Mac Sinise, the son of “Forrest Gump” actor Gary Sinise, has died at the age of 33 following a long illness with a rare form of cancer, his family has announced.

He died on January 5 and was laid to rest on January 23, according to a tribute published by the Gary Sinise Foundation, which offers support to wounded veterans of the military.

“Like any family experiencing such a loss, we are heartbroken and have been managing as best we can,” wrote Sinise.

“As parents, it is so difficult losing a child. My heart goes out to all who have suffered a similar loss, and to anyone who has lost a loved one.”

Mac, whose full name was McCanna Anthony Sinise, was described by his father as an “exceptional drummer.”

He played the drums since the age of nine and often performed alongside his father as part of the Lt. Dan Band, the actor added.

In 2018, he was diagnosed with Chordoma, a rare type of bone cancer that develops at the base of the skull, in a vertebra, or at end of the spine.

Chordoma affects only around 300 people in the United States per year, according to the National Cancer Institute.

Mac underwent surgery, his father said. However, the cancer returned and ultimately spread.

“This began a long battle that disabled him more and more as time went on,” wrote Sinise, eventually leaving Mac unable to play the drums.

Despite his worsening health, Mac learned to play the harmonica and worked with friends on an album of music called “Resurrection & Revival,” which went to press the week he died.

“While our hearts ache at missing him, we are comforted in knowing that Mac is no longer struggling, and inspired and moved by how he managed it,” wrote Sinise.

“He fought an uphill battle against a cancer that has no cure, but he never quit trying.”

“We were blessed to have you in our lives as son, brother, and friend…and we will miss you and love you for eternity,” Sinise, who signed the tribute as “Proud father of Mac Sinise,” added.

In addition to perhaps his most famous role as Lt. Dan in “Forrest Gump,” Gary Sinise has appeared in movies “Apollo 13,” “The Green Mile” and “Of Mice and Men,” as well as television series “CSI: NY.”