Asherson, P. Zhou, K., Anney, R. J. L. Franke B., Buitelaar, J., Ebstein, R., Gill, M., Altink, M., Arnold, P., Boer, F., Brookes, K-J., Buschgens, C., Butler, L. Campbell, D., Chen, W., Christiansen, H., Feldman, L., Fleischman, K., Fliers, E., Howe-Forbes, R., Goldfarb, A., Heise, A., Gabriels, I., Johansson, L., Lubetzki, I., Marco, R., Medad, S., Minderaa, R. B., Mulas, F., Müller, U., Mulligan, A., Rabin, K., Rommelse, N., Sethna, V. Sorohan, J., Uebel, H., Psychogiou, L., Weeks, A., Barrett, R., Xu, X., Banaschewski, T., Sonuga-Barke, E. J. S., Eisenberg, J., Manor, I., Miranda, A. Oades, R. D., Roeyers, H., Rothenberger, A., Sergeant, J. A., Steinhausen, H-C., Taylor, E. A., Thompson, M., & Faraone, S. V.
A high density SNP linkage scan with 142 combined subtype ADHD sib pairs identifies replicated linkage regions on chromosomes 9 and 16. Molecular Psychiatry, 13, 514-521 (2008) doi 10.1002/gepi.20265. (request a copy): View Article

Introduction: This report is of an affected sibling pair study of 142 narrowly defined DSM-IV combined type ADHD proband-siblng pairs performed in the context of the International Multicenter ADHD Genetics project (IMAGE).

Results in context - 1 -
a) We found suggestive linkage on chromosome 9 & 16 with non-parametric multipoint peak LOD scores of 2.13 & 3.1 respectively.
b) There have been several previous ADHD linkage scans published to date.
c) The UCLA study (Fisher et al. 2002; Ogdie et al. 2003) , the Dutch study (Bakker et al. 2003) & a German study (Hebebrand et al. 2006) & the MGH study (Faraone et al. 2007) applied the Affected Sib-Pair (ASP) strategy; the 4th used extended pedigrees ascertained from a population isolate in Columbia (Arcos-Burgos et al. 2004).

Results in detail - 2 -
First: No linkage was observed on the most established ADHD linked genomic regions from these studies on 5p & 17p:
Second: The highest multi-point non-parametric linkage signal on chromosome 16q23 at 99 cM (Decode map lod 3.1) overlapped with data published from UCLA (LOD>1, ~90cM) & The Netherlands (LOD>1, ~100cM):
Third: We found the second highest peak at chromosome 9q22 at 90cM (lod 2.13); interestingly, both the UCLA study and the German study also found some evidence of linkage at almost the same location (UCLA LOD>1, 72 cM; German LOD=0.68, 99.7cM):

Conclusions:
The overlap of the 2 main peaks from this study with those from previous studies is suggestive that true linked loci true lie within these regions. Further work will aim to combine these data with whole genetic association data to identify associated alleles that give rise to the linkage signals.
Support: NIH.