Tag Archives: Genetics

Mosaic Me

DNA polymerase (which copies our DNA during cell division) makes an average of one uncorrected mistake per 100,000,000 bases.  Given that our genome consists of three billion bases, this means that an average of 30 alterations are made each time our DNA is copied.  As a result, not only are some of our cells genetically different from the others, in truth few if any of them are 100% identical.  We are all mosaic creatures.

Some types of cells, such as epithelial cells, can produce a new “generation” once a day.  This means that after three years, some of our cells are part of generation 1,000, and by the time we are thirty years old, some of our cells are in generation 10,000, with DNA that has drifted from the divinely inspired parental genome by some 300,000 bases.  While that is still only 0.01%  of the total – i.e., one part in ten thousand – 300,000 is still an alarming number.  No wonder I don’t get along with myself as well as I used to.

This sort of thing does call into question the logic of using a cheek swab or a blood sample to calculate a person’s genetic code.  In some situations, a person might be told they are at a high risk of, say, liver cancer, when the applicable mutations don’t appear in liver cells at all.  The real problem, though, is to speak of a person’s genetic code as if it were a single thing.  Our bodies are like multi-core computers, where (a) each core is running a different variant of the operating system, (2) each of those variants is a mish-mash of different versions, and (d) none of those operating systems have been through any but the most rudimentary quality assurance testing.

Surely this situation calls for action.  Unfortunately, as I understand it, various individuals have contacted the Original Equipment Manufacturer (OEM) to complain, only to be told that the system warranty was rendered null and void during a previous epoch.  Something to do with a pilfered apple.  For my part, I feel we’ve been sold a lemon.

Rather than complain, however, let’s look at the bright side: we now have one more reason to embrace diversity and renounce bigotry.  Viva le difference.