Scientists find way to silence extra chromosome that causes Down syndrome

Scientists find way to silence extra chromosome that causes Down syndrome

For patients suffering from Down syndrome, the source of their condition can be traced back to just one extra chromosome inherited during development – chromosome 21.

While it is still unclear exactly how this extra copy causes the symptoms of Down syndrome – also known as trisomy 21, its presence in a person’s genetic code is associated with delayed cognitive ability, slowed physical development and a whole host of health conditions, including congenital heart disease, cancer and early on-set Alzheimer’s.

But now, researchers say they have found a way to turn off the extra copy of chromosome 21.

In a new study published online in the journal Nature, scientists from University of Massachusetts Medical School (UMMS) harnessed the abilities of a naturally occurring gene called XIST that acts as an “off switch” in X chromosomes.  In a culture of stem cells, the researchers were able to repurpose the XIST gene so that instead of silencing X chromosomes, it silenced the extra chromosome 21 instead.

Though the research only shows proof-of-principle for turning off the chromosome – meaning the method is a long way from being utilized in humans – the findings have huge implications for the future of Down syndrome research. Researchers hope this study will pave the way for a better understanding of the disorder’s pathology and potentially help to create new therapeutic targets for therapies.

“This is the beginning of this idea, and we’re hoping more investigators get interested,” lead researcher Jeanne Lawrence, professor of cell and developmental biology at UMMS, told FoxNews.com. “… We used epigenetics, a new concept, to change the way the DNA is expressed, not changing the DNA itself. This could have a lot of promise in other ways for Down syndrome and other disorders.”

Each human inherits 23 chromosomes from their mother and 23 from their father, equaling 46 chromosomes in each cell.  Individuals with Down syndrome inherit three (instead of two) copies of chromosome 21, which ultimately causes their “trisomy 21.” 

According to Lawrence, the team’s method for silencing this chromosome was inspired by a naturally occurring process that occurs in women every day.

“What’s important in biology is not that you have the right sequence to your DNA, but you have the right balance of DNA,” Lawrence said.  “Women have two X chromosomes and men have one X and Y.  Since the Y chromosome lacks a lot of the genes in the X chromosomes, women have more expression of X chromosome genes than men – well that wouldn’t work biologically.  So nature had to devise a mechanism to equalize that.”

Lawrence had contributed to a previous study, which had identified that mechanism as the XIST gene, a piece of DNA located in the X chromosome that controls whether or not the chromosome can be silenced.  The XIST gene makes a unique non-coding RNA, which accumulates in the nucleus of the cell of the chromosome, triggering changes to the way the chromosome is packaged within the cell.  This ultimately renders the chromosome inactive – preventing its DNA from producing proteins and other components.

Hoping to recreate this effect, Lawrence and first author Dr. Jun Jiang, along with UMMS colleague Dr. Lisa Hall, devised a way to insert the XIST gene into the extra chromosome 21 of trisomic cells.  In a culture of pluripotent stem cells derived from the skin cells of a Down syndrome patient, the XIST gene was inserted into the chromosomes through the use of zinc finger nuclease (ZFN) technology. The technique ultimately allowed them to cut each chromosome at a specific location in its sequence and then paste the gene into that cut site.

“(Once the gene was inserted), we split the cultures, and took half the cells and turned on the XIST gene to silence the chromosome and (in) the other half we didn’t do that,” Lawrence said.  “Then we directly compared how the cell behavior changes…and the neural progenitor cells formed much more quickly in the (cultures) that we had silenced. So you can quickly start to say, ‘What are the pathologies of the different cells and the different organs?’”

According to Lawrence, the success of their findings will ultimately help researchers better understand the different cell pathologies in patients and how the disorder progresses during development.  She also noted the more significant implication of their research: that it could ultimately lead to the utilization of chromosome therapies in Down syndrome patients.  However, it may be many years before these treatments are realized.

Approximately 6,000 babies with Down syndrome are born each year in the United States, according to the Centers for Disease Control and Prevention.  Risk factors for Down syndrome include having a parent with a chromosomal disorder or having a sibling with Down syndrome or another chromosomal disorder. However, the mechanisms behind the condition are still largely unknown. Lawrence hopes that her lab’s findings will help get more people interested in better understanding the disorder.

