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Archive - Apr 8, 2011

Researchers Develop New Method to Screen and Analyze Mutations

A single change to even one of the thousands of DNA codes that make up each gene in the human genome can result in severe diseases such as cancer, cystic fibrosis, or muscular dystrophy. A similarly minor change in the DNA of a virus or bacteria can give rise to drug-resistant strains that are difficult for physicians to treat with standard drug therapies. For these reasons, scientists have long sought ways to study the effects genetic mutations can have on an organism but have been hampered in these efforts by an inability to easily and efficiently produce and analyze the thousands of potential changes possible in even one small gene. A new study by scientists at the University of Massachusetts Medical School, published in PNAS online on April 4, 2011, describes a novel technique to produce all potential individual mutations and using deep sequencing technology simultaneously analyze each change's impact on the cell. "In nature, genetic mutations actually occur infrequently and at random," said Dr. Daniel N. A. Bolon, assistant professor of biochemistry & molecular pharmacology and lead author of the PNAS study. "But these small changes have profound consequences on an organism's ability to survive. We've developed an approach that allows us to generate all the possible individual changes and, at the same time in the same test tube, study the impact of each change." Using sequencing technology inspired by the human genome project, Bolon and colleagues have developed a method called EMPIRIC to analyze hundreds of different mutations in a single test tube. Ordinarily used to read a DNA sequence over an entire genome, Dr. Bolon utilizes the ability of a band-aid-sized sequencing chip to accurately count and record the abundance of hundreds of distinct cells in a test tube that differ by individual mutations.

Caffeine and Diabetes

A growing body of research suggests that caffeine disrupts glucose metabolism and may contribute to the development and poor control of type 2 diabetes, a major public health problem. A review article in the March 2011 inaugural issue of Journal of Caffeine Research: The International Multidisciplinary Journal of Caffeine Science, a quarterly peer-reviewed journal from Mary Ann Liebert, Inc. publishers, examines the latest evidence, contradicting earlier studies suggesting a protective effect of caffeine. The entire issue is available free online. Dr. James Lane, of Duke University, describes numerous studies that have demonstrated caffeine's potential for increasing insulin resistance (impaired glucose tolerance) in adults that do not have diabetes, an effect that could make susceptible individuals more likely to develop the disease. In adults with type 2 diabetes, studies have shown that the increase in blood glucose levels that occurs after they eat carbohydrates is exaggerated if they also consume a caffeinated beverage such as coffee. This effect could contribute to higher glucose levels in people with diabetes and could compromise treatment aimed at controlling their blood glucose. "More than 220 million people worldwide have diabetes, says Editor-in-Chief Dr. Jack E. James, School of Psychology, National University of Ireland, Galway, Ireland. "The links that have been revealed between diabetes and the consumption of caffeine beverages (especially coffee) are of monumental importance when it is acknowledged that more than 80% of the world's population consumes caffeine daily. Dr.

Gene for Autism and Epilepsy Identified

Researchers from the CHUM Research Centre (CRCHUM) in Montreal, Canada, and colleagues have identified a gene that, when mutated, predisposes people to both autism and epilepsy. Led by the neurologist Dr. Patrick Cossette, the research team found a severe mutation of the synapsin gene (SYN1) in all members of a large French-Canadian family suffering from epilepsy, including individuals also suffering from autism. This study also includes an analysis of two cohorts of individuals from Quebec, which made it possible to identify other mutations in the SYN1 gene among 1% and 3.5% of those suffering respectively from autism and epilepsy, while several carriers of the SYN1 mutation displayed symptoms of both disorders. "The results show for the first time the role of the SYN1 gene in autism, in addition to epilepsy, and strengthen the hypothesis that a deregulation of the function of synapse because of this mutation is the cause of both diseases," notes Dr. Cossette, who is also a professor with the Faculty of Medicine at the Université de Montréal. He adds that "until now, no other genetic study of humans has made this demonstration." The different forms of autism are often genetic in origin and nearly a third of people with autism also suffer from epilepsy. The reason for this comorbidity is unknown. The synapsin gene plays a crucial role in the development of the membrane surrounding neurotransmitters, also referred to as synaptic vesicles. These neurotransmitters ensure communication between neurons. Although mutations in other genes involved in the development of synapses (the functional junction between two neurons) have previously been identified, this mechanism has never been proved in epilepsy in humans until the present study.