How does gene therapy contribute to treating rare diseases?

Gene therapy contributes to the treatment of rare diseases by correcting the genetic mutations that cause them. Most rare diseases, approximately 80%, are caused by a defect in a single gene [1]. Gene therapy works by replacing the gene that is not functioning correctly with a healthy gene, or by modifying the existing gene so that it works efficiently, thereby addressing the root cause of the disease at the genetic level [1].

Rare diseases are conditions that affect a small number of people, defined in the United States as affecting fewer than 200,000 people. However, there are more than 10,000 known rare diseases affecting millions of people worldwide [2]. These diseases are often life-threatening, and most of them do not have approved treatments [2].

Mechanism of Gene Therapy

The mechanism of gene therapy focuses on targeting the genes responsible for the disease. In some rare diseases, mutations in DNA cause a gene or protein to function incorrectly. Gene therapy aims to 'fix' these problems at the genetic level. For example, in cases of Spinal Muscular Atrophy (SMA), which is a group of rare genetic disorders that cause the loss of nerve cells that control skeletal muscles, gene therapy can target the SMN2 gene to produce more SMN protein, which is essential for nerve and muscle health [1]. There are also gene therapies that use a safe virus to deliver a new copy of the SMN gene to nerve cells to improve muscle movement in children under the age of two [1].

Examples of Rare Diseases That Benefit from Gene Therapy

Notable examples of rare diseases targeted by gene therapy are Spinal Muscular Atrophy (SMA) and Duchenne Muscular Dystrophy (DMD) [1]. In the case of Spinal Muscular Atrophy, which results from a mutation in the SMN1 gene, gene therapies help compensate for the lack of the vital protein that maintains the health of the nerves that control muscle movement [1]. As for Duchenne Muscular Dystrophy, which is the most common type of muscular dystrophy in children and results from mutations in the genes that make the protein dystrophin, gene therapies can help muscles produce more of this protein to maintain the stability and strength of muscle membranes [1].

Challenges and Future Prospects

Despite the great promise of gene therapy, the development of new treatments for rare diseases is often time-consuming, complex, and expensive [1]. Furthermore, the small number of patients with a specific rare disease makes conducting clinical trials difficult [2]. However, research is ongoing to ensure the safety and efficacy of these treatments, especially in cases such as Duchenne Muscular Dystrophy, where high doses of viral gene therapy require study to minimize side effects [1]. You can learn more about the general challenges in diagnosing and treating rare diseases by visiting Rare Diseases: Diagnosis, Challenges, and the Future of Gene Therapy (Arabic).

Important Considerations for Patients

Patients considering gene therapy for rare diseases should discuss the available options with their specialized physicians. It is important to understand that gene therapy may not be available or suitable for all rare diseases or for all patients, and that results may vary. Seeking out specialists in genetic diseases and organizations that support patients with rare diseases can be helpful in obtaining information and guidance about available and new treatments [3].

Medical references

• Gene therapies are a promising path to treating rare diseases
• Rare Diseases at FDA
• Rare Diseases