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Human P2X7 pore function predicts allele linkage disequilibrium
Loren C Denlinger1, Douglas B Coursin, Kathleen Schell
1Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA. ldenling@wisc.edu
Clinical Chemistry
|April 15, 2006
Summary
Investigating P2X7 receptor function revealed new alleles and functional insights. Direct pore activity analysis links genetic variations to immune response modulation in various disorders.
Area of Science:
- Immunology
- Genetics
Background:
- Leukocyte P2X7 receptor (an extracellular nucleotide-gated pore) amplifies innate immune responses.
- Low P2X7 pore activity correlates with loss-of-function genotypes and altered cytokine ratios, impacting infectious and inflammatory diseases.
Purpose of the Study:
- To identify novel P2X7 alleles and functional correlates by evaluating individuals with discordant P2X7 genotype and pore status.
- To explore linkage disequilibrium and genotype-phenotype relationships.
Main Methods:
- Optimized whole-blood P2X7 pore activity assay threshold using ROC analysis.
- Identified novel alleles and haplotypes via sequencing and linkage analysis in 200 healthy participants.
Main Results:
- Refined assay threshold showed low predictive value for known loss-of-function variants (2%), but 59% positive predictive value for identifying known alleles.
- Discovered 28 P2X7 sequence variations; identified independent inheritance of A1513C, T1729A, and G946A, despite disequilibrium with other alleles.
- Nonsynonymous variations (G474A, A1405G) modulated P2X7 pore activity.
Conclusions:
- Direct P2X7 pore activity analysis reveals functional interactions between P2X7 alleles.
- The whole-blood pore assay facilitates correlating genomic variations with functional performance in clinical research.