Objective: Individuals with schizophrenia and substance use disorders have a poor prognosis and increased psychiatric symptoms. The present study aimed to explore the association of 106 genes in individuals with schizophrenia and comorbid substance use through a next-generation sequencing (NGS) analysis and different in silico algorithms. Methods: We included 105 individuals diagnosed with schizophrenia and a family history of schizophrenia, of whom 49 (46.67%) presented comorbid substance use. Using NGS, we sequenced 106 genes previously associated with schizophrenia. Logistic regression models were used to assess differences in allele frequencies, and a generalized gene-set analysis was performed at the gene level. Functional annotations were performed using different algorithms and databases. Results: We identified a total of 3,109 variants, of which 25 were associated with schizophrenia and comorbid substance use and were located in regulatory and coding regions. We found low-frequency variants in COMT p.Ala72Ser, independently of p.Val158Met, that were associated with substance use. The endocannabinoid functional variant FAAH p.Pro129Thr was also associated with substance use. Conclusions: Genetic variants of genes related to dopaminergic and cannabinoid neurotransmitter systems were associated with comorbid substance use in schizophrenia. Nevertheless, more studies with larger sample sizes are needed to confirm our findings.

Abstract Introduction It has been hypothesized that pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS) etiology results from an abnormal immune response to streptococcal infection. There is evidence that the serotonergic system is involved in both obsessive-compulsive disorder (OCD) physiopathology and immunological processes. In the 5’ promoter region of 5-HTT, gene encoding for the serotonin transporter we can find the 5-HTTLPR polymorphism that has been associated with OCD. Being PANDAS a disorder with OCD symptoms and likely immune abnormalities, 5-HTT polymorphisms may be particularly relevant for this disorder. Objective This study aimed to test the association between the 5-HT genotypes and the presence of serum antibodies in patients with PANDAS. Method We compared the genotype frequencies and serum anti-streptococcal, anti-neural, and anti-enolase antibodies titers between 56 patients with PANDAS and 20 healthy controls from Mexico and Cuba. Results Antibody titers were higher (anti-enolase, anti-streptococcal) in PANDAS patients compared to healthy controls. No differences in anti-neural antibody levels between both groups were detected. The anti-enolase and anti-neural antibody titer increased according to the polymorphism of the PANDAS patients as follows: LL >SL >SS. Discussion and conclusion This is the first study evaluating the association between the 5-HTTLPR genotypes and antibody titers in PANDAS patients. Associations between polymorphisms in serotonergic genes and immune response could provide valuable information about the interaction between both systems. Our results suggest an association between the S allele and elevated antibody levels in PANDAS patients.

Resumen Introducción Se ha hipotetizado que el trastorno pediátrico neuropsiquiátrico autoinmune asociado a estreptococo (PANDAS) es resultado de una respuesta inmune anormal a una infección estreptocócica. Existe evidencia de que el sistema serotoninérgico está involucrado tanto en la fisiopatología del trastorno obsesivo compulsivo (TOC) como en procesos inmunológicos. En la región promotora de 5-HTT, gen que codifica el transportador de serotonina, podemos encontrar el polimorfismo 5-HTTLPR que se ha asociado con el TOC. Siendo PANDAS un trastorno con síntomas de TOC y probables anormalidades inmunes, los polimorfismos de 5-HTT pueden ser relevantes en este trastorno. Objetivo Evaluar la asociación entre los genotipos de 5-HT y la presencia de anticuerpos séricos en pacientes con PANDAS. Método Comparamos la frecuencia de genotipos de 5-HT y los títulos de anticuerpos anti-estreptococo, antineurales y antienolasa en suero de 56 pacientes con PANDAS y 20 controles sanos de México y Cuba. Resultados Los títulos de anticuerpos antienolasa y antiestreptococo fueron mayores en pacientes con PANDAS en comparación con los controles. El título de anticuerpos antienolasa y antineural aumentó de acuerdo con el polimorfismo de los pacientes con PANDAS de la siguiente manera: LL >SL >SS. Discusión y conclusión Éste es el primer estudio que evalúa la asociación entre los genotipos de 5-HTTLPR y anticuerpos en pacientes con PANDAS. Las asociaciones entre polimorfismos de genes serotoninérgicos y la respuesta inmune podrían proporcionar información sobre la interacción entre ambos sistemas. Nuestros resultados sugieren una asociación entre el alelo S y niveles altos de anticuerpos en pacientes con PANDAS.

