Category Archives: Gene therapy

Engineering a patients own immune cells to resist HIV could eliminate the need for lifelong antiretroviral therapies.

The immune cells of HIV patients can be genetically engineered to resist infection, say researchers. In a small study in humans, scientists report that by creating a beneficial mutation in T cells, they may be able to nearly cure patients of HIV.

In a study published in the New England Journal of Medicine on Wednesday, researchers report that they can use genome editing to re-create the rare mutations responsible for protecting about 1 percent of the population from the virus in infected patients. They report that some of the patients receiving the genome-modifying treatment showed decreased viral loads during a temporary halt of their antiretroviral drugs. In one patient, the virus could no longer be detected in his blood.

Zinc-finger nucleases are one of a few genome-editing tools that researchers use to create specific changes to the genomes of living organisms and cells (see Genome Surgery). Scientists have previously used genome-editing techniques to modify DNA in human cells and nonhuman animals, including monkeys (see Monkeys Modified with Genome Editing). Now, the NEJM study suggests the method can also be safely used in humans.

From each participating patient, the team harvested bone marrow stem cells, which give rise to T cells in the body. They then used a zinc finger nuclease to break copies of the CCR5 gene that encodes for proteins on the surface of immune cells that are a critical entry point of HIV. The stem cells were then infused back into each patients bloodstream. The modification process isnt perfect, so only some of the cells end up carrying the modification. About 25 percent of the cells have at least one of the CCR5 genes interrupted, says Edward Lanphier, CEO of Sangamo Biosciences, the Richmond, California, biotech company that manufactures zinc finger nucleases.

Because the cells are a patients own, there is no risk of tissue rejection. The modified stem cells then give rise to modified T cells that are more resistant to infection by HIV, say the researchers.

One week after the infusion, researchers were able to find modified T cells in the patients blood. Four weeks after the infusion, six of the 12 patients in the study temporarily stopped taking their antiretroviral drugs so the researchers could assess the effect of the genome-editing treatment on the amount of the virus in the patients bodies. In four of these patients, the amount of HIV in the blood dropped. In one patient, the virus could no longer be detected at all. The team later discovered that this best responder had naturally already had one mutated copy of the CCR5 gene.

Patients who carry one broken copy of the CCR5 progress to AIDS more slowly than those who dont, says Bruce Levine, a cell and gene therapy researcher at the University of Pennsylvania School of Medicine and coauthor on the study. Because all of the cells in that best-responder patient already carried one disrupted copy of CCR5, the modification by the zinc finger nuclease led to T cells with no functional copies of the gene. That means the cells are fully resistant to HIV infection. The team is now working to increase the number of immune cells that end up carrying two broken copies of CCR5.

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Can Gene Therapy Cure HIV?

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HIV attacks a type of immune cell known as a T cell (shown here) using a protein encoded by the CCR5 gene.

A clinical trial has shown that a gene-editing technique can be safe and effective in humans. For the first time, researchers used enzymes called zinc-finger nucleases (ZFNs) to target and destroy a gene in the immune cells of 12 people with HIV, increasing their resistance to the virus to the virus. The findings are published today in The New England Journal of Medicine1.

This is the first major advance in HIV gene therapy since it was demonstrated that the Berlin patient Timothy Brown was free of HIV, says John Rossi, a molecular biologist at the Beckman Research Institute of the City of Hope National Medical Center in Duarte, California. In 2008, researchers reported that Brown gained the ability to control his HIV infection after they treated him with donor bone-marrow stem cells that carried a mutation in a gene called CCR5. Most HIV strains use a protein encoded by CCR5 as a gateway into the T cells of a hosts immune system. People who carry a mutated version of the gene, including Brown's donor, are resistant to HIV.

But similar treatment is not feasible for most people with HIV: it is invasive, and the body is likely to attack the donor cells. So a team led by Carl June and Pablo Tebas, immunologists at the University of Pennsylvania in Philadelphia, sought to create the beneficial CCR5 mutation in a persons own cells, using targeted gene editing.

The researchers drew blood from 12 people with HIV who had been taking antiretroviral drugs to keep the virus in check. After culturing blood cells from each participant, the team used a commercially available ZFN to target the CCR5 gene in those cells. The treatment succeeded in disrupting the gene in about 25% of each participants cultured cells; the researchers then transfused all of the cultured cells into the participants. After treatment, all had elevated levels of T cells in their blood, suggesting that the virus was less capable of destroying them.

