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kottke.org posts about Sarah Zhang

When you do a DNA test and find out your dad is not your father

posted by Jason Kottke   Jul 18, 2018

Sarah Zhang writes about a support group on Facebook for people who have discovered surprising parentage through DNA testing.

Lisa, 44, admits she is still trying to go of that anger. She had always felt out of place in her family. Her hair — which she always straightened — was naturally fine and curly, her skin dark. “People would think I’m Hispanic, and would speak Spanish to me on the street,” she says. So when an DNA test in 2015 revealed her biological father was likely African American, it clicked into place. But her mom denied it. “She wouldn’t answer me. She would change the subject,” recalls Lisa. When she kept pressing, her mother broke down, saying it would destroy the family and that her dad — the man she grew up with — would kill her. She refused to say anything else about Lisa’s biological father.

I’ve written about this before (here and here) and reading these stories never gets any less heartbreaking. Back in 2010, I shared this:

I know someone who adopted a baby and they have never told her that she’s adopted and don’t plan to (she’s now in her 20s). When DNA testing becomes commonplace in another 5-15 years, I wonder how long that secret will last and what her reaction will be.

DNA testing confirms what we should have known all along: family is more than what biology says it is. Families already look quite differently than they did 40-50 years ago and they will continue to shift in the future, MAGA be damned.

Possible roadblock to CRISPR use in humans: we might be immune to it

posted by Jason Kottke   Jan 11, 2018

Researchers from Stanford have published a study showing that immunity might hinder the use of the CRISPR gene editing technique in humans. The Cas9 bacterial protein commonly used in CRISPR is found in and around human bodies, so many of those bodies have already built up an immunity to it. That means if you send Cas9 into a body to do some gene editing, that body’s immune system might attack and destroy it before it can do its work. Sarah Zhang wrote about the study for The Atlantic.

Porteus and his colleagues focused on two versions of Cas9, the bacterial protein mostly commonly used in CRISPR gene editing. One comes from Staphylococcus aureus, which often harmlessly lives on skin but can sometimes causes staph infections, and another from Streptococcus pyogenes, which causes strep throat but can also become “flesh-eating bacteria” when it spreads to other parts of the body. So yeah, you want your immune system to be on guard against these bacteria.

It sounds like this was something geneticists were well aware of but wasn’t common knowledge among non-technical CRISPR enthusiasts. As Chang notes, scientists are already employing strategies to route around the potential immunity roadblock:

Modify Cas9 or use a different CRISPR protein altogether: It may be possible to redesign Cas9 to hide it from the immune system or to find other bacterial proteins that can do the job of Cas9 without provoking the immune response. Many different bacteria have CRISPR systems. “We already have lots of Cas enzymes and could get many more,” George Church, a geneticist at Harvard and a founding scientific advisor of Editas, wrote in an email.