Archive for CCR5-Δ32

The Reason I’m Alive

Posted in Biographical, LGBT with tags , , , on February 27, 2021 by telescoper

For a variety of reasons I’ve always considered myself to have been exceptionally lucky, but last week I got news that increased still further the extent of this sense of good fortune. I hesitated before putting anything about this on here because it is rather personal and there are details I’m going to leave out about how I came by the information.

Over a month ago I posted some thoughts about the TV series It’s A Sin based on my own experiences back in the 1980s. That post ended with this:

… a question that often troubles me returned once again to my mind: why am I still alive, when so many people I knew back then are not?

In response to this a former colleague of mine suggested I get my DNA sequenced to see if I had any innate resistance to HIV infection. I wasn’t sure how to go about doing this but one of the advantages of having worked in several different universities is that I know people in several bioscience and biomedical departments, including people who work on the data science aspects of genetics. After emailing around for advice I eventually ended up talking to a very distinguished scientist in that field to whom I explained the situation.

Since I didn’t really want to have a copy of my entire genome sequence – that’s a lot of data most of which I wouldn’t understand – but just wanted to know the answer to one question it seemed a waste of money to have this done commercially (although at around €1000 it’s not enormously expensive). Instead a plan emerged in which I would offer my (suitably anonymized) DNA as part of a scientific study in return for the small piece of information I wanted.

After a few days I received a kit for taking oral swabs, a medical questionnaire and quite a lot of paperwork to do with ethical considerations and data protection. I sent everything back by return post. Last week the results came back. There was some general info about my genetic make-up – which shows a considerable dollop of Scandinavian ancestry – alongside the answer the question I had asked.

The full DNA sequence of my genome reveals that I have the CCR5-Δ32 genetic mutation. Not just that. I have it twice (i.e. it’s homozygous), which means that I inherited it from both parents.

Of order 1% of the European population has this mutation, which is thought to have arisen in a single Scandinavian individual at some stage during the Viking era and subsequently propagated through mainly Northern Europe where about 10% have one copy, and about 1% have two.

Here is a map of the geographical distribution in Europe (from this paper) :

It’s nowhere near as prevalent in Asia or African populations.

So what does this mean?

Heterozygotic CCR5-Δ32 (i.e. one mutated gene) confers some protection against HIV infection but the homozygotic CCR5-Δ32 mutation involving both copies confers virtually total immunity. I was terrified of AIDS in the 1980s but it turns out I was immune all the time without knowing it. This explains why to my great surprise the HIV test I took in the 1980s came back negative despite my sexual history and behaviour.

As a friend told me when I passed this news on: “you’re a f**king lucky bugger”. Indeed I am. I already considered myself to have been very lucky but this absolutely takes the biscuit.

P.S. My immediate “reward” for having this genetic peculiarity is to take part in further scientific study on it, which I am of course very happy to do.