Immune Checkpoint Inhibitors in "Special" NSCLC Populations: A Viable Approach?

Over the last decade, the therapeutic scenario for advanced non-small-cell lung cancer (NSCLC) has undergone a major paradigm shift. Immune checkpoint inhibitors (ICIs) have shown a meaningful clinical and survival improvement in different settings of the disease. However, the real benefit of this therapeutic approach remains controversial in selected NSCLC subsets, such as those of the elderly with active brain metastases or oncogene-addicted mutations. This is mainly due to the exclusion or underrepresentation of these patient subpopulations in most pivotal phase III studies; this precludes the generalization of ICI efficacy in this context. Moreover, no predictive biomarkers of ICI response exist that can help with patient selection for this therapeutic approach. Here, we critically summarize the current state of ICI efficacy in the most common "special" NSCLC subpopulations.

Investigating an in silico approach for prioritizing antidepressant drug prescription based on drug-induced expression profiles and predicted gene expression.

In clinical practice, an antidepressant prescription is a trial and error approach, which is time consuming and discomforting for patients. This study investigated an in silico approach for ranking antidepressants based on their hypothetical likelihood of efficacy. We predicted the transcriptomic profile of citalopram remitters by performing an in silico transcriptomic-wide association study on STAR*D GWAS data (N = 1163). The transcriptional profile of remitters was compared with 21 antidepressant-induced gene expression profiles in five human cell lines available in the connectivity-map database. Spearman correlation, Pearson correlation, and the Kolmogorov-Smirnov test were used to determine the similarity between antidepressant-induced profiles and remitter profiles, subsequently calculating the average rank of antidepressants across the three methods and a p value for each rank by using a permutation procedure. The drugs with the top ranks were those having a high positive correlation with the expression profiles of remitters and that may have higher chances of efficacy in the tested patients. In MCF7 (breast cancer cell line), escitalopram had the highest average rank, with an average rank higher than expected by chance (p = 0.0014). In A375 (human melanoma) and PC3 (prostate cancer) cell lines, escitalopram and citalopram emerged as the second-highest ranked antidepressants, respectively (p = 0.0310 and 0.0276, respectively). In HA1E (kidney) and HT29 (colon cancer) cell types, citalopram and escitalopram did not fall among top antidepressants. The correlation between citalopram remitters' and (es)citalopram-induced expression profiles in three cell lines suggests that our approach may be useful and with future improvements, it can be applicable at the individual level to tailor treatment prescription.

Whole Blood Transcriptome Characterization of 3xTg-AD Mouse and Its Modulation by Transcranial Direct Current Stimulation (tDCS).

The 3xTg-AD mouse is a widely used model in the study of Alzheimer's Disease (AD). It has been extensively characterized from both the anatomical and behavioral point of view, but poorly studied at the transcriptomic level. For the first time, we characterize the whole blood transcriptome of the 3xTg-AD mouse at three and six months of age and evaluate how its gene expression is modulated by transcranial direct current stimulation (tDCS). RNA-seq analysis revealed 183 differentially expressed genes (DEGs) that represent a direct signature of the genetic background of the mouse. Moreover, in the 6-month-old 3xTg-AD mice, we observed a high number of DEGs that could represent good peripheral biomarkers of AD symptomatology onset. Finally, tDCS was associated with gene expression changes in the 3xTg-AD, but not in the control mice. In conclusion, this study provides an in-depth molecular characterization of the 3xTg-AD mouse and suggests that blood gene expression can be used to identify new biomarkers of AD progression and treatment effects.

Genetic determinants of circulating VEGF levels in major depressive disorder and electroconvulsive therapy response.

Alterations in peripheral vascular endothelial growth factor (VEGF) levels were observed in major depressive disorder and relative treatments and were shown to be influenced by genetic variants. The study objective was to explore, at a genome-wide level, possible interplaying effects between the genetic background and major depressive disorder in regulating VEGF levels. Moreover, we aimed to investigate the association between these variants and response to electroconvulsive therapy. A genome-wide association study was carried out both on controls and patients with major depressive disorder (n = 145; n = 121) in correlation with serum VEGF levels determined by ELISA. Five SNPs not included in SNP arrays were additionally genotyped. Seventy-one patients with treatment-resistant depression underwent electroconvulsive therapy and were evaluated as responders/nonresponders. An association between VEGF levels and a locus in 6p21.1, downstream the VEGF gene, was evidenced both in controls (best SNP: FDR-corrected p = 2.4 × 10-5 ) and in patients with major depressive disorder (best SNP: FDR-corrected p = 2.6 × 10-3 ). The alleles associated with lower VEGF concentrations in patients were also associated with nonresponse to electroconvulsive therapy (p = .01). These results confirm a role of SNPs in 6p21.1 locus as major influencers of circulating VEGF levels also in patients affected by major depressive disorder and indicate a possible implication in response to electroconvulsive therapy.

