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Study after study has shown that high blood levels of C-reactive protein (CRP), a marker of inflammation, are associated with increased risk of cardiovascular disease. But what hasn&#8217;t been clear is whether CRP actually causes heart disease, or just indicates the presence of artery-blocking atherosclerosis.
Researchers from Imperial College London set out to answer this question using a genetic approach.   They reasoned that if high CRP levels really do cause heart disease then genetic variants associated with increased CRP should also be associated with increased heart disease risk.   Their results, published today in <a href="http://jama.ama-assn.org/cgi/content/full/302/1/37?home" target="_blank" rel="noopener">Journal of the American Medical Association</a>, indicate that CRP might not be a key player after all.
Using a sample of 28,000 heart disease patients and 10,000 controls, Paul Elliott and colleagues examined several SNPs in the CRP gene. They found a significant association between the SNPs and CRP levels, and between CRP levels and heart disease – but not between the genetic variations and heart disease.
For example, each T at rs1205 lowered CRP by 20%.   Based on previous studies of CRP, this should have translated into 6% lower odds of heart disease. But there was no association of rs1205 with heart disease at all.
The researchers also identified four SNPs in other genes that were associated with CRP levels.   One was associated with heart disease in the expected direction (that is, the version associated with lower CRP was also associated with decreased heart disease risk). But two others had an inverse relationship with heart disease risk.   The final SNP affected CRP levels but had no relationship with heart disease risk either way.
Medical Implications
The JUPITER trial, published in the <a href="http://content.nejm.org/cgi/content/full/NEJMoa0807646" target="_blank" rel="noopener">New England Journal of Medicine</a> in November, showed that middle-aged men and women with low LDL cholesterol (below 130 mg/dL), but high CRP (greater than 2 mg/L) reduced their CRP levels by 37% and cut their risk of heart attack by 54% by taking rosuvastatin (Crestor ®).
These results suggest that CRP should be taken into account when deciding whether to prescribe statins to a patient, a move that would result in millions more Americans taking the drugs.
But the results of this new genetic study suggest that lower CRP doesn&#8217;t necessarily translate into a lower heart disease risk.   These findings support skeptics of the JUPITER trial, who argued that the improvements in cardiovascular disease risk seen with rosuvastatin treatment could have been due solely to their reduction (50%) of the study participants&#8217; already low cholesterol levels.
But the new study doesn&#8217;t necessarily mark end of the road for CRP testing.   In an <a href="http://jama.ama-assn.org/cgi/content/extract/302/1/92" target="_blank" rel="noopener">editorial</a> accompanying the new report in JAMA, Svati Shah and James de Lemos argue that even if CRP does not cause heart disease, it might still be valuable as a marker for identifying people who are at risk but do not exhibit traditional indicators such as high cholesterol.

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Genetic Study Casts Doubt On Inflammatory Marker As Cause of Heart Disease

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Much to the surprise of many scientists, a lot of the SNPs identified in genome wide association studies have not been in the parts of genes that encode the molecular machinery of a cell.
Instead, many SNPs have been found on the edges of genes, in regions of DNA that control when the genes get turned on or off, in parts of genes that get cut out before the final proteins are made, or even in so-called &#8220;gene deserts,&#8221; areas of DNA that don&#8217;t seem to contain any genes at all.
Rs6983267 is one of these gene desert SNPs.   People with two copies of the G version of this SNP have about 1.4 times the odds of developing colorectal cancer compared to people who have two Ts, but so far no one has been able to figure out why.   Two new reports show that, even though this SNP seems to be out in the middle of nowhere in the genome, it can interact with components of a signaling pathway known to be overactive in more than 90% of all colorectal cancers.
Results from <a href="https://dx.doi.org/10.1038/ng.406" target="_blank" rel="noopener">Tuupanen et al.</a> and <a href="https://dx.doi.org/10.1038/ng.403" target="_blank" rel="noopener">Pomerantz et al.</a>, both published online this week in the journal Nature Genetics, show that the region of DNA containing rs6983267 is an &#8220;enhancer&#8221; that can turn up the amount of protein made from the MYC gene. The riskier G version of the SNP appears to make the enhancer stronger than the T version.
In colorectal cancer, increased MYC expression can often be traced to overactivity of a molecular signaling pathway known as <a href="https://en.wikipedia.org/wiki/Wnt_signaling_pathway" target="_blank" rel="noopener">Wnt</a>.   Both groups of researchers found that the region of DNA containing rs6983267 was responsive to Wnt signaling, thus connecting this SNP to a well-established cancer mechanism.
Drugs that attack the Wnt pathway are attractive candidates for cancer therapies.   According to Tuupanen et al., the new results suggest that these same types of drugs might be useful for personalized cancer prevention treatments in people who carry the riskier version of rs6983267.

