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Genetic Linkage

Anticipation

Jordan and Hailey Kohl. Spinocerebellar ataxia type 2 affects several members of their family, including Jordan.
“Anticipation .. is keepin’ me waitin’,” sings Carly Simon in her song made famous in a ketchup commercial. But “anticipation” in the genetic sense is just the opposite of Carly’s croon – it means a disease that begins earlier with each generation.

Doctors once blamed patients for anticipation, as if people with sick older relatives could worry themselves into suffering similarly. Then, in 1991, discovery of a new type of mutation explained the curious worsening of fragile X syndrome: an expanding triplet repeat.  Read More 
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The Y Chromosome: Size Matters

The human Y chromosome
Let me get this straight: The human Y chromosome has barely changed from that of a rhesus macaque, a monkey from whom we parted ways some 25 million years ago, and that’s good news? I suppose compared to disappearing, it is.

For several editions now, my human genetics textbook has run an “In Their Own Words” essay in which MIT’s David Page, protector of the Y, has defended the measly male chromosome against charges from Jennifer A. Marshall-Graves, of Australian National University, that it is disappearing. She helpfully points out in my book, “You can lack a Y and not be dead, just female,” then goes on to call the Y “a pathetic little chromosome that has few genes interposed with lots of junk.”  Read More 
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Older Dads Have More Mutations

As a genetic counselor, I hate telling a woman over 35 that she’s of “advanced maternal age,” which raises the risk of conceiving a child who has an extra chromosome. Now older men are in the reproductive spotlight too.

Since the nineteenth century, physicians have noted that Down syndrome babies tend to be the  Read More 
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My New View of DTC Genetic Testing

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“Are you still collecting stories about DTC testing? I've got one for you!” my grad student L.W. e-mailed a few days ago. Little did I know her family's experience would change my mind about direct-to-consumer genetic testing.

L.W. had taken my online course “Genethics” in 2008 for the master’s program at the Alden March Bioethics Institute of Albany Medical College. Read More 
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Gene Therapy Changes the Brain

It doesn't take a brain scientist to see that the visual cortex of this formerly-blind woman lights up -- after gene therapy.
It isn’t often that a brain scan chokes me up, but this one did. The fMRI shows area 17 of the visual cortex coming to life in a woman born with Leber congenital amaurosis type 2 (LCA2). She’s part of the very same gene therapy clinical trial chronicled in my upcoming book The Forever Fix: Gene Therapy and the Boy Who Saved It. The symbolic boy is Corey Haas, who, four days after gene therapy in 2008 at age 8, screamed when he saw the sun at the Philadelphia zoo, his shadow world suddenly brightened. Read More 
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