Gene Editing
There are several different types of gene editing technologies. Our programs use the highly efficient CRISPR-Cas system which consists of two key molecules. The first is an enzyme called Cas9 which acts as a pair of molecular scissors that can cut DNA at specific locations so that bits of DNA can then be added or removed. The second is a guide RNA that brings the Cas9 enzyme to the proper location in the genome.
What it is
In contrast to gene replacement, which delivers healthy genes to compensate for mutated ones, gene editing uses genetic engineering technologies to insert, delete, or replace DNA.
Why it matters
Acting like molecular scissors, gene editing can target the precise location of the genetic error among the more than three billion base pairs in our genome. Importantly, gene editing avoids the potential of delivering too much of the “Rett gene.”
Status
RSRT is funding two programs in gene editing. Beam Therapeutics, a leading editing biotech, is tackling specific mutations while a collaboration of powerhouse labs at the University of Massachusetts Medical School seeks to edit a large section of the Rett gene where 97% of the mutations reside.
A Deeper Dive
into the Science
Genes are made up of specific nucleotide bases (A, T, C and G) which encode for amino acids. Every three bases code for a specific amino acid. The MECP2 gene has 1497 nucleotide bases (A,T,C,G) that code for the 498 amino acids in the MECP2 protein. Alterations in the MECP2 gene range from a single letter to large sections of the gene being deleted or inserted. (To learn more about the genetics of Rett Syndrome please visit our Genetics Primer.)
Beam Therapeutics is focused on editing point mutations — mutations caused by a single nucleotide base error. This approach, known as “base editing,” would require a novel therapeutic to be developed for each point mutation. Another group, led by Jonathan Watts at University of Massachusetts Medical School, is pursuing “exonic editing” in which a single therapeutic would replace all of the 1,435 nucleotides in exons 3 and 4 and thereby correct 97% of all known mutations that cause Rett Syndrome.
The technology is amazing and provides a unique opportunity to potentially do something very meaningful for Rett patients.

A cure for Rett.
You want it.
We want it.
Great achievements happen when people stand up and say I’m in. I will be part of the solution!
Rett may be a rare disorder but together we are powerful.