The filmmaker who chronicled Prince Frederik of Luxembourg’s battle with the rare genetic disorder PolG has shared her experience working with the royal, who passed away on Mar. 1 at 22. Commissioned by Frederik’s mother,

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 the third son of Prince Robert, cousin of Grand Duke Henri of Luxembourg. The death of Prince Frederik of Nassau, at the age of 22, has caused deep sadness in the Grand Duchy of Luxembourg, but also among citizens worldwide who have been touched by his story.