¹Institute of Human Genetics, University of Bonn, Wilhelmstr 31, D-53111 Bonn, Germany

²Department of Psychiatry, University of Bonn, Sigmund-Freud-Str 25, D-53105 Bonn, Germany

³Mental State Hospital Haar, Vockestr 72, D-85540 Haar, Germany

⁴Department of Psychiatry, University of Würzburg, Füchsleinstr 15, D-97080 Würzburg, Germany

⁵Department of Psychiatry, University of Frankfurt, Heinrich-Hoffmann-Str 10, D-60528 Frankfurt/Main, Germany

⁶Department of Psychiatry, TU Dresden, Fetscherstr 74, D-01307 Dresden, Germany

⁷Department of Psychiatry, University of Mainz, Untere Zahlbacher Str 8, D-55131 Mainz, Germany

⁸Department of Psychiatry, Hadassah University, Jerusalem, Israel

⁹Institute for Medical Biometry, Informatics, and Epidemiology, University of Bonn, Sigmund-Freud-Str 25, D-53105 Bonn, Germany

¹⁰Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium

Correspondence to: Dr S Cichon, Institute of Human Genetics, University of Bonn, Wilhelmstr 31, 53111 Bonn, Germany. E-mail: cichon@mailer.meb.uni-bonn.de

In an attempt to identify susceptibility loci for bipolar affective disorder, we are currently conducting a systematic genome screen with highly polymorphic microsatellite markers at an average marker spacing of 10 cM in a series of 75 families, comprising 66 families from Germany, eight families from 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 individuals with recurrent unipolar depression, 51 with a minor psychiatric diagnosis, and two individuals with a diagnosis of schizophrenia. One hundred and seventy-one individuals are unaffected. Here, we present results from chromosome 10. Linkage analyses using a total of 33 microsatellite markers with parametric and non-parametric methods provided evidence for linkage at chromosomal region 10q25-q26. The highest two-point LOD score (2.86, = 0.05) was obtained for D10S217 using a dominant genetic model and a broad definition of affection status. The GENEHUNTER program localized the putative susceptibility locus within a ca 15-cM interval between markers D10S1483 and D10S217 with a maximum NPL(all) score of 3.12 (P = 0.0013). Positive linkage findings that have been reported by two independent studies further support the hypothesis of a susceptibility gene for bipolar affective disorder on 10q25-q26. Molecular Psychiatry (2001) 6, 342-349.

manic depression; gene localization; genetics; sib pair