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Genetic Linkage

A Child’s Unusual Chromosomes Illustrate the Value of Supportive Therapies

To a trained eye, the chromosome chart (karyotype) above has 4 irregularities, circled in red. They're chromosome pairs of uneven size.

 

The chromosomes represent genetic material missing or extra, but also a beautiful girl. Her father contacted me after he read my recent post about a friend's child with a rare mutation in a single gene, a more typical driver of so-called "diagnostic odysseys." Did I have any insight on treatments for his daughter? He'd send her lab reports.

 

The notations were in Hebrew, but the universal language of chromosome charts spoke clearly to me. The chromosome pairs are size-ordered, its members matching, but pairs 9, 14, 15, and 16 look like tall and short dance partners. This was something more profound than a single gene glitch, or even a missing or extra chromosome.

 

To continue reading, go to DNA Science, where this post first appeared.

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Using young blood to battle Alzheimer’s could be ‘an exciting new start in a frustrating field’

Regular transfusions of the blood of a younger, physically fit donor can significantly retard the aging process," proclaims a middle-aged CEO being hooked up to an intravenous line to the buff, young Bryce, the "transfusion associate." It's a parabiosis procedure, the CEO explains, in episode 5 of season 4 of Silicon Valley.

 

He's right. Parabiosis experiments have indeed shown value to receiving young blood – if you're a mouse. And vice versa for sending old blood into a young rodent.

 

Although nothing short of a time machine or death can halt the aging process, the idea of therapeutic benefits from "young blood" has been around a long time. Now, results of a phase 2 clinical trial indicate that something, or some mix of somethings, in young blood is apparently safe and offers the first hints that it might slow the cognitive decline of mild to moderate Alzheimer's disease.

 

To continue reading, go to Genetic Literacy Project, where this post first appeared.

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Celebrating the Pioneering Experiments in Genetics

It seems that lately everything in genetics, which has morphed into genomics, is big, big, big.

  • Data on half a million people represented in the UK Biobank are highlighting genome regions associated with difficult-to-study traits, like sexuality and handedness.
  • The All of Us initiative at the National Institutes of Health, which plans to capture info on a million or more people, is ever-expanding, from embracing Native communities to welcoming health care providers.
  • A pair of articles in the latest Nature Genetics describes algorithms that shift the mindset from "the" human genome to the many variations on the theme. Capturing how we differ will speed diagnoses, ease the finding of relatives, and fill in our evolutionary trees.

Another new Nature Genetics report, "A reference genome for pea provides insight into legume genome evolution," took me back to the origins of genetics and Gregor Mendel, who deduced the two basic laws of heredity by breeding pea plants with a handful of distinctive characteristics. A way for the general public to better understand what science is and how scientists think would be to set aside the mega studies for a moment and look back at the brilliant experiments that built the field of genetics, from those of Mendel to the beginnings of molecular biology.

 

So here are six of my favorite experiments in genetics, from Mendel's peas to double helices, chosen for their insight and creativity. These are in addition to my DNA Science post about the 19-year-old college student who invented gene mapping, paving the way to genome sequencing and consumer DNA ancestry tests.

 

To continue reading, go to my DNA Science blog at Public Library of Science.

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Retiring the Single Gay Gene Hypothesis

The once-prevailing concept of a sole "gay gene" dictating sexual orientation has been put to rest in a powerhouse study published in Science. The work illustrates the nature of science: evolving with the input of new data, especially the large-scale contributions of bioinformatics and crowd-sourcing.

 

"We formed a large international consortium and collected data for more than 500,000 people, comparing DNA and self-reported sexual behavior. This is approximately 100 times bigger than any previous study on this topic," said lead author Andrea Ganna, of the Institute of Molecular Medicine in Finland and an instructor at Massachusetts General Hospital and Harvard Medical School, opening a news conference earlier this week.

 

Human Sexuality is Nuanced and Complex

 

The investigation lowers the estimate of the genetic contribution to same-sex sexual behavior, thanks to analysis of a trove of data from the UK Biobank and the consumer genetic testing company 23andme.

I hope that the demonstration of a diminished role for genetics will counter the idea that having sex with a person of the same sex is something biologically broken that needs to be fixed. "Using these results for prediction, intervention, or a supposed 'cure' is wholly and unreservedly impossible," points out Melinda Mills, a sociologist from the University of Oxford in an accompanying Perspective.

 

To continue reading go to my DNA Science blog at Public Library of Congress, where this post first appeared.

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