By Michael Rios and Kathleen Magramo

(CNN) — Prince Frederik of Luxembourg, the youngest son of Prince Robert of Luxembourg and Princess Julie of Nassau, has died after a lifelong battle with a rare genetic disorder known as POLG mitochondrial disease. He was 22.

Frederik died in Paris on March 1, his family announced in a statement on the website of the POLG Foundation, which Frederik founded in 2022. “One light was extinguished, but so many remain,” his father said in the statement.

POLG is a “genetic mitochondrial disorder that robs the body’s cells of energy, in turn causing progressive multiple organ dysfunction and failure,” according to the foundation’s website.

Frederik was diagnosed with POLG at age 14, the family said. Because the disease causes such a wide range of symptoms and affects many different organ systems, it can be difficult to diagnose.

The prince died a day after Rare Disease Day, an international day of awareness for rare diseases. An estimated 300 million people live with a rare disease.

“As is the case for 300 million people like Frederik worldwide, these diseases are usually hard to recognise even by physicians, and patients’ families may never know what they are suffering from as they may only be identified very late in their progression,” his father, Robert, said.

There is currently no treatment or cure for POLG.

“One might compare it to having a faulty battery that never fully recharges, is in a constant state of depletion and eventually loses power,” Robert said.

“Frederik and the POLG Foundation … are committed to finding therapies and a cure to save other patients from suffering what Frederik and our family have endured,” he added.

Despite his condition, Frederik “found the strength and the courage to say goodbye to each of us in turn – his brother, Alexander; his sister, Charlotte; me; his three cousins, Charly, Louis, and Donall; his brother-in-law, Mansour; and finally, his Aunt Charlotte and Uncle Mark,” Robert wrote.

“Though Prince Frederik always made it very clear that he did not want the dreadful disease to define him, he devoted himself to spreading awareness on the rare disease,” the family said, including participating in medical trials “with the goal of finding treatments and, perhaps, ways of repurposing molecules to help patients with his condition.”

Frederik’s father, Robert, is a first cousin of the current head of state of Luxembourg, Grand Duke Henri, and is 15th in the line of succession.

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