(CNN) Scientists began to uncover a link between sugar and heart disease about 60 years ago, and now, the general consensus among experts is that sugar intake is associated with heart disease risk.

But why did it take so long for researchers to inspect this link?

A group then called the Sugar Research Foundation funded some of the early research on fat as the primary risk factor for heart disease, a "sophisticated" tactic to overshadow other research that placed blame on sweets as a risk factor, according to researchers.

The foundation, now called the Sugar Association , questioned the new paper's findings in a response to CNN, saying it's "challenging for us to comment on events that allegedly occurred 60 years ago, and on documents we have never seen." The organization was founded in 1943 by members of the American sugar industry and was dedicated to the scientific study of sugar's role in food, as well as communicating that role to the public.

Researchers said the early heart disease research has implications for Americans' health today.

"If we could rewind the script back to 1965 and we had said, 'You know what, we're not just going to worry about fat and heart disease, we're also going to look at carbohydrates and in particular sugar, because that's a concentrated form of carbohydrate,' things might be really different," said Laura Schmidt, a professor of health policy in the University of California, San Francisco's School of Medicine and a co-author of the new analysis.

"If we had not dismissed the idea that carbohydrates played a significant role in heart disease, we would be potentially in a different place today in terms of our obesity and heart disease rates."

Whatever happened to Yudkin's theory? Researchers suggest that when the sugar industry "manipulated" the scientific debate on heart disease, his theory -- along with other sugar consumption research -- was swept under the rug.

The new paper was led by Cristin Kearns, a postdoctoral researcher at the UCSF School of Dentistry, who collected letters dating from 1959 to 1971 between executives at the Sugar Research Foundation and various scientists.

In one instance, according to the new analysis, foundation Vice President John Hickson received drafts of a review by Hegsted and replied, "Let me assure you this is quite what we had in mind and we look forward to its appearance in print."

"It isn't unusual for faculty who die, for their documents and materials to be stored or given as a gift to the university where they worked," Schmidt said.

"It just so happened that Roger Adams had a long history of working with the sugar organization, and his materials happened to contain documents by industry executives and are one window into how the industry manipulated science."

Kearns, Schmidt and their colleague Stan Glantz, a professor of medicine at UCSF, analyzed the letters and other heart disease research-related public documents -- from symposium proceedings to annual reports -- from the 1950s and 60s.

"It's all the same tricks. ... There was a pretty clear case emerging that eating sugar increased triglycerides, which increased heart disease risk. I think if the science had been left to its own devices, within a few years, there would have been a consensus that there was a causal link, which then should have influenced regulatory policy."

Sugar warnings, then and now

"Experts are still debating what the role of sugar and heart disease is, even though there was evidence going back to the '50s and '60s that a segment of the population with high triglyceride levels should potentially be concerned about their sugar consumption," Kearns said. "Had we come to this conclusion much earlier, people who had this triglyceride level would have been counseled much differently."

The paper suggests that a diet high in added sugars can cause a three-fold increase in the risk of death due to heart disease.

A representative for the Sugar Association emailed a statement from the association to CNN, questioning the new paper's findings about the history of heart disease research and the sugar industry.

"We acknowledge that the Sugar Research Foundation should have exercised greater transparency in all of its research activities, however, when the studies in question were published funding disclosures and transparency standards were not the norm they are today. Beyond this, it is challenging for us to comment on events that allegedly occurred 60 years ago, and on documents we have never seen," the statement said.

"Generally speaking, it is not only unfortunate but a disservice that industry-funded research is branded as tainted. What is often missing from the dialogue is that industry-funded research has been informative in addressing key issues," the Sugar Association statement said. "Most concerning is the growing use of headline-baiting articles to trump quality scientific research -- we're disappointed to see a journal of JAMA's stature being drawn into this trend."

Additionally, rates of obesity -- which puts people at a higher risk of heart disease -- have skyrocketed among both children and adults since the 1970s, according to the Centers for Disease Control and Prevention.

