Stories about: orphan diseases

An unusual dog, a new approach to muscular dystrophy: Stimulating a protective gene

muscular dystrophy
Vieira with Ringo

Ringo was a golden retriever that defied the odds. Despite having the gene mutation for Duchenne muscular dystrophy (DMD), he remained healthy. And he’s provided a new lead for boosting muscle strength in DMD, one of the most common forms of muscular dystrophy. Unlike other dogs with the dystrophin mutation, who are weak and typically die by 2 years of age, Ringo was able to walk and run normally and lived to the age of 11, within the normal range for golden retrievers.

What made Ringo so resilient?

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The autism-GI link: Inflammatory bowel disease found more prevalent in ASD patients

brain gut connection autism IBD ASDReports from parents and a growing number of studies over the past 10 to 15 years suggest that children with autism spectrum disorder (ASD), especially more severe ASD, are prone to gastrointestinal disorders. Researchers have attributed the association to altered GI microbiota, abnormal intestinal physiology, immune alterations and other mechanisms. Some speculate that the connection results from unusual eating patterns in children with ASD.

A 2012 study led by bioinformatician Isaac Kohane, MD, PhD, of Boston Children’s Hospital and Harvard Medical School grouped autism patients according to the gene expression patterns in their blood, and one group had altered immunologic and inflammatory pathways. A more recent study went a step further, finding similar gene expression profiles in the intestines of children with ASD and those with inflammatory bowel disease (IBD).

Looking at IBD (Crohn’s and colitis) sets the bar a little higher, since IBD is uncommon and also unlikely to be caused by dietary factors (though it can certainly be aggravated by them). In a new study in the journal Inflammatory Bowel Disease, Kohane and colleagues crunched three large databases to create what they believe is the largest ASD/IBD study to date.

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Gene therapy to germline editing: Promises, challenges, ethics

A report this April rocked the scientific world: scientists in China reported editing the genomes of human embryos using CRISPR/Cas9 technology. It was a limited success: of 86 embryos injected with CRISPR/Cas9, only 71 survived and only 4 had their target gene successfully edited. The edits didn’t take in every cell, creating a mosaic pattern, and worse, unwanted DNA mutations were introduced.

“Their study should give pause to any practitioner who thinks the technology is ready for testing to eradicate disease genes during [in vitro fertilization],” George Q. Daley, MD, PhD, director of the Stem Cell Transplantation Program at Boston Children’s Hospital, told The New York Times. “This is an unsafe procedure and should not be practiced at this time, and perhaps never.”

As Daley detailed last week in his excellent presentation at Harvard Medical School’s Talks@12 series, the report reignited an ethical debate around tampering with life that’s hummed around genetic and stem cell research for decades. What the Chinese report adds is the theoretical capability of not just changing your genetic makeup, but changing the DNA you pass on to your children.

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Advancing clinical trials for Niemann-Pick type C: Sweet news for cyclodextrin

Febreze-Human Zoom-Creative CommonsOlaf Bodamer, MD, PhD, is associate chief of the Division of Genetics and Genomics at Boston Children’s Hospital and is launching a multidisciplinary clinic this spring for lysosomal storage diseases—including Niemann-Pick type C, sometimes referred to as “childhood Alzheimer’s.”

Niemann-Pick disease type C (NP-C) has come a long way since its first description as an entity in the 1960s. Part of a group of rare metabolic disorders known as lysosomal storage diseases, NP-C leaves children unable to break down cholesterol and other lipid molecules. These molecules accumulate in the liver, spleen and brain, causing progressive neurologic deterioration.

I still vividly remember when I diagnosed my first patient with this devastating disease, a 3-year-old boy who had global developmental delay, restricted eye movement, loss of motor coordination and loss of speech. I spent hours with the family, explaining what was known about NP-C. When faced with the question about treatability and outcome, I could barely find the right words, but had to acknowledge that the outcome was inevitably fatal and that there was no specific treatment other than supportive measures to treat his symptoms.

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Wise health care spending for children with medical complexity

Spending on children with medical complexityJay Berry, MD, MPH, is a pediatrician and hospitalist in the Complex Care Service at Boston Children’s Hospital.

Growing up, my parents repeatedly reminded me that “money doesn’t grow on trees.” They pleaded with me to spend it wisely. I’ve recently been thinking a lot about my parents and how their advice might apply to health care spending for my patients.

As a general pediatrician with the Complex Care Service at Boston Children’s Hospital, I care for “medically complex” children. These children—numbering an estimated 500,000 in the U.S.— have serious chronic health problems such as severe cerebral palsy and Pompe disease. Many of them rely on medical technology, like feeding and breathing tubes, to help maintain their health.

These children are expensive to take care of. They make frequent health care visits and tend be high utilizers of medications and equipment. Some use the emergency department and the hospital so often that they’ve been dubbed frequent flyers.

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A 28-gene test for kidney disease

dialysis nephrotic syndrome
Understanding the genetic causes of nephrotic syndrome could lead to better drug treatments that reduce the need for dialysis or a kidney transplant. (Image: Wikimedia Commons)

Nephrotic syndrome is one of the worst diseases a child can have. It strikes the filtering units of the kidney, structures known as glomeruli. There’s no good treatment: Steroids are the main therapy used, but 20 percent of cases are steroid-resistant. In the syndrome’s most severe form, focal segmental glomerulosclerosis (FSGS), children are forced onto chronic dialysis and often require a kidney transplant—often only to have their disease recur in the new organ.

