In contrast, adult-onset USS, consisting exclusively in pregnancy-induced TTP, included a smaller and distinct panel of <i>ADAMTS13</i> sequence variations (<i>n</i> = 20) because of one mutation (p.Arg1060Trp) present in 82% of patients.
The high prevalence of R1060W ADAMTS-13 in adult onset TTP, together with its absence in childhood congenital TTP cases reported elsewhere, suggests it may be a factor in the development of late onset TTP.