Schmidt, Kearns and Glantz have done the science community "a great public service" by resurfacing the history of funded heart disease research, said Marion Nestle, a professor of nutrition, food studies and public health at New York University, in an editorial accompanying the new paper in JAMA Internal Medicine.

"As George Santayana famously said in 'Reason of Common Sense' (1905), 'Those who cannot remember the past are condemned to repeat it,' " she wrote.

"We have to ask ourselves how many lives and dollars could have been saved, and how different today's health picture would be, if the industry were not manipulating science in this way," he said in the statement. "Only 50 years later are we waking up to the true harm from sugar." </s> The sugar industry began funding research that cast doubt on sugar's role in heart disease -- in part by pointing the finger at fat -- as early as the 1960s, according to an analysis of newly uncovered documents.



In 1964, the group now known as the Sugar Association internally discussed a campaign to address "negative attitudes toward sugar" after studies began emerging linking sugar with heart disease, according to documents dug up from public archives.



In an editorial published Monday that accompanied the sugar industry analysis, New York University professor of nutrition Marion Nestle noted that for decades following the study, scientists and health officials focused on reducing saturated fat, not sugar, to prevent heart disease.



The American Heart Association cites a study published in 2014 in saying that too much added sugar can increase risk of heart disease, though the authors of that study says the biological reasons for the link are not completely understood.



The findings published Monday are part of an ongoing project by a former dentist, Cristin Kearns, to reveal the sugar industry's decades-long efforts to counter science linking sugar with negative health effects, including diabetes. </s> Influential research that downplayed the role of sugar in heart disease in the 1960s was paid for by the sugar industry, according to a report released on Monday.

With backing from a sugar lobby, scientists promoted dietary fat as the cause of coronary heart disease instead of sugar, according to a historical document review published in JAMA Internal Medicine.

Though the review is nearly 50 years old, it also showcases a decades-long battle by the sugar industry to counter the product’s negative health effects.

The findings come from documents recently found by a researcher at the University of San Francisco, which show that scientists at the Sugar Research Foundation (SRF), known today as the Sugar Association, paid scientists to do a 1967 literature review that overlooked the role of sugar in heart disease.

SRF set an objective for the review, funded it and reviewed drafts before it was published in the New England Journal of Medicine, which did not require conflict of interest disclosure until 1984. The three Harvard scientists who wrote the review made what would be $50,000 in today’s dollars from the review.

Marion Nestle, a nutrition, food studies and public health professor at New York University, said the food industry continues to influence nutrition science, in an editorial published alongside the JAMA report.

“Today, it is almost impossible to keep up with the range of food companies sponsoring research – from makers of the most highly processed foods, drinks, and supplements to producers of dairy foods, meats, fruits, and nuts – typically yielding results favorable to the sponsor’s interests,” Nestle said. “Food company sponsorship, whether or not intentionally manipulative, undermines public trust in nutrition science, contributes to public confusion about what to eat, and compromises Dietary Guidelines in ways that are not in the best interest of public health.”

The cushy relationship between food companies and researcher has been captured in recent investigations by the Associated Press and New York Times. The AP revealed in June that candy trade groups were funding research into sweets. And in 2015, the New York Times showed how Coca-Cola has funded millions in research to downplay the link between sugary beverages and obesity.

The Sugar Association said in a statement that SRF “should have exercised greater transparency” in its research, but also accused the study authors of having an “anti-sugar narrative”.

“We question this author’s continued attempts to reframe historical occurrences to conveniently align with the currently trending anti-sugar narrative, particularly when the last several decades of research have concluded that sugar does not have a unique role in heart disease,” the Sugar Association said. “Most concerning is the growing use of headline-baiting articles to trump quality scientific research – we’re disappointed to see a journal of JAMA’s stature being drawn into this trend.”

The findings were based on documents found by Cristin Kearns, a postdoctoral fellow at UCSF, in library archives.

The scientists and executives involved are no longer alive.

