Boston Children’s Hospital filed a lawsuit against a Saudi Arabian prince, alleging that he owes the hospital $3.5 million for the care of a Saudi Arabian child whose care he agreed to fund.

The lawsuit, filed in U.S. District Court in Boston this week, said the 2-year-old child has been treated at Children’s Hospital since November 2017 and is still a patient there.

The child, who is not named in the lawsuit, has type 1 spinal muscular atrophy, a rare genetic disease affecting muscle strength and movement that requires life-long treatment. The costly drug used to treat the condition, Spinraza, is not available in Saudi Arabia, according to the lawsuit.