Written by Michael D. Purugganan
11 August 2011, Philippine Star | Star Science
We are our genomes, or at least a good part of who we are is engraved
in our DNA. It was about a decade ago that the sequence of the human genome
was released, the completion of a monumental 11-year international
effort costing over P130 billion. Knowing the sequence of the human
genome — the more than three billion letters that make up our DNA, including our approximately 25,000 genes — has revolutionized biology, and the science of genomics has changed research in medicine, agriculture and the environment.
Today, we roughly know the genome sequences of about 1,000 humans on
the planet, part of an international effort to understand how humans
differ in their DNA. But as far as I know the genome sequence
of a Filipino has never been read completely, and we still remain
largely ignorant of what our genes look like. Will we be able to read
our genetic past in order to understand our present? Are we able to
explain who and what we are based on our DNA?
I became curious and decided to use myself as a guinea pig by reading
about one million letters of my own genome. So last June I had my DNA
extracted from my saliva and scanned on the Illumina human DNA chip. I
got the results a few weeks later, and armed with this data I peered
into my genes.
The first thing I wanted to see was what my genome told me about my
ancestors, and my first stop was the mitochondrial genome. Our
mitochondria are small organs within our cells that contain DNA
inherited by all of us from our mothers. My mitochondrial DNA is a legacy given to me from the female Kapampangan ancestors on my mother’s side.
My genome scan shows that the DNA in my mitochondria belongs to a
group called B4, which evolved about 13,000 years ago in the aboriginal
pre-Chinese groups of Taiwan. My specific mitochondria type, B4a1a1,
split off from this Taiwanese DNA about 9,000 years ago as ancient
migrants left that island and started going south and east toward the
Philippines and Polynesia. The genes in my Kapampangan mitochondria are a
clear legacy of that ancient migration.
Just as my mitochondrial DNA comes from my mother, my Y-chromosome is
strictly inherited from my father. My father was born in Manila in the
1920s but his father hails from Cagayan Valley. My genome scan showed my
Y-chromosome is classified in the group O3, a very Asian Y-chromosome.
This is an old line that started to evolve about 30,000 years ago and is
found among Chinese, Koreans, Malaysians and, yes, Filipinos. My
particular Y-chromosome, called O3a3c1 appears to have left China around
265 AD, spreading to Yunnan, Tibet, mainland Southeast Asia, and
clearly the Ilocos region of Luzon, from where my father’s male
ancestors come from.
Then there are the other chromosomes I have, which are a mixture of
genetic pieces from all my ancestors. Comparing my genome with a
database from people around the world, I find I am clearly Asian, but
that large chunks of my DNA, about 29 percent, are European — thanks to
my Spanish paternal grandmother Maria Aldeguer. Like many Filipinos, my
genome displays that blend of Asia and Europe that is the genetic legacy
of our colonial heritage.
I also found out about some of my own genetic traits. My genome scan
confirmed my eye color as brown, my hair is slightly curly and I am
above average in height for a Filipino.
My DNA says I am not resistant to malaria and will have a
higher propensity for male pattern baldness (how depressing). According
to my genes I digest caffeine more slowly than most (which may explain
why I can get wired from a single espresso), and that if I were to take
up heroin there is a good possibility I will get addicted. If I contract
hepatitis C I have a reduced chance of responding to treatment. I have a
higher risk of getting asthma or migraines, but I have lower genetic
risk for melanoma, multiple sclerosis and some types of cancers.
Of course,
my genes are only half the story — whether or not I get any of these
diseases depends heavily on the environment as well. But it’s good to
know I should pay extra attention to certain potential problems to my
health.
Read the full article
Read the full article
Michael Purugganan is the co-director of the Center for Genomics and Systems Biology
and the Dorothy Schiff professor of Genomics at New York University. He
graduated BS Chemistry at UP Diliman in 1985, and went to the US to get
an MA at Columbia and Ph.D. at the University of Georgia. He has been
awarded a Sloan Young Investigator Award, a Guggenheim Fellowship,
honored by the Ayala Foundation/PhilDev Foundation and is a member of
PAASE. You can learn more about his impractical research at
http://puruggananlab.bio.nyu.edu/
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