A young girl in the U.K. is in cancer remission thanks to her sister’s lifesaving bone marrow donation.

Ruby Leaning, 10, was diagnosed with acute lymphoblastic leukemia after collapsing on the school playground in Jan. 2020, according to SWNS, the British news service.

The rare blood cancer required an urgent bone marrow transplant to keep the 6-year-old alive.

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After several tests, Leaning’s then 2-year-old sister, Mabel Leaning, came up as a "perfect match."

The Leaning sisters' grandmother, Amanda Fawcett, confirmed to SWNS that Ruby Leaning received treatment with Mabel Leaning’s stem cells.

Sisters Mabel and Ruby Leaning

Sisters Mabel Leaning, left, and Ruby Leaning hold hands in the hospital. The younger sister saved the older one with a bone marrow transplant. (Amanda Fawcett via SWNS)

Ruby Leaning was declared cancer-free in 2022 — meaning Mabel Leaning "saved Ruby’s life for sure," Fawcett said.

"She's a happy, normal and healthy 10-year-old who loves swimming, dancing and piano lessons."

"We [weren’t] expecting her to be a match at first, but thankfully she was, so we just couldn't believe our luck," she said. 

"It was amazing – we were so thankful."

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Fawcett recalled the moment her granddaughter was diagnosed with cancer at Sheffield Children’s Hospital.

"It's just every parent and grandparent's nightmare," she said to SWNS.

"I was in the room with her mom when we found out, and you just can't take anything in at all. It was all just heart-shattering."

Ruby Leaning in the hospital

Ruby Leaning, pictured in the hospital, was diagnosed with acute leukemia in 2020. (Amanda Fawcett via SWNS)

Dr. Katharine Patrick, hematology consultant at Sheffield Children’s NHS Foundation Trust, shared in a statement with Fox News Digital that most children with acute lymphoblastic leukemia (ALL) can be treated with just chemotherapy.

"However, Ruby’s rare form of ALL meant she also needed a bone marrow transplant to get better," she said.

"When Ruby's leukemia did not respond well to chemotherapy, she received a relatively new drug called blinatumomab, which got her leukemia into remission and allowed us to perform her bone marrow transplant."

Ruby Leaning and Mabel Leaning

Ruby and Mabel Leaning have "a great relationship between them," grandmother Amanda Fawcett said. (Amanda Fawcett via SWNS)

The doctor said she considered Mabel Leaning's donation "wonderfully brave" at only 2 years old.

"We’re so pleased with Ruby’s progress and wish her and her family all the best for these next steps," she told Fox News Digital.

Fawcett described her granddaughters as "so close," telling SWNS that they are "amazing girls."

"They've got a great relationship between them," she said.

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"Mabel will be asking to borrow Ruby's shoes when she realizes [she saved her life] – and we do laugh about how it will be fun and games."

Fawcett said Ruby Leaning has been "doing fantastic" in remission and is "back to her normal self."

"She's a happy, normal and healthy 10-year-old who loves swimming, dancing and piano lessons," she said.

"We’re so pleased with Ruby’s progress and wish her and her family all the best for these next steps."

The grandmother is currently raising money for the Parents Association of Children with Tumors and Leukemia (PACT), which supported the Leaning family, according to SWNS.

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"None of us could be there for Ruby, which was horrendous for us, because of the pandemic, but they were an amazing support," Fawcett shared.

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