February 17, 2010
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A great report on GenomeWeb yesterday by Andrea Anderson reviews two JAMA papers that failed to show a clinically useful role for SNP genetic testing in predicting heart disease risk. Instead,
“traditional risk information based on factors such as family history and plasma biomarker levels were better for predicting heart disease.”
Anderson ties these results back to a January paper in the British Medical Journal that found that
“non-genetic factors were more useful for predicting type 2 diabetes than a set of 20 SNPs.”
The GenomeWeb article quotes the lead author of one JAMA paper as finding the results “surprising and a little disappointing;” but I am inclined to think some context is missing, since only the most die-hard genetic determinist should be either surprised or disappointed.
Two factors suggest that these conditions, and many others, will resist accurate prediction based on genomic sequence analysis:
- They are genetically complex. The prospective studies looked at data sets with between 12 and 101 SNPs. Simple calculations suggest that the number of genetic permutations is itself staggering, never mind the physiological complexity of multigenic interactions.
- There are massive environmental components. Diet and exercise, among many other factors, will have a tremendous impact on clinical outcomes. These habits are learned, not inherited, and are even “contagious” within social groupings.
My bottom line: In an age when genomic sequences are becoming increasingly accessible, it should be reassuring to know that even your medical future is not written in stone. We always suspected as much. Now we have the genetic data to prove it.
February 5, 2010
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Several neurological related stories this week and quantum biology?
Glial Cells – They’ll turn against you: An unusual molecule can turn glial cells, which normally surround neurons, into killer cells that attack the neurons they are suppose to protect. Researchers made the surprising discovery of proNGF’s role while trying to figure out its function in the eye. They found that it can activate glial cells to turn against retinal neurons and potentially cause vision impairment or loss. Some of the molecular details were also worked out and they describe the significance of TNFalpha and p75NTR proteins in this cell death process. These results shed light on potential routes for therapeutic targets to prevent certain cases of vision loss. The study, published in the early on-line edition of the Proceedings of the National Academy of Sciences, is a collaboration involving Dr. Adriana Di Polo at Université de Montreal and Dr. Philip Barker at the Montreal Neurological Institute.
Unexpected Heart Failure and Treatment: Researchers studying mouse models for neuronal diseases, such as Alzheimer’s, noticed progressive abnormalities in the rodent’s heart function. The mice had slower heart rates (as expected) but they also had difficulty pumping blood and researchers soon realized that they may have stumbled upon a possible mechanism of human heart failure. The genetic modification in these mice resulted in decreased levels of the neurotransmitter, acetylcholine. In contrast to previous reports on heart failure, this is the first study suggesting that slower heart rates may lead to cardiac dysfunction. Furthermore, the administration of the drug Pyridostigmine, which increases acetylcholine levels and is approved for treating muscle weakness, corrected the cardiac dysfunction. The research team of Drs. Marco Prado and Vania Prado at the Robarts Research Institute at The University of Western Ontario describe their findings in the latest edition of Molecular and Cellular Biology.
Early Stages of Huntington’s: Insight into the cellular mechanisms in the brain that causes Huntington’s disease is described in this article appearing in the journal Neuron. Using mouse models expressing the gene mutations causing the disease, scientists discovered increased numbers of NMDA receptors surrounding the synaptic connections between neurons. The increased NMDA receptor activity also diminishes survival signals leading to brain cell death. In other words, the neurons become confused and triggers cell death (excitotoxicity). Although it is not known why the receptors accumulate outside of the neuron, a therapeutic drug is already available (for Alzheimer’s) to treat the early stages of the disease. Memantine can control the abnormal NMDA receptor signaling specifically outside the synapses and not disrupt the normal activity within the synapse, thereby reducing side effects. Clinical trials are underway. Dr. Lynn Raymond at the University of British Columbia led the research team.
Algae + Quantum Biology?: It appears that algae, a very simple organism, figured out quantum mechanics nearly two billion years ago. During the process of photosynthesis, antenna proteins in the light-harvesting complexes absorb light and transmit the energy between molecules to proteins in the reaction centre. Researchers at the University of Toronto decided to study this energy transfer and discovered quantum mechanics at play in this photosynthetic process. This is just a bit beyond the scope of our blog but you can read Drs. Greg Scholes and Paul Brumer’s commentary here or enrich yourself with the detailed study here in the journal Nature.
July 2, 2009
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Some suggestions for things to do:
And some suggestions for things not to do: