What is the long term prognosis for someone with osteogenesis imperfecta and ankylosing spondilitis?

Depends on type. Oi is a geneticly influenced syndrome of several types. Type 2 is the most severe & can result in perinatal death, usually from respiratory failure. Type I and 4 may have a normal lifespan & die natural causes. Type 3 is heavily influenced by bony deformities & respiratory difficulties, ave lifeapan 6yr, range 1-28. Their bony problems are structural not inflamatory. See mcallion, jclinpath1996.
Hard to know. Ost. Imperfecta, a genetic bone & connective tissue disorder with brittle bones, affects about 1/20, 000 people. Ank. Spondylitis, a genetic autoimmune disorder with gradual fusion of spine joints, affects about 1/400 people. That means the chance of having both would be very rare, about 1/8, 000, 000. A patient's genetics, rheumatology, and orthopedics doctors can shed more light on his prognosis.