LACK OF ASSOCIATION BETWEEN DOPAMINE D4 RECEPTOR GENE AND SCHIZOPHRENIA

An intriguing property of the dopamine D4 receptor gene is a hypervari able segment in the coding region characterized by a varying number of direct imperfect 48 bp repeats (2-8 or 10 repeats) in the third exon of he gene [Lichter et al., 1993: Hum Mol Genet 2:767-773]. The author s analyzed 70 unrelated schizophrenics and 70 normal controls to deter mine the allele and genotype frequencies created by length polymorphis m of dopamine D4 receptor gene. All patients and controls were unrelat ed and from the Japanese population. Patients were divided into three groups with regard to age at onset, familial loading, and severity of symptoms assessed strictly with Manchester scale. There were no statis tically significant differences if the distributions of alleles and ge notypes were analyzed for schizophrenia as a whole or analyzed in cons ideration of those clinical subtypes, Lichter and colleagues [1993] ha ve reported that at least 25 haplotypes exist for this polymorphic reg ion of the. dopamine receptor D4 gene, In this study only the alleles created by length polymorphism were analyzed, and further investigatio n to determine the haplotypes of patients and controls on using a much larger sample size will be required. (C) 1995 Wiley-Liss, Inc.