“Down syndrome hasn’t received as much attention for therapeutics, partly because it’s so complex and there (are) other procedures people use to treat it,” Lawrence said.  “Also, people think Down syndrome is going away, but it’s not going away.  I think it’s good if this can help draw attention to research (for the disorder).”



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Hundreds Offer To Adopt Baby With Down Syndrome To Save It From Abortion

Amazing to see so many people offer to save a child prenatally diagnosed with Down syndrome. If only more families would offer their baby up for adoption, as there are hundreds of families waiting to adopt a baby with DS.

Of course there will be negativity to this also, as I saw one article that was totally hating on the idea of saving a baby with Down syndrome from an abortion. So sickening. Reminds me of this song.

Hundreds call to adopt Down syndrome baby, save it from abortion

When the Rev. Thomas Vander Woude learned about a young couple planning to abort their unborn baby that had been diagnosed with Down syndrome, the priest reached out and offered a deal: Deliver the child and he would help find an appropriate adoptive family.

But he had to act fast.

The woman, who has not been identified for her privacy and her protection, was just shy of six months pregnant and lives in a state that prohibits abortions past 24 weeks — which meant he had a short time to find a family willing to make a lifelong commitment.

So Father Vander Woude, the lead pastor at Holy Trinity Catholic Church in Gainesville, Va., approached a volunteer who helped manage the church’s social media pages, and she posted an urgent plea on Facebook early Monday morning.

“There is a couple in another state who have contacted an adoption agency looking for a family to adopt their Down Syndrome unborn baby. If a couple has not been found by today they plan to abort the baby. If you are interested in adopting this baby please contact Fr. VW IMMEDIATELY,” the post read. “We are asking all to pray for this baby and the wisdom that this couple realize the importance of human life and do not abort this beautiful gift from God.”

The post asked people to call the church’s office after 9:30 a.m. Monday or to email Father Vander Woude.

No one expected the response they received.

“When we got in and opened up around 9:30, it was nearly nonstop. All day long, we were receiving phone calls from people who wanted to adopt the baby,” church staff member Martha Drennan said. “Father Vander Woude has gotten over 900 emails in regard to the baby.”

The offers were narrowed to three families, which the unborn child’s parents are reviewing with the help of an adoption agency.

Ms. Drennan said the church received phone calls from all over the United States and around the world, including from England, Puerto Rico and the Netherlands.

“I think it is a wonderful use of social media, that word can so quickly get all over the country and even to foreign countries and that the people who see the value of life are stepping up and saying, ‘I will take that baby and raise that baby as mine,’” Ms. Drennan said. “It was a beautiful witness all day long that so many people wanted this child and believed in the dignity of that child — Down syndrome or not.”

The president and founder of the International Down Syndrome Coalition, Diane Grover, stressed the importance of informing couples who are considering abortion for babies with Down syndrome that adoption is a viable option, pointing to the fast and overwhelming response her organization received about this one unborn child as an amazing example.

“When [couples are] in that position, a lot of people wonder if their child [with Down syndrome] would actually get adopted,” Ms. Grover said. “There’s a lot of people waiting, and we are happy to always help.”

David Dufresne, a seminary student who plans to become a priest next year, volunteered to help the overwhelmed church staff take calls.

“I was taking calls for about three hours straight, just talking to people who are willing to adopt this little baby they never knew about until that morning,” Mr. Dufresne said. “I mean, all day long, just receiving phone calls from people who were so generous and within a couple minutes made a life-changing decision. I was really inspired by the goodness of people and what they would do to save a life.”



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Drug Improves Cognitive Function in Mouse Model of Down Syndrome

This was posted on the DSTNI listserv by Richard and I thought I'd share here:

Drug Improves Cognitive Function in Mouse Model of Down Syndrome

July 2, 2013 — An existing FDA-approved drug improves cognitive function in a mouse model of Down syndrome, according to a new study by researchers at the Stanford University School of Medicine.

The drug, an asthma medication called formoterol, strengthened nerve connections in the hippocampus, a brain center used for spatial navigation, paying attention and forming new memories, the study said. It also improved contextual learning, in which the brain integrates spatial and sensory information.

