Haemophilia figured prominently in the history of European royalty in the 19th and 20th centuries. Queen Victoria of the United Kingdom, through two of her five daughters – Princess Alice and Princess Beatrice – passed the mutation to various royal houses across the continent, including the royal families of Spain, Germany, and Russia. Victoria's youngest son, Prince Leopold, Duke of Albany, also had the disease, though none of her three elder sons did. Tests on the remains of the Romanov imperial family show that the specific form of haemophilia passed down by Queen Victoria was probably the relatively rare haemophilia B. The presence of haemophilia B within the European royal families was well-known, with the condition once popularly known as "the royal disease".