Association study between HTR2A rs6313 polymorphism and early response to risperidone and olanzapine in schizophrenia patients.

Antipsychotic drugs are the preferred choice for schizophrenia treatment; however, response is highly variable. In the context of the search for predictors of antipsychotic treatment effectiveness, the evaluation of response within 2 weeks has been indicated to predict long-term outcome. Moreover, a focus on symptomatological domains could be helpful to better characterize antipsychotic response, identifying more specific predictors. Pharmacogenetic studies have indicated a role for rs6313 in the serotonin receptor gene HTR2A in affecting response to antipsychotics, with heterogeneous results. With the aim to test for the first time the application of a dimensional approach for the evaluation of early response, we carried out a genetic association study between rs6313 and antipsychotic response in two groups of schizophrenia patients in monotherapy with risperidone (n = 121) and olanzapine (n = 100). Patients were evaluated at the baseline and after 1 and 2 weeks of treatment. When comparing early responders versus early nonresponders, no association was detected for the two drugs separately, whereas by taking into consideration the two drugs together it was observed that carriers of the T allele had a higher response probability compared to noncarriers. Considering 2-week improvements, changes in PANSS total scores, subscores and in PANSS Emsley's symptomatological dimensions were associated with rs6313 for both risperidone and olanzapine. Moreover, the repeated measures analysis indicated an association of rs6313 with the disorganized thought dimension for risperidone, and with the depressive and anxiety dimensions for olanzapine. These data add support to the hypothesis that the HTR2A gene is involved in antipsychotic treatment outcome.

Genome-wide analysis of consistently RNA edited sites in human blood reveals interactions with mRNA processing genes and suggests correlations with cell types and biological variables.

BACKGROUND: A-to-I RNA editing is a co-/post-transcriptional modification catalyzed by ADAR enzymes, that deaminates Adenosines (A) into Inosines (I). Most of known editing events are located within inverted ALU repeats, but they also occur in coding sequences and may alter the function of encoded proteins. RNA editing contributes to generate transcriptomic diversity and it is found altered in cancer, autoimmune and neurological disorders. Emerging evidences indicate that editing process could be influenced by genetic variations, biological and environmental variables. RESULTS: We analyzed RNA editing levels in human blood using RNA-seq data from 459 healthy individuals and identified 2079 sites consistently edited in this tissue. As expected, analysis of gene expression revealed that ADAR is the major contributor to editing on these sites, explaining ~ 13% of observed variability. After removing ADAR effect, we found significant associations for 1122 genes, mainly involved in RNA processing. These genes were significantly enriched in genes encoding proteins interacting with ADARs, including 276 potential ADARs interactors and 9 ADARs direct partners. In addition, our analysis revealed several factors potentially influencing RNA editing in blood, including cell composition, age, Body Mass Index, smoke and alcohol consumption. Finally, we identified genetic loci associated with editing levels, including known ADAR eQTLs and a small region on chromosome 7, containing LOC730338, a lincRNA gene that appears to modulate ADARs mRNA expression. CONCLUSIONS: Our data provides a detailed picture of the most relevant RNA editing events and their variability in human blood, giving interesting insights on potential mechanisms behind this post-transcriptional modification and its regulation in this tissue.

SNP array and FISH analysis of a proband with a 22q13.2- 22qter duplication shed light on the molecular origin of the rearrangement.

BACKGROUND: In about one third of healthy subjects, the microscopic analysis of chromosomes reveals heteromorphisms with no clinical implications: for example changes in size of the short arm of acrocentric chromosomes. In patients with a pathological phenotype, however, a large acrocentric short arm can mask a genomic imbalance and should be investigated in more detail. We report the first case of a chromosome 22 with a large acrocentric short arm masking a partial trisomy of the distal long arm, characterized by SNP array. We suggest a possible molecular mechanism underlying the rearrangement. CASE PRESENTATION: We report the case of a 15-year-old dysmorphic girl with low grade psychomotor retardation characterized by a karyotype with a large acrocentric short arm of one chromosome 22. Cytogenetic analysis revealed a normal karyotype with a very intense Q-fluorescent and large satellite on the chromosome 22 short arm. Fluorescence in situ hybridisation analysis showed a de novo partial trisomy of the 22q13.2-qter chromosome region attached to the short arm of chromosome 22. SNP-array analysis showed that the duplication was 8.5 Mb long and originated from the paternal chromosome. Haplotype analysis revealed that the two paternal copies of the distal part of chromosome 22 have the same haplotype and, therefore, both originated from the same paternal chromosome 22. A possible molecular mechanism that could explain this scenario is a break-induced replication (BIR) which is involved in non-reciprocal translocation events. CONCLUSION: The combined use of FISH and SNP arrays was crucial for a better understanding of the molecular mechanism underlying this rearrangement. This strategy could be applied for a better understanding of the molecular mechanisms underlying cryptic chromosomal rearrangements.

