Prince Frederik, who was the youngest son of the Prince and Princess of Nassau, has died following a battle with an illness.

His father, Prince Robert of Luxembourg announced his son died at the beginning of March from the rare genetic condition POLG Mitochondrial disease which “robs the body’s cells of energy, in turn causing progressive multiple organ dysfunction and failure,” according to the POLG Foundation. He was diagnosed with the condition when he was 14 years old.

His father said in the statement … “Last Friday, February 28th, on “Rare Disease Day”, our beloved son called us in to his room to speak to him for one last time. Frederik found the strength and the courage to say goodbye to each of us in turn … 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.”

He says Prince Frederik died with his family by his side adding … “Even in his last moments, his humour, and his boundless compassion, compelled him to leave us with one last laugh….to cheer us all up.”

He leaves behind his father, his mother Princess Julie of Nassau, his brother, Alexander, his sister, Charlotte, his three cousins, Charly, Louis, and Donall, his brother-in-law, Mansour, and his Aunt Charlotte and Uncle Mark.

Prince Frederick was 22.