ELi5: What is Genetic Imprinting? How is it different of other Chromosomal and Genetic errors like Addition or Deletion?


I’ve been trying to wrapped around it and read multiple books but nowhere I got satisfactory explanation.

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I assume you mean genomic imprinting. First of all, it’s simply not an error at all. It does not imply any deviation from what the genetic code “should” be and is a nomal part of how everyone human’s genes work (though there are plenty of other organisms which don’t use it). In fact if this mechanism doesn’t work, you get certain diseases.

Genes can be turned on and off without changing the genetic code. This is very important because if every cell in your body started producing every protein encoded in your genome completely unregulated, you would stop existing very quickly. One way to turn genes on or off is through epigenetic modifications and that’s what genomic imprinting is about. If a gene is affected by this mechanism, then you’ll recieve one allele from each parent exactly as you “should”, but only the one you got from your father is turned on and the other is off (or vice versa). Again, this has no impact on the genetic code, the sequence of A,T,C and G is the exact same whether it’s on or off. Epigenetics is mostly about DNA methylation and histone modification.

Literally little tags are added on to the DNA molecule like those sticky tabs added to notebook pages to tell you where to read

These are able to control the level of gene expression by affecting protein behaviour. They can ‘silence’ genes by suppressing expression, for instance.

Often regarding suppressing gene activity, the ‘tags’ are methyl groups that become attached to specific areas of the DNA. There are other types of tags for different things too.

These ‘epigenetic’ tags do not change your DNA sequence, that’s what makes it different from addition and deletion, which affect sequence. There is no affect on your DNA code, it only affects how the code is expressed. And a very large portion of the tags are removed in the process of producing sperm/egg, so they are not necessarily inhereted.