Author: Nancy Fliesler

With no time to lose, parents drive CMT4J gene therapy forward

CMT4J
Talia Duff’s disorder, CMT4J, is a rare form of Charcot-Marie-Tooth. It has been modeled in mice that will soon undergo a test of gene therapy, largely through her parents’ behind-the-scenes work.

In honor of Rare Disease Day (Feb. 28), we salute “citizen scientists” Jocelyn and John Duff.

When Talia Duff was born, her parents realized life would be different, but still joyful. They were quickly adopted by the Down syndrome parent community and fell in love with Talia and her bright smile.

But when Talia was about four, it was clear she had a true problem. She started losing strength in her arms and legs. When she got sick, which was often, the weakness seemed to accelerate.

Talia was initially diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), an autoimmune disease in which the body attacks its own nerve fibers. Treated with IV immunoglobulin infusions to curb the inflammation, she seemed to grow stronger — but only for a time. Adding prednisone, a steroid, seemed to help. But it also caused bone loss, and Talia began having spine fractures.

“We tried a lot of different things, but she never got 100 percent better,” says Regina Laine, NP, who has been following Talia in Boston Children’s Hospital’s Neuromuscular Center the past several years, together with Basil Darras, MD.That’s when we decided to readdress the possibility that it was genetic.”

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A gene therapy advance for muscle-wasting myotubular myopathy

X-linked myotubular myopathy XLMTM gene therapy
Nibs, a carrier of MTM whose descendants provided the basis for the gene therapy study. (Read more of her story.)

For more than two decades, Alan Beggs, PhD, at Boston Children’s Hospital has explored the genetic causes of congenital myopathies, disorders that weaken children’s muscles, and investigated how the mutations lead to muscle weakness. For one life-threatening disorder, X-linked myotubular myopathy (XLMTM), the work is approaching potential payoff, in the form of a clinical gene therapy trial.

Boys with XLMTM are born so weak that they are dependent on ventilators and feeding tubes to survive. Almost half die before 18 months of age.

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Honoring rare disease ‘citizen scientists’

citizen scientists

The global theme of this year’s Rare Disease Day (February 28) is research, and in keeping with that, we salute a very important group of people: citizen scientists. These can-do patients and family members are putting previously undiagnosed rare diseases on the map and driving the search for treatments. Citizen scientists play multiple roles: They keep scientists focused on therapeutic development, conduct online research to connect ideas, set up patient networks and data registries, raise money and start companies. They’ve earned a voice in clinical trial design and were instrumental in the passage of the 21st Century Cures Act.

Meet a few citizen scientists who have inspired us recently.

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Abraham Rudolph, MD: The path of a pediatric cardiology pioneer

Abraham Rudolph MD
Rudolph (left) at Boston Children’s Hospital with Cardiologist-in-Chief Alexander Nadas, MD, c. 1958.

Abraham Rudolph, MD, who recently turned 93, has watched his chosen corner of the medical profession — pediatric cardiology — grow from rudimentary beginnings into a robust, multivariate discipline. Yet while his name is known worldwide in pediatric cardiology circles, he entered cardiology more than 50 years ago only by happenstance.

Born in South Africa in 1924, Rudolph came to the United States in 1951 to train in cardiology by invitation of Charles Janeway, MD, then Physician-in-Chief at Boston Children’s Hospital. Concerned about providing for his wife and newborn daughter, he chose cardiology over hematology or neurology because it offered a salary; many other physician-training opportunities at the time were unpaid. That first year, as the hospital’s first cardiology fellow, he made $3,000 — thanks to a family donation.

He stayed on for nine years, becoming director of the cardiac catheterization laboratory. There he found his focus.

“I became more and more interested in the physiology of the circulation, particularly the problems surrounding infancy,” he said in a 1996 interview with the American Academy of Pediatrics. “At that time, there were relatively few places that were doing anything about infants with heart disease. Most of the emphasis was on older children.”

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Science Seen: Brain myelination in tuberous sclerosis complex

tuberous sclerosis brain myelination improved with CTGF deletion

Tuberous sclerosis complex (TSC) strikes about 1 in 6,000 people and is marked by numerous benign tumors in the brain, kidneys, heart, lungs and other tissues. Children with TSC often have epilepsy, intellectual disability and/or autism, showing disorganized white matter in their brains. Work in the lab of Mustafa Sahin, MD, PhD, has shown that the TSC1 mutation disrupts the brain’s ability to adequately wrap its nerve fibers in myelin, the insulating coating that enhances nerves’ ability to conduct signals. A new study from the lab shows why: neurons lacking functional TSC1 secrete increased amounts of connective tissue growth factor (CTGF). This impairs the development of oligodendrocytes, the cells that do the myelinating. Here, electron microscopy in a TSC mouse model shows a decreased number of nerve fibers wrapped in myelin (dark ovals) on the left. On the right, genetic deletion of CTGF increases myelination. Sahin plans to delve further to develop potential pharmaceutical approaches to restore myelination in TSC. Read more in the Journal of Experimental Medicine. (Image: Ebru Ercan et al.)

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Stem cell workaround cracks open new leads in Diamond Blackfan anemia

Diamond Blackfan anemia iPS cells hematopoietic progenitor cells
Though not bona-fide stem cells, hematopoietic progenitor cells produce red blood cells when exposed to certain chemicals. Could some of these compounds lead to new drugs for Diamond Blackfan anemia?

Diamond Blackfan anemia (DBA) has long been a disease waiting for a cure. First described in 1938 by Louis K. Diamond, MD, of Boston Children’s Hospital and his mentor, Kenneth Blackfan, MD, the rare, severe blood disorder prevents the bone marrow from making enough red blood cells. It’s been linked to mutations affecting a variety of proteins in ribosomes, the cellular organelles that themselves build proteins. The first mutation was reported in 1999.

But scientists have been unable to connect the dots and turn that knowledge into new treatments for DBA. Steroids are still the mainstay of care, and they help only about half of patients. Some people eventually stop responding, and many are forced onto lifelong blood transfusions.

Researchers have tried for years to isolate and study patients’ blood stem cells, hoping to recapture the disease process and gather new therapeutic leads. Some blood stem cells have been isolated, but they’re very rare and can’t be replicated in enough numbers to be useful for research.

Induced pluripotent stem (iPS) cells, first created in 2006 from donor skin cells, seemed to raise new hope. They can theoretically generate virtually any specialized cell, allowing scientists model a patient’s disease in a dish and test potential drugs.

There’s been just one hitch. “People quickly ran into problems with blood,” says hematology researcher Sergei Doulatov, PhD. “iPS cells have been hard to instruct when it comes to making blood cells.”

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Gene therapy restores whisper-fine hearing, balance in Usher syndrome mice

gene therapy for deafness
Sensory hair cells contain tiny cilia that get wiggled by incoming sound waves, sparking a signal to the brain that ultimately translates to hearing. Gene therapy restored this tidy “V” formation. (Credit: Gwenaelle Géléoc and Artur Indzkykulian)

The ear is a part of the body that’s readily accessible to gene therapy: You can inject a gene delivery vector (typically a harmless virus) and it has a good chance of staying put. But will it ferry the corrected gene into the cells of the hearing and/or vestibular organs where it’s most needed?

Back in 2015, a Boston Children’s Hospital/Harvard Medical School team reported using gene therapy to restore rudimentary hearing in mice with genetic deafness. Previously unresponsive mice began jumping when exposed to abrupt loud sounds. But the vector used could get the corrected genes only into the cochlea’s inner hair cells. To really restore significant hearing, the outer hair cells need to be treated too.

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Why I’m tall and you’re short: GIANT effort finds rare, potent height genes

height genes that make us tall or short

Height is the “poster child” of complex genetic traits, meaning that it’s influenced by multiple genetic variants working together. Because height is easy to measure, it’s a relatively simple model for understanding traits produced by not one gene, but many.

“Mastering the complex genetics of height may give us a blueprint for studying multifactorial disorders that have eluded our complete understanding, such as diabetes and heart disease,” says Joel Hirschhorn, MD, PhD, a pediatric endocrinologist and researcher at Boston Children’s Hospital and the Broad Institute of MIT and Harvard.

Hirschhorn chairs the Genetic Investigation of Anthropometric Traits (GIANT) Consortium, an international group that’s just probed more deeply into the genetics of height than ever before. Its findings, reported today in Nature, reveal previously unknown biological pathways tied to height.

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Pediatric brain tumor genomics arrives, as the need for new therapies grows

Allison was the first pediatric brain tumor patient in the world to receive a treatment targeting the BRAF mutation, originally developed to treat adults with melanoma who have the same mutation.

Precision cancer medicine – the vision of tailoring diagnosis and treatments to a tumor’s genetic susceptibilities – is now ready to impact the care of a majority of children with brain tumors. It’s led, for example, to a current clinical trial testing the anti-melanoma drug dabrafenib in a variety of brain tumors with the same BRAF mutation – including metastatic anaplastic astrocytoma and low-grade glioma.

In the largest study of its kind to date, investigators at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center genetically tested more than 200 brain tumor samples. They found that many had genetic irregularities that could guide treatment, in some cases with approved drugs or agents being evaluated in clinical trials.

The findings, reported online today by the journal Neuro-Oncology, also demonstrate that testing pediatric brain tumor tissue for genetic abnormalities is clinically feasible.

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DNA methylation patterns linked to obesity and its complications

DNA methylation obesity
(Methylated DNA: Christoph Bock, Max Planck Institute for Informatics/Wikimedia Commons)

Why do some people seem to be prone to weight gain? Obesity has been linked to a variety of genetic changes, yet these differences don’t fully explain the variation in people’s body mass index (BMI). “Even though we’ve genetically sequenced more and more people at greater and greater breadth and depth, we haven’t completely explained who develops obesity and why,” says Michael Mendelson, MD, ScM, a pediatric cardiologist with Boston Children’s Hospital’s Preventive Cardiology Program.

Nor do prior studies explain why some overweight people develop health complications from obesity, like cholesterol problems, diabetes, hypertension and heart disease, while others don’t. Now comes strong evidence that an important factor is DNA methylation — a so-called epigenetic modification that influences whether genes are turned on or off.

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