Both hippocampal function and contextual learning, which are impaired in Down syndrome, depend on the brain having a good supply of the neurotransmitter norepinephrine. This neurotransmitter sends its signal via several types of receptors on the neurons, including a group called beta-2 adrenergic receptors.

"This study provides the initial proof-of-concept that targeting beta-2 adrenergic receptors for treatment of cognitive dysfunction in Down syndrome could be an effective strategy," said Ahmed Salehi, MD, PhD, the study's senior author and a clinical associate professor of psychiatry and behavioral sciences. The study will be published online July 2 in Biological Psychiatry.

Down syndrome, which is caused by an extra copy of chromosome 21, results in both physical and cognitive problems. While many of the physical issues, such as vulnerability to heart problems, can now be treated, no treatments exist for poor cognitive function. As a result, children with Down syndrome fall behind their peers' cognitive development. In addition, adults with Down syndrome develop Alzheimer's-type pathology in their brains by age 40. Down syndrome affects about 400,000 people in the United States and 6 million worldwide.

In prior Down syndrome research, scientists have seen deterioration of the brain center that manufactures norepinephrine in both people with Down syndrome and its mouse model. Earlier work by Salehi's team found that giving a norepinephrine precursor could improve cognitive function in a mouse model genetically engineered to mimic Down syndrome.

The new study refined this work by targeting only one group of receptors that respond to norepinephrine: the beta-2 adrenergic receptors in the brain. The researchers began by giving mice a compound that blocks the action of beta-2 adrenergic receptors outside the brain. They then gave the mice formoterol, a drug that can partially cross the blood-brain barrier and that was already known to activate beta-2 adrenergic receptors. Because people with Down syndrome are prone to heart problems, the researchers avoided activating a different group of norepinephrine-sensitive receptors, the beta-1 adrenergic receptors, which predominate in the heart.

The scientists saw improvement on a standard test of contextual learning in mice. In contextual learning, the brain integrates sensory and spatial information to remember the layout of a complex environment: for instance, a person using sounds, smells and sights to remember the location of a store in a shopping mall is using contextual learning. The researchers also saw more synapses and a more complex structure of dendrites, the nerves' outgoing ends, in the hippocampus after the affected mice received formoterol.

"The fact that such a short period of giving medication can make these neurons much more complex is very interesting," Salehi said, noting that mice in the study received the drug for a maximum of two weeks.

Further tests will be needed to determine whether formoterol might be an appropriate treatment for people with Down syndrome or whether to use another drug that activates the same receptors, Salehi said. The dose used in this study was many times higher than that used for asthma treatment, he cautioned, so it is not known whether it is safe. A lower dose might work, or other drugs that affect beta-2 adrenergic receptors might be safer and more effective in humans. Researchers also want to explore what parts of learning -- taking in new information, remembering it or both -- are affected by the drug treatment.

Prior research to improve cognitive function in children with Down syndrome has sometimes raised concerns from families that cognitive treatments would alter positive attributes of these children's personalities, but Salehi said that is not the goal of his team's research.

"Our aim is to enable these children to do better in school," Salehi said. "It is absolutely not to change their personalities or the way they react to society." Changing a child's personality would be much more complicated than activating a subgroup of receptors in the brain, he said.

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Jumpy Monkey Coffee - Helping Individuals with Disabilites Get A Job

This came across the Einstein-Syndrome listserv last week and I thought I'd share:

On Hatteberg's People, creating a meaningful and enriching life for the developmentally disabled is the goal of a non-profit company called Mosaic in Winfield. In a unique relationship, they are partnering with local businesses to enrich the lives of the Mosaic clients, and the key is.... coffee.

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Young Man with Down Syndrome Gets His Driver's License - John Marrs

I've posted a few times about John Marrs, via updates from his mom, Jenny, over the years. John has recently graduated highschool and is now going to a local college. This is the most recent update which his mom shared:

John went into the DMV and took his driver's test yesterday. In IL a student starts driver's training as a 15 year old. You must pass the written portion of the IL test before you get your permit to drive with an adult, which John did. Then, if the driver's ed teacher sees fit, the student is given a license following his 16th birthday. Our teacher was not our best friend. So, John had to wait until after he was 18 to test at the DMV. We finally got around to taking him in yesterday for his driver's test. When he returned from his drive, I was told, "he is amazing!" John is now a licensed driver!

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