The "Grandmother of Europe" left a legacy unlike that of any other monarch--Hemophilia--the disease that is fully manageable today that keeps blog from clotting. Alexei, the last Tsaravitch of Russia, is the best known of these.
Note: unless otherwise noted, all images are in the public domain.
Victoria's second daughter, Alice, was a carrier of hemophilia.
Her son, Prince Friedrich of Hesse was a hemophiliac who died after falling from a window as a toddler. This family would suffer more tragedy, losing Alice and her daughter, Marie, within days of each other from diptheria.
Alice's grandson, Prince Heinrich of Prussia (also the nephew of Kaiser Wilhelm), died after a fall when he was just four years old thanks to his hemophilia.
Victoria's youngest son, Prince Leopold, was the first of the royal hemophiliacs. He lived long enough to marry and father two children--one of whom was born after his death. His daughter, Princess Alice of Albany, passed the hemophilia gene on to son, Rupert, and possibly to her son Maurice who died in infancy.
Princess Beatrice (Princess Henry of Battenberg after her marriage) was Victoria's youngest child and the one she kept at home. Her children grew up in Victoria's household, as the family moved with the Queen in her seasonal migration from Osborne on the Isle of Wight, to Windsor, to Balmoral, etc.
Beatrice's son, Prince Leopold of Battenberg (after World War I he was known as Lord Leopold Mountbatten) as a hemophiliac. Leopold was shown in uniform during World War I but was a hemophiliac. He died during an operation in his early 20s.
Alfonso's younger brother, Gonzalo, was also a hemophiliac. Gonzalo lived to his late 20s. He died from internal bleeding following a car accident. He and Alfonso were put into special padded suits to protect them when they played outside.
Prince Albert Victor, son of King Edward VII, may have been deaf like his mother Queen Alexandra, but functioned well enough to deal with the Army.
Down's Syndrome and Intellectual Development Disorders
King George V and Queen Mary's youngest child, Prince John, is best know as an epileptic and as the subject of the television show "The Lost Prince." He had some form of intellectual development, though given the times he lived in not much could have been done to aid him. (It is important to remember that the "Lost Prince" is merely "based" on his life--there is no evidence, for example, that John ever mastered playing the coronet as was show in the program, though there is a good deal of evidence that he did enjoy gardening like his two eldest brothers, Edward VIII and George VI did.
[Many readers will now search for the two Bowes-Lyon cousin's of Queen Elizabeth who were famously institutionalized and written out of Burke's Peerage. They are not descendants of Queen Victoria and so are not profiled here.]
The German decscendants of Queen Victoria include the only known royal with Down Syndrome. Princess Alexandrine of Prussia, a granddaughter of Kaiser Wilhelm, lived at home and was frequently photographed. She died in 1980.