READ IN UP' : CRISPR: Revolution in human history or mega time bomb?
Mutation, epimutation: what are we talking about?
A mutation is commonly defined as a change in the genetic information contained in an organism, whether in the form of DNA or RNA. Mutations are hereditary. They may be "silent", meaning they have no involvement in the metabolism of the body. They can also affect the expression of one or more genes, altering metabolism.
Epimutations belong to the family of mutations affecting the expression of a genetic sequence but which are not due to a modification of the genetic sequence itself. They may, for example, be due to a change in the chemical composition of the DNA building blocks, the nucleotides.
Preparation of cells to be transformed
The simple culture of cells induces mutations.
Vectorization, I mean...
The interim report of the SC of the silent HCB on these mutations
Selecting and regenerating "modified" cells is not without effect.
The theory behind backcrossing
The limits of the theory
Sequencing and associated computer tools? Anything but a guarantee of certainty!
On 7 April, at the hearing organised by the Parliamentary Office for the Evaluation of Scientific and Technical Choices (OPECST), André Choulika, CEO of Cellectis, stated on the subject of off-target effects ". resequencing the entire [plant genome] is really important [...] because in the approval, you are asked for the entire sequence again. ». Except that, on closer inspection, the sequencing results obtained are far from being absolutely reliable.
So-called "new generation" sequencing is today relatively cheap and fast. But there are several "problems" with its implementation, reading and use of the results.
First of all, several steps of the sequencing itself "parasitize" the reliability of the final result. One must know how to extract the DNA correctly, cut it into pieces and then sequence them using various platforms and methods. These platforms and methods are quite different from each other, both in terms of limitations and reliability of results .
These results should then be read by trying to put the read sequences back together to reconstruct the entire genome. The resulting sequences are then compared with other sequences that are considered "reference" sequences and stored in databases that already contain errors themselves .
These steps introduce significant imprecision into the final results of unintended effects detection and thus risk assessment, with uncertainties about sequences increasing with polyploid genomes or numerous repeated sequences . Moreover, the mutations identified may not ultimately be of the same biological significance  ...
Numerous articles summarize the difficulties encountered at each stage, compare the methods, platforms  and associated software , discuss gold standards and standards to be implemented to make the entire process more reliable . In short, as these authors point out, these are all techniques and stages that are in the process of being improved because they have not reached maturity, are evolving and therefore require a number of verifications for case-by-case evaluations.
According to many researchers, knowing how to deal with the accumulation of very many results (one of those famous "big data"), some with multiple errors, and using them rigorously is one of the challenges of today's molecular biology. Moreover, in the face of the skepticism raised by any sequencing result, the minimal demands of scientific article reviewers are such that more and more researchers are now obliged to present longer sequence results to ensure the seriousness of their raw results .