A miR-137-Related Biological Pathway of Risk for Schizophrenia Is Associated With Human Brain Emotion Processing.

BACKGROUND: miR-137 is a microRNA involved in brain development, regulating neurogenesis and neuronal maturation. Genome-wide association studies have implicated miR-137 in schizophrenia risk but do not explain its involvement in brain function and underlying biology. Polygenic risk for schizophrenia mediated by miR-137 targets is associated with working memory, although other evidence points to emotion processing. We characterized the functional brain correlates of miR-137 target genes associated with schizophrenia while disentangling previously reported associations of miR-137 targets with working memory and emotion processing. METHODS: Using RNA sequencing data from postmortem prefrontal cortex (N = 522), we identified a coexpression gene set enriched for miR-137 targets and schizophrenia risk genes. We validated the relationship of this set to miR-137 in vitro by manipulating miR-137 expression in neuroblastoma cells. We translated this gene set into polygenic scores of coexpression prediction and associated them with functional magnetic resonance imaging activation in healthy volunteers (n1 = 214; n2 = 136; n3 = 2075; n4 = 1800) and with short-term treatment response in patients with schizophrenia (N = 427). RESULTS: In 4652 human participants, we found that 1) schizophrenia risk genes were coexpressed in a biologically validated set enriched for miR-137 targets; 2) increased expression of miR-137 target risk genes was mediated by low prefrontal miR-137 expression; 3) alleles that predict greater gene set coexpression were associated with greater prefrontal activation during emotion processing in 3 independent healthy cohorts (n1, n2, n3) in interaction with age (n4); and 4) these alleles predicted less improvement in negative symptoms following antipsychotic treatment in patients with schizophrenia. CONCLUSIONS: The functional translation of miR-137 target gene expression linked with schizophrenia involves the neural substrates of emotion processing.

Role of allelic variants of FK506-binding protein 51 (FKBP5) gene in the development of anxiety disorders.

BACKGROUND: Anxiety disorders exhibit remarkably high rates of comorbidity with major depressive disorder (MDD). Mood and anxiety disorders are considered stress-related diseases. Genetic variations in the co-chaperone FK506-binding protein 51, FKBP5, which modulates the function of glucocorticoid receptors, have been associated with an increased risk for the development of posttraumatic stress disorder, but data regarding its role in MDD are controversial. The aims of this study were to clarify the role of the FKBP5 gene in depression and anxiety disorders through a case-control study and an association study with personality traits using the Temperament and Character Inventory (TCI) in healthy subjects. METHODS: Six hundred fifty-seven MDD patients, with or without an anxiety disorder in comorbidity, and 462 healthy volunteers were enrolled in the study. Two hundred fifty-six controls agreed to fill out the TCI. RESULTS: The results showed that the T allele of rs1360780 was more frequent among the patients affected by MDD with a comorbidity of anxiety disorders, compared to those without (P < .001). Among the controls, we found that the T allele more often exhibited personality traits associated with an increased vulnerability to anxiety. CONCLUSIONS: These results support the hypothesis that allelic variants of FKBP5 are a risk factor for anxiety disorders. The identification of genetic variants involved in anxiety may have implications for the optimization of therapeutic interventions.

LRRK2 Kinase Inhibition Attenuates Astrocytic Activation in Response to Amyloid ß1-42 Fibrils.

