Scientists are finding that it’s quite common for an individual to have multiple genomes

[n2doc]

By CARL ZIMMER
September 16, 2013
From biology class to “C.S.I.,” we are told again and again that our genome is at the heart of our identity. Read the sequences in the chromosomes of a single cell, and learn everything about a person’s genetic information — or, as 23andme, a prominent genetic testing company, says on its Web site, “The more you know about your DNA, the more you know about yourself.”

But scientists are discovering that — to a surprising degree — we contain genetic multitudes. Not long ago, researchers had thought it was rare for the cells in a single healthy person to differ genetically in a significant way. But scientists are finding that it’s quite common for an individual to have multiple genomes. Some people, for example, have groups of cells with mutations that are not found in the rest of the body. Some have genomes that came from other people.

“There have been whispers in the matrix about this for years, even decades, but only in a very hypothetical sense,” said Alexander Urban, a geneticist at Stanford University. Even three years ago, suggesting that there was widespread genetic variation in a single body would have been met with skepticism, he said. “You would have just run against the wall.”

But a series of recent papers by Dr. Urban and others has demonstrated that those whispers were not just hypothetical. The variation in the genomes found in a single person is too large to be ignored. “We now know it’s there,” Dr. Urban said. “Now we’re mapping this new continent.”

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http://mobile.nytimes.com/2013/09/17/science/dna-double-take.html

[cantbeserious]

1. Fascinating

eom

[frogmarch]

2. Fascinating!

Women can also gain genomes from their children. After a baby is born, it may leave some fetal cells behind in its mother’s body, where they can travel to different organs and be absorbed into those tissues. “It’s pretty likely that any woman who has been pregnant is a chimera,” Dr. Randolph said.

Wow!

[spin]

3. Very interesting. (n/t)

[byronius]

4. Whatever works -- that's what the universe codes for.

This is like JavaScript interfacing with Html of something. Very interesting.

[aquart]

5. Does this mean serious genetic testing requires multiple samples?

From different organs or places on/in the body?

[mike_c]

7. that or perhaps specific cells from specific tissues...

...expressing genetic diseases, i.e. if they're chimeric, sequencing DNA from other cells might not catch the mosaic.

But I don't think this is that big a deal, most of the time. Most individuals still likely express elements of one genome during development, for example-- many of the examples the article cited involved proliferation of chimeric cell mosaics later in life. Some developmental chimeras have long been known (I'm talking animals here-- chimeras are very common in plants). Transplants generally involve mosaicism by definition, of course. Proliferation of natal cells in maternal tissue is fascinating for its implications regarding cell-cell recognition, but it's hard to imagine there being any extensive clinical consequences, but if there are, this at least gives another place to look for pathologies.

[Rozlee]

6. Fascinating.

I wish now my sister had been able to have her DNA tested before she died. She was dextro-cardiac, left-handed and had many characteristics of a mirror twin, although she'd been a single birth. She had a couple of doctors that theorized her twin might have died in utero and she'd absorbed it. I wonder if their DNA would have been too identical to detect any differences though, if such a theory has any validity at all.