Luxembourg is grieving the loss of Prince Frederik, the son of Prince Robert — cousin of Grand Duke Henri — and Princess Julie, who passed away on 1 March in Paris after a long battle with PolG mitochondrial disease, a rare and incurable genetic disorder. He was 22 years old.

The news was confirmed by Prince Robert on 7 March through a statement on the PolG Foundation website. He shared that Frederik passed away just a day after he gathered his parents, siblings Prince Alexander and Princess Charlotte, and other family members in his room to speak to them one last time.

In an emotional statement, Prince Robert recalled his son's final words to him: "Papa, are you proud of me?" Despite Frederik's weakened state, his father was deeply moved by his clarity in that profound moment. "The answer was very easy," he said, adding that Frederik had always known how proud they were of him but still sought that reassurance before he peacefully passed.

Robert described his son as a "superhero" to their family and many others, praising his remarkable strength and inspiring spirit despite his long battle with the disease. Frederik was diagnosed with PolG mitochondrial disease at 14 years old, a condition that progressively affects organs and has no cure.

The prince also shared that even in his final moments, Frederik kept his humor and kindness intact. After bidding farewell to each family member, including his mother who stayed by his side for 15 years, he left them with a heartfelt family joke — a final gesture that filled the room with warmth and laughter.

Frederik would have celebrated his 23rd birthday later this month. His family continues to honor his legacy through the PolG Foundation, which aims to raise awareness and support for those battling the rare genetic disease.