Affected-sib-pair analyses of bipolar disorder using data on chromosome 18

Our aim was to analyze the GAW10 bipolar data on chromosome 18, using three well-known affected-sib-pair methods. Analyses were carried out on both individual and combined data sets. In these analyses we defined the affected phenotype to include only individuals with diagnosis of bipolar I. We observed suggestive evidence for linkage to a few markers on the peri-centromeric region of chromosome 18. In the COLUMBIA data set, D18S45 showed statistically significant results (p-value < or = 0.001). Also for the combined analyses, D18S53 gave a consistently significant linkage signal.