Two novel ADAMTS13 gene mutations in thrombotic thrombocytopenic purpura/hemolytic-uremic syndrome (TTP/HUS).
BACKGROUND
Thrombotic thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS) are now considered to be variants of one single syndrome called thrombotic thrombocytopenic purpura/hemolytic-uremic syndrome (TTP/HUS). Key features are thrombocytopenia, hemolytic anemia, and subsequently impaired function of different organs, especially the kidneys and the central nervous system (CNS). One possible reason is the deficiency of von Willebrand factor-cleaving protease (vWF-CP) resulting in persistence of uncleaved, ultralarge von Willebrand factor multimers (ULvWFM).


METHODS
We report a patient who was initially diagnosed with Evans syndrome (hemolytic anemia and autoimmune thrombocytopenia) as infant. At 10 years of age he developed HUS-like disease with gastrointestinal tract infection, hemolytic anemia, thrombocytopenia,and acute renal failure. However, enteropathogenic Escherichia coli-like or Shiga-like toxins were not detected.


RESULTS
Further investigations revealed severe deficiency (<3%; normal >40%) of vWF-CP activity caused by compound heterozygosity of two novel ADAMTS13 gene mutations (1170 G>C [W390C] and 3735 G>A [W1245X]. vWF-CP autoantibodies were not detected. Periodic (every 2 weeks) treatment with fresh frozen plasma (FFP) maintained both platelet level and kidney function within normal range and prevented new episodes of TTP/HUS.


CONCLUSIONS
Enteropathogenic E. coli- and Shiga-like toxin-negative patients who present with hemolytic or thrombocytopenic episodes and HUS like symptoms should be tested for vWF-CP deficiency and other noninfectious reasons for TTP/HUS since plasma substitution possibly provides an efficient therapeutic option for this subgroup of patients.
Licht
Christoph
C
Department of Pediatric Nephrology and Pediatric Hematology/Oncology, University Children's Hospital of Cologne, Cologne, Germany.
Stapenhorst
Ludwig
L
Simon
Thorsten
T
Budde
Ulrich
U
Schneppenheim
Reinhard
R
Hoppe
Bernd
B
D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; D002648:Child; D006463:Hemolytic-Uremic Syndrome / Q000097:blood / Q000235:genetics*; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases / Q000097:blood / Q000235:genetics*; D010375:Pedigree; D017354:Point Mutation; D011697:Purpura, Thrombotic Thrombocytopenic / Q000097:blood / Q000235:genetics*
D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human