Towards disentangling the genetic complexity and clinical heterogeneity of psychotic disorders: from family-based approaches to gene-environment studies
- Autores: Jordi Soler Garcia
- Directores de la Tesis: María del Mar Mestre (dir. tes.), Lourdes Fañanás Saura (codir. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2021
- Idioma: inglés
- Tribunal Calificador de la Tesis: Sergi Mas Herrero (presid.), Norma Verdolini (secret.), Rosa Ayesa Arriola (voc.)
- Programa de doctorado: Programa de Doctorado en Biomedicina por la Universidad de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
Psychotic disorders are psychiatric conditions with a worldwide prevalence of around 4% and a tremendous personal, economic and social burden. As complex phenotypes, psychotic disorders are caused by multiple genetic variants, environmental factors and their interaction. According to this, a better understanding of the genetic and environmental influences underlying these disorders may provide a way to dissect the biology of psychosis and, ultimately, allow developing novel therapies. However, the study of the aetiological basis of schizophrenia and other psychotic disorders, though, has a serious limitation in the high biological heterogeneity underlying these pathologies. The heterogeneity of clinical profiles and the high phenotypic variability, in turn, causes uncertainty on the genetic results related to these disorders. Thus, the reduction of phenotypic complexity has become an essential step to contribute to the genetic dissection of brain complex phenotypes. The present dissertation aimed to contribute disentangling the heterogeneity of psychotic disorders by means of different approaches: the use of family-based studies, the use of psychosis-associated intermediate phenotypes and the use of gene-environment interaction studies. Three specific hypotheses related to these approaches have been tested, giving rise to six manuscripts submitted to international peer reviewed journals. The results of the present thesis reveal that the combined use of family-based designs and intermediate phenotypes related to psychosis may facilitate the identification of more homogeneous forms of psychotic disorders in terms of genetic aetiology. Thus, by means of this strategy, two different subclinical phenotypes such as schizotypy (a set of personality traits) and the cognitive dimension of attention and working memory have been identified as familial vulnerability markers for psychosis in samples of families affected with schizophrenia and bipolar disorder, respectively. The study of the familial aggregation pattern of these phenotypes have lead to the identification of subgroups of families with similar phenotypic –and, therefore also genotypic– profiles. Moreover, by using family-based association designs, different genes involved in the modulation of synaptic plasticity (DAOA, ZNF804A, AKT1) have been associated with the risk for psychosis, as measured with the expression of intermediate phenotypes, including schizotypy and cognitive performance. Also, results from this thesis provide evidence of the role genetic variability on cognitive performance and also as a modulator of the effect of cannabis use on the variance of other intermediate phenotypes. Particularly, it has been revealed the effect of AKT1 gene on attentional processes and, also, the effect of ZNF804A gene on the expression of schizotypy conditional to the cannabis use. Despite the last advances in the comprehension of the aetiology of psychosis, the identification of the involved genetic factors has still a long way to go. Thus, it is necessary to continue making efforts towards understanding the aetiopathogenic basis of psychotic disorders, taking into account both genetic and environmental factors. The present dissertation has intended to provide our grain of sand to the collective construction of knowledge on the aetiology of psychosis by means of using different strategies that have proven to contribute to elucidating the heterogeneity underlying these disorders, which in turn might lead to an improvement of the identification of the underlying causal genetic variants
