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

Genetic linkage of schizophrenia to markers at 5q11.2-13.3 had been reporte d previously in five Icelandic and two British families, but attempts at re plication 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 t he 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 s amples. Although it is possible that a rare locus is present, perhaps in th e region 5p14.1-13.1 rather than 5q11.2-13.3, it appears most likely that t he 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 c ould have arisen by chance.