Better Understanding of Colorectal Cancer-Associated SNP Could Guide Treatment

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Not surprisingly, there has been intense interest in the genetics of obesity in recent years.   Obesity is a major health problem, resulting in tens of thousands of premature deaths and billions of dollars in healthcare costs each year in the United States, and it is known from twin and family studies that weight is a highly heritable trait.
The genetic mutations and variations identified so far explain only a small percentage of the variability in body mass seen in the population.   Some exciting clues have been found, however, as to why some people are more prone to obesity than others and how this might be counteracted.   But new research, published online this week in the <a href="http://www.cell.com/AJHG/abstract/S0002-9297(09)00238-9" target="_blank" rel="noopener">American Journal of Human Genetics</a>, shows that caution must be taken in moving from genetic discoveries to drug development.
Variations in the FTO gene have consistently been associated with obesity. On average, people who carry two copies of the &#8220;risky&#8221; version of this gene weigh six to eight pounds more than those who carry none. Mice completely lacking the FTO gene were shown to be leaner than their normal littermates, despite being less active.   These results have led some to suggest that inhibiting the FTO protein with a drug could be a good for obesity treatment or prevention.
(23andMe customers can see their FTO data in the Obesity Research Report.)
But an international team of researchers led by Sarah Boissel of the UniversitÃ© Paris Descartes in France has found that a mutation that interferes with the function of the FTO protein is associated with a lethal genetic condition.   Members of a large, inbred Palestinian family born with two copies of this mutation had multiple developmental abnormalities and died before the age of three.   Based on their results, Boissel and her colleagues warn that any research exploring the use of FTO inhibitors as obesity treatments must include a &#8220;careful assessment&#8221; of the potential to cause birth defects and other toxic side effects.
More about FTO:
<a href="https://blog.23andme.com/2008/12/11/snpwatch-gene-variant-linked-to-obesity-affects-food-choices-in-children/" target="_blank" rel="noopener">SNPwatch: Gene Variant Linked to Obesity Affects Food Choices in Children</a>
<a href="https://blog.23andme.com/articles/it%E2%80%99s-not-genes-or-environment-it%E2%80%99s-genes-and-environment" target="_blank" rel="noopener">It’s Not Genes or Environment, It’s Genes AND Environment</a>

Researchers Warn That Drug Development Based On Obesity Genetics Could Deliver More Than Is Bargained For

