John Koko, vocalist and bass player for the influential Hawaiian group Makaha Sons, died as a result of heart problems on Monday. John was 51. According to the Associated Press, Koko was looking into a heart transplant around the time of his passing.

The Makaha Sons of Ni‘ihau, which formed in 1976, has enjoyed quite a bit of success over the years, and helped popularize Hawaiian music outside of the culture. Following the death of the Kamakawiwo?ole brothers, the remaining members, Louis “Moon” Kauakah, Jerome Koko, and John Koko, dropped the “of Ni’hau” from their name. Over the years, the band has released over 20 albums and one DVD, all of which were distributed courtesy of their own label. In addition appearing on the TODAY show with Bryant Gumbel and Katie Couric, they’ve also played for President Bill Clinton and Vice President Al Gore.

In addition to their musical output, the band has recently taken to helping out local musicians who specialize in traditional Hawaiian music. The Makaha Sons Foundation also supports numerous charitable organizations, and has even helped families suffering from illnesses and provided scholarships to high school seniors.

John Koko, who grew up in Nanakuli, joined the band in 1982. According to his brother, Jerome, John suffered from heart problems all of his life. These issues, which prevented the talented musician from completing high school, ultimately derailed his dreams of becoming a baseball and football player. However, in 1999, John succeeded in obtaining his GED, an accomplishment he was reportedly very proud of.

Sadly, due to John’s increasingly poor health, the band was forced to postpone recent shows in Argentina, Brazil, and Germany. “He was a fighter,” his brother explained. “After a while, you could see it on his face.”

Koko is survived by his wife, four sons, and two grandchildren.