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Gene Therapy Lab

Gene therapy can modify mutations in genes or deliver an extra, healthy copy of an allele to treat inherited forms of blindness. Dr. Mahajan was a surgeon in the recent trial for gene therapy using a viral vector that successfully rescued vision loss in patients with Leber Congenital Amaurosis. The development of pre-clinical models to test gene therapy approaches for other forms of blindness, as well as testing gene therapy treatments in these pre-clinical animal models, is necessary and important to lead to clinical trials for human patients.

We are treating human patient stem cells and translational animal models with gene therapy approaches. We are also developing animal models for various inherited retinal degenerative diseases by introducing human genes or human mutations into the animals.

Pluripotent stem cells are made in the lab from patient volunteers with retinal degenerations. We then use gene editing (CRISPR) to correct the patient mutations in their own cells. Our lab was the first to correct a human blindness gene in human stem cells. These gene-corrected cells can then be used to test therapies and create transplants that replace diseased retinas.


Fixing faulty genes.
Direct modification of DNA in living cells.
Gene therapy correction in pre-clinical models of retinal disease.


May 15 2019 | Posted In: 20/20 Blog
Palo Alto, CA – What is genetic testing?
Feb 25 2019 | Posted In: 20/20 Blog
Palo Alto, CA —The Mahajan Lab in Stanford University’s Department of Ophthalmology is one of four 2018 recipients of the Stanford Alliance for Innovative Medicines (AIM) Grant.
Feb 13 2019 | Posted In: 20/20 Blog
Palo Alto, CA — Byers Eye Institute was recently selected to join the Foundation Fighting Blindness Consortium (FFB).
Feb 4 2019 | Posted In: 20/20 Blog
Palo Alto, CA — How can physicians and scientists make clinical trials faster, cheaper, and more likely to succeed? The answer may be proteomic analysis.
Dec 14 2018 | Posted In: 20/20 Blog
Palo Alto, CA — Why volunteer for a clinical trial? The rigorous process of turning a new therapy into the standard of care depends on patient volunteers. 


CRISPR Repair Reveals Causative Mutation in a Preclinical Model of Retinitis Pigmentosa: A Brief Methodology, Wu, Wen-Hsuan, Tsai Yi-Ting, Justus Sally, Cho Galaxy Y., Sengillo Jesse D., Xu Yu, Cabral Thiago, Lin Chyuan-Sheng, Bassuk Alexander G., Mahajan Vinit B., et al. , Retinal Gene Therapy, p.191–205, (2018)
Translation of CRISPR Genome Surgery to the Bedside for Retinal Diseases., Xu, Christine L., Cho Galaxy Y., Sengillo Jesse D., Park Karen S., Mahajan Vinit B., and Tsang Stephen H. , Front Cell Dev Biol, 2018, Volume 6, p.46, (2018)
Autologous stem cell therapy for inherited and acquired retinal disease, Apatoff, Mary Ben L., Sengillo Jesse D., White Eugenia C., Bakhoum Mathieu F., Bassuk Alexander G., Mahajan Vinit B., and Tsang Stephen H. , Regenerative medicine, (2018)
Gene Therapy Restores Mfrp and Corrects Axial Eye Length, Velez, Gabriel, Tsang Stephen H., Tsai Yi-Ting, Hsu Chun-Wei, Gore Anuradha, Abdelhakim Aliaa H., Mahajan Maryann, Silverman Ronald H., Sparrow Janet R., Bassuk Alexander G., et al. , Scientific reports, Volume 7, p.16151, (2017)
CRISPR-Mediated Ophthalmic Genome Surgery, Cho, Galaxy Y., Abdulla Yazeed, Sengillo Jesse D., Justus Sally, Schaefer Kellie A., Bassuk Alexander G., Tsang Stephen H., and Mahajan Vinit B. , Current ophthalmology reports, Volume 5, p.199–206, (2017)
CRISPR-Cas Genome Surgery in Ophthalmology, DiCarlo, James E., Sengillo Jesse D., Justus Sally, Cabral Thiago, Tsang Stephen H., and Mahajan Vinit B. , Translational vision science & technology, Volume 6, p.13–13, (2017)