Presentation and acuity of congenital TTP. There is a bimodal distribution of presentation, in the neonatal period/early childhood and early adulthood, increased in women of child-bearing age. Acute TTP episodes are more common in children (<18 years) and organ involvement (brain, heart, and kidneys) with permanent end organ damage related to delayed cTTP diagnosis from presentation. The international registry does not document an increase in acute TTP episodes with age, but there does appear to be a higher risk of end organ damage when they occur.