My sister Ginny recently learned about telomeres, tiny fuses
that cap the end of our chromosomes, protecting them from damage by their neighboring
peers. Every time a cell replicates the
fuse shortens until it disappears and the cells die; eventually they all die,
and so do we. "I felt really comforted by this," she said. "That
we just wear down, nothing we can do about it. We just end." I told Ginny
that I had received a similar comfort after getting my DNA results.
At the urging of my daughter, I had sent my first spit sample
to ancestry.com, which has a clever system for family trees that not only
allows you to locate and add relatives, but provides links to historical records,
if available, which may even have stories about your forebears.
For example, I am directly descended from Miles Standish, referred
to as Captain Shrimp by his peers. No longer a Pilgrim icon, famous during my
childhood as Pricilla Alden's rejected suitor, he is disappearing into the
ashes of history, a nasty, short soldier who stabbed and killed a native chief during
peace negotiations. I also discovered John Darby among my forebears, who, when
he was about forty, impulsively joined up with a pirate crew one afternoon,
leaving his wife and five children. Unfortunately,
he was killed two weeks later by the British militia and was subsequently referred
to as the Neophyte Pirate. And, then there was my extended great grandfather
Andrew Elliott, a Salem judge who hanged witches and later apologized.
Amused but not necessarily comforted by the human examples
of my genetic heritage, I decided to learn more about its medical implications,
especially my risk for Alzheimer's, which ravaged my father's brain. So, even
though no measures exist to prevent this from happening to me, I sent another
saliva vial to 23&me, a site that focuses on physical traits, and then paid
five dollars to another site, promethease.com, to pick up my DNA results for
additional findings. Promethease
provides more information on disease risk than 23&me by identifying studies
that are looking at specific genes.
Using both sites, I learned that I wasn't a carrier of a
dozen or so very rare diseases and that I was likely to have blue eyes and wet
earwax and I wasn't a photic sneezer. I'm
4% Neanderthal, which is a higher percentage than that of 99% of the population,
and I also have a warrior gene and one that suggests low empathy levels, all of
which might produce whimsical impulses for piracy, hanging witches, sticking
knives into people, and getting married three times.
I was relieved to find no APOE4 gene, currently the one most
strongly associated with Alzheimer's risk, but it's still early days for research into genetic causes of
complicated diseases like this one. Collaboration among
other genetic and biologic factors could contribute to brain eating, so I'm
still not out of the woods.
It's important to note that drug companies scrambling to
transform bad genes with zillion-dollar custom-made pills are funding much of
this research. Little money is looking at beneficial genes that might already
protect us, because they are unlikely to become cash cows. And even if scads of
non-pharma research money were available, studying the microscopic DNA cosmos and
figuring out how it hurts or helps us is literally an astronomical task that
will take years to sort out.
Sixteen years ago scientists put together the first draft of
one entire human genome. Because everyone's genome is roughly like everyone
else's, the current way of analyzing an individual's genetic profile is to
reference it against that first draft. The results that come back from ancestry
and 23&me are mostly about SNPs (single nucleotide polymorphisms), which
are single variations on a DNA base. Their
locations on specific genes help supply information on individual physical
traits as well as susceptibilities to disease and environmental factors.
It should be noted, however, that just 20,000 genes, more or
less, provide the codes for manufacturing the basic stuff of our life force. They
comprise only about 1% of the whole genome and are scattered like planets among
3.2 billion DNA base pairs, most of which form large non-coding patches. A few
of these structures have been found to perform key functions, such as switches
that turn genes on and off, but, so far, most appear to just float around uselessly,
micro-asteroids within the genomic universe.Too add to the complexity, we also have about 14,000
pseudo-genes, which don't code but are inherited from one generation to the
other and hang out like freeloading cousins.
And there are problems in gene duplication. Think of a malfunctioning book printing press. Sometimes it makes multiple copies of a page. Sometimes it skips a few, which at best means losing a couple pages (i.e. couple of sentences) in a Henry James novel or, worst case, missing key parts of a Harry Bosch plot.
Bottom line, by the time scientists have doped out all the genetic factors and processes that lead to my Alzheimer's risk, I will have long since personally experienced the answer relevant to my own biologic fate and passed on.
So, to return to the conversation with my sister, where is comfort in all this? After attempting
to puzzle out and failing to understand the science of genetics on any
non-superficial level, I was left lying on some mental earth staring at those
billion or so DNA bases carrying their light-years of information within their
coiling and uncoiling packages, the double helix, dancing to the unceasing
music of Irreconcilable Dualities -- digital and analog, particle and wave, male
and female, order and chaos, life and death. I experienced the same ecstatic
insignificance as I would looking into the dark backdrop of the night. Just as the
external stars don't belong to me, neither does my DNA; it is merely renting me
as it twirls through my time-space until the last telomere drops off. And if
this doesn't comfort you, nothing will.
A few weeks ago, I went to a family reunion, the 90th
birthday of my last aunt, one of six sisters who all had various numbers of
children, so that I ended up with 24 cousins on my mother's side. So here we were, genetic comrades, most over sixty, eating cake, singing the
same schlocky camp songs of our childhood, harboring similar left-wing
politics, and locked into matching bone sets, silently sharing our internal
histories of Captain Shrimp, hanging judges, and low-browed Neanderthals
witnessing their own extinction. It was probably one of the last times we will all
be together living and lively, so there was an element of sadness. But at the end of the evening, our wonderful
aunt, on the verge of finality and cloaked in mild dementia for most of the
night, looked up at this crowd of children, nieces, and nephews all winding and
spiraling about her, and she laughed.
[Note: one terrific way to crash your way through this DNA
thicket of information is a series called Game of Genomes, in which Carl
Zimmer, the author, decided to get his entire genome analyzed by a number of
experts and to write very clearly about it.
(https://www.statnews.com/feature/game-of-genomes/season-one/)]
