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Archive - Aug 4, 2014

Researchers ID Gene That May Increase Risk of Alzheimer’s in African-Americans

Researchers from Boston University School of Medicine (BUSM) report that two rare variants in the AKAP9 gene significantly increase the risk of Alzheimer's disease (AD) in African-Americans. This previously unknown association furthers the understanding of the role of genetic factors in the development of AD, according to the researchers, whose findings appeared in the July 2013 issue of Alzheimer's & Dementia. AD is the most frequent age-related dementia affecting 5.4 million Americans including 13 percent of people age 65 and older and more than 40 percent of people age 85 and older. Up to 75 percent of AD cases are thought to have a genetic basis; however the specific genes involved likely differ between ethnic populations. The most well-known AD risk gene, APOE4, does not play as strong a role in AD risk in African-Americans as it does in Caucasians, despite the fact that a higher proportion of African-Americans than Caucasians are afflicted with this disorder. By analyzing the DNA sequence for all genes from participants of the Multi-Institutional Research on Alzheimer Genetic Epidemiology (MIRAGE) Study and Genetic and Environmental Risk Factors for Alzheimer's Disease among African-Americans (GenerAAtions) Study, researchers identified two genetic variants in AKAP9 unique to African-Americans that are enriched in individuals with AD. They then confirmed this association in several thousand other African American subjects in the Alzheimer Disease Genetics Consortium dataset. Carriers of either of these AKAP9 variants have a respective 2.8 and 3.6 times greater risk of developing AD. According to the researchers, AKAP9 encodes a protein with multiple forms, One of these, AKAP450, is expressed in the brain and responsible for microtubule anchoring and organization.

Better Tool to Visualize, Analyze Human Genomic Data

Scientists at the University of Maryland (UMD) have developed a new, web-based tool that enables researchers to quickly and easily visualize and compare large amounts of genomic information resulting from high-throughput sequencing experiments. The free tool, called Epiviz, was described in a paper published online on August 3, 2014 in the journal Nature Methods. Next-generation sequencing has revolutionized functional genomics. These techniques are key to understanding the molecular mechanisms underlying cell function in healthy and diseased individuals and the development of diseases like cancer. Data from multiple experiments need to be integrated, but the growing number of data sets makes a thorough comparison and analysis of results challenging. To visualize and browse entire genomes, graphical interfaces that display information from a database of genomic data—called "genome browsers"—were created. Epiviz offers a major advantage over browsers currently available: Epiviz seamlessly integrates with the open-source Bioconductor analysis software widely used by genomic scientists, through its Epivizr Bioconductor package. "Prior tools limited visualization to presentation and dissemination, rather than a hybrid tool integrating interactive visualization with algorithmic analysis," says Dr. Héctor Corrada Bravo, assistant professor in computer science at UMD. He also has an appointment in the Center for Bioinformatics and Computational Biology of the University's Institute for Advanced Computer Studies.

Makine Sense of Scents in Mice

For many animals, making sense of the clutter of sensory stimuli is often a matter of literal life or death. Exactly how animals separate objects of interest, such as food sources or the scent of predators, from background information, however, remains largely unknown. Even the extent to which animals can make such distinctions, and how differences between scents might affect the process were largely a mystery – until now. In a new study, described in an August 3, 2014 online paper in Nature Neuroscience, a team of researchers led by Dr. Venkatesh Murthy, Professor of Molecular and Cellular Biology at Harvard University, showed that while mice can be trained to detect specific odorants embedded in random mixtures, their performance drops steadily with increasing background components. The team also included Drs. Dan Rokni, Vikrant Kapoor, and Vivian Hemmelder, all from Harvard University. "There is a continuous stream of information constantly arriving at our senses, coming from many different sources," Dr. Murthy said. "The classic example would be a cocktail party – though it may be noisy, and there may be many people talking, we are able to focus our attention on one person, while ignoring the background noise. "Is the same also true for smells?" he continued. "We are bombarded with many smells all jumbled up. Can we pick out one smell "object" – the smell of jasmine, for example, amidst a riot of other smells? Our experience tells us indeed we can, but how do we pick out the ones that we need to pay attention to, and what are the limitations?" To find answers to those, and other, questions, Dr. Murthy and colleagues turned to mice. After training mice to detect specific scents, researchers presented the animals with a combination of smells – sometimes including the "target" scent, sometimes not.