Capture of elusive cystic fibrosis gene prompts new approaches to treatment

Article Abstract:

The identification of the cystic fibrosis (CF) gene, which was announced on Sep 8, provided new knowledge about the function of the protein for which the gene encodes as well as indications for future therapy. The CF gene is a fragment of the DNA 250,000 base-pairs of chromosome 7; it is the code for a protein, comprised of 1,480 amino acids, which has been named CF transmembrane conductance regulator (CFTR). In 85 percent of CF patients this protein appears to be unable to ferry chloride ions across cell membranes properly, causing a decrease in extracellular water, and a thickening of mucous secretions which affects the respiratory, gastrointestinal and reproductive systems, sweat and salivary glands, and in severe cases, the pancreas and liver. Most CF patients die before the age of 30 due to lung infections. From the time of diagnosis, usually within the first few years of life, daily management includes dietary controls, enzyme replacement, and physical and respiratory therapy. Research will now explore genetic therapy by using retroviruses (which carry RNA, genetic material) to deposit information at the CFTR gene site into cells of the lung so that mucus secretions will become thinner. The Cystic Fibrosis Foundation has contributed $27 million annually for research and is now expected to increase grant monies for exploring drug and genetic therapies. When the CFTR defects in the additional 15 percent of CF patients are known prenatal diagnosis and carrier screening will become much simpler. Future screening will probably be achieved by analyzing the DNA from epithelial cells gathered from a mouth rinse.

Diagnosis, Gene therapy, Genetic disorders, Cystic fibrosis, Cystic Fibrosis Foundation

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Promising new technique may accelerate genome mapping

Article Abstract:

A new technique has been developed which may increase the rate of completion for mapping sets of genes in the chromosomes of human cells, the human genome. This technique uses landmarks called sequence tagged sites (STS). Currently, there is no uniform system of identifying landmarks on the chromosomes during the process of genome mapping. Up until now, different groups of investigators used varying methods of identifying segments of the human genome. With the new technique, researchers can identify newly mapped genes by providing the sequences of a unique track of deoxyribonucleic acid (DNA) contained within the clone, a group of identical cells derived from a single common cell. Use of a universal system will allow information to flow more easily from one group of researchers to another. STSes can be used to rewrite all existing chromosomal maps and, by using the STSes as landmarks, future discoveries can easily be added to these maps. The addition of new information would have the effect of improving the clarity and sharpness of the picture of the previously known map. There appears to be widespread enthusiasm among researchers for the use of STSes. Having a uniform system for identifying chromosomal landmarks would greatly simplify the job of synthesizing new genome mapping research. In addition, it would speed up the process and reduce its cost.

Methods, Human genetics, Chromosome mapping

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More details of AIDS-linked, viruslike infectious agent revealed

Article Abstract:

Recent reports by Shyh-Ching Lo, head of the AIDS pathology division of the Armed Forces Institute of Pathology's molecular pathobiology laboratory, have discussed the isolation and cloning of a previously unknown virus-like infectious agent (VLIA). The material was taken from a patient with AIDS and grown in tissue culture, and ultimately two DNA probes (biologic agents which allow the detection of VLIA in other cells) were prepared. The VLIA was detected in cells from 7 of 10 patients infected with AIDS. Brain and lymph tissue samples from these 7 patients, as well as brain tissue from 11 individuals who died from non-AIDS causes, were subjected to immunohistochemical analysis (the use of immunologically active stains to monitor activity in microscopic preparations of tissue). Although tissue from all 7 AIDS patients stained positively for the VLIA, none of the material from the non-AIDS patients was stained, indicating the absence of infection with the VLIA. In addition, Lo and his colleagues have shown that inoculation of monkeys with the VLIA leads to a fatal disease in which the VLIA is found at autopsy within the brain, liver and spleen of the test animals. Both the causative agent, VLIA, and the other produced reagents will shortly be released to the general scientific community for confirmatory studies.

AIDS (Disease), AIDS research, Lo, Shyh-Ching

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