Six of the 12 participants then stopped their antiretroviral drug therapy, while the team monitored their levels of virus and T cells. Their HIV levels rebounded more slowly than normal, and their T-cell levels remained high for weeks. In short, the presence of HIV seemed to drive the modified immune cells, which lacked a functional CCR5 gene, to proliferate in the body. Researchers suspect that the virus was unable to infect and destroy the altered cells.

They used HIV to help in its own demise, says Paula Cannon, who studies gene therapy at the University of Southern California in Los Angeles. They throw the cells back at it and say, Ha, now what?

In this first small trial, the gene-editing approach seemed to be safe: Tebas says that the worst side effect was that the chemical used in the process made the patients bodies smell bad for several days.

The trial isnt the end game, but its an important advance in the direction of this kind of research, says Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases in Bethesda, Maryland. Its more practical and applicable than doing a stem-cell transplant, he says, although it remains to be seen whether it is as effective.

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Gene-editing method tackles HIV in first clinical test

PHILADELPHIA University of Pennsylvania researchers have successfully genetically engineered the immune cells of 12 HIV positive patients to resist infection, and decreased the viral loads of some patients taken off antiretroviral drug therapy (ADT) entirelyincluding one patient whose levels became undetectable. The study, appearingtoday in the New England Journal of Medicine, is the first published report of any gene editing approach in humans.

The phase I study was co-authored by researchers at Penn Medicine, the Albert Einstein College of Medicine and scientists from Sangamo BioSciences, which developed the zinc finger nuclease (ZFN) technology, the T cell therapy approach used in the clinical trial.

This study shows that we can safely and effectively engineer an HIV patients own T cells to mimic a naturally occurring resistance to the virus, infuse those engineered cells, have them persist in the body, and potentially keep viral loads at bay without the use of drugs, said senior author Carl H. June, MD, the Richard W. Vague Professor in Immunotherapy in the department of Pathology and Laboratory Medicine at Penns Perelman School of Medicine. This reinforces our belief that modified T cells are the key that could eliminate the need for lifelong ADT and potentially lead to functionally curative approaches for HIV/AIDS.

June and his colleagues, including Bruce L. Levine, PhD, the Barbara and Edward Netter Associate Professor in Cancer Gene Therapy in the department of Pathology and Laboratory Medicine and the director of the Clinical Cell and Vaccine Production Facility at Penn, used the ZFN technology to modify the T cells in the patientsa molecular scissors, of sorts, to mimic the CCR5-delta-32 mutation. That rare mutation is of interest because it provides a natural resistance to the virus, but in only 1 percent of the general population. By inducing the mutations, the scientists reduced the expression of CCR5 surface proteins. Without those, HIV cannot enter, rendering the patients cells resistant to infection.

For the study, the team infused the modified cells known as SB-728-Tinto two cohorts of patients, all treated with single infusionsabout 10 billion cellsbetween May 2009 and July 2012. Six were taken off antiretroviral therapy altogether for up to 12 weeks, beginning four weeks after infusion, while six patients remained on treatment.

Infusions were deemed safe and tolerable, the authors report, and modified T cells continued to persist in the patients during follow up visits. One week after the initial infusion, testing revealed a dramatic spike in modified T cells inside the patients bodies. While those cells declined over a number of weeks in the blood, the decrease of modified cells was significantly less than that of unmodified T cells during ADT treatment interruption. Modified cells were also observed in the gut-associated lymphoid tissue, which is a major reservoir of immune cells and a critical reservoir of HIV infection, suggesting that the modified cells are functioning and trafficking normally in the body.

The study also shows promise in the approachs ability to suppress the virus. The viral loads (HIV-RNA) dropped in four patients whose treatment was interrupted for 12 weeks. One of those patients viral loads dropped below the limit of detection; interestingly, it was later discovered that the patient was found to be heterozygous for the CCR5 delta-32 gene mutation.

Since half the subject's CCR5 genes were naturally disrupted, the gene editing approach was building on the head start provided by inheriting the mutation from one parent, said Levine. This case gives us a better understanding of the mutation and the bodys response to the therapy, opening up another door for study.

