Monthly Archives: August 2017

People often ditch statins due to side effects

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By Viviane Callier

Should you take statins? The common drugs are a safe and effective way to lower cholesterol and prevent heart disease, but many of those taking them give up due to painful side effects. Furthermore, in some people, this pain may be caused by the nocebo effect, rather than the drug itself. But genetic screening could help reduce side effects and reassure people they are unlikely to feel any pain, encouraging more people to take statins.

Deepak Voora of Duke University, North Carolina, and his colleagues have been researching a gene associated with muscle pain in people taking statins. The gene encodes a protein that carries drugs into liver cells. A variant of this gene has been linked to aches in response to statins.

To find out if this variant affects what side effects someone experiences from different statins, Voora and his team reanalysed data from a clinical trial that had randomly assigned three types of this drug. They found that people with the gene variant had the highest risk of side effects when they were given a statin called simvastatin, but this risk was much lower when they took pravastatin.

The researchers then ran a trial in 159 people to see if genetic screening could help prescribe the most appropriate statin for each person. All the participants had previously stopped taking statins due to muscle pain.

First, everyone was given a genetic test, but only one group were told their results. For this group, a doctor explained whether or not their DNA put them at risk of statin-related muscle pain. Those at risk were recommended a statin that was less likely to cause side effects for their genetic variant, while those not at risk were told they could try any type.

The other participants werent told their test results, and instead received standard, generic recommendations from their doctor.

Of those told their results, around 57 per cent decided to start taking statins again within the next three months, compared with only a third of those who received generic recommendations. By the end of the eight-month study, those who knew their results had blood LDL cholesterol levels that were, on average, 10 to 15 per cent lower than the others.

Thats pretty remarkable given these were patients that were initially refusing to take statins, says Jason Vassy of Harvard Medical School.

By improving a persons perception of a drug, you can boost how many take it and keep taking it, which has been a major problem, says Voora. He hopes the approach could be extended to help doctors and patients feel more confident about other drugs. This concept of using precision medicine to address the psychology of how patients feel about drugs might be a winning combination, he says.

Read more: Statin muscle aches are all in my head? I beg to differ

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Genetic test helps people avoid statins that may cause them pain - New Scientist

Once difficult and expensive even for the most technologically advanced labs, genetic testing is fast becoming a cheap and easy consumer product. With a little spit and 200 dollars, you can find out your risk for everything from cystic fibrosis to lactose intolerance.

But its important to remember that not all genetic tests are created equal. And even the best clinical genetic test, carried out in a medical lab under a doctor's supervision, isn't perfectgenes are important, but they don't seal your fate.

Genetic tests are diagnostic, so anyone who is curious about their health can get one done. But they're more informative if you think you might be at risk for a genetic disorder.

Heavy-duty genetic tests have been used as a clinical tool for almost half a centurylong before 23andMe and Ancestry.com began offering direct-to-consumer tests. Lets say that many women in your family have had breast cancer. You can get a genetic test to see if you may have inherited an abnormal version of the BRCA gene, known to increase your risk for breast cancer.

Heidi Rehm, associate professor of pathology at Harvard Medical School, is the director of the Laboratory for Molecular Medicine, where patients get tested for diseases that can be traced to specific genetic roots. She says it is most common for people to get tested when they either suspect or know that they have a genetic disease; it may have affected multiple people in their family or they could show symptoms of something widely known to be genetic, like sickle cell anemia. For these people, genetic tests can provide a much-needed explanation for an illness and help doctors determine the best course of treatment. Babies are often tested for genetic diseases, either while they are still fetuses or shortly after birth.

Others get genetic tests if they and their partner both have family histories of an inherited diseaseeven if they dont have the disease themselves. For example, cystic fibrosis is linked to one particular gene, but you have to inherit the abnormal version of the gene from both your parents to get the disease. If you only inherit one copy, you may never knowyou wont display any of the symptoms. But if you and your partner both carry one copy of the faulty gene, your child could still inherit two copies. Genetic tests can forewarn you of that possibility.

But Rehm says there has been a recent trend of healthy people getting tested to predict whether theyll get certain diseases. I do think there are settings where predictive genetic testing is incredibly important and useful, Rehm says; for example, knowing that youre at risk for breast cancer gives you the opportunity for early intervention (remember when Angelina Jolie got a double mastectomy upon finding out she had a mutated BRCA gene?)

But Rehm also points out that genetic tests may not be as straightforward as they seem. For example, some genes are thought to increase risk of getting a certain disease, but it might only happen if you have specific family history, or you might be able to reduce your risk with lifestyle changes. So remember that a genetic test isnt the final verdictthere are other factors at play too.

Not entirelyits scope is limited. For starters, not all diseases are caused by genes. Plenty of conditions stem from environmental and lifestyle factors; they may interact with your genes, but the external factors are the real trigger.

But even if a disease is caused solely by faulty instructions written in your genes, you wont necessarily be able to test for it. Thats because genetic tests are mainly used for diseases that are penetrant, a term that scientists use to describe a strong connection between having a certain gene (or multiple genes) and getting a disease.

Genetic tests are surprisingly simple on the surface. All thats required of you is a small sample of cells, like a blood sample or saliva (which doesnt have DNA itself, but picks up cheek cells during its journey out of your mouth). It get sent to a lab where sequencing machines match up small pieces of synthetic DNA with your DNA to figure out the overall sequence.

