Dataset Information

NHBLI TOPMed: Pharmacogenomics of Hydroxyurea in Sickle Cell Disease (PharmHU)

ABSTRACT:

Sickle cell disease (SCD) is characterized by the presence of sickle hemoglobin (HbS) within circulating erythrocytes resulting in hemolytic anemia, vascular occlusion, and end organ damage due to alterations in the shape and deformability of the cell membrane. The disease is inherited in an autosomal recessive pattern, and is most commonly caused by a single nucleotide substitution in the hemoglobin subunit beta (HBB) gene located on chromosome 11. Participants in this study include children with SCD treated with hydroxyurea to pharmacologically increase fetal hemoglobin (HbF) levels and reduce disease severity. Therefore, the primary phenotype of interest in this study is the change in HbF levels in response to hydroxyurea treatment. Genetic factors have been shown to influence inter-individual variation in drug response, and identification of novel genes and variants associated with clinical outcomes in SCD will be achieved through collaboration between Baylor College of Medicine, Augusta University, Columbia University Medical Center, Emory University School of Medicine and Children's Healthcare of Atlanta, and St. Jude Children's Research Hospital. The NHLBI TOPMed Program is designed to generate scientific resources to enhance understanding of fundamental biological processes that underlie heart, lung, blood and sleep disorders (HLBS). It is part of a broader Precision Medicine Initiative, which aims to provide disease treatments that are tailored to an individual's unique genes and environment.

PROVIDER: phs001466 | dbGaP |

SECONDARY ACCESSION(S): PRJNA413114PRJNA413115

REPOSITORIES: dbGaP

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			Action	DRS
	GapExchange_phs001466.v1.p1.xml	Xml
	dbGaPEx2.1.5.xsd	Other
	phs001466.v1-Documents.zip	Other
	Study_Report.phs001466.TOPMed_WGS_PharmHU.v1.p1.MULTI.pdf	Pdf
	manifest_phs001466.TOPMed_WGS_PharmHU.v1.p1.c1.HMB.pdf	Pdf

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Project description:In sickle cell disease, ischemia-reperfusion injury and intravascular hemolysis produce endothelial dysfunction and vasculopathy characterized by reduced nitric oxide (NO) and arginine bioavailability. Recent functional studies of platelets in patients with sickle cell disease reveal a basally activated state, suggesting that pathological platelet activation may contribute to sickle cell disease vasculopathy. Studies were therefore undertaken to examine transcriptional signaling pathways in platelets that may be dysregulated in sickle cell disease. We demonstrate and validate here the feasibility of comparative platelet transcriptome studies on clinical samples from single donors, by the application of RNA amplification followed by microarray-based analysis of 54,000 probe sets. Data mining an existing microarray database, we identified 220 highly abundant genes in platelets and a subset of 72 relatively platelet-specific genes, defined by more than 10-fold increased expression compared to the median of other cell types in the database with amplified transcripts. The highly abundant platelet transcripts found in the current study included 82% or 70% of platelet abundant genes identified in two previous gene expression studies on non-amplified mRNA from pooled or apheresis samples, respectively. On comparing the platelet gene expression profiles in 18 patients with sickle cell disease in steady state to 12 African American controls, at a 3-fold cut-off and 5% false discovery rate, we identified ~100 differentially expressed genes, including multiple genes involved in arginine metabolism and redox homeostasis. Further characterization of these pathways using real time PCR and biochemical assays revealed increased arginase II expression and activity and decreased platelet polyamine levels. These studies suggest a potential pathogenic role for platelet arginase and altered arginine and polyamine metabolism in sickle cell disease and provide a novel framework for the study of disease-specific platelet biology. Experiment Overall Design: There are 18 sickle cell samples and 12 control samples from healthy African American volunteers.

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NHBLI TOPMed: Pharmacogenomics of Hydroxyurea in Sickle Cell Disease (PharmHU)

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