Thom earned his Ph.D. from the University of Texas Graduate School of Biomedical Sciences in the Houston Texas Medical Center. His postdoctoral studies were in Immunogenetics and molecular biology. These led to his interest in genetically engineered mouse models for biomedical research. In 1987 he started work in the University of Michigan Transgenic Animal Model Core established by Dr. Sally Camper.

During his tenure as Transgenic Core Director, he pioneered application of bacterial artificial chromosome transgenesis to the development of mouse models. He used C57BL/6 embryonic stem cell to generate mouse models before the importance of B6 ES cells were recognized by the International Mouse Knockout Project. He established transgenic rat methods that are as efficient as transgenic mouse methods. He was an early adopter of gene editing nucleases for the produce gene-targeted mice and rats. His group produced models for thousands of genes and genetic conditions, including deafness, muscular dystrophy, and skin cancer. He trained numerous scientists in transgenic technology from around the world. He developed methods for mouse and rat transgenesis that sets or exceeds standards in the published literature. The ultimate goal of his efforts is to rapidly provide researchers preclinical models of human disease to improve human health.

In his free time Thom enjoys spending time with his children, going for long walks in the park with his dog, reading spy fiction, curating his music collections, and enjoying friendships.