Abstract
Introduction and Objectives: Hemolytic uremic syndrome (HUS) is one of the major causes of renal failure in children. In most cases the disease is caused by infection with Shiga toxin-producing Escherichia coli (STEC) and is preceded by diarrhea (typical HUS). Only in 15% of cases the infection leads to HUS. Genetic predisposition of a patient to develop typical HUS after STEC infection might play a role, but very few reports on this subject are available so far. Here we describe a novel heterozygous missense sequence variation in the GP1BA gene encoding platelet-receptor glycoprotein Iba (GPIba) in a severely affected HUS patient. Material and Methods: GP1BA was screened by means of PCR and DNA sequencing using genomic DNA of the HUS patient, 192 healthy controls were analyzed for the presence of novel sequence variation. Impact of the found missense sequence variations on the protein function was analyzed using the in silico prediction programs (SIFT and Polyphen-2) and available structural data. Recombinant GPIbα and VWF fragments were produced, purified and their binding was analyzed using Biacore. The hematological studies included analyses of mean platelet volume, VWF multimers, platelet activation markers (CD63, PAC-1, CD62p), and ristocetin-induced platelet agglutination in the presence of 0.5, 0.6, 0.7, 0.8, 0.9 and 1.52 mg/mL of ristocetin. Results: The detected variation p.Pro46Leu was not found in 192 healthy controls or reported previously. The affected amino acid residue is highly conserved and is located in the proximity to one of the two von Willebrand factor (VWF) binding sites, based on the available structural data. It is predicted as damaging by mutation analysis programs SIFT and PolyPhen-2. Biacore experiments show that the p.Pro46Leu change results in a modest increase in the strength of binding of GPIbα to VWF (Kd = 690 ± 3 nM for wild type GPIbα versus Kd = 630 ± 2 nM for p.Pro46Leu (P <0.001)), This increase is small in comparison to the more than 30-fold stronger binding observed by us for platelet-type von Willebrand disease mutation p.Met255Val in the similar experiment, consistently, the hemostasis analysis of patient blood after recovery from HUS shows normal values. Conclusions: The described change in the conserved residue affects GPIbα interactions with VWF in a mild gain-of-function manner and might have contributed to a prothrombotic state in the patient and the development of typical HUS.
Original language | English |
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Pages (from-to) | 55 |
Number of pages | 1 |
Journal | Zoonoses and Public Health |
Volume | 59 |
Publication status | Published - 1 Jul 2012 |
Keywords
- von Willebrand factor
- ristocetin
- genomic DNA
- DNA
- marker
- glycoprotein
- amino acid
- thrombocyte receptor
- human
- Escherichia coli infection
- patient
- Shiga toxin producing Escherichia coli
- infection
- mutation
- thrombocyte activation
- diarrhea
- hemolytic uremic syndrome
- genetic predisposition
- computer model
- child
- protein function
- wild type
- thrombocyte
- von Willebrand disease
- prediction
- thrombocyte volume
- kidney failure
- thrombocyte agglutination
- binding site
- gene
- hemostasis
- blood
- normal value
- DNA sequence