Therapies based on the CCR5 mutation have gained steam over the last six years, particularly after a man known as the Berlin Patient was functionally cured. Diagnosed with acute myeloid leukemia (AML), he received a stem cell transplant from a donor who had the CCR5 mutation in both alleles (from both parents) and has remained off ADT since 2008. Researchers are attempting to replicate this phenomenon because allogeneic transplantswhich carry a high mortality risk and require lengthy hospitalizationsare not a practical solution for HIV patients who do not have blood cancers. Nor are they effective in ridding the body of HIV unless the donor has the mutated gene in both alleles, as shown recently in two Boston patients who were thought to have been functionally cured from transplants, only to see their viral loads spike.

Though disappointing to the research community, the Boston patients results highlight key factors when combating the virus.

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Personalized Gene Therapy Locks Out HIV, Paving the Way to Control Virus Without Antiretroviral Drugs

Injections of a normally silent gene sparked recovery in pigs induced to have heart attacks

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When a heart attack brings blood flow to a screeching halt, thats only the first assault on our fist-size organ. Among survivors, the recovery itself fuels more permanent damage to the heart. Scar tissue can harden once-flexible heart muscle, making it less elastic. And as tentacles of this tissue creep over the aorta the heart muscle can no longer fully contract. This long-term damage can minimize the amount of oxygen-rich blood sent throughout the body, which can send patients spiraling into heart failure. Heart transplants are one way to circumvent these scar tissue issues, but donor hearts are always in short supply. Devising other truly effective solutions has long eluded researchers. A form of gene therapy, however, is now showing promise in pigs. It turns out that a normally silent gene called Cyclin A2, or CCNA2, can be coaxed into action to combat the formation of scar tissue in pigs that suffer a heart attack. This treatment sparked regeneration of heart muscle cells in pigs as well as improvements in the volume of blood pushed out with every beat. The finding is published in the February 19 issue of Science Translational Medicine. Gene therapy, the authors hope, may one day join stem cell treatments as a contender for transforming the way doctors treat heart failure. Stem cellbased therapies have already resulted in more healthy tissue and decreased scar mass in human clinical trials as well as small improvements in how much blood the heart can pump from one chamber to another. But as Scientific American reported in April 2013, many questions remain about which stem cells to use and how to prepare them. For this study, researchers randomly assigned 18 pigs recovering from heart attacks to either receive injections of the gene expressed under a promoter (which would force it to be expressed) or the same solution without the gene. Pigs treated with the gene had greater success pushing out blood with each heartbeat, but also produced a greater number of heart muscle cells. These findings echo the teams earlier heart regeneration successes in mice and rats. The researchers replicated their findings in a petri dish and watched adult porcine heart muscle cells treated with the same regimen of gene therapy undergo complete cell division in the dishdemonstrating under a microscope how the heart cells were dividing and thriving with the gene therapy. This new approach mimics the kind of regeneration we see in the newt and zebra fish, says lead author Hina Chaudhry, the director of cardiovascular regenerative medicine at The Mount Sinai Hospital in New York City. If the technique proves successful in humans, it could boost patient recovery rates by helping strengthen heart muscles and improving blood flow, all while giving a needed lift to gene therapy research, which has been slow to gain momentum in the U.S. In 1999 Jesse Gelsinger, 18, died after a gene therapy experiment cost him his life. The virus used to deliver a gene that would potentially control his rare digestive disorder fueled a massive and fatal immune reaction. That highly publicized case, along with other gene therapy missteps, put a pall on the field. Chaudhry says that her team is proceeding with caution and plans to be careful when administering this treatment to patient populations. For patients who have a large heart attack who are at risk of heart failure, I think the therapy is going to be very beneficial, she says. If you have a small heart attack, it probably wont make as much of a difference in overall survival because of advances with todays medicines. As more researchers look to gene therapy for previously intractable human conditions, a success with heart attack treatments could send ripples throughout the field.

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Gene Therapy Shows Promise for Treating Heart Attack Victims

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NEW YORK(CBSNewYork) It has been called the cancer breakthrough of the year by a major scientific journal.

