SANTA CLARA (CBS SF) — Greg Clark, who played at Stanford and with the San Francisco 49ers, has died of an undisclosed illness, but was suffering from chronic traumatic encephalopathy. He was 49.

Clark’s family announced his death with a statement on Friday.

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“It is with great sadness we announce the unexpected passing. of Greg Clark, 49, cherished husband, father, son, brother and friend to so many. Greg was a dedicated family man who was successful at everything he did, from his academic and athletic achievements as a Stanford scholar athlete to his role as tight end for the San Francisco 49ers, to the creation of a successful real estate platform throughout the Bay Area.”

“Most importantly, he was a cherished and dedicated father of three sons, and a loving husband to his wife of 23 years. His recent suffering from CTE symptoms cannot extinguish the breadth of his impact on us and others and we are forever grateful for the time we have had with him. It is our hope that through further research we can gain more knowledge surrounding CTE.”

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Clark’s family said that they planned to participate in brain research into CTE and concussions and their impact on those suffering from the malady.

In a statement, the 49ers said: “Our organization is deeply saddened to learn of the passing of Greg Clark. Our thoughts and prayers are with his family and friends.”

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San Francisco drafted Clark in the 3rd round of the NFL 1997 draft. In four years with the team, Clark caught 92 passed for 909 yards and four touchdowns in 55 games.