Mike Porcaro, the musician best known as the bassist in arena rockers Toto, died on Sunday following a long battle with Lou Gehrig’s disease. He was 59. His death was first reported by his brother, Toto keyboardist Steve Porcaro, who confirmed the news on his Facebook page.

Born in 1955, Porcaro was the son of Joe Porcaro, a well-respected jazz percussionist. Porcaro’s brothers Jeff and Steve founded Toto in 1977 with Steve Lukather, David Paitch, David Lungate, and Bobby Kimball, and Mike was brought into the fold in 1982 following Lungate’s departure. Mike performed with the band on the tour behind Toto IV, the band’s biggest hit, and he continued to perform with the band through its various lineup changes until 2007, when his health began to decline. Toto’s most recent tour in 2010 was done to raise money for Mike’s medical expenses and for ALS research.

On his Twitter page, Lukather expressed his sorrow for his “brother” Mike’s passing. “I will miss him more than I can ever put into words,” he said. “My deepest love to the family. God Bless.”