Once they have your sequence, geneticists can compare it with "normal" or disease-causing sequences. In the end, they might give you a yes or no answer, or sometimes youll get a probabilitya measure of how much your genes increase your risk of developing the disease. Then, its up to your doctor to figure out what these genes (in combination with your lifestyle, family history and other risk factors) mean for your health.

With penetrant diseases, theres a very, very high ability to explain the disease, Rehm says. For example, the breast cancer-related gene BRCA1 can give you a 60 percent chance of getting breast cancer (in Jolies case, with her family history, the risk was 87 percent.)

This makes genetic tests better at detecting so-called rare diseases, says Steven Schrodi, associate research scientist at the Marshfield Clinic Research Institutes Center for Human Genetics, but theyre less useful when it comes to more common diseases, like heart disease or diabetes. Genetics can increase your likelihood of getting these disease, but scientists still dont know quite how much. Part of the problem is that there may be dozens or hundreds of genes responsible for these diseases, Schrodi says.

We have an incomplete understanding of why people get diseases, Schrodi says. A large part of it hinges on how we define diseases. Perhaps physicians have inadvertently combined multiple diseases together into a single entity.

Consumer genetic teststhe ones where you send in samples from homesometimes claim to test for these more complex traits, but be careful: Their results might not be very medically relevant, Rehm says. If they tell you that your genes make you twice as likely to develop diabetes, for example, that's a marginal increase that doesn't significantly affect your risk, especially when you take into account lifestyle factors.

Genes do seem to play a role in determining lifespan. After all, some family reunions stretch from great-great-grandparents all the way down to infants. Scientists have studied centenarianspeople who lived to be 100 years oldand found that people with certain versions of genes involved in repairing DNA tend to live longer.

This makes sense because aging leaves its mark on your DNA. Environmental factors can damage DNA, and even the routine chore of replicating cells can introduce errors as the three billion units of your DNA are copied over and over. Long-lived individuals have different sequences that seem to make their cells better at keeping DNA in mint condition.

But figuring out your expiration date is more complex than just testing for a few genes, says Jan Vijg, professor of genetics at Albert Einstein College of Medicine. In theory, you could design a test that looks at specific genes that might measure your risk for developing Alzheimers Disease or other age-related diseases, or your risk for aging quickly. To some extent, yes: Biomarkers will tell you something about your chances of living a long life, Vijg says. Still, that will only work if you live a careful life. And that means no accidents, infections, or cancers.

Aging also affects the exposed ends of your DNA, called "telomeres." DNA is stored as chromosomes, those X-like structures that you may have seen in biology textbooks. The most vulnerable parts of the chromosome are the chromosomes tips, which get shorter as you age because they arent properly replicated. But while telomere length might let you compare your DNA now with your DNA from a decade ago, you cant compare your own telomeres with other peoples telomeres. Theres a lot of variation between individuals, Vijg says. Some of us are just old souls (on the genomic level, that is.)

The methylation test, which looks at how the presence of small chemical groups attached to your DNA changes as you age, might be a better bet. A study at UCLA showed that changes were slower in longer-lived people. But Vijg is hesitant: I would not put my hopes on that as a marker to predict when exactly youre going to die.

For now, just enjoy your life, because you cant predict death. And if you decide to unlock the secrets of your DNA with an at-home test, don't take those results for more than their worth.

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What can genetic testing really tell you? - Popular Science

Could vitamin C help drugs fight leukaemia?

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By Aylin Woodward

Injections of vitamin C could be a way to help fight blood cancer. Experiments in mice suggest that the nutrient helps tell out-of-control cells to stop dividing and die.

Some blood cancers, including acute and chronic leukaemia, often involve mutations affecting a gene called TET2. This gene usually helps ensure that a type of stem cell matures properly to make white blood cells, and then eventually dies. But when TET2 mutates, these cells can start dividing uncontrollably, leading to cancer. Mutations in TET2 are involved in around 42,500 cancers in the US a year.

Luisa Cimmino and Benjamin Neel at the New York University School of Medicine and their colleagues have genetically engineered mice to have variable TET2 function. They found that a 50 per cent reduction in TET2 activity can be enough to induce cancer, but that TET2 activity needs to remain low if the disease is to continue developing. If we genetically restore TET2, it blocks unhealthy replication and kills the cells, says Cimmino.

Next, the team turned to vitamin C, because it is known to have an effect in embryonic stem cells, where it can activate TET2 and help keep cell replication in check.

The team injected mice with low TET2 activity with very high doses of vitamin C every day for 24 weeks and found that it slowed the progression of leukaemia. By the end of this period, a control group that got no injections had three times as many white blood cells a sign of pre-leukaemia.

When the team exposed human leukaemia cells in a dish to a cancer drug, they found they got better results when they added vitamin C.

Neel hopes that high doses of vitamin C will eventually be incorporated into cancer therapies. People who have acute myeloid leukemia are often of advanced age, and may die from chemotherapy. Vitamin C in combination with cancer drugs may provide an alternative approach.

But taking large amounts of vitamin C is unlikely to prevent you from getting cancer, says Neel. The mice were given 100 milligrams of vitamin C in each injection, the equivalent of about two oranges. But the average person weighs about 3000 times as much as a mouse. Because the body stops taking in the vitamin after around 500 milligrams, any therapies would need to supply vitamin C intravenously. You cant get the levels of it necessary to achieve the effects in this study by eating oranges, he says.

Journal reference: Cell, DOI: 10.1026/j.cell.2017.07.032

Read more: Choosing alternative cancer treatment doubles your risk of death

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Vitamin C helps genes to kill off cells that would cause cancer - New Scientist