[Lack of association between the insertion/deletion polymorphism in serotonin transporter gene, T102C polymorphism of the 5HT2A receptor gene and schizophrenia--family based study].

Aim: The aim of the study was to estimate the transmission of two candidate genes' alleles (according to the serotonergic hypothesis of schizophrenia) by parents to their children with schizophrenia. The genes under investigation were the following: 5HTR2A (polymorphism T102C) and SLC6A4 (polymorphism 5-HTTLPR).
Method: There were 116 families in the group under investigation (patient and his/her both parents). Due to the missing genotypes or unlikely inheritance (other biological parent or genotyping error) the number of analysed trios differs for particular polymorphisms (these trios were not excluded from the study, however they were not analysed in the case of a given polymorphism). The patients and their parents were examined using the SCID (Structured Clinical Interview for DSM-IV Axis I Disorders). No mental disorders were found with all the patients' parents. The DNA was extracted from the peripheral blood leukocytes by the salting out method. The polymorphisms were studied by the PCR method (PCR-RFLP method for: 5HTR2A and PCR-VNTR method for: SLC6A4). The statistical analysis of the frequency of transmission of alleles was carried out by the TDT (Transmission Disequilibrium Test) method. To analyse the transmission disequilibrium of alleles under examination, the Haploview v. 3.2. programme was used.
Results: According to the results obtained, no association between the analysed polymorphism of genes: 5HTR2A (T102C), SLC6A4 (5-HTTLPR) and schizophrenia was found.
Conclusions: Thus it seems advisable to carry out further examinations of the role of these polymorphisms in schizophrenia by means of TDT method and the classical association method.