Genetics
Study shows importance of DNA “junk” in disease processes. The Encyclopedia of DNA Elements (ENCODE) study was enormous: It is being published in some three dozen papers and review articles in four scientific journals, and 440 scientists from 32 labs around the world contributed to it. Its implications are also enormous: it suggests that bits of DNA that are part of the human genome, but do not contain instructions for proteins, nonetheless play a crucial role in controlling the development and behavior of cells. These DNA bits, which have heretofore been informally referred to by researchers as “junk,” apparently contain genetic switches that influence which genes are used in a cell and when they are used. As much as 18% of the human DNA sequence may have a role in regulating the 2% of DNA that codes for proteins. Researchers say there are at least four million such gene switches in the genome, and that many human diseases seem to be caused by changes in the switches. Such changes have been linked, for example, to increased risk for multiple sclerosis, lupus, rheumatoid arthritis, Crohn’s disease, and celiac disease. The research also suggests why disease processes are often not similar in identical twins: environmental factors may affect the genetic switches, causing one twin to be susceptible to disease while the other is not.
Study authors see ENCODE, which was begun in 2003 and was coordinated by the National Human Genome Research Institute (part of the National Institutes of Health), as a successor to the Human Genome Project. They believe that it eventually will have comparable importance on the clinical level. The insights that researchers gain as they analyze the study’s raw data—some 15 trillion bytes—are likely to lead not only to a better understanding of how DNA junk contributes to disease, but to the development of drugs that can affect the disease process on the genetic level. What is learned may also increase clinicians’ understanding of the complex interplay between genetic and environmental factors in a broad range of diseases.
Infectious Diseases
West Nile and hantavirus outbreaks spur disease control efforts. It was a bad summer for the spread of zoonotic diseases, and the Centers for Disease Control and Prevention (CDC) and other stakeholders are reviewing the data and working on strategies to use in summers to come. The number of cases of West Nile virus, spread by mosquitoes, was unusually high, particularly in north Texas, which prompted Dallas to initiate an unusual aerial spraying program in August. As of mid-September, nearly 700 cases of West Nile had been reported in the United States, almost half in Texas, and there had been 26 deaths. Approximately 60% of the cases involved encephalitis, meningitis, or other neuroinvasive diseases. Entomologists have linked the high number of cases to the hot, wet summer experienced by much of the nation, and the concomitant greater than average number of mosquitoes, which become carriers of the disease after they have bitten infected birds.
Meanwhile, Yosemite National Park was the site of a dangerous hantavirus outbreak. At least three visitors have died of the disease, and at least five more were diagnosed and are recovering. Hantavirus, which results from human contact with the feces, urine, or saliva of infected rodents but cannot be transmitted from person to person, was first definitively isolated in 1978. Diagnosis includes serum testing for antibodies IgG and IgM using Semi-Quantitative Enzyme-Linked Immunosorbent Assay methodology. The fatality rate is 38%. After the Yosemite outbreak, officials contacted thousands of people who had visited and camped at the park, urging them to be alert to the flu-like symptoms that appear during the onset of the disease.
Cancer
Study shows potential for more targeted lung cancer therapies. In a study published online in the journal Nature last month, a nationwide consortium of scientists has reported the first comprehensive genetic analysis of squamous cell carcinoma of the lung. The study found that almost 75% of the patients’ cancers have mutations that can be targeted with drugs that are available commercially or for clinical trials. The Cancer Genome Atlas project, which is supported by the National Cancer Institute and the National Human Genome Research Institute, combines efforts of the nation’s leading genetic sequencing centers, including The Genome Institute at Washington University, to describe the genetics of common tumors.
The study examined the tumors and normal tissue of 178 patients with lung squamous cell carcinoma. The investigators found recurring mutations common to many patients in 18 genes. Almost all of the tumors showed mutations in a gene called TP53, known for its role in repairing damaged DNA. Interestingly, researchers noted that lung squamous cell carcinoma shares many mutations with head and neck squamous cell carcinomas, supporting emerging evidence that cancers may be more appropriately classified by their genetics rather than by the primary organ they affect.
Current treatment for squamous cell lung cancers includes chemotherapy and radiation, but there are no drugs specifically designed to target this type of lung cancer. Squamous cell lung cancer is linked to smoking and is responsible for 30% of all lung cancer cases.
Endocrinology
Endocrine Society calls for screening adults for hypertriglyceridemia every five years. The Society recommends screening as part of a lipid panel in a Clinical Practice Guideline (CPG) for the diagnosis and treatment of hypertriglyceridemia. Triglycerides, a type of fat found in the blood, are associated with cardiovascular risk and, when levels are very high, pancreatitis. The most common reasons for high triglycerides include being overweight, lack of exercise, the metabolic syndrome, type 2 diabetes, and familial combined hyperlipidemia, which results in high triglycerides, high “bad” (low-density lipoprotein, or LDL) cholesterol, and low “good” (high-density lipoprotein, or HDL) cholesterol. The CPG appears in the September 2012 issue of the Journal of Clinical Endocrinology and Metabolism.
