Annals of Human Genetics



New DNA markers with increased informativeness show diminished support for a chromosome 5q11–13 schizophrenia susceptibility locus and exclude linkage in two new cohorts of British and Icelandic families


G. KALSI a1, B. MANKOO a1, D. CURTIS a3, R. SHERRINGTON a1, G. MELMER a1, J. BRYNJOLFSSON a1, T. SIGMUNDSSON a2, T. READ a1, P. MURPHY a1, H. PETURSSON a2 and H. GURLING a1
a1 Molecular Psychiatry Laboratory, Windeyer Institute for Medical Research, Department of Psychiatry and Behavioural Sciences, Windeyer Building, University College London Medical School, Cleveland Street, University of London, London W1P 7PN
a2 Department of Psychiatry, University of Iceland, General Hospital, Reykjavik 108, Iceland
a3 Joint Academic Department of Psychological Medicine, St Bartholomew's and Royal London School of Medicine and Dentistry, 3rd Floor Alexander Wing, Turner Street, London E1 1BB

Abstract

Genetic linkage of schizophrenia to markers at 5q11.2–13.3 had been reported previously in five Icelandic and two British families, but attempts at replication in independent samples have been unsuccessful. We report here an update on the diagnoses and results of linkage analyses using newer highly polymorphic microsatellite markers at or near the loci D5S76 and D5S39 in the original sample of pedigrees and in two new family samples from Iceland and from Britain. The new results show a reduction in evidence for linkage in the original sample and evidence against linkage in the two new family samples. Although it is possible that a rare locus is present, perhaps in the region 5p14.1–13.1 rather than 5q11.2–13.3, it appears most likely that the original positive lod scores represent an exaggeration of the ‘true’ lod scores due to random effects and that the small lod scores we now obtain could have arisen by chance.

(Received December 23 1998)
(Accepted May 5 1999)