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It&#8217;s not enough to teach genetics, says Michael Dougherty, director of education for the American Society for Human Genetics.   It has to be taught in the right way.
&#8220;Current teaching practices may be producing a public that is unprepared to participate effectively as medical consumers in a world where personalized medicine will rely increasingly on genetic testing, risk assessment, predispositions, and ranges of treatment options that include biological and behavioral components,&#8221; writes Dougherty in an opinion piece published online today in the <a href="http://www.cell.com/AJHG/abstract/S0002-9297(09)00208-0" target="_blank" rel="noopener noreferrer">American Journal of Human Genetics</a>.
Dougherty calls for curriculum reform at all levels, from middle school all the way up through undergraduate education. The key, he says, is for students to understand that the genetics of most human traits and conditions are complex and, with only rare exceptions, not deterministic.
Dougherty suggests a new genetics curriculum that begins with lessons on traits that show continuous variation, such as height and weight, and focuses on how multiple inherited and environmental factors can affect these traits.   Teachers could then move on to discussions of genes and the molecular details of how they are passed from generation to generation.   Only here, in the later stages of their genetics education, would students learn about the rare single gene diseases, such as <a href="https://www.23andme.com/topics/carrier/cystic-fibrosis/">cystic fibrosis</a> and <a href="https://www.23andme.com/topics/carrier/phenylketonuria">PKU</a>, that make up the bulk of today&#8217;s genetics lessons.
&#8220;Our incompleteness of understanding and the messiness of complex-trait examples are poor arguments for maintaining the status quo in our genetics classrooms.   We know on theoretical grounds that the entirety of phenotype is defined by genes and environment, and substantial uncertainty still characterizes both.   To pretend such uncertainty does not exist is to deprive students of an appreciation of both modern genetics and the nature of science.&#8221;
Dougherty points to the Genes, Environment and Human Behavior module, funded by the Department of Energy and available from BSCS, as an example of the kind of lesson that could help correct the misconceptions that students already have.   The National Human Genome Research Institute also has available a <a href="https://www.genome.gov/10001551" target="_blank" rel="noopener noreferrer">Human Genetic Variation curriculum supplement</a>.   And of course, you can always check out the <a href="https://www.23andme.com/gen101/" target="_blank" rel="noopener noreferrer">Genetics 101</a> section of the 23andMe website for a basic introduction to genetics.

Curriculum Reform Needed For An Informed Public When It Comes To Genetics, Expert Says

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New research says that malaria, a robust evolutionary pressure in humans, has also shaped the baboon genome.
<h2>Impact of Malaria</h2>
Each year, at least 350 million people around the world are infected by malaria parasites.   More than one million people, mainly young children, succumb to the disease.
But these numbers would be even higher if not for genetic adaptations that have evolved in populations living in areas where malaria is a common threat.
For example, populations in Africa, Papua New Guinea, and Brazil carry variations in the DARC gene that protect them from infection by the P.vivax malaria parasite.   DARC encodes the Duffy antigen, a protein exploited by P.vivax to enter red blood cells.
<h2>Protective Genetic Variants</h2>
The protective variations prevent the DARC gene from expressing the Duffy antigen, leaving the parasite without a mode of entry to establish an infection.
Wild baboons are not usually infected by P.vivax or other malarial parasites that affect humans, but they are vulnerable to several closely related species.
In a new report, Duke University researchers show that, like some humans, groups of yellow baboons from Kenya&#8217;s Amboseli National Park carry variants affecting DARC gene expression that provide protection against malaria. These findings, published in the journal Nature this week, mark the first time that a genetic variation has been linked to complex traits in a wild non-human primate population.
<h2>Malaria Resistance</h2>
While the genetic variations that produce P. vivax malaria resistance in humans turn off the DARC gene, the variations that protect baboons from malaria actually increase the amount of protein made from the gene.
This suggests the mechanisms of resistance to malaria infection differ between the two species.   Researchers, however, are still impressed with the parallel nature of these evolutionary adaptations.
&#8220;It&#8217;s a nice example of how — in the vastness of the genome — the same gene was modified in the same way in two different species to produce the same kind of resistance,&#8221; Greg Wray, senior author of the report, said.   &#8220;That&#8217;s remarkable when you think of all the different ways malaria resistance might have evolved.&#8221;
Gathering the data for this study was no easy feat.
Graduate student Jenny Tung, the lead author of the report, spent three summers in the East African savanna collecting DNA-laden baboon feces and darting animals to take blood samples.
Wray says that the success of her work shows the power of combining fieldwork and genomic analysis.   According to him, the next challenge will be understanding how genetic variation contributes to complex behavioral traits like social status and aggression in wild primates.

