Genetic modifiers of the severity of sickle cell anemia identified through a genome-wide association study

Am J Hematol. 2010 Jan;85(1):29-35. doi: 10.1002/ajh.21572.

Abstract

We conducted a genome-wide association study (GWAS) to discover single nucleotide polymorphisms (SNPs) associated with the severity of sickle cell anemia in 1,265 patients with either "severe" or "mild" disease based on a network model of disease severity. We analyzed data using single SNP analysis and a novel SNP set enrichment analysis (SSEA) developed to discover clusters of associated SNPs. Single SNP analysis discovered 40 SNPs that were strongly associated with sickle cell severity (odds for association >1,000); of the 32 that we could analyze in an independent set of 163 patients, five replicated, eight showed consistent effects although failed to reach statistical significance, whereas 19 did not show any convincing association. Among the replicated associations are SNPs in KCNK6 a K(+) channel gene. SSEA identified 27 genes with a strong enrichment of significant SNPs (P < 10(-6)); 20 were replicated with varying degrees of confidence. Among the novel findings identified by SSEA is the telomere length regulator gene TNKS. These studies are the first to use GWAS to understand the genetic diversity that accounts the phenotypic heterogeneity sickle cell anemia as estimated by an integrated model of severity. Additional validation, resequencing, and functional studies to understand the biology and reveal mechanisms by which candidate genes might have their effects are the future goals of this work.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Anemia, Sickle Cell / complications*
  • Anemia, Sickle Cell / genetics*
  • Anemia, Sickle Cell / physiopathology
  • Child
  • Complement C8 / genetics
  • Computational Biology
  • Genome-Wide Association Study
  • Humans
  • MAP Kinase Kinase Kinases / genetics
  • Middle Aged
  • Phenotype*
  • Polymorphism, Single Nucleotide*
  • Potassium Channels, Tandem Pore Domain / genetics
  • Severity of Illness Index
  • Tankyrases / genetics
  • Young Adult

Substances

  • Complement C8
  • KCNK6 protein, human
  • Potassium Channels, Tandem Pore Domain
  • Tankyrases
  • TNKS protein, human
  • MAP Kinase Kinase Kinases
  • MAP3K13 protein, human