here are some references I found.
"I had a long talk with Dr. Derevenki. He told me that the Heir was prey to haemophilia, a hereditary disease which in certain families is transmitted from generation to generation by the women to their male chilrdern. Only males are affected. He told me that the slightest wound might cause the boy's death, for the blood of a bleeder had not the power of coagulating like that of a normal individual. Futher, the tissue of the arteries and veins is so frail that ane blow or shock may rupture the blood-vessel and bring on a fatial haemmorrhage."
Gillard: "Thirteen years at the Russian Court." pp. 37 & 38.
"The Czarevitch was in the schoolroom standing on a chair, when he slipped, and in falling hit his right knee against the corner of some piece of furniture. The next day he could not walk. On the day after the subcutaneous haemmorage had progressed, and the swelling which had formed below the knee rapidly spread down the elg. The skin, which wa greatly distended, had hardened under the force of the extravasated blood, which pressed on the nerves of the leg and thus caused shooting pains, which grew worse every hour.
".....Dr. Derevenko was anxious, as the haemorrhage had not been stopped and his temperature was rising. The inflammation had spread further and the pain was even worse than the day before." Golliard page 43.
"....As we were going on board the Czarevitch jumped at the wrong moment, and hs ankle caught the bottom of the ladder leading to the deck. At first I though this accident would have no ill effects, but towards the evening the boy began to be in pain and his suffering rapidly increased. Everything pointed to a serious crisis. Gilliard p. 97.
I'm sure those aren't all of Gilliard's references, but are some of the highlights. He does describe some syptoms. Will post more as I find more.