Malaria Drove Evolution in Humans And Baboons

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Genomewide association studies have had <a href="https://blog.23andme.com/2008/08/18/snpwatch-snps-in-ion-channel-genes-are-associated-with-type-2-diabetes-and-bipolar-disorder/" target="_blank" rel="noopener">some success</a> in finding DNA variants associated with increased risk for bipolar disorder.   But researchers from the MRC Centre for Neuropsychiatric Genetics and Genomics at Cardiff University in England have taken these studies a step further by looking for common functional themes running through the GWAS data. Their results, published online this month in the <a href="http://www.cell.com/AJHG/abstract/S0002-9297(09)00209-2" target="_blank" rel="noopener">American Journal of Human Genetics</a>, implicate some of the most basic biological pathways in the genesis of bipolar disorder.
Starting with the idea that the genetic variations increasing risk for a disorder are probably not randomly distributed throughout the genome, but instead are in one or more sets of related genes, Holmans et al. re-analyzed the SNP data from four previous studies that included a total of 4,387 cases of bipolar disorder and 6,209 controls. Researchers at the Children&#8217;s Hospital of Philadelphia recently took a similar approach (although the technical details of the analysis differ) for a study of <a href="https://blog.23andme.com/2009/02/26/researchers-make-progress-in-understanding-crohn%E2%80%99s-disease-by-looking-at-the-big-picture/" target="_blank" rel="noopener">Crohn&#8217;s disease</a>.
The bipolar disorder researchers found that biological pathways involved in broad control of cellular activity were overrepresented in the genetic variations association with bipolar disorder.   Two of the pathways, hormone activity and cellular self-digestion, are known to be impacted by lithium, the major medication used to treat bipolar disorder. As always, more research will be needed to substantiate these findings, as well as to understand how they can be used to help the more millions of people worldwide dealing with bipolar disorder.

Researchers Look For Common Themes In Bipolar Disorder Genetics

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Each one of us carries in our cells the vital genetic data, compliments of our parents, that code for many of our traits and attributes. &nbsp;Whether it&#8217;s our eye color, height or the ability to consume dairy products, the variations in our genes contribute to making us &#8216;one of a kind&#8217;. &nbsp;Unfortunately, these variations can also lead to the onset of disorders that aren&#8217;t so unique.
Technology now allows scientists to tap into our DNA as they attempt to unlock the underlying genetic causes of diseases that afflict so many of us. &nbsp;These studies, often called Genome-Wide Association Studies (GWAS) because of their comprehensive design, are producing some very compelling results. Under the present research model, individuals who are asked to consent to participating in these studies typically donate a blood or saliva sample and provide access to information about their particular disease (or drug response, in the case of pharmacogenetic studies) through their health records or through diagnostic interviews. &nbsp;Scientists then look for genetic correlations that can help direct the development of diagnostics and therapeutics.

This model is fairly steeped in tradition and protocol. &nbsp;Once your sample and information are collected, researchers go out of their way to break the link back to you, with the mindset that it&#8217;s a necessary measure to protect your privacy – and, frankly, minimize their liability to deliver and explain the data. The genetic information derived from your DNA is often &#8220;de-identified&#8221; or &#8220;anonymized&#8221; so that it can&#8217;t be traced back to you. &nbsp;As a &#8220;human subject&#8221; in a study such as this, you are not offered access to this very personal data. &nbsp;Yet it could be very important for you to know. Now that we have more knowledge about how our genes impact our lives, thanks to these very studies, shouldn&#8217;t you be given access to the data if you want it? Even if there&#8217;s little you can do to alter the course of your genetic predispositions – which are often not definitive – we&#8217;re seeing overwhelming evidence that a lot of people would like this information.
At 23andMe, we believe it&#8217;s time for a research revolution, where the people involved – let&#8217;s no longer call them human subjects – can play a more active role and contribute more directly to studies of most interest to them and their families. &nbsp;And if any individual would like access to his or her data, he or she should be granted that request.
In this spirit, 23andMe is proud to support www.HealthDataRights.org and the Declaration of Health Data Rights. &nbsp;We believe genetic data are an integral part of your health information, and you should have access if you so choose.

