Stories about: genetics

News note: GIANT study homes in on obesity genes

obesity genes
Illustration: Elena Hartley

Yes, some obesity is due to genetics. The largest and most powerful study to date has pinned down 14 variants in 13 genes that carry variations associated with body mass index. They provide new clues as to why some people tend to gain weight and have more trouble losing it. Eight of the variants were in genes not previously tied to human obesity.

The study, published last month, was conducted by the Genetic Investigation of Anthropometric Traits (GIANT) consortium, an international collaboration involving more than 250 research institutions — the same group that brought us height-related genes last year. It combined genetic data from more than 700,000 people and 125 different studies to find rare or low-frequency genetic variants that tracked with obesity.

The study focused on rarer variants in the coding portions of genes, which helped pinpoint causal genes and also helped discover variants with larger effects that those previously discovered by the GIANT consortium. For example, carriers of a variant in the gene MC4R (which produces a protein that tells the brain to stop eating and to burn more energy) weigh 15 pounds more, on average, than people without the variant.

Computational analysis provided some interesting insights into what the 13 genes do. Some, for example, play a role in brain pathways that affect food intake, hunger and satiety. Other variants affect fat-cell biology and how cells expend energy.

This study provided an important confirmation of the role of the nervous system in body weight regulation,” says Joel Hirschhorn MD, PhD, a pediatric endocrinologist and researcher at Boston Children’s Hospital and the Broad Institute of MIT and Harvard, who co-led the study with Ruth Loos, PhD, of the Icahn School of Medicine at Mount Sinai. “Many of the genes from this study were not known to be associated with obesity, but our computational analysis independently implicates these new genes in strikingly similar neuronal pathways as the genes that emerged from our previous work. In addition, our approach newly highlighted a role for genes known to be important in ‘brown fat,’ a type of fat that burns energy and may help keep people lean.”

The researchers think the new findings could help focus the search for new therapeutic targets in obesity.  Read more in Nature Genetics and this press release from Mount Sinai.

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Science and medicine in 2018: What’s the forecast?

2018 predictions for biomedicine

Vector consulted its many informants to find out which way the wind will blow in 2018. Here are their predictions for what to expect in genetics, stem cell research, immunology and more.

GENETICS

Gene-based therapies mature

We will continue to see successes in 2018 reflecting the maturation of gene therapy as a viable, generalizable platform for curing many rare diseases. Also, we will see exciting new applications of other maturing platforms, like CRISPR/Cas9 gene editing and oligonucleotide therapies for neurologic diseases, building on the success of nusinersen for spinal muscular atrophy.

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Taking a sideswipe at high-risk neuroblastoma

Microscopy image of human neuroblastoma cells.
Human neuroblastoma cells.

Cancer and other diseases are now understood to spring from a complex interplay of biological factors rather than any one isolated origin. New research reveals that an equally-nuanced approach to treating high-risk neuroblastoma may be the most effective way to curb tumor growth.

One challenge in treating pediatric cancers like neuroblastoma is that they are not initiated from the same kinds of genetic mutations as adult cancers, which usually arise from mutations related to an accumulation of DNA replication errors or environmental factors. In contrast, childhood cancers more often stem from genetic duplications, deletions or translocations, the latter of which occurs when a gene sequence switches its location from one chromosome to another.

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Why do some people with cystic fibrosis live much longer than others?

Lung tissue, which can be compromised by the genetic disorder known as cystic fibrosis, is seen under microscopic view.
Lung tissue under microscope.

The answer may be hidden in their genes.

Cystic fibrosis is an inherited disorder caused by genetic mutations that disrupt the normal movement of chloride in and out of cells. Among other health problems, cystic fibrosis compromises the lungs’ ability to fight infection and breathe efficiently, making it the most lethal genetic disease in the Caucasian population. Patients have an average lifespan of just 30 to 40 years.

Despite this narrow average lifespan, there is a big range in how severely cystic fibrosis (CF) affects the lungs and other organs depending on an individual’s specific genetic variation, and even in how long patients sharing the same, most common genetic mutation are able to survive with CF.

This led researchers at Boston Children’s Hospital to wonder if other genetic mutations could be protective against CF’s effects. Recent findings published in the American Journal of Respiratory Cell and Molecular Biology suggest that may be the case.

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Can rare pain syndromes point the way to new analgesics?

analgesic drug discovery could reduce prescription opioid use
Boston Children’s Hospital and Amgen will collaborate to discover and accelerate non-addicting pain drugs.

As the opioid epidemic deepens and drug overdoses increase, effective non-addicting painkillers are desperately needed. Efforts to discover new pain pathways to target with new drugs have thus far had little success. Other promising research is investigating triggerable local delivery systems for non-opioid nerve blockers, but it’s still in the early stages.

