Nel-Peter’s little sister, Franje, had cerebellar agenesis, a rare condition where the brain forms without a cerebellum

By Julie Mazziotta
May 08, 2019 04:18 PM
Tim Tebow/Instagram

Demi-Leigh Nel-Peters and her fiancé, former football player Tim Tebow, are mourning the death of her 13-year-old half-sister Franje.

The former Miss Universe, from South Africa, shared the sad news via on her Instagram on Saturday.

“My little Princess, Angel on Earth, biggest joy and baby sister, Franje, passed away earlier today,” Nel-Peters wrote. “Our hearts are aching beyond measure but I am grateful knowing she’s forever relieved of the pain she experienced on earth. She’s laughing, running and playing in heaven just like we always hoped she would on earth. She’s free!”

Franje was born with an extremely rare condition called cerebellar agenesis, where the brain forms without a cerebellum. The cerebellum provides motor control to the body, and helps with attention, language and coordination. Living without it can mean developmental delays and trouble with basic movement.

Franje Peters
Demi-Leigh Nel-Peters/Instagram

Nel-Peters and Tebow owe their relationship to Franje. The couple met at Night to Shine, his annual prom for kids with special needs, which benefits his Tim Tebow Foundation. Tebow invited Nel-Peters after learning about Franje.

“We met because of Night To Shine,” he told PEOPLE following their engagement in January. “So it’s great for her to experience the things that are important to me.”

Demi-Leigh Nel-Peters and Franje Peters
Demi-Leigh Nel-Peters/Instagram

Tebow also shared a tribute to Franje on his Instagram page on Saturday, along with a photo of all three of them.

“Our loss but heaven’s gain,” he wrote. “So grateful for the hope we have of being reunited with the ones we love through our Heavenly Father. Mr. & Mrs. Peters and @demileighnp we are praying for you and love you so much.”