SNPWatch: Taking Stock of Dengue Shock

Editor’s note: Pending an FDA decision, 23andMe no longer offers new customers access to health reports referred to in this post. Customers who purchased prior to November 22, 2013 will still be able to see their health reports, but those who purchased after that time will not. Those customers will have access to ancestry information as well as access to their uninterpreted raw data.

We all know that mosquitoes can be annoying. In many parts of the world, however, mosquitoes are more than just annoying–they are killers. Most people have heard of the mosquito-transmitted disease malaria, which has recently received much publicity through the work of The Bill & Melinda Gates Foundation and other non-profits. Dengue fever is another mosquito-borne disease, and although dengue receives less media attention than malaria, it nevertheless affects 50 million people each year.

Dengue has the greatest impact on those living in the tropics and sub-tropics, where the A. aegypti mosquito—the primary vector of the virus—can thrive. This, however, does not mean that those living elsewhere are unaffected; cases have been reported in southern Texas and Florida.

One of the active areas of research in dengue is investigating the huge variety of responses people can have to the virus. Many infected individuals have no symptoms, while others have mild flu-like symptoms; still others suffer life-threatening complications. One of these life-threatening complications is dengue shock syndrome (DSS), resulting from leaky blood vessels. Less than one percent of exposed individuals develop DSS, and whether one develops it depends on many factors, both genetic and non-genetic.

This month, a research team led by Chiea Khor from the Genome Institute of Singapore published in Nature Genetics a genome-wide association study on susceptibility to dengue shock syndrome after exposure to the dengue virus. They compared 3,855 Vietnamese children with DSS to 4,952 samples from the general Vietnamese population. Khor’s team found several genetic variants associated with DSS susceptibility located near the MICB gene on chromosome 6 and the PLCE1 gene on chromosome 10. Khor’s team found that in dengue-exposed Asians, each copy of the C version at in the MICB gene was associated with 1.34 times higher odds of developing DSS, and each copy of the T version at in the PLCE1 gene was associated with 0.8 times the odds of developing the complication.

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The MICB gene lies in a region of the genome known as the major histocompatibility complex (MHC), which contains many genes involved in the immune system.The PLCE1 gene, on the other hand, has also been associated with a kidney disease called nephrotic syndrome that has some symptoms similar to DSS’s symptoms.

This research shows that the development of dengue shock syndrome depends in part on individual genetics. In addition, the parallels between PLCE1 and nephrotic syndrome suggests common biological pathways may be involved in both diseases. Although more studies are needed to further confirm these discoveries, this paper presents exciting findings for the dengue research community.

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.