A new collaboration between Boston Children’s Hospital and the biopharmaceutical company Amgen is aimed at accelerating new pain treatments. Announced yesterday, it will revolve around patients with rare, perplexing pain syndromes. The scientists hope that the genetic variants they find in these patients will shed new light on pain biology and lead to new ways of controlling pain. 

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Gene therapy halts progression of cerebral adrenoleukodystrophy in clinical trial

David Williams, MD, the principal investigator of the clinical trial, discusses gene therapy and its impact on children with adrenoleukodystrophy

Adrenoleukodystrophy — depicted in the 1992 movie “Lorenzo’s Oil” — is a genetic disease that most severely affects boys. Caused by a defective gene on the X chromosome, it triggers a build-up of fatty acids that damage the protective myelin sheaths of the brain’s neurons, leading to cognitive and motor impairment. The most devastating form of the disease is cerebral adrenoleukodystrophy (CALD), marked by loss of myelin and brain inflammation. Without treatment, CALD ultimately leads to a vegetative state, typically claiming boys’ lives within 10 years of diagnosis.

But now, a breakthrough treatment is offering hope to families affected by adrenoleukodystrophy. A gene therapy treatment effectively stabilized CALD’s progression in 88 percent of patients, according to clinical trial results reported in the New England Journal of Medicine. The study was led by researchers from the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and Massachusetts General Hospital.

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In search of young medical geneticists

Nina Gold, MD, is Chief Resident of Medical Genetics at Boston Children’s Hospital.

During a quiet stretch of my final year in medical school, I read Sir Arthur Conan Doyle’s Sherlock Holmes stories. A master observer, the detective found secrets in wrinkles of clothes, tints of hair, scents of perfume, never satisfied until the truth was revealed. Sherlock was, simply, an expert diagnostician.

In the spring of 2014, I became the first student in my medical school to pursue residency training in a combined pediatrics and medical genetics program. Like Sherlock, pediatric geneticists are stalwart investigators. They are often called into a case long after other consultants and tasked with bringing a family’s diagnostic odyssey to an end. But unlike the emotionally obtuse fictional detective, geneticists must describe their findings with empathy and clarity to concerned families after they solve a mystery.

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Severe flu infections linked to underlying genetic variation

Flu virusesThe Center for Disease Control estimates that influenza virus–related illnesses account for more than 200,000 U.S. hospitalizations and 12,000 deaths annually. Young children, the elderly and people with respiratory, cardiac and other chronic health conditions are at particularly high risk for being hospitalized for influenza-related complications. Until now, there has not been a clear reason to explain why some individuals become severely ill from flu and not others.

New findings published in Nature Medicine, however, might change that.

“We’ve identified a genetic variant that we believe may put people at risk of getting life-threatening influenza infections,” says Adrienne Randolph, MD, MSc, a senior associate in pediatric critical care medicine at the Boston Children’s Hospital.

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Newly-discovered epigenetic mechanism switches off genes regulating embryonic and placental development

Artwork depicting DNA and the code of genes

A biological process known as genomic imprinting helps control early mammalian development by turning genes on and off as the embryo and placenta grow. Errors in genomic imprinting can cause severe disorders and profound developmental defects that lead to lifelong health problems, yet the mechanisms behind these critical gene-regulating processes — and the glitches that cause them to go awry — have not been well understood.

Now, scientists at Harvard Medical School (HMS) and Boston Children’s Hospital have identified a mechanism that regulates the imprinting of multiple genes, including some of those critical to placental growth during early embryonic development in mice. The results were reported yesterday in Nature.

“A gene that is turned off by epigenetic modifications can be turned on much more easily than a gene that is mutated or missing can be fixed,” said Yi Zhang, PhD, a senior investigator in the Boston Children’s Program in Molecular and Cellular Medicine, a professor of pediatrics at HMS and a Howard Hughes Medical Institute investigator. “Our discovery sheds new light on a fundamental biological mechanism and can lay the groundwork for therapeutic advances.”

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Late-breaking mutations may play an important role in autism

somatic mutations in autism may occur at different times in the embryo
Post-zygotic mutations, which arise spontaneously in an embryonic cell after sperm meets egg, are important players in autism spectrum disorder, a large study suggests.

Over the past decade, mutations to more than 60 different genes have been linked with autism spectrum disorder (ASD), including de novo mutations, which occur spontaneously and aren’t inherited. But much of autism still remains unexplained.

A new study of nearly 6,000 families implicates a hard-to-find category of de novo mutations: those that occur after conception, and therefore affect only a subset of cells. Findings were published today in Nature Neuroscience.

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