Intracerebral accumulation of amyloid-ß in the extracellular plaques of Alzheimer's disease (AD) brains represents the main cause of reactive astrogliosis and neuroinflammatory response. Of relevance, leucine-rich repeat kinase 2 (LRRK2), a kinase linked to genetic and sporadic Parkinson's disease (PD), has been identified as a positive mediator of neuroinflammation upon different inflammatory stimuli, however its pathogenicity in AD remains mainly unexplored. In this study, by using pharmacological inhibition of LRRK2 and murine primary astrocytes, we explored whether LRRK2 regulates astrocytic activation in response to amyloid-ß1-42 (Aß1-42). Our results showed that murine primary astrocytes become reactive and recruit serine 935 phosphorylated LRRK2 upon Aß1-42 fibril exposure. Moreover, we found that pharmacological inhibition of LRRK2, with two different kinase inhibitors, can attenuate Aß1-42-mediated inflammation and favor the clearance of Aß1-42 fibrils in astrocytes. Overall, our findings report that LRRK2 kinase activity modulates astrocytic reactivity and functions in the presence of Aß1-42 deposits and indicate that PD-linked LRRK2 might contribute to AD-related neuroinflammation and pathogenesis.

Genome-wide association studies of response and side effects to the BNT162b2 vaccine in Italian healthcare workers: Increased antibody levels and side effects in carriers of the HLA-A*03:01 allele.

The remarkable variability of response to vaccines against SARS-CoV-2 is apparent. The present study aims to estimate the extent to which the host genetic background contributes to this variability in terms of immune response and side effects following the administration of the BNT162b2 vaccine. We carried out a genome wide association study (GWAS) by genotyping 873 Italian healthcare workers who underwent anti-SARS-CoV-2 vaccination with the BNT162b2 vaccine and for whom information about anti-SARS-CoV-2 spike antibodies titers and vaccine side effects were available. The GWAS revealed a significant association between the HLA locus and the anti-SARS-CoV-2 Spike antibodies level at 2 months following the first dose of vaccine (SNP: rs1737060; p = 9.80 × 10-11 ). In particular, we observed a positive association between the antibody levels and the presence of the HLA-A*03:01 allele. The same allele was found associated with a 2-2.4-fold increased risk of experiencing specific side effects such as fever, chills and myalgia and a 1.5-1.8-fold increased risk of joint pain, nausea, fatigue, headache and asthenia, independently of age and sex. This study confirms that the heterogeneity in the immune response to the BNT162b2 vaccine and in its side effects are at least partially influenced by genetic variants. This information, integrated with individual biological and lifestyle-related correlates, could be of use in the definition of algorithms aimed at the identification of subjects in which the administration of additional vaccine doses would be particularly beneficial to maintain immunity against the virus.

Investigation on the high recurrence of the ATTRv-causing transthyretin variant Val142Ile in central Italy.

The p.Val142Ile variant in transthyretin (encoded by the TTR gene) is the most common genetic cause of transthyretin-related amyloidosis. This allele is particularly prevalent in communities ofAfrican descent compared with populations of different ancestries, where its frequency is two orders of magnitude lower. For this reason, p.Val142Ile has always been considered an "African" variant, with limited studies performed on individuals of European descent. However, recent reports of higher-than-expected prevalence in European-ancestry populations question the African specificity of this allele. Here we show that the high recurrence of p.Val142Ile in central Italy is due to a founder effect and not to recent admixture from African populations, highlighting how this may be the case in other communities. This suggests a probable underestimate of the global prevalence of p.Val142Ile, and further emphasizes the importance of routine inclusion of TTR in gene panels used for clinical genetic testing in hypertrophic cardiomyopathy (independently of the patient's geographical origin), that transthyretin-related amyloidosis can mimic.

Transcriptional Profiling of Rat Prefrontal Cortex after Acute Inescapable Footshock Stress.

Stress is a primary risk factor for psychiatric disorders such as Major Depressive Disorder (MDD) and Post Traumatic Stress Disorder (PTSD). The response to stress involves the regulation of transcriptional programs, which is supposed to play a role in coping with stress. To evaluate transcriptional processes implemented after exposure to unavoidable traumatic stress, we applied microarray expression analysis to the PFC of rats exposed to acute footshock (FS) stress that were sacrificed immediately after the 40 min session or 2 h or 24 h after. While no substantial changes were observed at the single gene level immediately after the stress session, gene set enrichment analysis showed alterations in neuronal pathways associated with glia development, glia-neuron networking, and synaptic function. Furthermore, we found alterations in the expression of gene sets regulated by specific transcription factors that could represent master regulators of the acute stress response. Of note, these pathways and transcriptional programs are activated during the early stress response (immediately after FS) and are already turned off after 2 h-while at 24 h, the transcriptional profile is largely unaffected. Overall, our analysis provided a transcriptional landscape of the early changes triggered by acute unavoidable FS stress in the PFC of rats, suggesting that the transcriptional wave is fast and mild, but probably enough to activate a cellular response to acute stress.

