title: Allelotyping of pooled DNA with 250 K SNP microarrays.
abstract: BACKGROUND
  Genotyping technologies for whole genome association studies are now available. To perform such studies to an affordable price, pooled DNA can be used. Recent studies have shown that GeneChip Human Mapping 10 K and 50 K arrays are suitable for the estimation of the allele frequency in pooled DNA. In the present study, we tested the accuracy of the 250 K Nsp array, which is part of the 500 K array set representing 500,568 SNPs. Furthermore, we compared different algorithms to estimate allele frequencies of pooled DNA.
  
  
  RESULTS
  We could confirm that the polynomial based probe specific correction (PPC) was the most accurate method for allele frequency estimation. However, a simple k-correction, using the relative allele signal (RAS) of heterozygous individuals, performed only slightly worse and provided results for more SNPs. Using four replicates of the 250 K array and the k-correction using heterozygous RAS values, we obtained results for 104.141 SNPs. The correlation between estimated and real allele frequency was 0.983 and the average error was 0.046, which was comparable to the results obtained with the 10 K array. Furthermore, we could show how the estimation accuracy depended on the SNP type (average error for A/T SNPs: 0.043 and for G/C SNPs: 0.052).
  
  
  CONCLUSIONS
  The combination of DNA pooling and analysis of single nucleotide polymorphisms (SNPs) on high density microarrays is a promising tool for whole genome association studies.
authors: Department of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany. s.wilkening@dkfz.de
authors: Stefan
authors: S
authors: Wilkening
authors: Bowang
authors: B
authors: Chen
authors: Michael
authors: M
authors: Wirtenberger
authors: Barbara
authors: B
authors: Burwinkel
authors: Asta
authors: A
authors: Försti
authors: Kari
authors: K
authors: Hemminki
authors: Federico
authors: F
authors: Canzian
mesh_terms: D000465:Algorithms; D000483:Alleles; D004247:DNA / Q000032:analysis*; D004252:DNA Mutational Analysis / Q000379:methods*; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation; D020641:Polymorphism, Single Nucleotide; D013048:Specimen Handling
chemical_list: D004247:DNA