It’s Your Data … Shouldn’t You Have Access To It?

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Only 250 miles separates the island of Madagascar from the southeast coast of Africa.   The short distance between the two land masses traditionally led the outside world to assume that the native inhabitants of Madagascar &#8211; known as the Malagasy &#8211; originally came from the west, probably from the present day southeast African nation of Mozambique.   Yet upon closer examination of the Malagasy&#8217;s language and their physical features, many scholars began to question this notion.   The Malagasy of the central plateau of Madagascar, known as the Highlanders, had light skin and facial features more akin to Southeast Asia or Indonesia.   They also practiced a rice culture that was not unlike the rice cultures of Asia.   And yet the coastal Malagasy, known as the CÃ´tiers, seemed just the opposite.   They had darker skin and curly hair that was more similar to modern day Africans.
But both the Highlanders and the CÃ´tiers speak the same language, which shares 90% of its vocabulary with a language spoken today in Southeast Borneo, and which has been officially classified as a branch of the Austronesian language family called West Malayo-Polynesian.   So how could a significant portion of Malagasy seem to share more in common with a region 5,000 miles away than they do with mainland Africa?   Trying to find the answers to these questions has vexed archaeologists, historians and linguists for generations.   Over the past several years, geneticists have entered the fray to try and unravel the mysterious origins of the Malagasy.   Their most recent effort appears this week in Molecular Biology and Evolution.
 
This study, led by Sergio Tofanelli of the University of Pisa, built upon a <a id="t0-g" title="2005" href="http://www.cell.com/AJHG/retrieve/pii/S0002929707607368" target="_blank" rel="noopener">2005</a> study by Matt Hurles and colleagues that was the first genetic exploration of the Malagasy people.   But Tofanelli and his colleagues wanted to dig even deeper into the genetic history of the Malagasy.   So they took the data analyzed by Hurles in addition to new DNA samples that were collected from people across the island of Madagascar.
They focused on two regions of the human genome often used in genetic ancestry studies:   the mitochondrial DNA (mtDNA) and the Y chromosome.   Because the mtDNA is used to trace maternal ancestry, and the Y chromosome to trace paternal ancestry, analyzing both in the same study can give a more complete picture of a group&#8217;s genetic history.
Tofanelli and his research team examined the mtDNA and Y chromosomes of Malagasy individuals scattered across the island, from both the Highlander and CÃ´tiers groups.   They were searching for any clues that would give an exhaustive understanding of how and when the island of Madagascar was first settled, and by whom.
The researchers&#8217; analysis revealed a mixture of both African and Asian genetic ancestry, in both the Highlanders and the CÃ´tiers, which is perhaps contrary to the two groups&#8217; physical apperance.   So what does this mean?   That even the CÃ´tiers people, who often look more African in appearance, have an ancestry that traced back to Asia, specifically Borneo.   These results fit well with Hurles&#8217; study and with what linguists have been saying for years; that the Malagasy language &#8211; while clearly tracing back to Borneo &#8211; also has some African elements that are significant.
The results from these analyses then begged the next question &#8212; how and when did the earliest inhabitants of Madgascar arrive on the island?   Was it in two separate migrations &#8211; one from the east and one from the west &#8211; or did the Asian/African genetic make-up of the Malagasy exist prior to their first steps on Madagascar?   It is easy to assume that any intermarriage between Africans and Southeast Asians happened after each arrived on the island.   In fact, Tofanelli describes the genetic make-up of the Malagasy as a consequence of &#8220;the encounter of people surfing the extreme edges of two of the broadest historical waves of expansion&#8221; in human history.   He is referring to the sub-Saharan African Bantu expansions that began 5,000 years ago and swept across Africa from Cameroon to Mozambique and southern Africa, and the Austronesian expansions about 4,000 years ago when seafarers journeyed from Taiwan to Borneo and beyond.
But Tofanelli proposes an alternative hypothesis as well.   He argues for a long history of contact between Bantu-speaking Africans and seafarers from Borneo dating back thousands of years.   As evidence he cites banana cultivation in Cameroon and Uganda that can be traced back to Southeast Asia, as well as the introduction of humped cattle into Africa from Asia.   If the Southeast Asians and eastern Africans shared farming techniques, it stands to reason that they may have shared genes as well.   Thus the people of Madagascar may have not simply been Africans and Southeast Asians arriving on the island from opposite directions, but rather they represent a more complex genetic history of proto-Malagasy arriving on Madagascar about 2,300 years ago, already containing a mixture of Asian and African ancestry.
This hypothesis most certainly needs additional evidence and data before it can be supported, but it brings a new level of understanding to the mysterious origins of the Malagasy.

