I had DNA analysis from 23andMe, however in the results there was no information about the BRCA1 and BRCA2 genes. Does that mean that I do not have these genes?
Does every human have these genes, or is it a mutation to have them?
BRCA1 and BRCA2 are the names of genes that every human has1, located on chromosome 17. These genes code for proteins that suppress tumors.
However, in some humans these genes carry mutations that mean that the tumor suppressing function doesn't work as well or at all. That's what people usually mean when they say that they "have" BRCA1/2, even though it's not the clearest way to phrase it.
Because in those cases suppression of tumor development is not as good as in people with the wild type (not mutated) version, these people are more at risk for certain cancers, specifically breast and ovarian cancer. In total, the mutations are probably responsible for about 10 percent of all breast cancers and 15 percent of all ovarian cancers.
For more information, the National Cancer Institute's fact sheet is a good resource.
1) it is possible that there are people who actually don't have the gene - I couldn't find any reports on that, but that doesn't mean it hasn't happened. However, that in itself is a mutation (a gene deletion). In a whole genome analysis, I can only hope that a missing gene would be listed as a result.