Molecular Genetic Studies of Early-Onset Schizophrenia

Early-onset schizophrenia is characterized by a more severe course and unfavorable outcome. We report here our studies of a number of genes which may be involved in the pathogenesis of this type of schizophrenia: the genes for brain-derived neurotrophic factor (the Val66Met polymorphism), the serotonin transporter (5-HTTLPR), the type 2A serotonin receptor (T102C), and the D2 dopamine receptor (Taq1A). The study group consisted of 65 patients (age at onset was less than 15 years). The control group consisted of 111 healthy subjects aged 6–26 years (mean age 18.9 ± 6.7 years). Among the genes studied, the only one found to be associated with the disease was the Val66Met polymorphism. The frequency of the ValVal genotype was higher in the group of patients with schizophrenia (p = 0.03; odds ratio 2.1, confidence interval 1.1–4.0). These results support our previous observation of a relationship between this genotype and the continuous form of schizophrenia identified in studies of an independent group of patients without evaluation of age at onset, and lead to the conclusion that the ValVal genotype can be regarded as a marker for the more severe form of schizophrenia.