Therapy that eradicates cancer using a patients own cells has already saved a number of terminal leukemia patients, CBS 2s Dr. Max Gomez reported.

It has been the Holy Grail of cancer therapy and it harnesses the patients own immune system to attack cancer.

Now, a major new study has shown how to do that when treating leukemia. It involves using gene therapy to convert a patients white blood cells into killers.

Ive had several doctors tell me there is nothing else that can be done, leukemia patient Paolo Cavalli said, It is difficult with a new family to think about those things.

After six years of chemotherapy, stem cell transplants, and multiple relapses Cavalli was out of options for his leukemia.

I dont think I had many days left, he said.

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Dr. Max Gomez: Gene Therapy Could Be Lifesaver For Cancer Patients

By combining a synthetic scaffolding material with gene delivery techniques, researchers at Duke University are getting closer to being able to generate replacement cartilage where it's needed in the body.

Performing tissue repair with stem cells typically requires applying copious amounts of growth factor proteins -- a task that is very expensive and becomes challenging once the developing material is implanted within a body. In a new study, however, Duke researchers found a way around this limitation by genetically altering the stem cells to make the necessary growth factors all on their own.

They incorporated viruses used to deliver gene therapy to the stem cells into a synthetic material that serves as a template for tissue growth. The resulting material is like a computer; the scaffold provides the hardware and the virus provides the software that programs the stem cells to produce the desired tissue.

The study appears online the week of Feb. 17 in the Proceedings of the National Academy of Sciences.

Farshid Guilak, director of orthopaedic research at Duke University Medical Center, has spent years developing biodegradable synthetic scaffolding that mimics the mechanical properties of cartilage. One challenge he and all biomedical researchers face is getting stem cells to form cartilage within and around the scaffolding, especially after it is implanted into a living being.

The traditional approach has been to introduce growth factor proteins, which signal the stem cells to differentiate into cartilage. Once the process is under way, the growing cartilage can be implanted where needed.

"But a major limitation in engineering tissue replacements has been the difficulty in delivering growth factors to the stem cells once they are implanted in the body," said Guilak, who is also a professor in Duke's Department of Biomedical Engineering. "There's a limited amount of growth factor that you can put into the scaffolding, and once it's released, it's all gone. We need a method for long-term delivery of growth factors, and that's where the gene therapy comes in."

For ideas on how to solve this problem, Guilak turned to his colleague Charles Gersbach, an assistant professor of biomedical engineering and an expert in gene therapy. Gersbach proposed introducing new genes into the stem cells so that they produce the necessary growth factors themselves.

But the conventional methods for gene therapy are complex and difficult to translate into a strategy that would be feasible as a commercial product.

This type of gene therapy generally requires gathering stem cells, modifying them with a virus that transfers the new genes, culturing the resulting genetically altered stem cells until they reach a critical mass, applying them to the synthetic cartilage scaffolding and, finally, implanting it into the body.

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Regenerating orthopedic tissues within the human body

Duke researchers use gene therapy to direct stem cells into becoming new cartilage on a synthetic scaffold even after implantation into a living body

By Ken Kingery

By combining a synthetic scaffolding material with gene delivery techniques, researchers at Duke University are getting closer to being able to generate replacement cartilage where it's needed in the body.

Performing tissue repair with stem cells typically requires applying copious amounts of growth factor proteinsa task that is very expensive and becomes challenging once the developing material is implanted within a body. In a new study, however, Duke researchers found a way around this limitation by genetically altering the stem cells to make the necessary growth factors all on their own.

They incorporated viruses used to deliver gene therapy to the stem cells into a synthetic material that serves as a template for tissue growth. The resulting material is like a computer; the scaffold provides the hardware and the virus provides the software that programs the stem cells to produce the desired tissue.

The study appears online the week of Feb. 17 in the Proceedings of the National Academy of Sciences.

An artistic rendering of human stem cells on the polymer scaffolds. Photo courtesy of Charles Gersbach and Farshid Guilak, Duke University

The traditional approach has been to introduce growth factor proteins, which signal the stem cells to differentiate into cartilage. Once the process is under way, the growing cartilage can be implanted where needed.

