Mia Robertson, daughter of Duck Dynasty star Missy and Jase Robertson, is grieving this week upon learning of the death of a man who made a huge difference in her life.

The teen's longtime surgeon Dr. David Genecov was killed in a car accident last Saturday. Missy Robertson shared the news on Instagram, explaining how his talents and medical inventions made a difference as Mia endured surgery after surgery to repair a cleft lip and palate.

"His caring nature helped calm her (and me), but his steadfast encouragement to both of us that we can do the hard things helped make both me and Mia stronger than we could have thought possible," Missy says.

Dr. Genecov's death was also confirmed on his website.

Mia Robertson's journey has been public since a very young age. In July she underwent a 14th surgery with hopes that it may be her last. Her Mia Moo Fund was set up to help ensure every kid has the chance to smile.

Missy Robertson says she shared the news with Mia and she's taking it very hard. Dr. Genecov's willingness to involve Mia in the decision making and his sharp dressing is part of how the family will remember him.

He was more than we could ask for or imagine for her cleft journey. We will miss him greatly, but we are so very grateful for the work he did for Mia and all his cleft patients and the legacy of medical innovations he leaves for generations to come!

Mia has not posted about the tragedy on social media yet. "She can't remember her life before Dr. David," her mother adds. "Please pray for his family and all of those who are grieving his loss."

PICTURES: See Inside Kevin Costner's Spectacular Colorado Ranch

Yellowstone star Kevin Costner lives the ranch life when he's off the set of the hit show, too. The Oscar-winning actor owns a 160-acre ranch in Aspen, Colo., that's a spectacular getaway, complete with a main residence, a lake house and a river house.

The luxury retreat also features a baseball field, a sledding hill, an ice rink, multiple hot tubs and views of the Continental Divide. The ranch property comfortably sleeps 27 people, and it's currently available to rent for 36,000 a night.

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