Residual plasmatic activity of ADAMTS13 is correlated with phenotype severity in congenital thrombotic thrombocytopenic purpura.

TitleResidual plasmatic activity of ADAMTS13 is correlated with phenotype severity in congenital thrombotic thrombocytopenic purpura.
Publication TypeJournal Article
Year of Publication2012
AuthorsLotta, LA, Wu, HM, Mackie, IJ, Noris, M, Veyradier, A, Scully, MA, Remuzzi, G, Coppo, P, Liesner, R, Donadelli, R, Loirat, C, Gibbs, RA, Horne, A, Yang, S, Garagiola, I, Musallam, KM, Peyvandi, F
JournalBlood
Volume120
Issue2
Pagination440-8
Date Published2012 Jul 12
ISSN1528-0020
KeywordsADAM Proteins, ADAMTS13 Protein, Adolescent, Adult, Age Factors, Aged, Blood Chemical Analysis, Blood Transfusion, Child, Child, Preschool, DNA Mutational Analysis, Female, Genetic Association Studies, Humans, Male, Middle Aged, Mutation, Plasma, Purpura, Thrombotic Thrombocytopenic, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Young Adult
Abstract

The quantification of residual plasmatic ADAMTS13 activity in congenital thrombotic thrombocytopenic purpura (TTP) patients is constrained by limitations in sensitivity and reproducibility of commonly used assays at low levels of ADAMTS13 activity, blunting efforts to establish genotype-phenotype correlations. In the present study, the residual plasmatic activity of ADAMTS13 was measured centrally by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (limit of detection = 0.5%) in 29 congenital TTP patients. The results were used to study correlations among ADAMTS13 genotype, residual plasmatic activity, and clinical phenotype severity. An ADAMTS13 activity above 0.5% was measured in 26 (90%) patients and lower levels of activity were associated with earlier age at first TTP episode requiring plasma infusion, more frequent recurrences, and prescription of fresh-frozen plasma prophylaxis. Receiver operating characteristic curve analysis showed that activity levels of less than 2.74% and 1.61% were discriminative of age at first TTP episode requiring plasma infusion < 18 years, annual rate of TTP episodes > 1, and use of prophylaxis. Mutations affecting the highly conserved N-terminal domains of the protein were associated with lower residual ADAMTS13 activity and a more severe phenotype in an allelic-dose dependent manner. The results of the present study show that residual ADAMTS13 activity is associated with the severity of clinical phenotype in congenital TTP and provide insights into genotype-phenotype correlations.

DOI10.1182/blood-2012-01-403113
Alternate JournalBlood
PubMed ID22529288
PubMed Central IDPMC3721603
Grant ListFS/10/013/28073 / / British Heart Foundation / United Kingdom
G0800671 / / Medical Research Council / United Kingdom
U54 HG003273 / HG / NHGRI NIH HHS / United States