Background Concurrence of substance use disorders (SUDs) is high in individuals with psychiatric illnesses; more importantly, individuals with both disorders (dual diagnosis) have more severe symptoms. Psychiatric disorders have been proposed to share a genetic susceptibility with SUDs. To explore this shared genetic susceptibility, we analyzed whether any of the polygenic risk scores (PRSs) for psychiatric disorders could be associated to dual diagnosis in patients with schizophrenia (SCZ) or bipolar disorder (BD). Methods We included 192 individuals of Mexican ancestry: 72 with SCZ, 53 with BD, and 67 unrelated controls without psychiatric disorders. We derived calculations of PRS for autism spectrum disorders, attention-deficit/hyperactive disorder, BD, major depression, and SCZ using summary genome-wide association statistics previously published. Results We found that dual diagnosis had a shared genetic susceptibility with major depressive disorder (MDD) and SCZ; furthermore, in individuals with BD, dual diagnosis could be predicted by PRS for MDD. Conclusions Our results reinforce the notion that individuals with dual diagnosis have a higher genetic susceptibility to develop both disorders. However, analyses of larger sample sizes are required to further clarify how to predict risks through PRS within different populations.

Abstract Background Schizophrenia (SCZ) and dementia, often related, are two of the most common neuropsychiatric diseases; epidemiological studies have shown that SCZ patients present a 2-fold increased risk for dementia compared to non-schizophrenic individuals. We explored the presence of rare and novel damaging gene variants in patients diagnosed with late-onset dementia of Alzheimer’s type (DAT) or SCZ. Methods We included 7 DAT and 12 SCZ patients and performed high-depth targeted sequencing of 184 genes. Results We found novel and rare damaging variants in 18 genes in these Mexican patients. Carriers of these variants showed extreme phenotypes, including, treatment-resistant SCZ or cognitive decline. Furthermore, we found a variation on ABCC1 as a possible link between psychosis and cognitive impairment. Discussion As an exploratory analysis, we report some interesting variations that should be corroborated in larger sample size studies.

Abstract: Introduction: The study of autistic spectrum disorders (ASD) at the genetic level is extremely important to understand their origin. In Mexico, there are few works addressed from this perspective. Objective: We investigated the role of the Brain Derived Neurotrophic Factor (BDNF) gene variant rs6265 G/A for single nucleotide polymorphism analysis in Mexican children with ASD using a case-control association design. Method: We made a pilot study by case-control analysis adjusting by gender, age, and ancestry. Results: Our study found no association between the BDNF rs6265 gene polymorphism and ASD [p = .419, OR = 1.597 (.514, 4.967)] Discussion and conclusion: Worldwide, the results of case-control association studies with the rs6265 of BDNF are controversial and do not always replicate. This may be due to the ethnicity of our population and additional factors not studied in the present work. Our study suggests that the SNP rs6265 is not contributing for ASD susceptibility in Mexican population.

Resumen: Introducción: El estudio de los trastornos del espectro autista a nivel genético es de suma importancia para entender su origen. En México existen pocos trabajos abordados desde esta perspectiva. Objetivo: Investigamos el papel de la variante del gen rs6265 G/A del factor neurotrófico derivado del cerebro (BDNF) para el análisis del polimorfismo de un solo nucleótido en niños mexicanos con TEA por medio de un diseño de asociación de casos y controles. Método: Realizamos un estudio piloto mediante un análisis de casos y controles ajustando por género, edad y ancestría. Resultados: Nuestro estudio no encontró asociación entre el polimorfismo del gen BDNF rs6265 y TEA [p = .419, OR = 1.597 (.514, 4.967)]. Discusión y conclusión: A nivel mundial, los resultados de estudios de asociación caso-control con el rs6265 de BDNF son controvertidos y no siempre se replican. Esto puede deberse a la etnicidad de nuestra población y a otros factores no estudiados en el presente trabajo. El estudio sugiere que el SNP rs6265 no contribuye a la susceptibilidad al TEA en población mexicana.