instagram pinterest linkedin facebook twitter goodreads facebook circle twitter circle linkedin circle instagram circle goodreads circle pinterest circle

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.

Be the first to comment

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.

Be the first to comment

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.

Be the first to comment

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.

Be the first to comment

‘We simply don’t yet know enough’: International commission urges caution with human germline editing

A small group of scientists, regulators, business people and patient advocates met recently at the National Academy of Sciences in Washington, D.C., to discuss the path forward in using genome editing tools, like CRISPR, to modify the human germline – that is, eggs, sperm or fertilized eggs. Such a change is heritable, passed to future generations.

 

It was the inaugural meeting of the International Commission on the Clinical Use of Human Germline Genome Editing. The tone during the day [August 13] was considerably more measured than the media splash that Victoria Gray, a 34-year-old from Mississippi with severe sickle cell disease, had made a few weeks earlier.

 

She's the first person to undergo a treatment using CRISPR, but the clinical trial she's in, sponsored by Vertex Pharmaceuticals, targets only cells that give rise to red blood cells, which shed their DNA as they mature. Victoria is the first of 45 patients expected to enroll, with results in summer 2022.

 

Altering the germline is a different story.

 

 

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

Be the first to comment

How a one-time CRISPR shot could obliterate lower back pain

 

Today [August 13] the US National Academy of Sciences is hosting the first meeting of the International Commission on the Clinical Use of Human Germline Genome Editing in Washington, to discuss controversial applications of CRISPR to human eggs, sperm, or fertilized ova, in the wake of Chinese researcher He Jiankui announcing the birth of CRISPR twins after a similar meeting in 2017 (See Do China's controversial CRISPR babies illustrate the need for an undo button?).

 

Although only one clinical trial is up-and-running for CRISPR to treat body cells, with an initial patient making the media rounds just last week to discuss her cells doctored to counter sickle cell disease, many other applications are in preclinical testing — animal models and human cells and organoids. And they're not restricted to rare diseases.

 

Imagine a single injection that quells the inflammation behind lower back pain — perhaps forever. CRISPR may make that possible by dampening the immune system's cytokine signals, according to a report in the July issue of Human Gene Therapy.

 

 

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

Be the first to comment

RIP Kary Mullis, Father of PCR

When the name Kary Mullis popped up in my news feed on Monday, I was excited to read what I thought would be an update on the renegade inventor I'd met years ago at a small biotech gathering in San Diego. Back then, in the late 1980s, I'd interviewed him for Genetic Engineering News, where I had the gene amplification beat – a field that began with the polymerase chain reaction, aka PCR.

 

An Eclectic Technology

 

Kary Mullis died on Monday, August 12, of heart disease and respiratory failure. He was so quirky that obituaries, like the one in the LA Times, led off with such descriptors as "LSD-dropping, climate-change-denying, astrology-believing, board surfing." That obit calls PCR a "discovery." But the technology wasn't laying around waiting for someone to find it, like an ancient skull. Instead, it was an invention deduced from the scrutinizing the mechanics of DNA replication.

 

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

 

 

Be the first to comment

6 Types of Exercise That Counter Inherited Obesity Risk

Exercise is a key component of any weight-loss plan, but it's especially important for people who've inherited a tendency to easily put on pounds. Results of a study published in the August issue of PLOS Genetics adds some granularity to that maxim, parsing 18 activities by their effect on the inherited risk of obesity.

 

Six activities come out on top, with the winner what the researchers call "regular jogging." 

 

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

Be the first to comment

‘Why did I get cancer?’ We can do more to alleviate ‘angst, guilt’ accompanying a diagnosis

When rocker Tom Petty sang "the waiting is the hardest part," he wasn't referring to genetic testing for breast cancer. But he could have been.

 

After the pathology report from a breast biopsy brings bad news, the next step is often a blood test for risk mutations, probing dozens of genes. Because that information guides the course of treatment, waiting for the findings can send one's stress level through the roof. I've been there.

 

If a mutation is found, removing the unaffected breast suddenly becomes an option, for it may already be on the road to cancer. Alerting children, siblings, cousins, and nieces and nephews to a familial risk may be appropriate.

 

Mutations interfere with natural DNA repair, which allows other mutations to persist that release the normal brakes on cell division. By the time a cancer has been around awhile, the errant cells are riddled with mutations.

 

But mutations in the DNA of white blood cells reflect only the 5 to 10 percent of cancers that are inherited — that is, present in the DNA of every cell of the body and dubbed "germline." The majority of cancers start in body (aka somatic) cells; they don't come in with a sperm or egg, but spring up in cells of the affected body part.

 

Most cancers are genetic but not inherited

 

I'm in several Facebook groups for breast cancer survivors. Every few days, someone posts a variation on "My genetic tests are negative. I have no family history, I'm thin, I do triathlons, I'm vegan and don't smoke or drink. So why do I have breast cancer?"

 

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

Be the first to comment

CRISPRed Exosomes Correct Rett Syndrome Communication Breakdown

CRISPR continues to be big news.

 

Condemnation of the gene editing technology was swift late last year when a researcher in China claimed to have used it to doctor the genomes of twin girls to enable them to resist HIV infection.

 

Agricultural and future medical applications of CRISPR continue to inspire debate, while the idea of gene drives to fuel extinctions of disease vectors, like mosquitoes, raises concern over the danger of tinkering too much with ecosystems.

 

CRISPR has entered fiction plots, such as last spring's ridiculous Rampage. The just-axed Netflix reboot of Designated Survivor transformed the acronym into a verb, as in "the bird flu gene was CRISPRed into the virus." Makes me think of biotech bacon.

 

Although curing disease, wiping out mosquitoes, and creating fictional bioweapons are exciting prospects, I'm more interested in the harnessing of CRISPR to peek at the origins of disease, in cells. Hollis Cline, PhD, and her colleagues at the Scripps Research Institute have done just that to investigate Rett syndrome, reporting in the Proceedings of the National Academy of Sciences.

 

A Neurological Syndrome 

 

Rett Syndrome affects 1 in every 10,000-15,000 girls, and very rarely boys. The son of NBC news correspondent Richard Engel is an exception; he has a mild mutation. The condition typically arises as a new, dominant mutation on the X chromosome in a gene called MECP2.

 

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

Be the first to comment