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Duke Scientists Map 'Silenced Genes'
palegray.net writes "Wired reports on new research into the phenomenon of 'silenced genes', genetic constructs that have no 'partner' in case one goes wrong over the course of your lifetime. Scientists at Duke University have mapped some 200 genes that may 'play a profound role' in the health of the average human. 'Many of the newly found imprinted genes are in regions of chromosomes already linked to the development of obesity, diabetes, cancer and some other major diseases, the researchers reported ... Scientists had thought imprinted genes would account for about 1 percent of the human genome. While scientists must double-check that the newly identified ones are truly silenced, the new map matches that tally.'"
Stay sentient. Don't drink bad milk.
you are correct, the gist of the research goes like this:
1) some genes can be switched on or off by environmental factors [chemicals, other genes etc.]
2)if one of these cells that has a switched on/off gene just happens to be a sperm cell or an egg, it can carry that epigenetics to the next generation.
3) some genes can only be inherited functional from one parent
4) if that parent happens to be the one that has the inactivated [switched off] gene then that gene is entirely non-functional in the offspring because there is no functional back up gene from the other parent.
this leads to the conclusion that environmental factors can alter gene expression which can be inherited to offspring which under some conditions and genes no longer have a functional gene that may or may not prevent disease, that is to say if the gene is inactivated you're likely to get the associated disease. In many cases, these genes are thought to be involved in obesity, heart disease, cancer etc. which means that environmental factors in your parent's lives or even your grandparent's may contribute to you being more likely to get a certain disease associated with a non-functional gene.
Sigs are too short to say anything truly profound so read the above post instead.
On the Duke news site they give more information about how they came to their findings. They mention that they fed data about the sequences of genes known to be imprinted, and likely to be non-imprinted genes into a computer to check for differences. Based on that, they searched for other sequences that resembled the imprinted ones. That's why the results are just good guesses and more research need to be done to determine if they are true positives.
Knowing that one of the copies is imprinted helps in three ways -
(a) It helps provide people with genetic counseling e.g. helps in deciding if you want to continue with a pregnancy if you know that your fetus has a genetic defect on the paternal copy (and the maternal copy is silenced) by sequencing an amniocentesis sample.
(b) More fundamental to this is that, is that this might help pin down a gene defect as the cause of a disease. For example you might find some locus often associated with a disease but in the patients you sequence the genes, it turns out one of them has got a perfect copy and the other has a mutation. Since it is difficult to say for a majority of mutations if they would affect function or are simple polymorphisms in the population, you continue searching other genes. OTOH, if you know one of the copies is shut down, and you see one copy has a mutation, you promptly analyze this candidate gene a lot more.
(c) Finally, of course for proper cure, it helps to know what the defect is. e.g. if you know it is a defect in an ion transporter, you might try some types of drugs and if it is an inflammatory defect you will try something else - so (b) is useful in guessing plus making animal models to test them.
(d) there is the hope that one day we will be able to fix things gene therapy which again is dependent on figuring out the molecular defect by (b).