Until recently, no one knew what caused nephrotic syndrome; the first causative gene was identified just a dozen years ago. The lab of Friedhelm Hildebrandt, MD, PhD, at Boston Children’s Hospital is one of a handful that’s been chipping away at the others.

Hildebrandt receives, on average, one blood sample a day from patients all over the world.

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“Deep sequencing” finds hidden causes of brain disorders

brain malformations sequencing mosaicism
New methods can find a mutation that strikes just 1 in 10 cells.

It’s become clear that our DNA is far from identical from cell to cell and that disease-causing mutations can happen in some of our cells and not others, arising at some point after we’re conceived. These so-called somatic mutations—affecting just a percentage of cells—are subtle and easy to overlook, even with next-generation genomic sequencing. And they could be more important in neurologic and psychiatric disorders than we thought.

“There are two kinds of somatic mutations that get missed,” says Christopher Walsh, MD, PhD, chief of Genetics and Genomics at Boston Children’s Hospital. “One is mutations that are limited to specific tissues: If we do a blood test, but the mutation is only in the brain, we won’t find it. Other mutations may be in all tissues but in only a fraction of the cells—a mosaic pattern. These could be detectable through a blood test in the clinic but aren’t common enough to be easily detectable.”

That’s where deep sequencing comes in. Reporting last month in The New England Journal of Medicine, Walsh and postdoctoral fellow Saumya Jamuar, MD, used the technique in 158 patients with brain malformations of unknown genetic cause, some from Walsh’s clinic, who had symptoms such as seizures, intellectual disability and speech and language impairments.

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‘Heart on a chip’ suggests a surprising treatment for a rare genetic disease

heart chip BarthIt was the variability that intrigued pediatric cardiologist William Pu, MD, about his patient with heart failure. The boy suffered from a rare genetic mitochondrial disorder called Barth syndrome. While he ultimately needed a heart transplant, his heart function seemed to vary day-to-day, consistent with reports in the medical literature.

“Often patients present in infancy with severe heart failure, then in childhood it gets much better, and in the teen years, much worse,” says Pu, of the Cardiology Research Center at Boston Children’s Hospital. “This reversibility suggests that this is a disease we should really be able to fix.”

Though it needs much more testing, a potential fix may now be in sight for Barth syndrome, which has no specific treatment and also causes skeletal muscle weakness and low white-blood-cell counts. It’s taken the work of multiple labs collaborating across institutional lines.

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The ‘de-riskers’: Orphan drug acceleration

De-risking drug development for orphan diseasePerhaps counter-intuitively, rare diseases can present attractive business opportunities for pharmaceutical companies. As discussed previously on Vector, they generally offer:

1) a population of patients with a high, unmet need, greatly lowering the bar to FDA approval

2) a closely networked disease community, greatly lowering the bar to creating disease registries and mounting clinical trials

3) well-studied disease pathways.

Recoiling from expensive failures of would-be blockbuster drugs, companies like Pfizer, Novartis, GlaxoSmithKline, Sanofi, Shire and Roche are embracing rare diseases, despite their small market sizes, because of their much clearer path to clinic. But in the current risk-averse industry environment, some projects are stalling. Industry may need more incentive to jump in—and Cydan Development is basing its business model on providing it.

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RNAi isn’t ready to be silenced

In this screengrab from a Nature video, a siRNA, cradled by an argonaute protein, binds to a messenger RNA. (Watch the full video at: https://www.youtube.com/watch?v=cK-OGB1_ELE)
An siRNA, cradled by an argonaute protein, binds to a messenger RNA. (More from Nature at www.youtube.com/watch?v=cK-OGB1_ELE)

RNA interference (RNAi) is a therapeutic technology that blocks gene expression with either small interfering RNAs (siRNA) or microRNAs (miRNA). RNAi’s discovery was considered transformative enough to earn the 2006 Nobel Prize for Physiology or Medicine, but from the start the challenge of delivering RNA-silencing therapeutics to the right tissues has hobbled efforts to use RNAi to treat patients.

Citing this challenge, the pharmaceutical giant Novartis is the latest major company to withdraw from RNAi research, following Merck and Roche. Forbes was prompted to write:

…for certain diseases where an RNAi therapeutant can be more readily introduced, such as the eye, or ‘privileged compartments’ such as the liver, RNAi still has potential. But given that these therapies would be expensive due to the high cost-of-goods involved in synthesizing these agents, they would have to be targeted to diseases where the cost of therapy would be justified by the beneficial medical effects. … to say that RNAi therapy will rival monoclonal antibodies in terms of revenue potential—well, that’s a bit of a stretch.

Barry Greene, COO of Alnylam Pharmaceuticals, a biotech that’s championed RNAi, countered in Fierce Drug Delivery: “Novartis pulling out is an exemplar of Big Pharma not being able to innovate, and historically they have never been able to innovate.”

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