In recent years, the link between fat and heart disease has become a more contentious topic – a 2010 review of scientific studies of fat in the American Journal of Clinical Nutrition found that “there is no convincing evidence that saturated fat causes heart disease”. The role of sugar in heart disease is still being debated. </s> NEW YORK (AP) — The sugar industry began funding research that cast doubt on sugar's role in heart disease — in part by pointing the finger at fat — as early as the 1960s, according to an analysis of newly uncovered documents.

The analysis published Monday is based on correspondence between a sugar trade group and researchers at Harvard University, and is the latest example showing how food and beverage makers attempt to shape public understanding of nutrition.

In 1964, the group now known as the Sugar Association internally discussed a campaign to address "negative attitudes toward sugar" after studies began emerging linking sugar with heart disease, according to documents dug up from public archives. The following year the group approved "Project 226," which entailed paying Harvard researchers today's equivalent of $48,900 for an article reviewing the scientific literature, supplying materials they wanted reviewed, and receiving drafts of the article.

The resulting article published in 1967 concluded there was "no doubt" that reducing cholesterol and saturated fat was the only dietary intervention needed to prevent heart disease. The researchers overstated the consistency of the literature on fat and cholesterol, while downplaying studies on sugar, according to the analysis.

"Let me assure you this is quite what we had in mind and we look forward to its appearance in print," wrote an employee of the sugar industry group to one of the authors.

The sugar industry's funding and role were not disclosed when the article was published by the New England Journal of Medicine. The journal, which did not require such disclosures at the time, began requesting author disclosures in 1984.

In an editorial published Monday that accompanied the sugar industry analysis, New York University professor of nutrition Marion Nestle noted that for decades following the study, scientists and health officials focused on reducing saturated fat, not sugar, to prevent heart disease.

While scientists are still working to understand links between diet and heart disease, concern has shifted in recent years to sugar and carbohydrates, and away from fat, Nestle said.

A committee advising the federal government on dietary guidelines says the available evidence shows "no appreciable relationship" between the dietary cholesterol and heart disease, although it still recommended limiting saturated fats.

The American Heart Association cites a study published in 2014 in saying that too much added sugar can increase risk of heart disease, though the authors of that study says the biological reasons for the link are not completely understood.

The findings published Monday are part of an ongoing project by a former dentist, Cristin Kearns, to reveal the sugar industry's decades-long efforts to counter science linking sugar with negative health effects, including diabetes. The latest work, published in the journal JAMA Internal Medicine, is based primarily on 31 pages of correspondence between the sugar group and one of the Harvard researchers who authored the review.

In a statement, the Sugar Association said it "should have exercised greater transparency in all of its research activities," but that funding disclosures were not the norm when the review was published. The group also questioned Kearns' "continued attempts to reframe historical occurrences" to play into the current public sentiment against sugar.

The Sugar Association said it was a "disservice" that industry-funded research in general is considered "tainted."

Companies including Coca-Cola Co. and Kellogg Co. as well as groups for agricultural products like beef and blueberries regularly fund studies that become a part of scientific literature, are cited by other researchers, and are touted in press releases.

Companies say they adhere to scientific standards, and many researchers feel that industry funding is critical to advancing science given the growing competition for government funds. But critics say such studies are often thinly veiled marketing that undermine efforts to improve public health.

"Food company sponsorship, whether or not intentionally manipulative, undermines public trust in nutrition science, contributes to public confusion about what to eat," wrote Nestle, a longtime critic of industry funding of science.

The authors of the analysis note they were unable to interview key actors quoted in the documents because they are no longer alive. They also note there is no direct evidence the sugar industry wrote or changed the manuscript, that the documents provide a limited window into the activities of the sugar industry group and that the roles of other industries and nutrition leaders in shaping the discussion about heart disease were not studied.

Nevertheless, they say the documents underscore why policy makers should consider giving less weight to industry-funded studies. Although funding disclosures are now common practice in the scientific community, the role sponsors play behind the scenes is still not always clear.

In June, the Associated Press reported on a study funded by the candy industry's trade group that found children who eat candy tend to weigh less than those who don't. The National Confectioners Association, which touted the findings in a press release, provided feedback to the authors on a draft even though a disclosure said it had no role in the paper. The association said its suggestions didn't alter the findings.

