Jennifer Doudna: The Development of CRISPR Gene Editing

In November 2018, Jennifer Doudna, the biochemist who co-invented the CRISPR-Cas9 gene-editing technology, received an email from He Jiankui, a biophysics researcher in China. The email informed her that he had used CRISPR technology to alter the embryonic DNA of twin girls, making them resistant to HIV. This marked the first instance of human germline editing, a genetic modification that is heritable.

Doudna had spent her career studying the fundamental chemistry of life and had actively advocated for the responsible use of CRISPR technology in medical applications, rather than for genetic enhancement or germline editing.

Early Life and Education

Jennifer Doudna grew up in Hilo, Hawaii, where her father was a professor at the University of Hawaii. Her interest in science was sparked by her observations of the unique flora and fauna in Hawaii's isolated ecosystem, leading her to appreciate the underlying mechanisms of biology.

A significant influence on her career path occurred in the sixth grade when she read The Double Helix by James Watson, an account of the discovery of the structure of DNA. The book introduced her to the process of scientific inquiry and structural biology. Despite Watson's dismissive portrayal of Rosalind Franklin, whose X-ray diffraction images were critical to the discovery, Doudna viewed Franklin as a role model, demonstrating that women could make foundational contributions to science.

Research on CRISPR-Cas9

Doudna’s academic research primarily focused on RNA and its 3D structural folding. As a professor at UC Berkeley, she was contacted in 2006 by Jillian Banfield, a microbiologist studying repeating DNA patterns in bacteria known as CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats).

CRISPR functioned as an adaptive immune system in bacteria. When infected by a virus, bacteria incorporate a segment of the viral DNA into their CRISPR array, using it to identify and defend against future infections. Doudna sought to understand the molecular mechanism behind this process.

In 2011, Doudna collaborated with Emmanuelle Charpentier, a microbiologist studying the Cas9 protein associated with the CRISPR system. Their joint research revealed that Cas9 acts as an endonuclease, guided by a specific piece of RNA to target and cut matching viral DNA sequences.

They further discovered that this system could be programmed. By synthesizing a custom guide RNA and attaching it to the Cas9 protein, they could direct Cas9 to cut specific DNA sequences. In 2012, Doudna and Charpentier published a foundational paper in Science detailing CRISPR-Cas9 as a programmable tool for gene editing, with significant implications for treating genetic diseases by precise DNA modification.

Ethical Implications and Advocacy

The development of CRISPR-Cas9 initiated a period of rapid biotechnology advancement and commercialization. However, Doudna grew increasingly concerned about the ethical implications of the technology, particularly the potential for human germline editing and genetic enhancement.

Motivated by concerns over misuse, Doudna organized a summit of leading biologists in Napa Valley in early 2015. The summit resulted in a joint publication in Science calling for a global moratorium on the clinical use of human germline editing to allow time for the establishment of ethical guidelines.

The 2018 Germline Editing Controversy

The urgency of these ethical concerns was realized with He Jiankui's announcement in 2018. He had deleted the CCR5 gene in embryos to confer HIV resistance, despite the availability of standard medical procedures to prevent HIV transmission and the unknown long-term health effects of the imprecise CRISPR edits.

Doudna publicly condemned the experiment at the Second International Summit on Human Genome Editing in Hong Kong, labeling it "truly unacceptable." The global scientific community widely criticized the work, and He Jiankui subsequently faced legal consequences in China for illegal medical practices.

Continued Work and Recognition

In 2020, Jennifer Doudna and Emmanuelle Charpentier were awarded the Nobel Prize in Chemistry for the development of a method for genome editing, marking the first time a science Nobel was awarded jointly to two women.

Doudna currently leads the Innovative Genomics Institute (IGI) at Berkeley, focusing on the therapeutic applications of CRISPR. In late 2023, the FDA approved the first CRISPR-based treatment for sickle cell disease. She continues to advocate for the responsible and regulated use of gene-editing technologies.