title: Comparison of artificial neural network analysis with other multimarker methods for detecting genetic association.
abstract: BACKGROUND
  Debate remains as to the optimal method for utilising genotype data obtained from multiple markers in case-control association studies. I and colleagues have previously described a method of association analysis using artificial neural networks (ANNs), whose performance compared favourably to single-marker methods. Here, the performance of ANN analysis is compared with other multi-marker methods, comprising different haplotype-based analyses and locus-based analyses.
  
  
  RESULTS
  Of several methods studied and applied to simulated SNP datasets, heterogeneity testing of estimated haplotype frequencies using asymptotic p values rather than permutation testing had the lowest power of the methods studied and ANN analysis had the highest power. The difference in power to detect association between these two methods was statistically significant (p = 0.001) but other comparisons between methods were not significant. The raw t statistic obtained from ANN analysis correlated highly with the empirical statistical significance obtained from permutation testing of the ANN results and with the p value obtained from the heterogeneity test.
  
  
  CONCLUSIONS
  Although ANN analysis was more powerful than the standard haplotype-based test it is unlikely to be taken up widely. The permutation testing necessary to obtain a valid p value makes it slow to perform and it is not underpinned by a theoretical model relating marker genotypes to disease phenotype. Nevertheless, the superior performance of this method does imply that the widely-used haplotype-based methods for detecting association with multiple markers are not optimal and efforts could be made to improve upon them. The fact that the t statistic obtained from ANN analysis is highly correlated with the statistical significance does suggest a possibility to use ANN analysis in situations where large numbers of markers have been genotyped, since the t value could be used as a proxy for the p value in preliminary analyses.
authors.affiliation: Academic Centre for Psychiatry, St Bartholomew's and Royal London School of Medicine and Dentistry, Royal London Hospital, Whitechapel, London, UK. david.curtis@qmul.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Curtis
mesh_terms: D016022:Case-Control Studies; D003198:Computer Simulation; D030541:Databases, Genetic; D005787:Gene Frequency; D005819:Genetic Markers / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D016571:Neural Networks, Computer; D020641:Polymorphism, Single Nucleotide
chemical_list: D005819:Genetic Markers