Differential DNA Methylation from Autistic Children Enriches Evidence for Genes Associated with ASD and New Candidate Genes.

The etiology of Autism Spectrum Disorders (ASD) is a result of the interaction between genes and the environment. The study of epigenetic factors that affect gene expression, such as DNA methylation, has become an important area of research in ASD. In recent years, there has been an increasing body of evidence pointing to epigenetic mechanisms that influence brain development, as in the case of ASD, when gene methylation dysregulation is present. Our analysis revealed 853 differentially methylated CpG in ASD patients, affecting 509 genes across the genome. Enrichment analysis showed five related diseases, including autistic disorder and mental disorders, which are particularly significant. In this work, we identified 64 genes that were previously reported in the SFARI gene database, classified according to their impact index. Additionally, we identified new genes that have not been previously reported as candidates with differences in the methylation patterns of Mexican children with ASD.

FOXP2 expression and gray matter density in the male brains of patients with schizophrenia.

Common genetic variants of FOXP2 may contribute to schizophrenia vulnerability, but controversial results have been reported for this proposal. Here we evaluated the potential impact of the common FOXP2 rs2396753 polymorphism in schizophrenia. It was previously reported to be part of a risk haplotype for this disease and to have significant effects on gray matter concentration in the patients. We undertook the first examination into whether rs2396753 affects the brain expression of FOXP2 and a replication study of earlier neuroimaging findings of the influence of this genetic variant on brain structure. FOXP2 expression levels were measured in postmortem prefrontal cortex samples of 84 male subjects (48 patients and 36 controls) from the CIBERSAM Brain and the Stanley Foundation Array Collections. High-resolution anatomical magnetic resonance imaging was performed on 79 male subjects (61 patients, 18 controls) using optimized voxel-based morphometry. We found differences in FOXP2 expression and brain morphometry depending on the rs2396753, relating low FOXP2 mRNA levels with reduction of gray matter density. We detected an interaction between rs2396753 and the clinical groups, showing that heterozygous patients for this polymorphism have gray matter density decrease and low FOXP2 expression comparing with the heterozygous controls. This study shows the importance of independent replication of neuroimaging genetic studies of FOXP2 as a candidate gene in schizophrenia. Furthermore, our results suggest that the FOXP2 rs2396753 affects mRNA levels, thus providing new knowledge about its significance as a potential susceptibility polymorphism in schizophrenia.

FOXP2 and language alterations in psychiatric pathology / FOXP2 and language alterations in psychiatric pathology

Abstract Background From the first reports of the linguist Noam Chomsky it has become clear that the development of language has an important genetic component. Several reports in families have shown the relationship between language disorders and genetic polymorphisms. The FOXP2 gene has been a fundamental piece for the understanding of language development. This gene codes for a transcription factor containing a forkhead domain of DNA binding and participates in the regulation of the expression of a large number of genes involved in the embryonic development of fundamental neuronal structures needed for the development of speech and language. Objective To present an updated view of the relationship between FOXP2 and language alterations in psychiatric pathology. Method Narrative review of information reported in databases on the recent advances supporting genetic participation in language disorders of psychiatric illness. Results Update of content related to FOXP2 and its participation in language alterations in psychiatric diseases. Discussion and conclusion Advances in the genetic study of language disorders in psychiatric pathology open up new avenues of investigation that allow us to explore how language emerged and how it evolved, as well as to carry out comparative studies on the structure and functioning of genes to approach the understanding of this complex characteristic that makes us human.

Resumen Antecedentes Desde los primeros reportes del lingüista Noam Chomsky ha quedado claro que el desarrollo del lenguaje tiene un importante componente genético. Diversos reportes en familias han mostrado la relación entre los trastornos del lenguaje y ciertos marcadores genéticos. El gen FOXP2 ha sido una pieza fundamental para entender el desarrollo del lenguaje. Se trata de un gen que codifica para un factor de transcripción con un dominio forkhead de unión al DNA y que participa en la regulación de la expresión de un gran número de genes durante el desarrollo embrionario de estructuras neuronales fundamentales para el desarrollo del habla y el lenguaje. Objetivo Presentar un panorama actualizado de la relación del gen FOXP2 en las alteraciones del lenguaje en la patología psiquiátrica. Método Revisión narrativa de la información reportada en diversas bases de datos sobre los recientes avances que soportan la participación genética en las alteraciones del lenguaje presentes en enfermedades psiquiátricas. Resultados Actualización del contenido relacionado con el gen FOXP2 y su participación en las alteraciones del lenguaje en las enfermedades psiquiátricas. Discusión y conclusión Los avances en el estudio genético de las alteraciones del lenguaje en la patología psiquiátrica abren nuevos caminos de investigación que permiten explorar cómo surgió y cómo ha evolucionado el lenguaje, así como para llevar a cabo estudios comparativos sobre la estructura y el funcionamiento de genes para aproximarse al entendimiento de esta compleja característica que nos hace humanos.

No association of HLA-DRB1 and TNF alleles in Mexican patients with autoimmune hepatitis.

