Internet of DNA (MIT Technology Review)
Emerging projects in Toronta, Santa Cruz and elsewhere are working toward being able compare DNA from sick people around the world via the Internet to identify hard-to-spot causes of disease—analogous to using the “Compare documents” function in Word.
Engineering the perfect baby (MIT Technology Review)
Since the birth of genetic engineering, people have worried about designer babies. Now, with gene editing and CRISPR, they might really be possible. Bioethicists and scientists weigh in on what “germ line engineering” would mean.
But like nature, business abhors a vacuum, and longs to fill it. Many companies and institutions have already jumped into the LDT ring, offering up genomic or pharmacologic services that they say would help guide patients’ and doctors’ treatment decisions and improve outcomes. Especially for patients with cancer.
How solid is the science behind these claims? And do vendors do a good job disclosing the strengths and weaknesses of personalized medicine? Those questions form the core of a study published this week in the Journal of the National Cancer Institute.
The collection of bacteria and other microorganisms living in our intestines—our microbiota—is now understood to play an important role in our physiology. Recent research indicates that it helps regulate our metabolism, immune system and other biological processes, and that imbalances in the microbiota are associated with everything from inflammatory bowel disease to diabetes.
Seth Rakoff-Nahoum, MD, PhD, wants to take this understanding to a new level. An infectious disease clinical fellow at Boston Children’s Hospital, he has systematically probed how genetics interact with environment—including the microbiota—to shape intestinal biology during different stages of development.
His investigations provide interesting clues to disorders that have their origins early in life, ranging from necrotizing enterocolitis in newborns to Hirschsprung’s disease (marked by poor intestinal motility) to food allergies.
Can you describe your work and its potential impact on patient care?
We modeled a form of heart-muscle disease in a dish. To do this, we converted skin cells from patients with a genetic heart muscle disease into stem cells, which we then instructed to turned into cardiomyocytes (heart-muscle cells) that have the genetic defect. We then worked closely with bioengineers to fashion the cells into contracting tissues, a “heart-on-a-chip.”
How was the idea that sparked this innovation born?
This innovation combined the fantastic, ground-breaking advances from many other scientists. It is always best to stand on the shoulders of giants.
Historically, the starting point for making a rare disease diagnosis is the patient’s clinical profile: the set of symptoms and features that together define Diamond Blackfan anemia (DBA), Niemann-Pick disease or any of a thousand other conditions.
For example, anemia and problems absorbing nutrients are features of Pearson marrow pancreas syndrome (PS), whereas oddly shaped fingernails, lacy patterns on the skin and a proneness to cancer point to dyskeratosis congenita (DC).
The resulting diagnoses give the child and family an entry point into a disease community, and is their anchor for understanding what’s happening to them and others: “Yes, my child has that and here’s how it affects her. Does it affect your child this way too?”
But as researchers probe the relationships between genes and their outward expression—between genotype and phenotype—some families are losing that anchor. They may discover that their child doesn’t actually have condition A; rather, genetically they actually have condition B. Or it may be that no diagnosis matches their genetic findings.
What does that mean for patients’ care, and for their sense of who they are?
About a third of children with epilepsy do not get better with drug treatment. Many physicians are inclined to try additional drugs to control the seizures—and there are many to choose from. However, analysis of data from tens of thousands of patients suggests that if two or more well-chosen drugs have failed, and surgery is a safe option, there’s no benefit in holding off.
The decision analysis, published in the February issue of Epilepsia, found that average life expectancy was more than five years greater when eligible children had surgery rather than prolonged drug treatment. And children spent more of their lives seizure-free.
Although clinical guidelines currently do call for earlier surgery, physicians tend to use it as a last resort—even when brain-mapping studies indicate that it’s unlikely to endanger vital brain structures.
Evolution is a strange thing: sometimes it favors keeping a mutation in the gene pool, even when a double dose of it is harmful—even fatal. Why? Because a single copy of that mutation is protective in certain situations.
A classic example is the sickle-cell mutation: People carrying a single copy don’t develop sickle cell disease, but they make enough sickled red blood cells to keep the malaria parasite from getting a toe-hold. (Certain other genetic disorders affecting red blood cells have a similar effect.)
Or consider cystic fibrosis. Carriers of mutations in the CFTR gene—some 1 in 25 people of European ancestry—appear to be protected from typhoid fever, cholera and possibly tuberculosis.
A Pancreas in a Capsule (MIT Technology Review)
Can stem cells solve the Type 1 diabetes puzzle? A handful of United States patients have had lab-grown pancreas cells, derived from human embryonic stem cells, transplanted in a human safety trial. Tech Review documents the challenges, and potential, of turning stem cells into real, functioning pancreas cells.
Maimuna (Maia) Majumder is an engineering systems PhD student at MIT and computational epidemiology research fellow at HealthMap.
The 2015 Disneyland measles outbreak in the United States, which started in late December and spread to more than 100 people in just 6 weeks, has recently become the subject of substantial media scrutiny.
Measles is extremely infectious, exhibiting a basic reproductive number between 12 and 18—one of the highest recorded in history. This means that for every 1 case who gets sick in a totally susceptible population, 12 to 18 other folks get sick, too. Thankfully, when uptake of the measles vaccine is high enough in a given community, it’s almost impossible for the disease to spread—thus halting a potential outbreak in its tracks.
But what happens when vaccine rates aren’t high enough?
Millions of people worldwide suffer from co-infection with tuberculosis (TB) and HIV. While prompt antibiotic and antiretroviral treatment can be a recipe for survival, over the years, physicians have noticed something: two or three weeks after starting antiretrovirals, about 30 percent of co-infected patients get worse.
The reason: immune reconstitution inflammatory syndrome, or IRIS. Doctors think it represents a kind of immune rebound. As the antiretrovirals start to work, and the patient’s immune system begins to recover from HIV, it notices TB’s presence and overreacts.
“It’s as though the immune system was blanketed and then unleashed,” says Luke Jasenosky, PhD, a postdoctoral fellow with Anne Goldfeld, MD, of Boston Children’s Hospital’s Program in Cellular and Molecular Medicine. “It then says, ‘I can start to see things again, and there are a lot of bacteria in here.'”
Though potentially severe, even fatal, IRIS may actually be a good sign: there is evidence that patients who develop it tend to fare better in the long run. But why does it arise only in some patients?