In November, the AP also reported on emails showing Coca-Cola was instrumental in creating a nonprofit that said its mission was to fight obesity, even though the group publicly said the soda maker had "no input" into its activities. A document circulated at Coke said the group would counter the "shrill rhetoric" of "public health extremists."

Coca-Cola subsequently conceded that it had not been transparent, and the group later disbanded. </s> NEW YORK – The sugar industry began funding research that cast doubt on sugar’s role in heart disease – in part by pointing the finger at fat – as early as the 1960s, according to an analysis of newly uncovered documents.

The analysis published Monday is based on correspondence between a sugar trade group and researchers at Harvard University, and is the latest example showing how food and beverage makers attempt to shape public understanding of nutrition.

In 1964, the group now known as the Sugar Association internally discussed a campaign to address “negative attitudes toward sugar” after studies began emerging linking sugar with heart disease, according to documents dug up from public archives. The following year the group approved “Project 226,” which entailed paying Harvard researchers today’s equivalent of $48,900 for an article reviewing the scientific literature, supplying materials they wanted reviewed, and receiving drafts of the article.

The resulting article that was published in 1967 concluded there was “no doubt” that reducing cholesterol and saturated fat was the only dietary intervention needed to prevent heart disease. The researchers overstated the consistency of the literature on fat and cholesterol, while downplaying studies on sugar, according to the analysis.

“Let me assure you this is quite what we had in mind and we look forward to its appearance in print,” wrote an employee of the sugar industry group to one of the authors.

The sugar industry’s funding and role were not disclosed when the article was published by the New England Journal of Medicine. The journal did not begin requesting author disclosures until 1984.

In an editorial published Monday that accompanied the sugar industry analysis, New York University professor of nutrition Marion Nestle noted that for decades following the study, scientists and health officials focused on reducing saturated fat, not sugar, to prevent heart disease.

While scientists are still working to understand links between diet and heart disease, concern has shifted in recent years to sugars, and away from fat, Nestle said.

A committee that advised the federal government on dietary guidelines said the available evidence shows “no appreciable relationship” between the dietary cholesterol and heart disease, although it still recommended limiting saturated fats. </s> A 1967 literature review in The New England Journal of Medicine pointed to fat and cholesterol as the dietary culprits of heart disease, glossing over evidence from the 1950s that sugar was also linked to heart disease. According to the new report, the NEJM review was sponsored by the Sugar Research Foundation (SRF), which is today the Sugar Association, although its role was not disclosed at the time.

In the report, Laura A. Schmidt of the University of California, San Francisco and colleagues point out that Harvard professor of nutrition Dr. Mark Hegsted co-directed the SRF’s first heart disease research project from 1965 to 1966. Schmidt and colleagues say communications between the SRF, Hegsted and another professor, Roger Adams, uncovered from the University of Illinois archives and the Harvard Medical Library reveal that the foundation set the objective for the literature review, funded it and reviewed drafts of the manuscript.

“I thought I had seen everything but this one floored me,” said Marion Nestle of New York University, who wrote an editorial on the new findings. “It was so blatant. And the ‘bribe’ was so big.”

“Funding research is ethical,” Nestle told Reuters Health by email. “Bribing researchers to produce the evidence you want is not.”

The researchers also reviewed symposium proceedings and historical reports. In 1954, they say, foundation president Henry Haas gave a speech highlighting the potential of reducing American fat intake and recapturing those calories as carbohydrates that would increase the per capita consumption of sugar more than a third.

In 1962, an American Medical Association nutrition report indicated that low-fat high-sugar diets may actually encourage the development of cholesterol. Two years later, according to the new report, SRF vice president John Hickson proposed that the SRF embark on a major program to counter “negative attitudes toward sugar.”

Increasingly, epidemiological reports suggested that blood sugar, rather than blood cholesterol or high blood pressure, was a better predictor of atherosclerosis. Two days after The New York Herald Tribune ran a full page story on the link to sugar in July 1965, the SRF approved “Project 226,” a literature review on cholesterol metabolism to be led by Hegsted and, among others, Fredrick Stare, another Harvard nutritionist with industry financial ties.

