Dr. Kalatzis has created a the first human cellular model of the Choroideremia retina. Scientists are unable to study the retinas of living Choroideremia patients to understand how the disease works on a cellular level. Also, experimental future therapies cannot be tested in living patients to determine if and how they work. To address this need, Dr. Kalatzis has taken skin biopsies from Choroideremia patients and induced them to evolve into stem cells, or iPS cells. iPS cells have the capability to then form any cell in the human body, including the photoreceptor and RPE cells that degenerate in Choroideremia patients. By performing this crucial step, Dr. Kalatzis can study Choroideremia at the cellular level in her laboratory to better understand the disease and its natural history. In addition, these iPS-derived retinal cells can be used to test experimental future therapies on human cells to determine how effectively they could work in patients. These cells will be used for testing an experimental drug called Ataluren in conjuction with Dr. Mariya Moosajee. Dr. Kalatzis has also used this model to prove the efficiency of a gene replacement therapy using a viral vector called AAV-5, which could deliver a healthy copy of the Choroideremia gene into affected cells. This work represents a crucial first step towards a clinical trial.