Bob Saget was best known for his comedy and his acting, but he did plenty of work beyond those realms as well.

Among his other projects was activism, specifically, his search for a cure for scleroderma, an autoimmune condition that ultimately took the life of his older sister, Gay.

According to the Mayo Clinic, scleroderma "is a group of rare diseases that involve the hardening and tightening of the skin and connective tissues."

Saget, who was found dead Sunday at age 65 in Florida, sat on the board of the Scleroderma Research Foundation (SRF), first joining the organization in 2003, according to the foundation's website.

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Bob Saget dedicated a great deal of time to helping to find a cure for scleroderma. (Getty Images)

"Bob’s openness and generosity brought many people to the SRF who would have otherwise never heard of scleroderma," their statement reads. "Our community often faces difficult losses, and Bob was uniquely driven to provide comfort and strength to all of us and the families most impacted by the disease. He was always the ‘big shoulder’ we could all lean on."

Saget's sister died of the disease in 1994 at age 47 after just three years battling the condition. In a 2011 interview with Ability magazine, Saget said his sister had been "misdiagnosed many times" before doctors found the correct condition she was suffering from.

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"Unfortunately, rheumatologists in a lot of places don’t have very many scleroderma patients come through their labs, and no one knew what to do with her," he said at the time. "I wish I’d known then what I know now."

In fact, Gay's battle with scleroderma was the basis of "For Hope," a 1996 made-for-TV movie Saget directed.

Bob Saget's sister Gay suffered from scleroderma, an autoimmune condition that seeks the skin and other connective tissues tighten. (Paul Archuleta/FilmMagic)

His advocacy against scleroderma began before his sister even got sick, however, as he was asked to appear at a benefit for the disease prior to her diagnosis.

"Nobody knew about the disease at that time. Rosie O’Donnell, Ellen DeGeneres and myself all got involved in the benefit, but this was 25 years ago, and none of us had any real television life to speak of," he recalled during the Ability interview. "Sharon Monsky, who founded the Scleroderma Research Foundation, organized that benefit."

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Among his work to find a cure for the disease was lobbying in Washington, D.C., he shared.

"We’ve really done some amazing stuff. My part of the effort has been to host benefits that raise consciousness and make a lot of money," he said. Saget counted Dana Carvey and the late Robin Williams among the celebrities who'd participated.

Bob Saget was found dead in a Florida hotel room on Jan. 9. (Getty Images)

Saget's involvement in activism came after a life full of family tragedies.

"My mother and father lost four children. All I saw was death," he told Ability.

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In addition to his sister Gay, Saget's family lost two children born before the actor, one had been given the name Bob.

Then in 1985, years before Gay's passing, Saget's other sister, Andrea, died of a brain aneurysm.

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"So please come back to me for the brain aneurysm issue!" he joked.