But a major limitation in engineering tissue replacements has been the difficulty in delivering growth factors to the stem cells once they are implanted in the body, said Guilak, who is also a professor in Dukes Department of Biomedical Engineering. Theres a limited amount of growth factor that you can put into the scaffolding, and once its released, its all gone. We need a method for long-term delivery of growth factors, and thats where the gene therapy comes in.

A microscopic view using electron microscopy of human stem cells and viral gene carriers adhering to the fibers of a polymer scaffold. Photo courtesy of Charles Gersbach and Farshid Guilak, Duke University

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Gene Therapy Might Grow Replacement Tissue Inside the Body

Stamford, CT (PRWEB) February 06, 2014

Alliance for Cancer Gene Therapy (ACGT) the nations only non-profit dedicated exclusively to cell and gene therapies for cancer is redoubling its efforts to treat and combat cancers in the New Year, and announces $1 million in recent grants.

The funding spread across three grants will support basic and clinical science at premier institutions in and outside the United States, with ACGTs mission top-of-mind: uncovering effective, innovative cancer treatments that supersede radiation, chemotherapy and surgery.

This January, ACGTs President and Co-Founder Barbara Netter has announced two Young Investigator Grants that provide promising researchers with $250,000 each for two- to three-year studies.

Young Investigator Fan Yang, PhD Assistant Professor of Orthopedic Surgery and Bioengineering at Stanford University will use the funds to research new treatment options for pediatric brain cancer, the leading cause of death from childhood cancer. Dr. Yangs study will deploy adult-derived stem cells to target solid brain tumor cells, which are often highly invasive and difficult to treat.

Arnob Banerjee, MD, PhD Assistant Professor of Hematology and Oncology at the University of Maryland will use ACGTs funding to further develop the long-term effectiveness of immune-mediated treatments, the most advanced form of gene therapy.

It is imperative that the best and brightest young scientists like Fan Yang and Arnob Banerjee have the funds necessary to study and treat cancer, Netter said. This was my husband Edwards vision in 2001, when gene cell therapy was a fledgling science. We are proud to continue his pioneering foresight today. Partnerships with Dr. Yang, a former fellow at MIT, and Dr. Banerjee, a former fellow and instructor at the University of Pennsylvania, dovetail with ACGTs record of funding outstanding researchers and physicians with the capability to make unprecedented breakthroughs.

The Young Investigator grants come on the heels of a $500,000 Investigators Award to John Bell, PhD, Senior Research Scientist and Professor of Medicine at the Ottawa Hospital Research Institute in Canada. Dr. Bell has worked extensively with oncolytic viruses man-made viruses that target only cancer cells, and spare patients the harrowing side-effects of chemotherapy, radiation or surgery and has discovered the enormous promise they offer in the war on cancer.

The research and trials funded by ACGTs grant have the potential to treat metastatic and recurrent brain cancer, extend patients survival timeline, and vastly improve patients quality of life during treatment, Dr. Bell said.

ACGT has served as a major funding engine in the fight against cancer since its formation in 2001, and has provided nearly $25 million in grants to date. ACGT was created by Barbara and Edward Netter after the loss of their daughter-in-law to breast cancer. Since Edwards passing in 2011, Barbara Netter has led the foundation as President and Co-Founder, continuing her husbands vision.

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Alliance for Cancer Gene Therapy (ACGT) Targets Brain, Pediatric Cancers with $1 Million in New Grants

Researchers used blood platelets and bone marrow cells to deliver potentially curative gene therapy to mouse models of the human genetic disorder Hurler syndrome -- an often fatal condition that causes organ damage and other medical complications.

Scientists from Cincinnati Children's Hospital Medical Center and the National Institute of Neurological Disorders and Stroke (NINDS) report their unique strategy for treating the disease the week of Feb. 3-7 in Proceedings of the National Academy of Sciences (PNAS).

Researchers were able to genetically insert into the cells a gene that produces a critical lysosomal enzyme (called IDUA) and then inject the engineered cells into mice to treat the disorder. Follow up tests showed the treatment resulted in a complete metabolic correction of the disease, according to the authors.

"Our findings demonstrate a unique and somewhat surprising delivery pathway for lysosomal enzymes," said Dao Pan, PhD, corresponding author and researcher in the Division of Experimental Hematology and Cancer Biology at Cincinnati Children's. "We show proof of concept that platelets and megakaryocytes are capable of generating and storing fully functional lysosomal enzymes, which can lead to their targeted and efficient delivery to vital tissues where they are needed."

