Haplotype analysis of chromosome 8p and 15q in Icelandic schizophrenic patients

The lack of highly significant linkage results in many common diseases such as schizophrenia is consistent with formal genetic studies suggesting that these disorders are influenced by numerous alleles. Their large number provide major problems in their detection. In successful cloning studies of common disorders, haplotype analysis was performed in families from genetically homogeneous human populations. The aim of our study was to apply a simple method for mapping comparing haplotypes. This approach uses parent-child pairs and basically extends the principle of allelic associations from within defined families, which underlies standard linkage analysis, to the distant relatives of distantly and unknowingly related individuals. Material: One hundred sixty-two schizophrenic patients according to DSM-IIIR from the records of the Department of Psychiatry at the National University Hospital in Iceland and one of their parents or children. This department admits about two thirds of psychiatric patients requiring hospitalization in Iceland. The great-grandparents of the patients were identified through the Icelandic Geneological Register in order to find the nearest relative with schizophrenia - this additional information has not yet been used in our preliminary analysis. One hundred sixty-two parent-child pairs, one affected, were genotyped using a dense map of markers. Results and Conclusion: In agreement with our previous genome scan, no evidence for involvement of the nicotinic receptor gene CHRNA7 on chromosome 15q was found in this new Icelandic schizophrenia sample. Preliminary evidence confirms the suggestion of an active locus on chromosome 8p.