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NEALE, B. M., Sham, P. C., Purcell,
S., Banaschewski, T., Buitelaar, J., Franke, B., Sonuga-Barke, E. J.
S., Ebstein, R., Eisenberg, J., Mulligan, A., Gill, M., Manor, I., Miranda,
A., Mulas, F., Oades, R. D., Roeyers, H., Rothenberger,
A., Sergeant, J. A., Steinhausen, H-C., Taylor, E. A., Thompson, M.,
Zhou, K., Asherson, P., & Faraone, S. V.
Population Differences in the International Multi-Centre ADHD
Gene Project. Genetic Epidemiology, 32, 98-107 (2008).
DOI: 10.1002/gepi.20265. (request
a copy): view
article
Introduction: The IMAGE sample consists of
674 families from 8 countries (Belgium, England, Germany, Holland, Ireland,
Israel, Spain, & Switzerland) ascertained from clinics for combined-type
attention deficit hyperactivity disorder in an offspring. 863 SNPs were
successfully genotyped across 47 autosomal genes implicated in psychiatric
disorders yielding an SNP density of about one SNP per 2.5 kb.
Results:
1) A global test of heterogeneity
showed 269 SNPs nominally significant (expected 43). Inclusion of
the Israeli population accounted for approximately 70% of these nominally
significant tests.
2) Hardy-Weinberg equilibrium
tests suggest that combining all these populations would induce
stratification, BUT that the Northern European populations
(Belgium, England, Germany, Holland, & Ireland) could be appropriate.
3) Tag SNPs were generated
using pair-wise & aggressive tagging from Carlson ea [2004] &
de Bakker ea [2005], respectively, in each population & applied
to the other populations. Cross-population performance across Northern
Europe was consistent with within population comparisons.
4) Smaller sample size for each population tended to yield
more problems for the generation of aggressive tags & the application
of pair-wise tags.
5) Any case-control sample employing
an Israeli sample with Northern Europeans must consider stratification.
Conclusion - A
Northern European tag set, however, appears to be appropriate for capturing
the variation across populations.
Support: NIH.
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