The cause was pneumonia, said his wife, Diane Drobnis Rosenberg. He had squamous cell carcinoma, a form of skin cancer.
When Dr. Rosenberg decided to specialize in human genetics in the early 1960s, motivated by his detective-like experience diagnosing rare hereditary disorders in children, the field scarcely existed. It was generally considered niche, a minor part of medicine — hardly worth pursuing for an ambitious young physician-scientist.
“Medical genetics? There is no such field!” a Yale University nephrologist told him.
Yet Dr. Rosenberg went on to become a leading figure in what is now a sprawling field of study, conducting influential research on metabolic disorders and training generations of scientists. In a five-decade teaching career, he started out at Yale, took a detour into the pharmaceutical industry and spent nearly 20 years at Princeton University, teaching undergraduates and then reshaping the high school science curriculum at Princeton Day School before retiring in 2018.
“He really was a visionary who recognized much, much, much earlier than almost everyone else that genetics — and now genomics — would play a role in medicine that would stand on its own,” said his former PhD student Huntington F. Willard, a geneticist and chief scientific officer at Genome Medical. “Almost everything has at least some connection to genetics and genomics, and he saw that human genetics couldn’t be tucked under some other wing. It deserved to be by itself.”
Shuffling between the hospital and the laboratory, Dr. Rosenberg treated patients like Robby, a comatose 8-month-old boy. In the late ’60s, he diagnosed Robby with methylmalonic acidemia, or MMA — in which the body struggles to break down certain fats and proteins — and developed a new way to manage the disorder through supplements of vitamin B12. He continued to invoke Robby’s name for decades, telling students the story of his former patient while declaring that clinical care and scientific research were inextricably linked.
“He was an extraordinary teacher,” said Harold T. Shapiro, a Princeton economist and former university president who helped recruit Dr. Rosenberg to the school. “He was untiring,” Shapiro added, “in his willingness to speak to students at length” about careers in medicine.
Even as he maintained a busy schedule, Dr. Rosenberg suffered periods of major depression, which he revealed in a 2002 essay, “Brainsick,” that was published in the magazine Cerebrum and excerpted by the Baltimore Sun. Even counting some 300 scientific papers, it was perhaps the most important thing he ever published, he said.
As Dr. Rosenberg revealed in the essay and in a self-published memoir, “Genes, Medicine, Moods,” he attempted to treat his depression with Prozac before attempting suicide in 1998, around the time he began teaching at Princeton.
Taken to the hospital by his wife and one of his daughters, he was examined by one of his former Yale students, a physician. “No one will believe that you, of all people, would try to take your own life,” the doctor told him.
Dr. Rosenberg was diagnosed with bipolar disorder and said he came to understand that he was “brainsick” when he tried to kill himself.
“I view my suicide attempt as the end result of mental illness in the same way I view a heart attack as the end result of coronary artery disease,” he wrote. “Both are potentially lethal, both have known risk factors, both are major public health problems, both are treatable and preventable, and both generate fear and grievance. But the shame associated with them differs greatly. Heart attack victims are consoled (‘Isn’t that a pity?’); suicide victims are cursed (‘How could he?’).”
Treated with electroconvulsive therapy and put on a low dose of lithium, he said he no longer experienced depression and found his professional productivity undiminished. With encouragement from his psychiatrist, his colleagues and his wife, he began speaking openly about his diagnosis — feeling, as his wife put it in a phone interview, “that mental illness was being swept under the rug.”
At times, he presented his case history to his students, bringing some of them to tears as he discussed his suicide attempt and bipolar disorder.
“It makes no sense to allow stigma, whose underlying premise is that people with mental illness are weak, to cow affected people into being unwilling to be diagnosed,” he wrote in the essay. “It is time that I and other physicians say so.”
The second of three sons, Leon Emanuel Rosenberg was born in Madison, Wis., on March 3, 1933, and grew up in the nearby town of Waunakee. His parents were Russian-Jewish immigrants; his father ran a general store, and his mother was a homemaker.
“He told me that his mother had a deformed thumb — she’d been in an accident,” his wife said. “All his childhood, he wanted to be a surgeon so he could fix it.”
Dr. Rosenberg graduated summa cum laude from the University of Wisconsin in 1954 and received his medical degree from the university in 1957, completing his internship at Columbia-Presbyterian Medical Center in New York. He worked for six years at the National Cancer Institute, where he began treating children with rare genetic disorders, before joining the Yale faculty in 1965.
By 1972, he had become the founding chairman of the school’s human genetics department. He later served as president of the American Society of Human Genetics and, in 1981, made headlines when he defended abortion rights at a Senate subcommittee hearing.
Invited to testify about an antiabortion bill with seven other doctors, Dr. Rosenberg was the only physician to condemn the proposed legislation, according to a New York Times report. In a rebuke to his colleagues, he said there was no scientific evidence that human life starts at conception and insisted that scientists who claimed otherwise had fallen prey to “personal biases.”
“Don’t ask science and medicine to help justify” a ban on abortion, he told the committee, “because they cannot. Ask your conscience, your minister, your priest, your rabbi, or even your God, because it is in their domain that this matter resides.” The bill died before it reached the Senate floor.
Beginning in 1984, Dr. Rosenberg served as dean of Yale’s medical school, leading an institution of more than 900 full-time faculty members while raising money, recruiting professors and launching a new Office of Minority Affairs, part of his effort to support and bolster the number of non-White students and faculty at the school. He left after seven years to become the chief scientific officer at Bristol-Myers Squibb.
The job offered him a chance to help develop new medical treatments and foster links between academia and the pharmaceutical industry. But he “found the culture of business not nearly as comfortable as that in academia,” he recalled in an autobiographical essay, “and barely managed to make it to mandatory retirement at age 65.” He was soon hired at Princeton as a senior molecular biologist and professor.
Dr. Rosenberg’s honors included the Kober Medal from the Association of American Physicians.
His marriage to Elaine Lewis ended in divorce. In 1979, he married Diane Drobnis, an editor for medical journals and textbooks, with whom he wrote a textbook of his own, “Human Genes and Genomes.”
In addition to his wife, of Lawrenceville, survivors include three children from his first marriage, Robert Rosenberg of Reading, Pa., Diana Clark of North Clarendon, Vt., and David Korish of San José, Costa Rica; a daughter from his second marriage, Alexa Rosenberg of Washington; a brother; six grandchildren; and a great-grandson.
Delivering a speech to the American Society of Human Genetics after he was elected the group’s president, Dr. Rosenberg addressed his “weary, wary and worried” colleagues, offering a bit of career and life advice:
“When your experiments don’t work, or your grant deadline is approaching, or your patients appear ungrateful, don’t unburden yourself to [your young colleagues]. Lock yourself in the closet, jog, complain to your spouse, have a beer, but don’t frighten the kids. They might just take you seriously. If you must tell it like it is, please be sure to give equal time to the privileges and pleasures of academic life, to the dazzling sense of well-being that follows a scientific discovery, and to the excitement that each of us knows lies beyond our current horizons.”