Exclusion of linkage to 5qll–13 in families with schizophrenia and other psychiatric disorders

Abstract

RECENTLY a linkage study on five Icelandic and two English pedigrees has provided evidence for a dominant gene for schizophrenia on 5q11–13 (ref. 1). In that study, families with bipolar illness were not included. Using the same probes, two similar but independent investigations on one Swedish pedigree2 and on fifteen Scottish families3 excluded linkage to schizophrenia. To evaluate whether the susceptibility gene on 5qll–13 is a common cause of schizophrenia in other populations, we examined five affected North American pedigrees using probes to the D5S39, D5S76 (ref. 4) and dihydrofolate reductase5 loci. Two families in the present series had cases of bipolar disorder. We found that linkage can be excluded by multipoint analysis. These results, taken together, suggest that the disease gene on 5qll–13 does not account for most cases of familial schizophrenia.