Abstract
BackgroundThe clinical course of schizophrenia varies among patients and is difficult to predict. Some patient populations present persistent negative symptoms, referred to as the deficit syndrome. Compared to relatives of non-deficit schizophrenia patients, family members of this patient population are at an increased risk of developing schizophrenia. Therefore, the aim of this study was to search for genetic underpinnings of the deficit syndrome in schizophrenia.MethodsThree SNPs, i.e., rs1799732 and rs6276 located within DRD2, and rs1800497 within ANKK1, were identified in the DNA samples of 198 schizophrenia probands, including 103 patients with deficit (DS) and 95 patients with non-deficit schizophrenia (NDS). Results: No significant differences concerning any of the analyzed polymorphisms were found between DS and NDS patients. However, significant links were observed between family history of schizophrenia and the deficit syndrome, G/G genotype and rs6276 G allele. In a separate analysis, we identified significant differences in frequencies of rs6276 G allele between DS and NDS patients with family history of schizophrenia. No significant associations were found between DRD2 and ANKK1 SNPs and the age of onset or schizophrenia symptom severity.ConclusionsThe results of our preliminary study fail to provide evidence of associations between DRD2 and ANKK1 polymorphisms with the deficit syndrome or schizophrenia symptom severity, but suggest potential links between rs6276 in DRD2 and the deficit syndrome in patients with hereditary susceptibility to schizophrenia. However, further studies are necessary to confirm this observation.
Highlights
The clinical course of schizophrenia varies among patients and is difficult to predict
Given that most antipsychotic drugs act as Dopamine D2 receptor (DRD2) antagonists, and the results of meta-analyses remain inconclusive [29, 36, 95,96,97,98], about 35% of case–control studies suggest that at least one Single nucleo‐ tide polymorphism (SNP) in DRD2 is significantly associated with schizophrenia [99], we assumed that its biological underpinnings are complex and that the differences in clinical phenotype may, at least in part, result from polymorphisms in DRD2 gene
It was demonstrated that the family members of Patients with deficit schizophrenia (DS) patients have a 1.75 times greater risk of schizophrenia compared to family members of non-deficit schizophrenia (NDS) patients, and that the presence of DS in the family increases the risk of the deficit syndrome in schizophrenia patients [11, 100, 101]
Summary
The clinical course of schizophrenia varies among patients and is difficult to predict. Some patient populations present persistent negative symptoms, referred to as the deficit syndrome. The aim of this study was to search for genetic underpinnings of the deficit syndrome in schizophrenia. None of the available classifications of diseases include the term “deficit schizophrenia”, the ICD-11 and DSM-5 identify schizophrenia with dominant negative symptoms [5, 6]. The deficit syndrome is linked with a stable progression of negative symptoms, observed from illness onset throughout the course of the disease [7,8,9,10], and its incidence in patients with chronic schizophrenia is estimated at 25–30% [11]. Associations with family history were found for the deficit syndrome [11]
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