Mike Porcaro, the longtime bass player for Grammy-winning rock band Toto, died early Sunday morning at 59 following a battle with amyotrophic lateral sclerosis (Lou Gehrig's Disease).

Toto keyboardist and Porcaro's brother Steve confirmed the news on Facebook, writing,  "Our brother Mike passed away peacefully in his sleep at 12:04 AM last night at home surrounded by his family. Rest in peace, my brother."

"My brother Mike Porcaro is now at peace," added Toto guitarist Steve Lukather on Twitter. "I will miss him more than I could ever put into words. My deepest love to the family. God Bless."

Porcaro became anofficial member of Toto following the departure of the band's original bass player David Hungate around the time of Toto's hugely successful 1982 album Toto IV, joining his brothers Steve and late drummer Jeff. As bassist, Porcaro appeared on such albums as Isolation (1984), Fahrenheit (1986), Mindfields (1998) and Through the Looking Glass (2002).