The cell's instruction library. In humans, about three billion letters (A, T, G, C) organized into 23 chromosome pairs.
A temporary copy of a recipe that leaves the nucleus so the cell can build a protein. Lasts hours or days; never modifies DNA.
A search-and-cut pair: a guide RNA locates an exact DNA sequence and the Cas9 enzyme cuts it. The cell's repair produces the edit.
The ~20-letter sequence that directs Cas9 to the exact point in the genome. Designing it is what makes editing programmable.
A CRISPR variant that swaps a single DNA letter without cutting both strands. Finer, lower-risk.
Precision editing that writes small changes using a reverse transcriptase. Newer, still in clinical development.
Outside the body (cells removed, edited, returned) or directly inside it. Almost all approved therapies today are ex vivo.
Treating disease by delivering genetic material: adding a working gene, silencing a harmful one, or editing the genome.
A disarmed virus used as a vehicle to insert a gene into cells. AAV (adeno-associated virus) is the most common.
A therapy that redesigns the patient's own immune cells to attack their cancer. Approved since 2017.
Designing and building biological systems that do not exist in nature: genetic circuits, organisms that make compounds.
Using engineered yeast or bacteria to make proteins and other compounds (insulin since the 1980s, dairy proteins without cows).
The microscopic fatty bubble that protects and delivers the mRNA in RNA vaccines.
The complete DNA set of an organism. The human one has about 20,000 protein-coding genes.
The machine that executes the instruction: built by the cell reading mRNA. Spikes, antibodies, and insulin are proteins.
A controlled study in people testing safety and efficacy. Phase I (safety, tens), II (dosing, hundreds), III (efficacy, thousands).
The public body that approves medicines: FDA (US), EMA (EU), MHRA (UK), and national equivalents.
A disease caused by one defective gene. These are gene therapy's first targets because the problem is locatable.
The hemoglobin a fetus makes, switched off after birth. Casgevy reactivates it to compensate for the faulty kind in sickle cell disease.
The short DNA sequence Cas9 must find beside its target. No PAM, no cut: a physical limit of the tool.