Copyright 2006 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2006
We are concerned that the results appearing to implicate an effect of DRD2 polymorphisms on the susceptibility to heroin dependence1 may represent statistical artifacts rather than a true genetic effect. To a very large extent, the results are based on estimating the frequencies of haplotypes in cases and controls and testing for a difference, the frequencies being estimated using the MLOCUS program.2 Likelihood ratio tests assuming a χ2 distribution were reported to produce P values as low as 10−10. A Fisher exact test for 1 haplotype produced a P value of 10−22.
Curtis D, Gurling H. Estimation of Haplotypes at DRD2 May Have Produced Misleading Results. Arch Gen Psychiatry. 2006;63(8):939. doi:10.1001/archpsyc.63.8.939-a