In 1970 he co-founded an international registry of cases to help identify and diagnose inherited skeletal disorders and to find their genetic underpinnings. In the first year, information was collected on 50 cases; now, with 19,000 cases, the registry is the world’s largest for skeletal disorders.

Dr. Rimoin cherished an honorary lifetime membership in Little People of America. In an interview for an oral history project on genetics, he said the group’s gesture was important to him because he knew he had offended some of its members by helping to set up a program at Cedars-Sinai offering limb-lengthening surgery to people with dwarfism, a grueling process that involves breaking bones.

“I know that in developing the limb-lengthening program, I angered many of them who are opposed to invading their society and trying to sort of eliminate it in many ways,” Dr. Rimoin said in the interview, “but I stuck to my guns and felt that if somebody wanted it, they should have availability of it.”

In the 1970s, Dr. Rimoin and Dr. Kaback developed the first large-scale screening program for Tay-Sachs disease, a fatal genetic disorder most likely to be carried by Ashkenazi Jews.

Dr. Kaback had developed a system for testing large numbers of people, but he said Dr. Rimoin had the drive and knowledge to take the test public and reach those who might benefit: nearly a million Jews in the Los Angeles area. Since then, testing has virtually eliminated the disease in the United States.

To make sure that practitioners who treated genetic disorders were qualified to do so, Dr. Rimoin led a team of experts in developing certification tests and got medical genetics recognized as a full medical specialty in the 1990s.