A 5-year-old Dutch boy who had become a well-known online figure to thousands of followers has died from a rare genetic disorder known as metachromatic leukodystrophy (MLD).
His mother, Sanne de Haan, announced his death on Instagram on June 16. "This morning at 4:00 a.m., our dear Jelte passed away very peacefully in my arms," she wrote on the Instagram page Love for Jelte. His father Hein and siblings Veerle, Linde, and Tibbe were asleep nearby in the living room when he took his final breath.
Jelte was born Oct. 13, 2020, and by all early appearances was a healthy child, according to his family's blog. Pregnancy tests and newborn screenings showed nothing of concern. He was bright and affectionate, and began speaking in full sentences before his second birthday—and yet something wasn't quite right with his physical development.
He was slow to walk, had low muscle tone, and was hypermobile, though the family was repeatedly reassured that boys often develop later.
The diagnosis came on Jan. 2, 2023, in a phone call from their pediatrician that Jelte's parents described as life-altering. "There will always be a life before and after this date," they wrote on the family blog. Both parents were found to be carriers of the gene defect responsible for MLD, meaning each of their children carried a 25 percent chance of inheriting the condition. Jelte had inherited two copies of the faulty gene—one from each parent. Their daughters were healthy.
What is MLD?
MLD is a hereditary disorder in which fatty substances called sulfatides accumulate in the brain, spinal cord, and peripheral nerves due to the body's inability to produce an enzyme that breaks them down, according to the Mayo Clinic. Over time, these sulfatides destroy the myelin—the protective sheath surrounding nerve cells—causing the nervous system to progressively fail. The late infantile form, which typically presents around age 2 or younger, is the most common and most aggressive. Children with this form often do not survive beyond childhood, and there is currently no cure.The condition affects roughly one child per year in the Netherlands, according to his family. "The chance of winning the lottery is greater."
In his final days, Jelte developed pneumonia after a high fever the family had initially hoped was a minor illness, his mother said in an Instagram post on June 15. The family chose not to return to the hospital. "His body is too weak," she wrote. He was sedated and kept at home, surrounded by family, as he entered what she described as "the very final part of his journey."
His funeral was held June 23 at the Frisian Museum of Natural History. The private ceremony was also livestreamed for those unable to attend in person. A procession from the family home to the museum allowed members of the public to pay their respects along the route.
Among those present was the Dutch music group Koester Music, who had formed a close bond with Jelte and his family over the years. They performed an original song at the service titled "Live Your Dreams," written specifically for Jelte, the music group said in their own tribute posted to Instagram.
"It was an honor to capture in music the feeling that everyone shared yesterday in the sunlit courtyard of the Frisian Museum of Natural History," the group wrote. "It left an indelible impression on us."