title: Association analysis of exon III and exon I polymorphisms of the dopamine D4 receptor locus in Mexican psychotic patients.
abstract: In this study, we investigated whether polymorphisms of the dopamine D4 receptor (DRD4) gene were associated with psychotic symptomatology rather than with a unique diagnosis such as schizophrenia. A number of association studies between the DRD4 gene 48 bp-VNTR polymorphism at exon 3 and psychotic disorders have been reported, but the results have been controversial. Both 48 bp-VNTR and the 12 bp-VNTR (at exon 1) polymorphisms of this gene were analyzed in a group of 149 unrelated Mexican subjects with a diagnosis of schizophrenia, schizoaffective disorder, schizophreniform disorder, major depression and bipolar disorder, both with psychotic symptoms, brief psychotic disorder, delusional disorder and non-specific psychotic disorder, and in 169 individuals free of psychiatric illnesses. There were no differences in allele or genotype frequencies between groups for the 12 bp-VNTR polymorphisms. However, a significant excess of "rare" alleles (3-, 5-, 6- and 8-48 bp repeats alleles) was found in the group of psychotics. Moreover, haplotypes 3-A1, 5-A1, 6-A1 and 8-A1 were significantly more frequently associated with cases. This positive association supports a role of this molecule as a genetic risk factor in psychotic disorders.
authors.affiliation: Departamento de Genética Psiquiátrica, Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría "Ramón de la Fuente", Calzada México-Xochimilco 101, Col. San Lorenzo Huipulco, cp 14370 D.F., México.
authors.forename: Ana Julia
authors.initials: AJ
authors.lastname: Aguirre
authors.forename: Rogelio
authors.initials: R
authors.lastname: Apiquián
authors.forename: Ana
authors.initials: A
authors.lastname: Fresán
authors.forename: Carlos
authors.initials: C
authors.lastname: Cruz-Fuentes
mesh_terms: D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis / Q000235:genetics; D003865:Major Depressive Disorder / Q000175:diagnosis / Q000235:genetics; D005006:Ethnicity / Q000235:genetics*; D005091:Exons / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D008297:Male; D008800:Mexico / Q000208:ethnology; D008875:Middle Aged; D018598:Minisatellite Repeats / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D011618:Psychotic Disorders / Q000175:diagnosis / Q000235:genetics*; D050638:Receptors, Dopamine D4 / Q000235:genetics; D012307:Risk Factors; D012563:Schizophrenia, Paranoid / Q000175:diagnosis / Q000235:genetics