CRISPR-Cas9: Revolutionizing Genome Editing and Genetic Disease Treatment

All living cells contain DNA, made up of four chemical bases —

• A (adenine)
• T (thymine)
• C (cytosine)
• G (guanine)

These bases are arranged in specific sequences to form genes, which act as instructions for building proteins. Proteins directly influence our phenotypes—observable traits—like eye color, hair texture, or whether someone develops white hair early in life.

Every cell in our body contains a full copy of DNA—over 20,000 genes made from 3 billion letters. These genes influence both our traits and our health. To study and control them, scientists need ways to edit DNA. A breakthrough method, CRISPR-Cas9, offers a powerful way to do this.

CRISPR is inspired by a natural defense system used by bacteria. When a virus attacks, the bacteria produce guide RNAs that match the virus's DNA. These RNAs combine with a protein called Cas9, which acts like molecular scissors to cut the viral DNA and disable it.

Scientists discovered that by changing the guide RNA, they can direct Cas9 to cut any DNA sequence in living cells. Once Cas9 makes a cut, the cell tries to repair it—often causing mutations that help researchers study the gene's function. If more precise changes are needed, scientists can insert a DNA template with the correct sequence to replace faulty genes.

A key strength of CRISPR is its ability to target multiple genes at once, which is especially useful for studying conditions influenced by several genetic factors.

CRISPR is rapidly advancing and is expected to have major impacts in research, agriculture, drug development, and potentially in treating human genetic diseases.

This article is inspired by a talk on CRISPR-Cas9 by McGovern Institute .