New Study Reveals Complex Origins of the Malagasy

It&#8217;s no secret that obesity rates are rising &#8212; quickly.   Between 2000 and 2005 the prevalence of obesity rose by 24%.   Extreme cases increased by more than 50%.   If current trends continue, more than half of all Americans will be clinically obese by the year 2030.
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Rapid changes in the prevalence of a disorder suggest that <a href="https://blog.23andme.com/2009/05/28/environment-not-genes-key-to-increasing-disease-rates/" target="_blank" rel="noopener noreferrer">environmental rather than genetic factors </a>are to blame. But scientists know from twin and adoption studies that body mass index (BMI) is highly heritable.  
So which is it: nature or nurture?
As with many aspects of human health, it&#8217;s both.   Some people have the bad luck to have inherited genetic variations that together with the modern environment — sedentary jobs and hobbies, easy access to calorie-dense foods — create the perfect storm for gaining weight.
Changing the environmental factors that lead to obesity in some people seems simple enough — more exercise, less food.  But public health campaigns touting these commonsense fixes have had little effect against the obesity epidemic. By understanding the genetic aspects of obesity, and how they interact with the environment, scientists may be able to develop more effective treatments and prevention strategies.
In the July issue of <a href="https://www.nature.com/nrg/journal/v10/n7/abs/nrg2594.html" target="_blank" rel="noopener noreferrer">Nature Reviews Genetics</a> Andrew J. Walley of Imperial College London and colleagues review the current state of obesity genetics research.   While much progress has been made, the authors make it clear that there is still a long way to go, as the genes identified thus far explain only a tiny fraction of the total genetic component.
One key to future advancements in obesity genetics research, say Walley et al., lies in improvements to current genomewide association study (GWAS) methods.
First, the authors recommend that researchers focus on recruiting extremely obese people for their studies to increase the likelihood of finding genes with large effects. They also suggest that scientists should stop using BMI as their primary measurement of obesity.   While simple and cheap, this method does not take fat distribution or the ratio of fat to muscle into account.   There are more sophisticated methods, such as CT scans, MRI scans and ultrasound imaging, as well as machines that use air displacement to measure body volume and weight and can calculate fat and fat-free body mass.   Technological advances that will reduce the costs associated with genotyping, and ultimately genetic sequencing, are also needed so that larger numbers of subjects can be studied.
Beyond these improvements to current GWAS methods, Walley et al. say studies of more than just common variations are needed.   They suggest that investigations of rare SNPs, copy number variations (duplications, insertions and deletions of DNA) and inherited changes that don&#8217;t affect the actual DNA sequence will be needed to fully understand the genetics of obesity.
There are several competing theories about the overall biological basis of obesity.   Some suggest that obesity is a disorder of energy balance in the body, while others think regulation of the growth of fat cells is the key.   Still others think obesity may be due to defects in the neurological control of appetite and food intake.   Continued advancements in understanding the genetics of obesity will help scientists tease these theories apart, and hopefully lead to a healthier future.<a href="https://blog.23andme.com/2008/05/04/snpwatch-mc4r-gene-associated-with-body-mass/" target="_blank" rel="noopener noreferrer"></a>

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