Some diseases stem from a missing or defective gene. Gene therapy aims to treat them by introducing a functional gene or correcting the existing one inside a patient’s cells. Viral vectors or non-viral delivery systems carry the therapeutic DNA or RNA.

Ex vivo approaches modify cells outside the body and return them to the patient; in vivo methods deliver the therapy directly. Approved treatments now exist for certain forms of inherited blindness, spinal muscular atrophy, and blood disorders. CRISPR-based editing is entering clinical trials.

Challenges include immune responses to vectors, precise targeting, and long-term expression. Safety monitoring remains intensive. Successful gene therapy can provide lasting benefit from a single treatment, transforming previously untreatable genetic conditions.

• Introduction or correction of genes to treat disease
• Uses viral or non-viral delivery
• Can be ex vivo or in vivo
• Emerging standard for certain genetic disorders