Aim. A functional polymorphism (5-HTTLPR: 5-hydroxytlyptamine transporter linked polymorphic region) in the promoter region of the serotonin transporter gene (SLC6A4) has been associated with a number of psychiatric disturbances. To our knowledge, the involvement of this polymorphism in the pathogenesis of schizophrenia has not been reported. The aim of the present study was to investigate the possibility that the 5-HTTLPR polymorphism might be associated with the psychopathology of schizophrenia.
Methods. We studied the functional polymorphism in the 5'flanking regulatory (promoter) region of the gene (SLC6A4) coding for the serotonin transporter protein in 242 patients with schizophrenia (according to the DSM-IV and ICD-10 criteria) and 192 control subjects. Patients were evaluated for psychotic symptomatology using the PANSS scale and typed for 5-HTTLPR variants using PCR techniques.
Results. 5-HTTLPR allele frequencies were not significantly different between controls and schizophrenics; genotype analysis also did not show any association. However in homozygotic patients the s allele of the 5-HTTLPR was associated with a decreased intensity of psychopathological symptoms measured by the PANSS scale. Similarly, in homozygotic schizophrenic women the s allele of the 5-HTTLPR contributed to the benignity of the disease.
Conclusions. A functional polymorphism in the promoter region of the serotonin transporter is not a risk factor for the development of schizophrenia. The s allele of 5-HTTLPR in homozygotic schizophrenic women is associated with a reduced psychotic symptomatology.