Nine months later, Schmidt and colleagues write, Hegsted explained that the project was delayed to continually rewrite rebuttals to new evidence linking sugar to heart disease that had been published in the interim.

By September of 1966, according to the report, Hickson was requesting additional drafts of the literature review from the Harvard researchers, though there is no direct evidence that the Foundation commented on or edited the drafts. By November 2, Hickson had approved the latest draft as “quite what we had in mind.” The two-part review, concluding that the only change necessary to prevent heart disease was to reduce dietary fat intake, was published in the NEJM the following year, with no mention of the SRF’s participation.

The journal did not require conflict of interest disclosure until 1984.

“The sugar association paid very prestigious Harvard scientists to publish a review focusing on saturated fat and cholesterol as the main causes of heart disease at the time when studies were starting to accumulate indicating that sugar is a risk factor for heart disease,” Schmidt told Reuters Health by phone. “That has an impact on the whole research community and where it’s going to go.”

“For example a lot of the messaging during this period around how to prevent heart disease focused on, why don’t you use margarine rather than butter, which has less saturated fat,” Schmidt said. Now we know that margarine is full of trans fat, which causes heart disease and has been nearly eradicated from the U.S. food supply.

“When manufacturers took out fat they added sugar,” she said. “We’ve really lost a lot of time in evaluating how sugar impacts coronary heart disease,” but the actual impact on public health over the last five decades is impossible to measure.

Large amounts of sugar and saturated fats are both detrimental to health and their effects are hard to separate, Nestle said, but it seems reasonable to keep sugar intake to about 10 percent of daily calories.

Today, industry money still funds plenty of scientific research, but increasingly journals and scientists disclose these funding sources, Schmidt said.

“We acknowledge that the Sugar Research Foundation should have exercised greater transparency in all of its research activities, however, when the studies in question were published funding disclosures and transparency standards were not the norm they are today,” the Sugar Association told Reuters Health in a statement. “Beyond this, it is challenging for us to comment on events that allegedly occurred 60 years ago, and on documents we have never seen.”

“The Sugar Association is always seeking to further understand the role of sugar and health, but we rely on quality science and facts to drive our assertions,” the statement said. </s> Image copyright Getty Images Image caption Scientists looked at the genes of people with pulmonary arterial hypertension to find out what was causing the condition

Scientists say they have identified genes that cause a deadly heart condition that can only be cured by transplants of the heart or lungs.

Pulmonary arterial hypertension kills 50% of those affected within five years, but little was known about what caused the condition in some people.

Now experts say they have discovered five genes that cause the illness.

The findings could lead to earlier detection of the disease and ultimately new treatments, researchers say.

Pulmonary arterial hypertension (PAH) currently affects around 6,500 people in the UK and causes the arteries carrying blood from the heart to their lungs to stiffen and thicken, ultimately leading to heart failure.

It is often diagnosed in people who have other heart or lung conditions, but it can affect people of any age and in about a fifth of people there is no obvious cause.

The only "cure" is a transplant of the heart and particularly the lungs, but there is a waiting list for organ transplants and the body will often ultimately reject them, particularly in the case of lungs.

For this latest research, published in Nature Communications, scientists carried out the largest ever genetic study of the disease by analysing the genomes - the unique sequence of a person's DNA - of more than 1,000 PAH patients for whom the cause of the illness was unknown.

They found that mutations in five genes were responsible for causing the illness in these people, including in four genes that were not previously known to be involved in the disease.

In people with the condition these genes fail to effectively produce the proteins that are required for the structure, function and regulation of the body's tissues, researchers found.

Nick Morrell, the lead author of the paper and professor at the British Heart Foundation, told BBC News: "Identifying the nature of these new genes and mutations in the new genes tells you what causes the disease.

"It allows you to design and come up with potential new ways of treating the disease because you have really well-grounded knowledge about what's actually causing it in cases where you find these mutations," he explained.

