Overview of CRISPR
CRISPR is an innovative mechanism that is reshaping lives and making significant strides in the healthcare sector. CRISPR, which denotes “Clustered Regularly Interspaced Short Palindromic Repeats,” exists in prokaryotes—tiny, unicellular entities devoid of organelles. These sequences are present in the genomes of prokaryotes, which neatly organize a cell’s DNA.
As a gene modification instrument, CRISPR is designed to alter specific DNA segments to address critical health conditions. It proves to be particularly effective in defending against viral attacks by integrating the foreign DNA into its own genetic material, thereby enabling it to identify and eliminate the virus during subsequent exposures. Notably, in comparison to other gene editing techniques, CRISPR offers greater accuracy and ease of programming, allowing for a more straightforward redesign of sequences. While traditional gene-editing tools typically utilize a single protein, CRISPR employs RNA-guided targeting in tandem with the Cas9 enzyme.
Mechanism of CRISPR
CRISPR operates by utilizing a natural immune system discovered in bacteria that enables them to detect and eliminate viral threats. When a virus infiltrates a bacterial cell (a prokaryote), the bacterium captures a fragment of the invader’s DNA within its genetic framework as a genetic “memory.” This allows the bacterium to recognize and react more efficiently to subsequent infections.
In the context of gene editing, this system is modified with two principal components: the Cas9 enzyme, acting as molecular scissors to sever DNA, and guide RNA, which navigates Cas9 to the precise genetic sequence requiring modification. Once the specific DNA is cleaved, the cell’s inherent repair processes take charge, permitting scientists to insert alterations into the genetic blueprint.
Unlike previous tools that depended on difficult-to-reprogram proteins, CRISPR’s RNA-based framework is more adaptable, simpler to design, and remarkably accurate. This straightforwardness and precision have enabled CRISPR to find applications across medicine, agriculture, production, and microbiology—such as engineering microbes for improved product yields. However, as this article will discuss, broader capabilities raise significant ethical dilemmas, particularly concerning germline modification and genetic enhancement.
First Patient to Receive Personalized CRISPR Treatment
In February 2025, the first-ever personalized CRISPR treatment was administered to a baby named KJ to address a deficiency in Carbamoyl Phosphate Synthetase 1 (CPS1)—an enzyme crucial for converting ammonia (which results from protein metabolism) into urea. A team headed by Dr. Rebecca Ahrens-Nicklas and Dr. Kiran Musunuru at the Children’s Hospital of Philadelphia developed this therapy following years of research in gene modification and collaboration with other medical professionals.
Their research concentrated on conditions affecting the urea cycle, leading to dangerous ammonia accumulation that harms vital organs such as the brain and liver. They customized KJ’s treatment specifically for his type of CPS1 deficiency, utilizing preclinical studies on analogous variants.
As of now, the only CRISPR treatments authorized by the U.S. FDA have targeted more prevalent conditions like sickle cell disease and beta thalassemia, which impact tens to hundreds of thousands of individuals. In KJ’s situation, his therapy was formulated within six months of his birth, targeting his unique CPS1 variant. The team devised a base editing method that was administered via lipid nanoparticles to his liver to rectify the dysfunctional enzyme.
The February treatment marked the first of three doses; KJ received the subsequent two in March and April 2025. Upon his last administration, he has shown no severe adverse effects, displays improved tolerance to dietary proteins, and requires reduced medication for ammonia management. Although continuous monitoring will be necessary, Ahrens-Nicklas has indicated that the outcomes thus far are encouraging.
Ethical Issues Surrounding CRISPR
With any pioneering technology, CRISPR brings forth intricate ethical challenges. Although its primary intention is to edit somatic cells for disease treatment, it may also target gametes, entering the contentious territory of germline editing. Modifying DNA that will be passed down to future generations is frequently viewed as unethical—especially when aimed at enhancing characteristics rather