Sledge was found unresponsive at her home in Phoenix on Friday and the cause of death has not been determined, according to a statement from the band's publicists.
The family of the 70s disco icon said in a statement: "On yesterday, numbness fell upon our family".
Sledge and sisters Debbie, Kim and Kathy formed Sister Sledge in 1971, but had to wait for the breakout success of We Are Family in 1979, when Atlantic Records teamed the little-known act with up-and-coming hitmakers Bernard Edwards and Nile Rodgers. "We were saying: "Well, maybe we should go to college and just become lawyers or something other than music, because it really is tough", she said. Sister Sledge is most notable for their enduring and hit dance song "We Are Family." .
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Joni Sledge was born September 13, 1956, to tap dancer Edwin Sledge and actress Florez Sledge.
The song celebrating sisterhood and female empowerment was nominated for a Grammy and sold more than one million copies, as did the album of the same name.
Sledge is survived by an adult son and her sisters.
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Hopkins was ordered by the High Court to pay £24,000 in damages to Monre after a 21-month legal battle. "I sued her for libel". He added: "Jack Monroe never did, and coming from a proud military family, never would".
Joni's website says her "extraordinary talent has been developed within the illustrious backdrop of her family legacy; Grand mother, Viola Beatrix Hairston Williams, (Julliard graduate and lyric soprano), was a dedicated coach".
The daughter of Broadway tap dancer, Edwin Sledge and actress Florez Sledge, Joni was the second oldest of the four sisters. But the trio of sisters continued to record and tour into the present, including a 2015 performance for Pope Francis. Her award-winning work has appeared in numerous magazine, newspaper, and online publications.
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