Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01034 (cystatin C)
 3,397 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human Pena/Penb alloantigen system represents a naturally occurring polymorphism of human platelet membrane glycoprotein (GP) IIIa, and has previously been implicated in the onset of two important clinical syndromes, neonatal alloimmune thrombocytopenic purpura and posttransfusion purpura. To investigate the molecular basis of the polymorphism underlying the Pen alloantigen system, we used the polymerase chain reaction to amplify platelet-derived GPIIIa mRNA transcripts. DNA sequence analysis of amplified GPIIIa cDNAs from nucleotides 161 to 1341 (encompassing amino acid residues 22-414) revealed a G526<==>A526 polymorphism that segregated precisely with Pen phenotype in twelve other individuals examined. This nucleotide substitution results in an Arg (CGA) to Gln (CAA) polymorphism at amino acid 143 of GPIIIa. Interestingly, this polymorphic residue is located within the putative RGD binding site (residues 109-171) of GPIIIa. Platelet aggregation patterns of a Penb/b individual, however, were nearly normal in response to all physiological agonists tested, indicating that this polymorphism does not grossly affect integrin function. Short synthetic peptides encompassing residue 143 were unable to mimic either the Pena or Penb antigenic determinants, suggesting that the Pen epitopes are dependent upon proper folding of the polypeptide chain. Finally, we constructed allele-specific recombinant forms of GPIIIa that differed only at amino acid residues 143. Whereas anti-Pena alloantibodies were able to recognize the Arg143 recombinant form of GPIIIa, anti-Penb antibodies were not. Conversely, anti-Penb alloantibodies were reactive only with the Gln143 isoform of the GPIIIa molecule. It thus appears that amino acid 143 of GPIIIa is not only associated with Pen phenotype, but specifically controls the formation and expression of the Pen alloantigenic determinants.
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PMID:An amino acid polymorphism within the RGD binding domain of platelet membrane glycoprotein IIIa is responsible for the formation of the Pena/Penb alloantigen system. 143 Feb 25

A total of 1,000 Chinese blood donors were typed for human platelet antigens (HPA) using a sequence specific primers -polymerase chain reaction (PCR-SSP) based HPA genotyping method. An individual with a rare HPA-10w(a+b+) genotype was found. In order to confirm the typing results, a fragment of HPA-10 gene was amplified by PCR and then sequenced. Sequencing data showed that a single G to A substitution at nucleotide 263 occurred, resulting in amino acid change from Arg(CGA) to Gln(CAA) at position 62 of GPa protein. The substitution generated antigenic specificity HPA-10bw. The detection of an HPA-10bw allele in the Chinese population suggests that this rare allele should be considered in platelet alloimmunization, such as neonatal alloimmune thrombocytopenia (NAIT), post-transfusion thrombocytopenic purpura (PTP) and post-transfusion refractoriness to platelets (PTR).
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PMID:[Case report of a rare platelet-specific antigen HPA-10bw allele found in Chinese mainland]. 1736 72

Immune thrombocytopenic purpura is an acquired autoimmune disorder that is the most common cause of thrombocytopenia in children. The endocannabinoid system is involved in immune regulation. We evaluated a common missense variant (CAA/CGG; Q63R) of the gene encoding the cannabinoid receptor type 2 (GeneID 1269) in 190 children with immune thrombocytopenic purpura and 600 healthy controls. The allelic frequencies and genotype distribution of the polymorphism in the patients were significant compared to control samples (P=0.006 and P=0.0001, respectively). Interestingly, when acute and chronic immune thrombocytopenic purpura patients were analyzed separately with respect to controls, a significant overrepresentation of the RR genotype and of the R allele was observed only for the chronic form (P=0.00021 and P=0.011, respectively). The relative odds ratio suggested the risk of developing chronic form was more than double in immune thrombocytopenic purpura children homozygous for the variant (odds ratio=2.349, 95% CI: 1.544-3.573; P<0.001).
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PMID:CNR2 functional variant (Q63R) influences childhood immune thrombocytopenic purpura. 2214 71