In this screen grab from a Nature video, a siRNA, cradled by an argonaute protein, binds to a messenger RNA. (More 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.” Full story »
The butterfly effect is defined as “the sensitive dependence on initial conditions, where a small change at one place in a deterministic nonlinear system can result in large differences to a later state.” In medicine, the identification of a rare disease or a genetic mutation may provide insights that spread well beyond the initial discovery.
And in genetics, scientists are learning just how widespread the effects are for mutations in one gene: filaminA (FLNA).
FLNA is a common cause of periventricular nodular heterotopia (PVNH), a disorder of neuronal migration during brain development. The syndrome was first described by the late Peter Huttenlocher, MD, and the gene was identified by Christopher Walsh, MD, PhD, of Boston Children’s Hospital.
In normal brain development, neurons form in the periventricular region, located around fluid-filled ventricles near the brain’s center, then migrate outward to form six onion-like layers. In PVNH, some neurons fail to migrate to their proper position and instead form clumps of gray matter around the ventricles. Full story »
This post is the first in a two-part series on clinical trials in autism spectrum disorders. Read part 2.
In the world of neurodevelopmental disorders, an exciting trend is the emergence of specific molecular targets and treatments through genetic research. A case in point is IGF-1 therapy for Rett syndrome, a devastating disorder in girls that affects their ability to speak, walk, eat and breathe. It causes autism-like behaviors, intellectual disability and repetitive hand-wringing movements—a hallmark of the disorder.
A Phase I trial, published this week in the Proceedings of the National Academy of Sciences Early Edition, has modest but consistent results suggesting improvements in some salient features of the disorder.
Current treatments for Rett syndrome address only the symptoms and comorbidities, such as seizures, anxiety and scoliosis, but not the disease itself. But in 2007, findings in a mouse model (which even replicated the hand-wringing) changed how scientists think about Rett and other neurodevelopmental disorders, previously thought to be untreatable. Full story »
Alison Frase with Nibs, a carrier of MTM whose descendants provided the basis for the gene therapy study.
Babies born with X-linked myotubular myopathy (MTM), which affects about one in 50,000 male births, are commonly referred to as “floppy.” They have very weak skeletal muscles, making it difficult to walk or breathe; survival requires intensive support, often including tube feeding and mechanical ventilation. Most children with MTM never reach adulthood.
One of these children, Joshua Frase, succumbed to MTM on Christmas Eve, 2010. The son of former NFL player Paul Frase, he lived to age 15. But his parents, who continue to actively support MTM research, now see a glimmer of hope for children born with the disease today.
A preclinical study on the cover of last week’s Science Translational Medicine, funded in part by the Joshua Frase Foundation, showed dramatic improvements in muscle strength using gene replacement therapy in mouse and dog models of MTM—paving the way for a potential clinical trial. Full story »
The Human Genome Project’s push to completely sequence the human genome ran a tab of roughly $2.7 billion and required the efforts of 20 research centers around the world using rooms full of equipment.
But that was using technology from the 1990s to early-2000s. As by a panel of genomics experts from industry and academia pointed out at last week’s National Pediatric Innovation Summit + Awards, a scientist in a single laboratory today can sequence a genome for as little as $1,000, making sequencing almost a medical commodity.
Now what? How do we go about making clinical genomics an everyday thing? The discussion left the answer to that question—and the other questions it raises—unclear. While the panelists expressed excitement about what’s possible, they cited great uncertainty among doctors, scientists, patients, payers, companies and regulators about how to make clinical genomics work. Full story »
An early innovation: Specially bred cows graze in front of Boston Children’s Hospital in 1919, providing safe, tuberculosis-free milk for patients.
Clinicians wanting to develop new devices and treatments for children face formidable barriers: regulators’ need to protect the most vulnerable coupled with a lack of commercial interest. But determined innovators do have options, including creative funding sources, says Thomas Krummel, MD
, director of surgical innovation at Stanford Medical School.
“Technology developed specifically for children has been a low priority,” Krummel began at a two-part talk at Boston Children’s Hospital this summer (read our coverage of the other part). “The FDA barriers are incredibly high, and ultimately, investors just demand returns that pediatric markets won’t necessarily deliver.”
As Krummel detailed, the FDA barriers are there for a reason: a past history of ethical abuses in human subjects research. In 1966, physician Henry Beecher, MD, exposed many examples in The New England Journal of Medicine, such as withholding effective treatment for the sake of research, proceeding with a treatment despite recognized hazards, or failing to disclose risk to patients. Institutional Review Boards (IRBs) arose in the mid-1970s to protect research subjects—protections that are especially strict when that research is done in children.
But there’s also a deep-seated reluctance to break with the status quo. Full story »
Obesity is more common among children with sickle cell disease than thought. Why?
Ask many doctors about their image of a child with sickle cell disease (SCD)
, and they’ll describe a short, skinny child, perhaps almost malnourished. For decades, that image was accurate.
That perception needs to change, though. A group of sickle cell specialists from hospitals in New England—members of the 11 institutions in the New England Pediatric Sickle Cell Consortium (NEPSCC)—recently made a surprising observation: Nearly a quarter of children with SCD are overweight or obese. The question is, why?
The answer may start with their red blood cells (RBCs). Full story »
Part 2 of a two-part series on kidney disease. Part 1 is here.
Analyzing blood samples, researchers have found that over one third of chronic kidney diseases are caused by single mutations on single genes
(Image: Graham Colm)
Friedhelm Hildebrandt, MD, receives around one blood sample in the mail per day from a patient with chronic kidney disease. Over 10 years, he’s collected more than 5,000 samples from patients all over the world—in hopes of finding the genetic mutations that cause them and, ultimately, new treatments.
Consider the mutation in an 8-month-old boy from Turkey, who had fluid collection under his skin and elevated protein in his urine—signs that his kidneys were failing. Doctors identified his disease as a form of nephrotic syndrome, one of the three main types of chronic kidney disease. The disease was proving to be hard to treat: Ten weeks of steroids had produced no result, and an immunosuppressant hadn’t been effective enough to justify its harsh side effects.
Only within the last year, genetic research has revealed that more than 30 percent of childhood chronic kidney diseases—like this child’s—stem from single mutations in single genes.
Full story »
A mechanosensory hair bundle in the cochlea. Each sensory cell, of which the human ear has about 16,000, has tiny hairs tipped with TMC1 and TMC2 proteins. When sound vibrations strike the bundle, it wiggles back and forth, opening and closing the TMC channels. When open, the channel allows calcium into the cell, initiating an electrical signal to the brain relayed by the 8th cranial nerve. (Image: Yoshiyuki Kawashima)
Ending a 30-year search by scientists, researchers have identified two proteins in the inner ear that are critical for hearing, which, when damaged by genetic mutations, cause a form of delayed, progressive hearing loss.
The proteins are essentially transducers: They form channels that convert mechanical sound waves entering the inner ear into electrical signals that talk to the brain. Corresponding channels for each of the other senses were identified years ago, but the sensory transduction channel for both hearing and the sense of balance had been unknown.
The channels are the product of two related genes known as TMC1 and TMC2. TMC1 mutations were first reported in people with a prominent form of hereditary deafness back in 2002 by Andrew Griffith, MD, PhD, of the National Institute on Deafness and Other Communication Disorders (NIDCD) and collaborators. Children with recessive mutations in TMC1 are completely deaf at birth. Full story »