As the last poster has mentioned, Crown Prince Alexi, was a Haemophiliac, who inherited the disease from his mother, who was a carrier, & would have died fairly young from fatal "bleeds", as a result of missing Factor VIII...
(Haemophilia was fairly common within the royal families of Europe, as a relative of Alexi, Prince Leopold died of the same disease, while fairly young...).
It could be argued that Alexi's condition accellerated the downfall of the Romanov Dynasty, in that his Mother, seeking a cure for his condition, & finding no medical cure, turns to faith healers such as Rasputin...
As a result, she like Marie Antonette, before her, became a target for vicious anti-Royalist rumours...