In a previous post (http://evmedreview.com/?p=1034), I discussed a study from Stuart Orkin’s lab that illustrated the exploitation of genetic variants that influence a disease-related phenotype to design a possible therapy for a murine version of sickle cell disease. Increased fetal hemoglobin expression had been demonstrated to diminish the severity of sickle cell disease in mice, [...]
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The consortium of investigators known as ENCODE (ENCyclopedia Of DNA Elements) published, with much publicity, a series of about thirty papers last fall purporting to “identify all functional elements in the human genome sequence” (https://www.genome.gov/ENCODE/). Dan Graur, an evolutionary geneticist at the University of Houston, and his associates have published a paper in Genome Biology [...]
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In the past six months, I have encountered a review, by Thomas Nagel in The New York Review of Books (2012), of Alvin Plantinga’s latest book (Where the Conflict Really Lies: Science, Religion, and Naturalism, 2011 ) and a review, by Alvin Plantinga in The New Republic (2012), of a Thomas Nagel’s latest book (Mind [...]
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In 1996, Dean et al. (Science), demonstrated that a loss-of-function allele (CCR5Δ32) encoding a version of the chemokine receptor, CCR5, confers very substantial resistance to infection with HIV-1 in the homozygous state and slows progression in the heterozygous state. Given the relatively recent origin of HIV-1, this finding raised the question of what source of [...]
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A major problem confronting physicians, nurses, and other hospital personnel is transmission of pathogens among inpatients or between medical personnel and inpatients (in either direction). A crucial component in efforts to control such infectious outbreaks in hospital wards is determining whether particular cases are linked by instances of person-to-person transmission. Standard methods of analysis involve [...]
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A paper recently appearing in Science (Näsvall et al. 2012) offers a new insights into the mechanisms by which gene duplication can lead to new genes, gene products, and functions. The new scheme is termed the innovation-amplification-divergence (IAD) model.
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Peter and Rosemary Grant have been responsible for what must be among the longest-running continuous field studies in evolutionary biology (2011). It will reach forty years in 2013. In this work, the Grants closely follow multiple species of finches on the Galápagos Island of Daphne Major. Their results have provided numerous valuable insights into the [...]
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Influenza A viruses continue to be of enormous interest to biomedical researchers and clinicians alike. In addition to the annual influenza epidemics, which have been inferred to cause substantial excess mortality, there is the ever-present threat of a global pandemic due to several features of influenza virus biology. A high mutation rate associated with a [...]
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In the book, The Winner-Take-All Society (1995), Robet H. Frank and Philip J. Cook discuss a hypothetical scenario in which a new genetic technique allows babies to be engineered so that they have a 99% chance of performing 15% better on the standardized tests used in American college admissions, such as the Scholastic Aptitude Test [...]
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A common consequence of the evolutionary process in many species is extensive genetic diversity. As has become apparent in recent studies (Tennessen et al., Science 2012; Nelson et al., Science 2012), the growth of the human population coupled with what is believed to be reduced selective pressure, presumably in part due to the life-promoting and [...]
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There have been claims that variations in the composition of the intestinal flora influence individual health going back at least to the early years of the 1900s. Late in his career, Ilya Mechnikov, co-receipient of the Nobel Prize for Physiology or Medicine in 1908 (along with Paul Ehrlich) and a pioneer in the study of [...]
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Both Nature and Science are currently celebrating the 100th anniversary of the birth of an icon of logic, computer science, and mathematical biology: Alan Turing. In reading Andrew Hodges’s spectacular biography of Turing (1983) many years ago I came to appreciate that the subject of the book was both a deeply creative and extraordinarily rigorous [...]
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The new tools for determining nucleotide sequences for whole genomes can sometimes present a problem of data analysis: How can mutations that influence important phenotypes be distinguished from mutations that may be of minimal or no impact on fitness, so-called passenger mutations that arise and persist primarily by chance and can greatly outnumber adaptive genetic [...]
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Natural selection depends on heritable phenotypic variation. The most obvious source of phenotypic variation is genotypic variation. A new study, by Casanueva et al. in Science (2012) suggests that in addition to genotypic variation, variation in life history and stochastic variations in gene expression can substantially affect phenotypic variation. These authors studied mutation penetrance in [...]
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As noted in my last post, the selective advantage of heterozygosity for the sickle allele at the beta-globin locus has been known since Allison’s report in 1954 (Lancet). Nevertheless, a plausible and detailed mechanism to account for the protective effect of an allele that is typically highly deleterious when homozygous has not been forthcoming until [...]
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There is probably no more canonical example of the relevance of evolutionary genetics to clinical medicine than sickle cell disease. The relevance of the sickle allele, in heterozygous form, at the beta-globin locus for resistance to falciparum malaria was published by Allison in 1954 (Lancet), and the precise amino acid substitution responsible for the phenotype [...]
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Posted in evolutionary medicine, Genetics on Nov 30th, 2011
As biomedical technology advances, the probability increases that evolution guided, constrained, or facilitated by scientists will be relevant to medicine. Of particular interest in this context is the increasing ability of investigators to engineer microbes to produce gene products of benefit to individuals in need of specific treatments or for the general maintenance of health. [...]
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Among the most pressing global public health problems at present is the AIDS epidemic. While it is clear that chemotherapy and behavioral interventions have much to offer in limiting the spread of infections by the causative virus, HIV-1, interest in developing a vaccine remains strong. Immunization would potentially provide a relatively cost-effective and scalable approach [...]
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In the May 26 (2011) issue of Nature, Vijaykrishna et al. address patterns of evolution and transmission exhibited by swine influenza A viruses (SwIV) isolated from pigs beings slaughtered in Hong Kong between May 1998 and January 2010. Although the focus of the study is on viruses that circulate in swine, this study is relevant [...]
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An assumption fundamental to medical genetics is that the DNA sequence of an allele at a particular locus will (in the vast majority of instances) be faithfully transcribed into RNA and translated into protein. This assumption has been largely accepted in spite of known rates of transcriptional and translational errors as well as special cases [...]
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