Autosomal dominant with high penetrance.
Not a problem in early life. Usually presents with recurrent nose bleeds. Red spots on lips, tongue and fingertips, not so obvious in young children. But potential for GI and pulmonary haemorrhage, pulmonary/liver/brain AVMs. Migraine common.
Iron deficiency a problem, of course!
Screening for AVMs done from age 16. Annual full blood count. Beware nasogastric interventions!