Prince Frederik of Luxembourg death: Who was Prince Frederik, what happened to him and everything to know | Explainer

Prince Frederik Henri Douglas Marie of Nassau’s name was splashed across global headlines when he died aged just 22.

The youngest son of Prince Robert of Luxembourg and Princess Julie of Nassau, he was born with the rare genetic condition POLG Mitochondrial disease, but it wasn’t diagnosed until he was a teenager.

Though the condition meant Frederik faced many challenges in his short life, it didn’t stop him from having a deep and lasting impact on the people and world around him.

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Now the world is mourning with his family and those who knew him best are remembering Frederik as he was; a vibrant, passionate young man who achieved so much in the short time he had and did his royal parents proud.

Prince Frederik was born on March 18, 2002, the youngest of three royal children.

His parents’ marriage was an uncommon one, as it went against centuries of tradition in the Luxembourgish royal family.

The story goes that Robert met Frederik’s mother Julie Elizabeth Houston Ongaro in 1987 while visiting his family’s summer house in Maine, USA.

Little is known about their romance, only that it was a surprise to many when the Luxembourgish prince announced his plans to marry the American ‘commoner’ in the early 1990s.

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The couple married in Julie’s childhood home city of Boston, Massachusetts, on January 29, 1994, but the marriage wasn’t dynastically approved by then-monarch Jean, Grand Duke of Luxembourg.

This meant Julie wasn’t granted a princess title at first, and any children the couple had would only receive the titles of Count or Countess of Nassau.

Julie gave birth to their first child, Princess Charlotte Katherine Justine Marie of Nassau, a little over a year later on March 20, 1995.

Their second child Prince Alexandre Théodore Charles Marie of Nassau arrived on April 18, 1997, followed by Frederik almost five years later.

The youngest of the trio, Frederik’s middle name ‘Henri’ was a tribute to his cousin once removed, Henri, Grand Duke of Luxembourg.

Frederik, his siblings and his mother all received the new titles of Prince or Princess of Nassau towards the end of 2004, when Grand Duke Henri issued an Arrêté grand-ducal to grant them upgraded titles and style of Royal Highness.

Frederik was just two at the time.

Despite being born into royalty and named for the reigning monarch of his home nation, Frederik was never destined to rule – nor were his siblings.

Their father Prince Robert is only cousin to Grand Duke Henri, putting him and any of his male offspring towards the bottom of the royal line of succession.

At the time of his death, Frederik was 17th in line to the Luxembourgish throne behind Henri’s children, grandchildren and brother, Prince Robert and Frederik’s older brother Prince Alexandre.

But Frederik never really seemed concerned with his place in the royal line of succession, instead dedicating his short life to charitable work and advocacy.

Though he was born with POLG Mitochondrial disease, his condition wasn’t diagnosed until 2016, when he was 14.

By that time, his parents had noticed concerning signs of the 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,” Robert wrote in a 2025 statement.

“Because POLG 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.”

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Frederik didn’t let his diagnosis stop him from making an impact on the world and in 2021, he established The POLG Foundation to help find treatments and ultimately a cure for the condition.

Through the charity, he was able to connect with some of the 300 million people with the condition worldwide and raise funds and awareness for a brighter future.

Frederik also launched the MITO clothing line, which used humour and fashion to further raise awareness and start important conversations about the disease that would ultimately kill him.

Outside of his charity work, the young prince was part of many medical trials and contributed to scientific research into POLG Mitochondrial disease with his parents’ support.

Mother Julie was by his side through it all, first as a proud parent and fellow advocate, and later as his carer.

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POLG Mitochondrial disease “robs the body’s cells of energy” and can cause progressive multiple organ dysfunction and failure, affecting the brain, nerves, liver, intestines, muscles and more.

Over the years, it took more and more from Frederik. By 2025, he struggled just to speak.

That didn’t stop him from gathering his closest loved ones – mum Julie, dad Robert, sister Charlotte and her new husband Mansour Shakarchi, brother Alexandre, and an aunt, uncle and three cousins – to say his goodbyes on February 28.

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Even in his final moments, Frederik didn’t let his diagnosis steal his voice.

“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,” Robert wrote.

“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.”

Some of Frederik’s final words to his father were as poignant as they were heartbreaking, perfectly summing up his short but passionate life.

“Papa,” he said, per Robert’s letter, “Are you proud of me?”

Robert said, “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.”

Frederik died on March 1, 2025, aged just 22.

Though his life was short, he will be remembered with so much love not just by those who knew him personally, but by all the people whose lives he touched even in the smallest ways through his charitable and advocacy work.

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