Comparison of selected methods used to analyze bipolar disorder.

Susceptibility genes on chromosome 18, and a parent-of-origin effect, have been suggested for bipolar disorder. We analyzed BP data sets provided by the National Institutes of Mental Health and Johns Hopkins University to the Genetic Analysis Workshop 10. Numerous statistical methods were applied to detect association, linkage, and parent-of-origin effects, under alternative diagnostic models. The methods were subsequently compared. Our results suggest that the evidence of linkage of BP to chromosome 18 markers tends to increase, often substantially, as the classification of "affected" individuals broadens. Additionally, a parent-of-origin effect was detected in some of the families.