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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.


Jul 6 2021 | Posted In: 20/20 Blog
Palo Alto, CA – As genetic testing and molecular biomarkers open new avenues for medical care, researchers are more reliant on samples from human subjects than ever.
Jun 15 2021 | Posted In: 20/20 Blog
Palo Alto, CA — A study by the Mahajan Lab, in close collaboration with Rajesh Rao’s lab at the University of Michigan, helps improve our understanding of vitreoretinal lymphomas (VRLs) and demonstrates how liquid vitreous biopsies c
May 6 2021 | Posted In: 20/20 Blog
Palo Alto, CA — Most people today, including many physicians, see the hypodermic needle as a mundane instrument that isn’t worth a second thought. This is not so for eye surgeons.
Apr 5 2021 | Posted In: 20/20 Blog
Palo Alto, CA — Interrupted patient care during the COVID-19 pandemic has been seen across the medical field with dire consequences. In ophthalmology, interrupted care can result in vision loss. 
Aug 11 2020 | Posted In: 20/20 Blog
Palo Alto, CA — Gene therapy has become a viable option for people with inherited eye disease, but because it is still a novel treatment, patient progress following gene therapy often relies on subjective measurements


Genetics of Uveitis., Cunningham, Emmett T., Pichi Francesco, Mahajan Vinit B., Rosenbaum James T., and Zierhut Manfred , Ocul Immunol Inflamm, 2021 Feb 17, Volume 29, Issue 2, p.215-218, (2021)
Telegenetics for inherited retinal diseases in the COVID-19 environment., Al-Moujahed, Ahmad, Kumar Aarushi, Chemudupati Teja, Tsang Stephen H., and Mahajan Vinit B. , Int J Retina Vitreous, 2021 Mar 29, Volume 7, Issue 1, p.25, (2021)
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)