Sammy Basso, an advocate for research into progeria, an ultrarare fatal disease that causes rapid aging in children, who was known for living with gusto and humor with the condition as he faced the certainty of premature death, died on Oct. 5 near his home in Tezze sul Brenta, in the Veneto region of northern Italy. He was 28.

Dr. Leslie B. Gordon, medical director of the Progeria Research Foundation, for which Mr. Basso served as global ambassador, said the cause was complications of the disease. Mr. Basso was the oldest known person living with classic progeria.

Mr. Basso, who lived with his parents, was diagnosed with progeria at age 2.

He was one of only about 150 people worldwide identified with the condition. He traveled internationally, most recently to China, to raise awareness; gave TED Talks; and participated with scientists from Harvard and the National Institutes of Health in a research group that is seeking a cure.

“You couldn’t watch a presentation by Sammy without being captivated by his courage, his spunk, his smarts and his sense of humor,” Dr. Francis S. Collins, a former N.I.H. director who has long researched progeria, said in an email.

Progeria, also known as Hutchinson-Gilford progeria syndrome, causes children to undergo rapidly accelerated aging. Its effects include baldness, wrinkled skin, hardening of the arteries and a wizened stature. Mr. Basso was about 4 feet 5 inches tall and weighed about 44 pounds.

Individuals with the condition, whose average life expectancy is 14.5 years, do not experience senility. Profiled in The New York Times in 2022, Mr. Basso joked that mental clarity in the face of certain premature death was either a blessing “or a damnation.”