Summary. Background: Common genetic variants of cell surface receptors contribute to differences in functional responses and disease susceptibility. We have previously shown that single nucleotide polymorphisms (SNPs) in platelet glycoprotein VI (GP6) determine the extent of response to agonist. In addition, SNPs in the GP6 gene have been proposed as risk factors for coronary artery disease. Methods: To completely characterize genetic variation in the GP6 gene we generated a high-resolution SNP map by sequencing the promoter, exons and consensus splice sequences in 94 nonrelated Caucasoids. In addition, we sequenced DNA encoding the ligand-binding domains of GP6 from non-human primates to determine the level of evolutionary conservation. Results: Eighteen SNPs were identified, six of which encoded amino acid substitutions in the mature form of the protein. The single nonsynonymous SNP identified in the exons encoding the ligandbinding domains, encoding for a 103Leu > Val substitution, resulted in reduced ligand binding. Two common protein isoforms were confirmed in Caucasoid with frequencies of 0.82 and 0.15. Variation at the GP6 locus was characterized further by determining SNP frequency in over 2000 individuals from different ethnic backgrounds. Conclusions: The SNPs were polymorphic in all populations studied although significant differences in allele frequencies were observed. Twelve additional GP6 protein isoforms were identified from the genotyping results and, despite extensive variation in GP6, the sequence of the ligand-binding domains is conserved. Sequences from non-human primates confirmed this observation. These data provide valuable information for the optimal selection of genetic variants for use in future association studies.
Objective. To investigate the origins of antiphospholipid antibodies associated with thrombosis and other disorders that are found in patients with systemic lupus erythematosus and primary antiphospholipid syndrome (APS).Methods. Characterization, idiotypic study, and nucleotide sequencing of a human monoclonal antiphospholipid antibody generated from a patient with primary APS. Identification of the germline genes from which the antibody is derived.Results. A human monoclonal antibody, BH1, was generated. This antibody has ligand‐binding properties that closely resemble those of the serum antiphospholipid antibodies found in our patient and in other individuals with APS: it recognizes negatively charged phospholipids, and has lupus anticoagulant activity; it does not bind to neutral phospholipids, or to singlestranded or double‐stranded DNA. The relevance of BH1 to the patient's serum antibodies is supported by our idiotypic studies. BH1 is encoded by a new germline VH gene, and by a λ light chain gene that displays >99% homology with the VλIII.1 germline gene.Conclusion. Serum antiphospholipid antibodies associated with thrombosis may be encoded by either germline or only slightly mutated variable‐region genes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.