The cause was pancreatic cancer, said Cedars-Sinai Medical Center, where he was director of the Medical Genetics Institute. He was a patient there at his death.

‘‘He was the world’s authority on dwarfism and diseases of bone and cartilage,’’ said Dr. Michael M. Kaback, an emeritus professor of pediatrics and reproductive medicine at the University of California, San Diego. The two were longtime research partners and had been collaborating on a study.

Dr. Rimoin’s research took him far and wide, and his subjects included African pygmies, circus performers with dwarfism, and Navajos with diabetes.

Studying the pygmies in Central Africa was an education in itself for a newly minted young doctor in the 1960s. Pygmies were treated as slaves by the Bantu, and Dr. Rimoin and his colleagues first had to pay the Bantu for permission to collect samples of the pygmies’ blood. The scientists then had to barter with the pygmies themselves, who drove hard bargains for machetes, salt, cigarettes, and, finally, costume jewelry that had belonged to Dr. Rimoin’s mother.

Entertainers with dwarfism and other growth disorders were among Dr. Rimoin’s patients in Los Angeles. One regular at the clinic was the actor Billy Barty, who founded Little People of America, an organization for people with dwarfism and other conditions causing short stature. Those conditions often cause nerve, bone, and vascular problems that need regular medical care.

Another of Dr. Rimoin’s patients, Rocky Dennis, inspired the movie ‘‘Mask,’’ about a young man whose face and skull are severely deformed and enlarged by a bone disorder, craniodiaphyseal dysplasia, also called lionitis. A doctor character in the movie was partly based on Dr. Rimoin.

Dr. Rimoin became a student of genetics not long after James D. Watson and Francis Crick ­deduced the structure of DNA, an exciting time when the field was poised to begin making discoveries that could greatly help patients. In the 1960s, Dr. Rimoin was among the first to suggest that diabetes was not one disease but one with different forms, probably caused by multiple genes. Though initially scorned by specialists, the idea was later proved correct. Recognition of differences in diabetes led to development of different treatments for the two major types of the disease.

Dr. Rimoin’s studies also pinpointed genetic defects that caused particular skeletal or growth disorders, revealing, for instance, that pygmies are short not because they lack growth hormone but because they carry an inherited trait that makes them biochemically resistant to the hormone’s ­effects.

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

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 1 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 specialists in developing certification tests and got medical genetics recognized as a full medical specialty in the 1990s.

David Lawrence Rimoin was born in Montreal. In 1961 he earned his medical degree from McGill University, where he was such a star student that he was personally invited to study further at Johns Hopkins University by Dr. Victor McKusick, who is regarded as the father of medical ­genetics. Dr. Rimoin earned a doctorate in human genetics at Johns Hopkins in 1967.

He later worked at Washington University in St. Louis and Harbor-UCLA Medical Center before joining Cedars-Sinai in 1986. He was coauthor of a classic textbook in medical genetics, first published in 1983 and now in its sixth edition.

At his death, Dr. Rimoin was working with Kaback on providing genetic testing for four inherited disorders most likely to occur in Persian Jews, including one that involves an unusual sensitivity to anesthesia.

Dr. Rimoin, who lived in Beverly Hills, Calif., leaves his wife, Ann; two daughters, Annie Rimoin and Lauren Rimoin; a son, Michael; and two sisters, Shirley Entis and Mona Deutsch.