LOS ANGELES — Mike Porcaro, son and brother of prominent musicians who carved out a successful career as bass player for the Grammy-winning group Toto, has died at age 59.

Porcaro died Sunday, said Toto’s publicist Keith Hagen.

No cause was given, but he had suffered from Lou Gehrig’s disease for several years. He left the group in 2007 because of declining health.

Lou Gehrig’s disease, which is amyotrophic lateral sclerosis, or ALS, attacks the cells that control muscles.

“Mike mentally is fantastic, and if you talk to him, his spirits are up and he’s great and like the old Mike Porcaro, except that he’s disabled, he’s in a wheelchair and can’t move, can’t walk and can’t play, which is a heartbreaking drag,” Toto’s keyboard player, David Paich, told the webzine “Something Else” in 2012.

Toto was formed in the late 1970s by Paich, Porcaro’s brothers Steve and Jeff, and other prominent session musicians who recorded and toured with Michael Jackson, Boz Scaggs, Steely Dan and numerous others.