Luke Bryan Thanks Fans for Prayers After Death of Infant Niece

Luke Bryant's infant niece on his wife's side has died after a protracted medical battle

Luke Bryan‘s infant niece, Sadie Brett Boyer, died Tuesday, a rep for the singer confirms to PEOPLE. The infant girl was the daughter of Bo and Ellen Boyer, on Bryan’s wife Caroline’s side of the family.

As of early February, Ellen Boyer had been posting regular Facebook updates about her daughter’s health battles, which included unspecified issues with her kidneys, liver and heart. As of late 2016 — per an update on Bryan’s app — Brett, as the family called her, was being treated at the pediatric cardiac unit at Vanderbilt University Medical Center’s Monroe Carell Jr. Children’s Hospital in Nashville.

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Bryan thanked fans for the outpouring of support via Twitter on Tuesday afternoon, writing, “We thank all of you for your prayers. Love y’all.”

It’s the latest in a series of grim tragedies to befall Bryan’s family. More than 20 years ago, his brother Chris died in a car accident, and his sister Kelly unexpectedly passed away in 2007. Just after Thanksgiving 2014, Bryan’s brother-in-law Ben (Kelly’s widower) died.

Bryan and his wife took Ben and Kelly’s teenage son Til into their family after Ben’s death. (Til’s sisters, Bryan and Caroline’s two nieces, are both old enough to be independent.)

“Obviously my nieces and nephew, they didn’t ask for this,” Bryan told PEOPLE in 2015. “Their life was amazing before Caroline and I took a more prominent role, even after losing their mother. Now my focus is trying to do what we can to help them.”