HLA-DRB1 alleles has been found implicated in susceptibility to autoimmune hepatitis (AIH) in populations from different genetic backgrounds. In Mexicans, HLA-DRB1*04:04 is recognized as a risk allele for AIH but, to date, there is no high-resolution data supporting this association. Also, the association of other nonclassical HLA genes, such as TNF-LTA locus, have not, to our knowledge, been evaluated in this population. The association of HLA-DRB1 alleles determined by sequence-based typing and two polymorphisms in the TNF locus with AIH in a sample of Mexican patients was evaluated. Fifty-six patients from Guadalajara, Mexico, diagnosed with AIH and 115 age-gender matched healthy volunteer blood donors, were genotyped for HLA-DRB1 by the sequencing exon 2 and for TNFA-308G>A and LTA + 252A>G polymorphisms. Increased frequencies of both HLA-DRB1*04:04:01 and *16:02:01:01 alleles (OR = 2.91; 95% CI = 1.08-7.84) and the haplotype (DRB1-TNFA-LTA) *04:04:01-G-A (OR = 5.33; 95% CI = 1.32-21.49) were observed in AIH patients. However, after corrections for multiple comparisons, associations were not significant. In conclusion, our study does not support the association of HLA-DRB1*04:04:01 with the susceptibility to AIH in Mexican population. More studies including patients from other Mexican regions and considering other genetic, immunological, and environmental factors should be performed.

Behavioral addictions in early-onset Parkinson disease are associated with DRD3 variants.

BACKGROUND: Impulse control disorders (ICDs) comprise abnormal behaviors frequently found in patients with Parkinson's disease (PD) receiving antiparkinsonian medication. ICDs in PD would develop when dopaminergic treatment overstimulates the dopamine receptor D3 (DR3). Here we studied whether DR3 gene (DRD3) is associated to ICD in PD patients with early-onset (EOPD). METHODS: We performed association analysis of the rs6280 DRD3 single nucleotide variation (SNV) (Ser9Gly) in a clinical sample of 126 non early-onset PD (NEOPD) and 73 EOPD (age at onset < 45). ICD was evaluated using the Questionnaire for Impulsive-Compulsive Disorders (QUIP) in PD. RESULTS: In the total sample, we found that a younger onset of PD is linked to ICD traits with a potentially addictive reinforcement (ICDARs, behavioral addictions) (p = .017) and a trend for total ICDs (p = .078) while punding was not associated (p = .75). EOPD sample showed an increase of DRD3 C+ genotype for ICD (p = .022) and ICDARs (p = .043) but not for punding (p = .170). The post-hoc analyses including the time of evolution and Pramipexol or Ropinirole treatments, confirmed the independent effect of the DRD3 upon ICDs (p = .028) and ICDARs (p = .041) as well as the interaction between DRD3 and Pramipexol treatment upon ICDARs (OR = 4.60, 95% CI 1.20-17.632, p = .026). The NEOPD group showed no association between DRD3 and ICDs. CONCLUSIONS: We found that behavioral addictions in PD are associated with an early onset of the disease, the rs6280 DRD3 SNV and the type of dopamine agonist. Further investigation in independent samples is warranted.

Analysis of cytokine gene polymorphisms in Mestizo and native populations from Mexico.

OBJECTIVES: To determine whether the well-known genetic structure of the Mexican population observed with other multiallelic markers can be detected by analyzing functional polymorphisms of cytokine and other inflammatory-response-related genes. METHODS: A total of 834 Mestizo individuals from five Mexican cities and 92 Lacandonians - an Amerindian group from southeastern Mexico - were genotyped for 14 polymorphisms in the CRP, IL10, IL6, TGFB1, TNFA, LTA, ICAM1 IFNG, and IL1RN genes. Allele and haplotype frequencies were used for genetic structure analysis using F-statistics pairwise distances and multidimensional scaling plot. Ancestry analysis was performed, as well. RESULTS: Significant interpopulational differences at the allele and haplotype frequency level were observed, mainly between Northern (Guadalajara, Monterrey, and Culiacan) and Southern (Tierra Blanca and Puebla) Mexican populations. Also, low but significant substructure was detected between some populations from these two broad regions. Interestingly, both Lacandonian populations were highly differentiated from each other and with respect to Mestizos. Consistent with previous data, Amerindian ancestry in the Southern Mexican groups was higher compared to Northern ones. CONCLUSIONS: The Mexican population exhibits regional differences in functional polymorphisms of inflammatory-response genes, as observed for other genetic markers. This information constitutes a reference for epidemiological studies that include these genetic markers to assess the susceptibility of the Mexican population to several immune-response-related diseases, such as diabetes, obesity, and renal disease, which have been shown to be common in the Mexican population but with prevalence differences within this country.

CYP2C9 and CYP2C19 Allele and Haplotype Distributions in Four Mestizo Populations from Western Mexico: An Interethnic Comparative Study.

AIMS: Polymorphisms in the CYP2C9 and CYP2C19 genes confer potential risk for specific adverse drug reactions and therapeutic effect failure. Their frequencies differ among ethnic groups. This study was aimed to describe the distribution of CYP2C9 and CYP2C19 alleles and haplotypes in four Mestizo populations from Western Mexico and their comparison with the reported data from other ethnic groups. METHODS: The CYP2C alleles (CYP2C9*2, CYP2C9*3, CYP2C19*2, and CYP2C19*3) were genotyped using polymerase chain reaction-restriction fragment length polymorphisms analyses using DNA samples from 477 healthy Mestizo individuals of Colima (n = 100), Jalisco (n = 147), Michoacán (n = 117), and Nayarit (n = 113). RESULTS: Frequencies ranged from 2.2-3.0% and 4.8-8.9% for CYP2C9*3 and CYP2C9*2 alleles, respectively, and 5.4-12.0% for CYP2C19*2, whereas the CYP2C19*3 allele was not found. Haplotype GACA, which harbors the loss-of-function allele CYP2C19*2, was the second most frequent (8.7%). Genetic heterogeneity between the Western Mexican populations studied here and the global population was evident (p < 0.05), except for most American populations and other Mexican Mestizo populations. CONCLUSION: Our findings increase the evidence for genetic variability at relevant pharmacogenetic loci and could be useful in association studies involving drugs that are substrates for CYP2C enzymes in the Western Mexican population.