A possible susceptibility locus for bipolar affective disorder in chromosomal region 10q25-q26

In an attempt to identify susceptibility loci for bipolar affective disorde r, we are currently conducting a systematic genome screen with highly polym orphic microsatellite markers at an average marker spacing of 10 cM in a se ries of 75 families, comprising 66 families from Germany, eight families fr om Israel, and one family from Italy. The families were ascertained through index cases with bipolar affective disorder. The distribution of diagnoses is as follows: 126 individuals with bipolar I disorder, 40 with bipolar II disorder, 14 with schizoaffective disorder of the bipolar type, 40 individ uals with recurrent unipolar depression, 51 with a minor psychiatric diagno sis, and two individuals with a diagnosis of schizophrenia. One hundred and seventy-one individuals are unaffected. Here, we present results from chro mosome 10. Linkage analyses using a total of 33 microsatellite markers with parametric and non-parametric methods provided evidence for linkage at chr omosomal region 10q25-q26. The highest two-point LOD score (2.86, theta = 0 .05) was obtained for D10S217 using a dominant genetic model and a broad de finition of affection status. The GENEHUNTER program localized the putative susceptibility locus within a ca 15-cM interval between markers D10S1483 a nd D10S217 with a maximum NPL(all) score of 3.12 (P= 0.0013). Positive link age findings that have been reported by two independent studies further sup port the hypothesis of a susceptibility gene for bipolar affective disorder on 10q25-q26.