Luxembourg's Royal Family has announced the death of Prince Frederick at 22 years old. Frederick's father, Prince Robert of Luxembourg, shared a statement regarding his son's death on the POLG Foundation website.

Prince Frederik of Luxembourg died at 22 after years of struggling with the rare mitochondrial disease PolG, according to a statement issued by his parents, Prince Robert and Princess Julie, on Monday.

Prince Frederik of Luxembourg has died at 22 from POLG mitochondrial disease, a genetic disorder he has had since birth. The family announced his death one day after Rare Disease Day, which is the last day of February.

Prince Frederik of Luxembourg, the youngest son of Prince Robert of Luxembourg and Princess Julie of Nassau, has died at 22 years old after a lifelong battle with POLG mitochondrial disease.