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Epigenetics: Why did my brother die and I didn’t?

same mutation, different outcomes/Center for Genomic Regulation

Well, isn’t that the key epigenetics question – what we really want to know.

From “Why Does the Same Mutation Kill One Person but Not Another?” (ScienceDaily, Dec. 7, 2011), we learn:

The vast majority of genetic disorders (schizophrenia or breast cancer, for example) have different effects in different people. Moreover, an individual carrying certain mutations can develop a disease, whereas another one with the same mutations may not. This holds true even when comparing two identical twins who have identical genomes. But why does the same mutation have different effects in different individuals?

Some researchers propose,

“In the last decade we have learned by studying very simple organisms such as bacteria that gene expression — the extent to which a gene is turned on or off — varies greatly among individuals, even in the absence of genetic and environmental variation. Two cells are not completely identical and sometimes these differences have their origin in random or stochastic processes. The results of our study show that this type of variation can be an important influence the phenotype of animals, and that its measurement can help to reliably predict the chance of developing an abnormal phenotype such as a disease .”

This team’s own research looked at the worm C. Elegans, the space shuttle blowup survivor. C. Elegans is too simple to feature many complicating factors.

They note,

The work suggests that, even if we completely understand all of the genes important for a particular human disease, we may never be able to predict what will happen to each person from their genome sequence alone. Rather, to develop personalised and predictive medicine it will also be necessary to consider the varying extent to which genes are turned on or off in each person.

Goodbye, “genetics is destiny.”

There is a sense in which no one can tell you why your brother died and you didn’t. Perhaps some day they can point to a gene abnormality that affected him fatally and you minimally – and offer a credible explanation of the cascade of outcomes. But that’s it. Some of what we need to know can only be addressed by philosophy, not science. Follow UD News at Twitter!

So far as we know, even if they started out identical, they just don't stay that way. News
I thought the word on the street was that identical twins do NOT have identical genomes- or are they saying there are some that do have identical genomes? Joe

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