The mice tested in the study modeled human Hurler syndrome, a subset of disease known as mucopolysaccharidosis type I (MPS I), one of the most common types of lysosomal storage diseases. MPS I is a lysosomal storage disease in which people do not make an enzyme called lysosomal alpha-L-iduronidase (IDUA).

IDUA helps break down sugar molecules found throughout the body, often in mucus and fluids around joints, according to the National Library of Medicine/National Institutes of Health. Without IDUA, sugar molecules build up and cause organ damage. Depending on severity, the syndrome can also cause deafness, abnormal bone growth, heart valve problems, joint disease, intellectual disabilities and death.

Enzyme replacement therapy can be used to treat the disease, but it is only temporary and not curative. Bone marrow transplant using hematopoietic stem cells also has been tested on some patients with mixed results. The transplant procedure can carry severe risks and does not always work.

Pan and her colleagues -- including Roscoe O. Brady, MD, a researcher at NINDS -- report that using platelets and megakaryocytes for gene therapy is effective and could reduce the risk of activating cancer-causing oncogenes in hematopoietic stem cells.

The authors said tests showed that human megakaryocytic cells were capable of overexpressing IDUA, revealing their capacity for potential therapeutic benefit. While engineering megakaryocytes and platelets for infusion into their mouse models of Hurler, the scientists report they were able to release IDUA directly into amply sized extracellular spaces or inside micro-particles as the cells matured or activated. The cells were able to produce and package large amounts of functional IDUA and retained the capacity to cross-correct patient cells.

After infusing mouse models of Hurler with the genetically modified cells, researchers said this led to long-term normalization of IDUA levels in the animal's blood with versatile delivery routes and on-target preferential distribution to the liver and spleen. The treatment led to a complete metabolic correction of MPS I in most peripheral organs of the mice.

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Gene therapy may be possible cure for Hurler syndrome: Mouse Study

PUBLIC RELEASE DATE:

4-Feb-2014

Contact: Nick Miller nicholas.miller@cchmc.org 513-803-6035 Cincinnati Children's Hospital Medical Center

CINCINNATI Researchers used blood platelets and bone marrow cells to deliver potentially curative gene therapy to mouse models of the human genetic disorder Hurler syndrome an often fatal condition that causes organ damage and other medical complications.

Scientists from Cincinnati Children's Hospital Medical Center and the National Institute of Neurological Disorders and Stroke (NINDS) report their unique strategy for treating the disease the week of Feb. 3-7 in Proceedings of the National Academy of Sciences (PNAS).

Researchers were able to genetically insert into the cells a gene that produces a critical lysosomal enzyme (called IDUA) and then inject the engineered cells into mice to treat the disorder. Follow up tests showed the treatment resulted in a complete metabolic correction of the disease, according to the authors.

"Our findings demonstrate a unique and somewhat surprising delivery pathway for lysosomal enzymes," said Dao Pan, PhD, corresponding author and researcher in the Division of Experimental Hematology and Cancer Biology at Cincinnati Children's. "We show proof of concept that platelets and megakaryocytes are capable of generating and storing fully functional lysosomal enzymes, which can lead to their targeted and efficient delivery to vital tissues where they are needed."

The mice tested in the study modeled human Hurler syndrome, a subset of disease known as mucopolysaccharidosis type I (MPS I), one of the most common types of lysosomal storage diseases. MPS I is a lysosomal storage disease in which people do not make an enzyme called lysosomal alpha-L-iduronidase (IDUA).

IDUA helps break down sugar molecules found throughout the body, often in mucus and fluids around joints, according to the National Library of Medicine/National Institutes of Health. Without IDUA, sugar molecules build up and cause organ damage. Depending on severity, the syndrome can also cause deafness, abnormal bone growth, heart valve problems, joint disease, intellectual disabilities and death.

Enzyme replacement therapy can be used to treat the disease, but it is only temporary and not curative. Bone marrow transplant using hematopoietic stem cells also has been tested on some patients with mixed results. The transplant procedure can carry severe risks and does not always work.

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Mouse study shows gene therapy may be possible cure for Hurler syndrome