Prince Frederik of Luxembourg died at 22 from a rare genetic condition

Prince Frederik of Luxembourg, the son of Prince Robert of Luxembourg and Princess Julie of Nassau, died at the age of 22 due to POLG mitochondrial disease, a rare genetic illness he was born with, according to his family.

Frederik de Nassau died in Paris on March 1, a day after International Rare Disease Day, which is observed on the final day of February, according to Prince Robert of Luxembourg in a statement posted on the POLG Foundation website. Prince Frederik established the organization in 2021 to increase awareness about the disease.

Prince Robert announced the news in a statement on the POLG Foundation's website.

"It is with a very heavy heart that my wife and I would like to inform you of the passing of our son," Prince Robert wrote in the statement, sharing that Frederik had died on March 1.

The day before on "Rare Disease Day," Prince Robert shared that Frederik spoke with his family, including his brother Alexander and sister Charlotte, as well as cousins and other extended family, "one last time."

"After gifting each of us with our farewells – some kind, some wise, some instructive – in true Frederik fashion, he left us collectively with a final long-standing family joke. Even in his last moments, his humor, and his boundless compassion, compelled him to leave us with one last laugh… to cheer us all up."

He further stated that Frederik inquired, "Papa, are you proud of me?".

"He had barely been able to speak for several days, so the clarity of these words was as surprising as the weight of the moment was profound. The answer was very easy, and he had heard it oh so many times, but at this time, he needed reassurance that he had contributed all that he possibly could in his short and beautiful existence and that he could now finally move on," his father wrote.

Frederik was born with POLG illness, but was not diagnosed until he was 14, according to his father.

The disease causes "such a wide range of symptoms and affects so many different organ systems, it is very difficult to diagnose and has no treatments much less a cure. POLG disease is a genetic mitochondrial disorder that robs the body’s cells of energy, in turn causing progressive multiple organ (brain, nerves, liver, intestines, muscles, swallowing and ocular function, etc.) dysfunction and failure. One might compare it to having a faulty battery that never fully recharges, is in a constant state of depletion and eventually loses power."

According to his father's statement, Frederik designed the style for the charity in the United States and founded the MITO clothing brand, which was promoted by Donna Karan.

He also "actively and literally gave of himself to develop multiple mouse models and cell lines in Switzerland, the United States, and Europe and to make these available to further facilitate research into POLG."

Prince Robert concluded, "On behalf of Frederik, Julie, Charlotte, Alexander, Mansour and the entire global POLG community, we thank you for helping this worthy cause that will honor our son. We will be resolutely focused on alleviating suffering for the POLG community and other diseases and conditions far beyond, associated with mitochondrial diseases."