Objective: The association between a putative functional promoter polymorphism, -141C insertion/deletion (Ins/Del), in the dopamine receptor D2 gene (DRD2) and schizophrenia was investigated in a Chinese Han population.
Methods: The polymorphism was studied in unrelated schizophrenia patients and unrelated healthy controls. Linkage relationships were explored in core families of the schizophrenic patients using the transmission disequilibrium test. The Positive and Negative Syndrome Scale was used to evaluate the severity of the disorder.
Results: The Del allele was significantly less frequently found in patients (13/120; 11%) than in controls (18/100; 18%). In the 32 core families studied, 16 parents were Ins/Del heterozygotes. Parents transmitted the Ins and Del alleles to their children in 10 and six cases, respectively. Data from core families did not demonstrate linkage. Age, age at onset of schizophrenia and sex were not significantly different between carriers of the Ins and Del alleles. The group with the Ins allele had a significantly higher positive symptom score (75.3 ± 23.4 versus 53.9 ± 21.9) and excitement score (83.6 ± 16.8 versus 50.3 ± 24.6) than the Del group. Groups did not differ significantly in negative symptom and general psychopathology scores.
Conclusions: The DRD2 -141C Ins/Del polymorphism may affect susceptibility to schizophrenia in a Chinese Han population.
Keywords: Positive and Negative Syndrome Scale; Schizophrenia; dopamine D2 receptor gene; polymorphism.