a type of blood cancer. a stem cell donor could give ryan the hope of a happy and healthy life but the chance of finding a suitable match are much lower because he is from a minority ethnic background, which is why doctors are desperate to get more donors from black and asian communities. danjohnson went to meet ryan and his mum hannah to find out more. i'm iron man, i'm iron man! this is a strong young man who's held back by a weakness in his blood. three—year—old ryan has a rare condition which means his white blood cells don't work properly. and he's vulnerable to infection. it affects us all the time, he can't go to play areas, he can't go to petting farms, he can't live a normal life like other children, because of this immune deficiency. it's tough. let's see the wigglies. ryan needs regular tests and he's waiting for a stem cell donation. but finding the right match is really difficult. it's like waiting every day, if you're going to get that phone call, to get that match. a part of me feels like,