'People should be more aware'

Image caption Wendy Callaghan was diagnosed with the condition five years ago

Wendy Callaghan, from west London, was diagnosed with PAH in 2013 after doctors became concerned about her persistent chest infection.

Her sister died from the condition 27 years ago at the age of 36, and her grandmother also died from a similar heart condition.

Wendy, who participated in the trial, has been told she has the genetic version of the illness and is now waiting to learn if her daughters and grandchildren have inherited the same deadly condition.

The 58-year-old said: "Even children can get it. People should be more aware of it and look out for the signs and persist with it if they think their child is not well.

"Especially as it does run in families, some people if they don't know they've got it could be passing those genes on to the next generation," Wendy added.

The research was part of a pilot study for the 100,000 Genomes Project - a huge initiative focused on understanding the genetics of cancer and rare diseases.

Prof Morrell said such genetic studies were helping to transform our understanding of rare diseases.

He said: "Often people with rare diseases go to lots of different specialists, everybody is scratching their head a bit, we don't know what the cause is, therefore it's hard to find a treatment for it.

"Now being able to [genetically] sequence people with rare diseases at scale allows you to push the genetics into the clinic and into the families, and it also gives you a cause for the disease which you can potentially do something about," he said.

Darren Griffin, professor of genetics at the University of Kent, who was not involved in the study, said the research was "one of the big successes" of the 100,000 Genome Project.

He said: "By studying the role of rare genetic variation in diseases, we come to a better understanding of the disease pathology itself, which can aid in early diagnosis and in tailoring treatment regimes."

Follow Alex on Twitter. </s> STOCKHOLM/LONDON (Reuters) - Japan’s Yoshinori Ohsumi won the 2016 Nobel prize for medicine for ground-breaking experiments with yeast which exposed a key mechanism in the body’s defenses where cells degrade and recycle their components.

Understanding the science behind the process, called “autophagy” or “self-eating”, has led to a better understanding of diseases such as cancer, Parkinson’s and type 2 diabetes, the prize committee said in its statement on Monday.

“Ohsumi’s discoveries led to a new paradigm in our understanding of how the cell recycles its content,” it said.

The Physiology or Medicine prize, the first of the Nobel prizes awarded each year, is worth 8 million Swedish crowns ($933,000).

Ohsumi, born in 1945 in Fukuoka, Japan, has been a professor at the Tokyo Institute of Technology since 2009. He told Kyodo News agency he was “extremely honored” to get the prize.

In a separate interview with broadcaster NHK, he said he had “always wanted to do something that other people wouldn’t do”.

“I thought the breakdown (of cells) would be interesting, and that was my start,” he said.

Yoshinori Ohsumi, a professor of Tokyo Institute of Technology, attends a news conference after he won the Nobel medicine prize at Tokyo Institute of Technology in Tokyo, Japan, October 3, 2016. REUTERS/Kim Kyung-Hooni

Ohsumi’s work - carried out in the 1990s and described by commentators as “paradigm-shifting” and “pioneering” - included locating the genes that regulate autophagy. This is important for medicine because it helps show why errors in these genes can contribute to a range of diseases.

David Rubinsztein, deputy director of Cambridge University's Institute for Medical Research, said Ohsumi had provided scientists around the world with "critical tools" to help them understand how disrupted autophagy can contribute to illnesses including infectious diseases, cancers and neurodegenerative diseases such as Huntington’s and Parkinson’s.

Infographic ID: '1jLPeM7'

Chister Hoog, a professor at Sweden’s Karolinska Institute, told Reuters the work helped explain crucial processes in human development, from growing up, to aging to succumbing to disease.

“In the very early stages (of a human’s development) your organs and your whole body is constantly being made over again – you are growing. So you need to get rid of the old stuff and generate new structures,” he said.

“When you undergo aging, you have structures that have to be taken away and this – autophagy – is the principle that gets rid of them.

“If you affect this system – the genes and proteins involved in autophagy – you no longer can take care of the waste, and once it accumulates you will get some type of disease.”

Slideshow (4 Images)

This year, the Karolinska Institute, which awards the Nobel medicine prize, has been immersed in a scandal over the hiring of a controversial surgeon. The Swedish government dismissed several members of the board in September.

