El-Zein earned her Medical Degree followed by a Masters in Human Genetics from the University of Alexandria. She then completed her Doctoral degree in Human Biological Chemistry and Genetics at the University of Texas Medical Branch with a focus on cancer genetics. In 1997, she joined the University of Texas MD Anderson Cancer Center as a postdoctoral fellow and rose through the ranks to Associate Professor in the Department of Epidemiology. In 2015, Dr. El-Zein joined Houston Methodist as a Professor in the Department of Radiology and a full member of the Research Institute.

Dr. El-Zein is an active member of the national and international scientific community. She serves/served as a reviewer for the National Institute of Health, National Lung, Heart and Blood Institute and the American Cancer Society. Internationally, she is a grant reviewer for the Italian Ministry of Health. Dr. El-Zein also serves as a peer reviewer for several high impact journals.