Coleen Rooney tweeted that her family has been left "heartbroken" after the death of her teenage sister Rosie McLoughlin.
The 14-year-old, who had a lifelong battle with the rare genetic disorder, Rett syndrome, died at her home in Liverpool in the early hours of Saturday morning surrounded by her family, a spokesman said.
Under the username @ColeenRoo, Mrs Rooney wrote: "Thank you so much for all your lovely messages and kind words. We are absolutely heart broken to have lost our angel Rosie.
"So glad we ended our holiday short, due to her deteriorating & we was able to spend the last few days together with her an our family! Sleep tight Rosie Mc x".
"We love you more than words can say x," she added.
The tweet followed a statement issued on behalf of Coleen, her husband, Manchester United star Wayne, and the rest of Rosie's family.
The family thanked everyone at Alder Hey Hospital and Claire House Children's Hospice, including "the many doctors, consultants, nurses, helpers and friends who all worked so hard and tirelessly to help make Rosie's life better.
"She was such a strong little girl and an inspiration to us all," the statement said.
"We shall cherish forever the memories we have shared and the love she showed us each and every day of her life."
Rosie's illness inspired Coleen and her husband to help raise funds for sick, disadvantaged and disabled children.
The couple reportedly told guests at their wedding that instead of gifts they wanted donations to Claire House Children's Hospice and Alder Hey.
Rett syndrome is a neurological disorder that affects just one in 12,000 females, according to the NHS. It causes severe physical and mental disability that begins in early childhood.