Prizes for achievements in science, literature and peace were first awarded in 1901 in accordance with the will of dynamite inventor and businessman Alfred Nobel. ($1 = 8.5776 Swedish crowns)

(This version of the story fixes the typo in the name of the Karolinska professor) </s> (CNN) Scientists are getting one step closer to snipping inherited genetic diseases out of human offspring using a gene-editing technique called CRISPR.

For the first time, scientists said, they corrected a gene mutation linked to inherited heart conditions in human embryos using the approach. A study demonstrating the technique was published in the journal Nature on Wednesday (PDF).

Last week, the MIT Technology Review released the first news of this scientific feat, describing the research as the first-known attempt at creating genetically modified human embryos in the United States.

However, Juan Carlos Izpisua Belmonte, a co-author of the study, described it as the first in the world to demonstrate gene-editing to be safe, accurate and efficient in correcting a pathogenic gene mutation in human embryos. Previous attempts by Chinese researchers were unsuccessful at achieving this without safety concerns.

"This is the first that has been demonstrated as safe and working," said Belmonte, a professor at the Salk Institute for Biological Studies' gene expression laboratory in La Jolla, California.

"All cells of the embryo were corrected," he said. "It seems to be working from these samples that we have chosen, but we need to do much more basic research with many other genes."

The study was a collaboration between the Salk Institute, the Oregon Health & Science University in Portland and Korea's Institute for Basic Science.

Scientists estimate that more than 10,000 human diseases may result from mutations to a single gene occurring in all cells of the body, according to the World Health Organization

Cutting and correcting gene mutations

The study used 75 human zygotes in which the father carried a mutation on the MYBPC3 gene, Belmonte said. The eggs used to produce the zygotes did not carry that gene mutation. The researchers noted that they received informed consent from the donors of the eggs, sperm and embryos used in the study.

Hypertrophic cardiomyopathy also is thought to be the most common inherited or genetic heart disease in the US, according to the Centers for Disease Control and Prevention

Newly fertilized eggs before gene editing, left, and embryos after gene editing and a few rounds of cell division.

In a lab dish, the researchers used CRISPR, a gene-editing technique, to remove the harmful MYBPC3 mutation from the human zygotes. Then, the zygotes' own DNA-repair mechanism replaced what was cut out with a copy of a MYBPC3 gene from the mother, which did not carry a mutation, Belmonte said.

"A male research subject known to be heterozygous for this gene mutation was recruited for the study, as were several healthy young egg donors," Dr. Paula Amato, an obstetrician-gynecologist at Oregon Health & Science University, said Tuesday. She was a co-author of the study.

"CRISPR was introduced at the time of sperm injection," she said. "Then, DNA repair of the embryos was assessed."

The researchers found that about 72% of zygotes were properly and safely corrected on the MYBPC3 gene, Belmonte said.

JUST WATCHED On China: Genetically modifying human embryos Replay More Videos ... MUST WATCH On China: Genetically modifying human embryos 01:44

This method significantly differed from studies in which scientists used the CRISPR tool to replace what was cut out with whatever the scientists desired.

"The previous human studies done in China had very small numbers, and one of them used abnormal embryos," Amato said. "So we think this is the first, largest study from which you could draw some reasonable conclusions."

Some gene-editing attempts in human embryos have been problematic, resulting in an issue called mosaicism , in which the corrections made in one gene failed to replicate once that cell divided into two cells, those two cells divided into four cells and so on.

"So when the baby is born, all the cells do not have the mutation anymore. ... This study, it shows that we can correct the embryo and then, after the division, all the cells are corrected, so there's not what we call mosaicism," said Belmonte, who is also a member of the National Academies of Sciences, Engineering and Medicine's committee on human gene editing.

This year, the academies published a report on human genome editing that addressed potential applications of the technology, including the possible prevention or treatment of inherited diseases or conditions.

The future of gene editing

Though the researchers have expressed enthusiasm around their new study, they also noted that the findings must be replicated in followup research before this gene-editing approach can move forward to clinical trials.

