RT Journal
A1 Curtis D, Gurling H
T1 EStimation of haplotypes at drd2 may have produced misleading results
JF Archives of General Psychiatry
JO Archives of General Psychiatry
YR 2006
FD August 1
VO 63
IS 8
SP 939
OP 939
DO 10.1001/archpsyc.63.8.939-a
UL http://dx.doi.org/10.1001/archpsyc.63.8.939-a
AB 
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.