Prior posts have noted that gene functioning can be modified by a number of processes, such as methylation. Recently animal tests have found that some of these modifications are passed on to off-spring even though no change is made to the gene itself, only to its expression. Prior posts have also noted, for example, that cancers differ one from other in terms of the number of gene malfunctions that must go wrong for the cancer to progress; some require only a few, some require many. Now researchers have sought to ascertain if genetic differences could predict 24 different disease, including several cancers, heart disease, and Alzheimer's.
The researchers reviewed medical data on 53,666 twin pairs. They did not decipher the twin's genome, but used medical data to develop a formula to predict the minimum and maximum risk of getting 24 different disease. For all but four, the genetic data was seen to fail to determine who is likely to contract the condition. A "positive result" was deemed a person having a 10+% chance of developing a particular disease. The likely reason is that, as noted in prior posts, genes are only part of the causative equation.
Genetic testing for four diseases (thyroid autoimmunity, Type 1 diabetes, Alzheimer's, and death from coronary heart disease in men) could predict 75+% of those who got the disease. These diseases may have fewer genes as the underlying cause, or the genes may have a stronger effect than for other diseases.
The study can be found at: http://stm.sciencemag.org/content/early/2012/04/02/scitranslmed.3003380.
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