Endothelial Protein C Receptor Gene Variants Not Associated with Severe Malaria in Ghanaian Children

<div><p>Background</p><p>Two recent reports have identified the Endothelial Protein C Receptor (EPCR) as a key molecule implicated in severe malaria pathology. First, it was shown that EPCR in the human microvasculature mediates sequestration of <i>Plasmodium falciparum</i>-infected erythrocytes. Second, microvascular thrombosis, one of the major processes causing cerebral malaria, was linked to a reduction in EPCR expression in cerebral endothelial layers. It was speculated that genetic variation affecting EPCR functionality could influence susceptibility to severe malaria phenotypes, rendering <i>PROCR</i>, the gene encoding EPCR, a promising candidate for an association study.</p><p>Methods</p><p>Here, we performed an association study including high-resolution variant discovery of rare and frequent genetic variants in the <i>PROCR</i> gene. The study group, which previously has proven to be a valuable tool for studying the genetics of malaria, comprised 1,905 severe malaria cases aged 1–156 months and 1,866 apparently healthy children aged 2–161 months from the Ashanti Region in Ghana, West Africa, where malaria is highly endemic. Association of genetic variation with severe malaria phenotypes was examined on the basis of single variants, reconstructed haplotypes, and rare variant analyses.</p><p>Results</p><p>A total of 41 genetic variants were detected in regulatory and coding regions of <i>PROCR</i>, 17 of which were previously unknown genetic variants. In association tests, none of the single variants, haplotypes or rare variants showed evidence for an association with severe malaria, cerebral malaria, or severe malaria anemia.</p><p>Conclusion</p><p>Here we present the first analysis of genetic variation in the <i>PROCR</i> gene in the context of severe malaria in African subjects and show that genetic variation in the <i>PROCR</i> gene in our study population does not influence susceptibility to major severe malaria phenotypes.</p></div

Association tests of <i>PROCR</i> haplotypes with severe malaria, cerebral malaria, and severe malaria anemia.

<p>Aff, affected individuals; unaff, unaffected individuals.</p>a<p>Refers to SNP number as designated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115770#pone-0115770-t002" target="_blank">Table 2</a>.</p>b<p>Results of haplotypic-specific score tests adjusted for gender, age, and ethnicity assuming an additive mode of inheritance.</p>c<p>Simulation p-values are computed based on a permuted re-ordering of the trait and covariates in Haplo Stats <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115770#pone.0115770-Schaid1" target="_blank">[29]</a>.</p><p>Association tests of <i>PROCR</i> haplotypes with severe malaria, cerebral malaria, and severe malaria anemia.</p

PROCR rare variant analyses including SNPs with MAF ≤1%.

<p>CMC, combined and multivariate collapsing; WSS, weighted sum statistic; VT, variable thresholds methods.</p>a<p>Adjusted for age, gender, and ethnic group.</p><p>PROCR rare variant analyses including SNPs with MAF ≤1%.</p

Multivariate analysis of the association between CRP levels and other parameters, and parasitemia, malaria and septicemia in 548 patient visits.

<p>Multivariate analysis of the association between CRP levels and other parameters, and parasitemia, malaria and septicemia in 548 patient visits.</p

Test quality of CRP levels for the prediction of parasitemia, malaria and septicemia.

<p>Test quality of CRP levels for the prediction of parasitemia, malaria and septicemia.</p

Univariate analysis of the association between CRP levels and parasitemia, malaria and septicemia in 548 patient visits.

<p>Univariate analysis of the association between CRP levels and parasitemia, malaria and septicemia in 548 patient visits.</p

Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)-2

<p><b>Copyright information:</b></p><p>Taken from "Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)"</p><p>http://www.malariajournal.com/content/6/1/163</p><p>Malaria Journal 2007;6():163-163.</p><p>Published online 9 Dec 2007</p><p>PMCID:PMC2234423.</p><p></p>dence rates in the placebo arm. A, stratified by month of birth (red diamonds and lines [linear regression, R0.54, p < 0.006], children from the SP arm; blue circles and lines [linear regression R0.05, p = 0.475], children from the placebo arm. B, stratified by village of residence (red diamonds and lines [linear regression, R0.90, p < 0.001], children from the SP arm; blue circles and lines [linear regression, R0.89, p < 0.001], children from the placebo arm). Panel C and D, correlation between malaria incidence rates and incidence rates in the placebo arm. C, stratified by month of birth (red diamonds and lines [slope 0.07, p < 0.80], children from the SP arm; blue circles and lines, children from the placebo arm as comparison [slope 1]). D, stratified by village of residence (red diamonds and lines [slope 0.67, p < 0.007], children from the SP arm; blue circles and lines, children from the placebo arm as comparison [slope 1]). PYAR, person year at risk

Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)-3

<p><b>Copyright information:</b></p><p>Taken from "Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)"</p><p>http://www.malariajournal.com/content/6/1/163</p><p>Malaria Journal 2007;6():163-163.</p><p>Published online 9 Dec 2007</p><p>PMCID:PMC2234423.</p><p></p>the respective study arm in each village. A, stratified by month of birth (Wald test, p = 0.118). B, stratified by village of residence (Wald test, p < 0.001). Blue circles and lines (linear regression), children from placebo arm; red diamonds and lines (linear regression), children from SP arm. PYAR, person year at risk

Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)-0

<p><b>Copyright information:</b></p><p>Taken from "Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)"</p><p>http://www.malariajournal.com/content/6/1/163</p><p>Malaria Journal 2007;6():163-163.</p><p>Published online 9 Dec 2007</p><p>PMCID:PMC2234423.</p><p></p>year, beginning at the time of recruitment. A, PYAR stratified for the month of birth of the children; B, PYAR stratified for the village of residence of the children. PYAR, person year at risk

Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)-1

<p><b>Copyright information:</b></p><p>Taken from "Malaria incidence and efficacy of intermittent preventive treatment in infants (IPTi)"</p><p>http://www.malariajournal.com/content/6/1/163</p><p>Malaria Journal 2007;6():163-163.</p><p>Published online 9 Dec 2007</p><p>PMCID:PMC2234423.</p><p></p> after the drug administration (blue circles and line, after IPTi-1; red diamonds and line, after IPTi-2; green triangles and line, after IPTi-3) and malaria incidence rates per PYAR for the same time periods in the placebo arm. A, stratified by month of birth (IPTi-1, R0.63, p < 0.003; IPTi-2, R0.29, p = 0.07; IPTi-3, R0.37, p < 0.04); B, stratified by village of residence (IPTi-1, R0.48, p < 0.04; IPTi-2, R0.33, p = 0.11; IPTi-3, R0.04, p = 0.60). PYAR, person year at risk