Association of DRD4 in children with ADHD and comorbid conduct problems.
Recent family and twin study findings suggest that ADHD when comorbid with conduct problems may represent a particularly familial and heritable form of ADHD. Although several independent groups have shown association between the DRD4 7 repeat allele and ADHD, others have failed to replicate this finding. Previous TDT analyses of UK and Eire samples had also been negative. We set out to further examine the role of DRD4 but selecting a subgroup of children with ADHD and comorbid conduct problems. Families were recruited from Manchester, Ireland, Birmingham and London clinics. From these, 67 children who fulfilled diagnostic criteria for ADHD and who displayed conduct disorder symptoms were selected. TDT analysis, which had previously yielded negative results for the total sample, showed evidence of association between DRD4 and "ADHD with conduct problems" (7 repeat allele-24 transmissions, 13 non-transmissions; one-tailed P=0.05). These results provide further support for the role of DRD4 in ADHD. Furthermore, these results when considered together with family and twin study findings, suggest that those children with ADHD and comorbid conduct problems may be particularly informative for molecular genetic studies of ADHD. Further work is needed to examine these phenotype issues.
Holmes
Jane
J
Department of Psychological Medicine, University of Wales College of Medicine, Heath Park, Cardiff, Wales, United Kingdom.
Payton
Antony
A
Barrett
Jennifer
J
Harrington
Richard
R
McGuffin
Peter
P
Owen
Michael
M
Ollier
William
W
Worthington
Jane
J
Gill
Michael
M
Kirley
Aiveen
A
Hawi
Ziarih
Z
Fitzgerald
Michael
M
Asherson
Philip
P
Curran
Sarah
S
Mill
John
J
Gould
Alison
A
Taylor
Eric
E
Kent
Lyndsey
L
Craddock
Nick
N
Thapar
Anita
A
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000235:genetics* / Q000523:psychology; D002648:Child; D019955:Conduct Disorder / Q000150:complications / Q000235:genetics* / Q000523:psychology; D004247:DNA / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D050638:Receptors, Dopamine D4
C493599:DRD4 protein, human; D017448:Receptors, Dopamine D2; D050638:Receptors, Dopamine D4; D004247:DNA