Jul
03
2009
SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.
Schizophrenia, a devastating mental illness that affects about one out of every 100 people, is known to have a large genetic component. But scientists have had little luck in finding genes that are responsible for large numbers of cases. This in turn has hindered the search for new treatments that could provide relief to the tens of millions of schizophrenics worldwide.
But now new research has identified several common DNA variants that can influence the risk of developing schizophrenia. The key to this new success was data sharing - three large consortia combined their data to enable analysis of almost 13,000 people with schizophrenia and more than 34,000 controls. Continue Reading »
Tags: bipolar disorder, common variants, International Schizophrenic Consortium, MGS, schizophrenia, SGENE
Jul
02
2009
Not many people could survive the harsh conditions of the Sahara Desert. Yet the Tuareg have lived in the the region for millennia.
The Tuareg call themselves the Imazghan, meaning “free people.” Today they are known for a distinctive dark blue turban worn by the men, and for their long history as gatekeepers of the Sahara Desert. They are a semi-nomadic people who inhabit the West-Central Sahara, which encompasses parts of western Libya, Algeria, Mali, Niger, and some neighboring countries.
The Tuaregs were first mentioned by the ancient Greek historian Herodotus, who spoke of a group known as the Garamantes living in the Fezzan region of southwest Libya that operated trans-Saharan trade routes, connecting the heart of Africa to the North African coast. It is now believed that he was speaking of the Tuareg.
Though known to scholars since Herodotus’ depiction thousands of years ago, the Tuaregs remain shrouded in mystery. Their extreme isolation in one of the earth’s harshest environments has made them difficult for cultural anthropologists to study. There have been only a handful of studies published on the Tuaregs’ genetic history, and even these examined only the genetics of western Tuaregs from Mali, Niger and Nigeria. The eastern Tuaregs who inhabit the Fezzan of Libya remain far less studied. So a team of scientists decided to rectify this lack of genetic data, analyzing the mitochondrial DNA (mtDNA) of more than 100 Tuaregs from the Fezzan region of Libya. Their results are reported in the July issue of Annals of Human Genetics.
Continue Reading »
Tags: Libya, mtDNA, Tuareg
Jul
01
2009
On August 20, 79 AD, a series of small tremors and earthquakes began to shake the two ancient Roman cities of Pompeii and Herculaneum. Lying in the shadow of Mount Vesuvius — about 150 miles south of the Roman capital — the two cities were often hit by tremors and earthquakes, so most residents were unperturbed. After all, the tremors were relatively mild, especially compared to a severe earthquake that had hit both towns 17 years earlier.
They did not know, however, that this new string of tremors was in fact due to increasing pressure inside Mount Vesuvius; they did not know that Mount Vesuvius was in fact an active volcano; and they did not know that it was about to erupt.
Just four days later, on August 24, Vesuvius did just that. The cities of Pompeii and Herculaneum were taken completely off guard. So much so, in fact, that many residents were unable to escape the rain of pumice and ash that fell to dozens of meters high, burying people inside their homes. Even those who did survive the ash were unable to outrun the pyroclastic flow, a wave of white-hot cinders that tumbled down Mt. Vesuvius at over 100 mph. In just a few days, these cities became buried, and soon were forgotten.
Continue Reading »
Tags: Ancient DNA, Herculaneum, Mount Vesuvius, Pompeii, Rome
Jun
30
2009
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’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 Journal of the American Medical Association, indicate that CRP might not be a key player after all. Continue Reading »
Tags: atherosclerosis, CRP, heart disease, JUPITER
Jun
29
2009
Much to the surprise of many scientists, a lot of the SNPs identified in genomewide 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 “gene deserts,” areas of DNA that don’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. Continue Reading »
Tags: cancer, colorectal, gene desert, GWAS, MYC, SNP, Wnt
Jun
26
2009
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 American Journal of Human Genetics, shows that caution must be taken in moving from genetic discoveries to drug development. Continue Reading »
Tags: AJHG, drug development, FTO, obesity
Jun
25
2009
It’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.
“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,” writes Dougherty in an opinion piece published online today in the American Journal of Human Genetics. Continue Reading »
Tags: AJHG, ASHG, education, personalized medicine
Jun
24
2009
Malaria, a strong evolutionary pressure in humans, has also shaped the baboon genome, new research says.
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 it weren’t for genetic adaptations that have evolved in populations living in areas where malaria is a common threat.
Populations in Africa, Papua New Guinea and Brazil, for example, 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. The protective variations prevent expression of the Duffy antigen by the DARC gene, 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’s Amboseli National Park carry variants affecting DARC gene expression that provide protection against malaria. These findings, published this week in the journal Nature, mark the first time that a genetic variation has been linked to complex trait in a wild non-human primate population. Continue Reading »
Tags: baboon, DARC, Duffy, Kenya, Malaria
Jun
23
2009
Genomewide association studies have had some success 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 American Journal of Human Genetics, 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’s Hospital of Philadelphia recently took a similar approach (although the technical details of the analysis differ) for a study of Crohn’s disease. Continue Reading »
Tags: American Journal of Human Genetics, bipolar disorder, Crohn's disease, Genes, GWAS
Jun
22
2009
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. Whether it’s our eye color, height or the ability to consume dairy products, the variations in our genes contribute to making us ‘one of a kind’. Unfortunately, these variations can also lead to the onset of disorders that aren’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. 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. Scientists then look for genetic correlations that can help direct the development of diagnostics and therapeutics.
Continue Reading »
Tags: data access, Declaration of Health Data Rights, DNA, genetic data, genome-wide association studies, GWAS, research
