—What we have and have not done does not concern you. You were brought here for a very specific purpose.
—I was just mmm … making conversation.
—Then converse about the people who died in London. The medical examiner said they all died of sepsis.
—Close enough.
—Are you saying they did not die of sepsis?
—Not exactly. They died of a systemic inflam … matory response, but sepsis implies there is an infection present. There’s no harmful pathogen in the gas, no virus, no b … no bacteria, at least that’s what I think.
—What you think? Did you not analyze the gas samples they sent you?
—There was nothing to analyze. The ca … canisters were empty when I received them. But, based on the cell samples I looked at, I believe the gas contains a really, really smart molecule, one that binds to long DNA chains and causes the gene to cr … create a different protein, one that the body doesn’t recognize. The body thinks every cell is infected and starts attacking itself. The reaction is extremely severe, and almost ins … tantaneous.
—Is there anything out of the ordinary about the genetic makeup of the victims?
—I didn’t check, but no.
—I brought you here because of your expertise in genetics. I cannot understand why you would not see it fit to perform even the most basic genetic profiling on the victims.
—I didn’t count the bodies in London m … myself, but the report you gave me says that about four million people were exposed to the gas, and that around two … two thousand people survived.
—Exactly 1,988, by the latest count.
—That’s about five out of ten thousand, 5 percent of 1 p … percent. That means 99.95 percent of the people exposed to the gaseous agent died. I don’t need to do a lot of t … testing to tell you that there’s nothing really unique about 99.95 percent of the population. The living, all 1,988 of them, are a lot more … interesting.
—Very well. What can you tell me about the living? I trust you have at least examined the survivors we flew here.
—I’ve done a full genome sequencing on all t … twenty-seven of them. They have really bad ge … genetics.
—How so?
—They all share a co … cocktail of genetic variations and mutations, most of which are bad for you. These people shouldn’t even exist.
—Because of poor genetics?
—Because of rrr … because of rare genetics. There shouldn’t be more than one person with all these anomalies.
—Please explain.
—There are little “errors” in everyone’s DNA. Most of them are SNPs—
—Pardon me, I know very little about genetics.
—They’re differences in only one base pair of nu … nucleotides, one pair of letters. Replace a T and an A with a G and a C, that t … type of thing. The vast majority of these differences are in noncoding areas between the ge … genes and no one really cares, or knows anything about them. Those that occur inside genes are usually more interesting, and we’re beginning to understand how … some of them work. Differences that are more common are called p … polymorphisms, those that occur in less than 1 percent of the population are called mutations. People shouldn’t share multiple mmm … mutations.
—And the survivors do?
—A lot of them. Enough so that the molecule in the alien agent doesn’t re … recognize any of the long DNA chains it’s looking for. This many people should definitely not share this mmmany mutations. It just doesn’t happen.
—It obviously does. How unlikely is it?
—Well, let me give you an example. All the people you s … sent me have a mutation in their TREM2 gene. One of the things TREM2 does is help re … regulate immune response to disease and injury in the brain. There are all sorts of mutations that can make TREM2 not function p … properly. These people all have the same one: variant R47H. That one is rare. It occurs in a little more than half a percent of the po … population in certain places like Iceland, and it’s even harder to find everywhere else. All of the survivors have the same TREM2 mutation, in both co … copies of the gene. That’s rare enough, I don’t even have frequencies for it.
—Is it debilitating?
—It’s been shown to increase the risk of developing Alzheimer’s, but most people with the mutation won’t get the d … the disease, so no. There is also a mutation in the BCR2 gene. It increases your risk of br … breast cancer.
—Do all the survivors have it?
—They do. Both copies of the gene.
—How uncommon is that mutation?
—It’s ha … hard to tell. It’s more frequent in certain ethnic groups, but overall, it’s found in less than half of one percent of the general population. You see w … what I’m getting at. Assuming the two mutations are unrelated, half a percent times half a percent means that out of a mi … million people, you should only find about twenty-five with both mutations. Of course, that’s not all the survivors have in common.