation that cannot be passed on to your children/future children.