A meta-analysis of chromosome 18 linkage data for bipolar illness

We find a meta‐data set (715 families, up to 1,124 sib pairs) for bipolar illness to have a strong signal in a 10 cM region around D18S40, and excess paternal sharing on the q arm near marker D18S64. We describe a method for meta‐analysis of microsatellite marker data using affected sib‐pair (ASP) methodology. Inherent difficulties in such analysis include heterogeneity of allele frequencies and protocol design, measurement errors in genotyping, and map construction. Using identity‐by‐descent (IBD) allele sharing as the dependent variable, a logistic regression to test for heterogeneity finds only mild heterogeneity, and a limited parent‐of‐origin effect. © 1997 Wiley‐Liss, Inc.