"The fact that it is, apparently, a new and poorly understood mechanism and it is not the now standard CRISPR 'cut and replace' method adds to the time needed for research into its safety and effectiveness," said Hank Greely, professor of law and genetics at Stanford University, who was not involved in the new study.

Yet future research can come with some political challenges, Amato said.

"First of all, there are regulations regarding use of federal funds for embryo research, so the (US National Institutes of Health) does not currently support embryo research, so that's one barrier. The other barrier is, the (US Food and Drug Administration) is prohibited from considering any clinical trials related to germline genetic modification," she said.

In this new study the embryos were only allowed to mature to day three after fertilization before they were disaggregated, or isolated into various components, for further analysis.

In the far-off future, a clinical trial could include transplanting corrected embryos into a uterus with the goal of establishing pregnancy and then monitoring the embryos as they develop into children.

Still, "it is way too early to contemplate implanting the edited embryos for the purpose of actually establishing a pregnancy," said Dana Carroll, a professor of biochemistry at the University of Utah who was not involved in the new study but has used CRISPR in his own research.

JUST WATCHED On GPS: Are designer babies in our future? Replay More Videos ... MUST WATCH On GPS: Are designer babies in our future? 01:16

"The genome editing tools are currently not sufficiently efficient and specific to be reliable, and regulatory and oversight processes have not been established," Carroll said, adding that the work on the new study was "well-done" and "well-presented."

"The authors have made an important discovery regarding the repair of CRISPR-induced DNA breaks in human eggs just at the time of fertilization," he said.

"This information will help to guide ongoing research, and it demonstrates that research on early-stage human embryos will be necessary to establish safe and effective procedures in the long run," he said. "There is still a lot of work to do to understand repair processes in very early embryos and to optimize the use of the CRISPR reagents, but this study makes a valuable contribution."

Some CRISPR critics have argued that gene editing may give way to eugenics and to allowing embryos to be edited with certain features in order to develop so-called designer babies

However, the researchers wrote in their study that they hope CRISPR could be considered as an alternative option to preimplantation genetic diagnosis, also known as PGD, for couples at risk of passing on an inherited disease.

'This opens up the possibility for those embryos'

JUST WATCHED What to make of 'Designer Babies' Replay More Videos ... MUST WATCH What to make of 'Designer Babies' 01:28

When only one parent carries a heterozygous mutation on a gene, about half of the embryos from that parent should be mutation-free while the others would have the mutation. Selectively, the parents' doctor would chose the healthy embryos to be implanted and discard the embryos with the mutations, Belmonte said.

Sometimes, "a couple that wants to have a baby and they have a mutation, they may not have enough embryos to choose from," he said. This is when CRISPR can come in.

"This technology, independent of the embryos that are there, it would go on and correct all of them. ... This opens up the possibility for those embryos," he said. "That's important because after the first implantation, if it doesn't work, you can do it again."

The researchers wrote in their study, "PGD may be a viable option for heterozygous couples at risk of producing affected offspring. In cases when only one parent carries a heterozygous mutation, 50% of embryos should be mutant. In contrast, targeted gene correction can potentially rescue a substantial portion of mutant human embryos, thus increasing the number of embryos available for transfer."

Nonetheless, using CRISPR in that way remains a long way off.

Join the conversation See the latest news and share your comments with CNN Health on Facebook and Twitter.

Shoukhrat Mitalipov, director of the Oregon Health & Science University's Center for Embryonic Cell and Gene Therapy, helped lead the new study. In 2013, Mitalipov and his colleagues reported the first success in cloning human stem cells , reprogramming human skin cells back to their embryonic state. In 2007, a research team led by Mitalipov announced that they created the first cloned monkey embryo and extracted stem cells from it.

Now, when it comes to using CRISPR to correct gene mutations in embryos, Mitalipov said Tuesday, "We've done some ground work. ... There is still a long road ahead, and it's unclear at this point when we will be allowed to move on."
A researcher from the University of California, San Francisco discovers that the sugar industry may have manipulated studies about heart diseases.