OBJECTIVE: The authors investigated the possibility that genetic
variation or mutation of the dopamine D5 receptor gene might modify
susceptibility to schizophrenia. METHOD: Twenty-three Icelandic and English
pedigrees containing multiple cases of schizophrenia were genotyped by
using a highly informative microsatellite for the D5 dopamine receptor gene
DRD5. RESULTS: By means of three different affection models, negative lod
scores were obtained under assumptions of autosomal dominant and recessive
inheritance. There was no evidence for locus heterogeneity. Nonparametric
extended relative pair analysis also produced negative results.
CONCLUSIONS: These data indicate that mutations of the D5 dopamine receptor
gene are not a major cause of schizophrenia in these pedigrees. Because of
the probable existence of locus heterogeneity, the D5 receptor gene may be
of etiologic importance in other families with schizophrenia.