Clinical and Histological Prognostic Factors of Recurrence and Malignant Transformation in a Large Series of Oral Potentially Malignant Disorders.

Background: Oral potentially malignant disorders (OPMDs) represent a heterogeneous set of different histological lesions, characterized by the capacity to transform in oral squamous cell carcinoma (OSCC). Despite optimal surgical treatment, approximately 20%-30% of OPMDs may evolve into OSCC. No clear clinical/histological factors are able to identify OPMDs at higher risk of malignant transformation. Materials and Methods: We considered surgically treated patients with a diagnosis of OPMDs, enrolled from 1996 to 2019 at ASST Spedali Civili of Brescia without a diagnosis of OSCC within the previous 2 years. Clinical and histological characteristics were recorded. Outcomes of interest were recurrence-free survival (RFS), defined as the time from surgery for primary OPMD to any relapse of OPMD or malignant transformation, whichever occurred first, and carcinoma-free survival (CFS), defined as the time from surgery for OPMD to malignant transformation. Results: We retrospectively reviewed 106 OPMDs cases. Median age at first diagnosis was 64 years old (IQR = 18.75); female patients comprise 51.9% of the cases. During a median follow-up of 30.5 months (IQR = 44), in 23.5% of patients, malignant transformation occurred. RFS at 1, 5, and 10 years was 92.4%, 60.9%, and 43.2%, respectively. Female sex and history of previous OSCC were independent risk factors for RFS. CFS at 1, 5, and 10 years of follow-up was 97.1%, 75.9%, and 64.4%, respectively. Previous OSCC was an independent risk factor for CFS. Conclusions: In this large series of OPMDs, only previous diagnosis of OSCC was a prognostic factor for further OSCC occurrence. Given the lack of additional clinical/pathological prognostic factors, we advocate further studies into molecular characterization of OPMDs to better stratify the risk of malignant transformation.

Analysis of complete mitochondrial genomes of patients with schizophrenia and bipolar disorder.

The present study aims at investigating the association between common and rare variants of mitochondrial DNA (mtDNA), and increased risk of schizophrenia (SZ) and bipolar disorder (BPD) in a cohort of patients originating from the same Italian population. The distribution of the major European mtDNA haplogroups was determined in 89 patients and their frequencies did not significantly differ from those observed in the Italian population. Moreover, 27 patients with high probability of having inherited the disease from the maternal side were selected for whole mitochondrial genome sequencing to investigate the possible presence of causative point mutations. Overall, 213 known variants and 2 novel changes were identified, but none of them was predicted to have functional effects. Hence, none of the sequence changes we found in our sample could explain the maternal component of SZ and BPD predisposition.

Alterations observed in the interferon α and ß signaling pathway in MDD patients are marginally influenced by cis-acting alleles.

Major depressive disorder (MDD) is a common psychiatric disorder with a multifactorial aetiology determined by the interaction between genetic and environmental risk factors. Pieces of evidence indicate that inflammation and immune activation may contribute to the onset of MDD playing a role in the pathogenetic mechanism. To date, it is not known to which extent the association between MDD and inflammation is shaped by the genetic background or by the presence of environmental factors. To clarify this issue, we analyzed genotype and blood RNA profiles of 463 MDD cases and 459 controls (NIMH-Study 88/Site621) estimating the Genetic and Environmental Regulated eXpression component of gene expression (GReX and EReX respectively). Both components were tested for association with MDD. Many genes belonging to the α/ß interferon signaling pathway showed an association between MDD and EReX, only two between MDD and GReX. Also other MDD differentially expressed genes were more influenced by the EReX than by GReX. These results suggest that impact of the genetic background on MDD blood gene expression alterations is much lower than the contribution of environmental factors and almost absent for the genes of the interferon pathway.

Clinical validation of a combinatorial PharmAcogeNomic approach in major Depressive disorder: an Observational prospective RAndomized, participant and rater-blinded, controlled trial (PANDORA trial).

BACKGROUND: Major depressive disorder (MDD) is a common, chronic, debilitating mood disorder that causes serious functional impairment and significantly decreased quality of life. Pharmacotherapy represents the first-line treatment option; however, only approximately one third of patients respond to the first treatment because of the ineffectiveness or side effects of antidepressants. Precision medicine in psychiatry might offer clinicians the possibility to tailor treatment according to the best possible evidence of efficacy and tolerability for each subject. In this context, our study aims to carry out a clinical validation of a combinatorial pharmacogenomics (PGx) test in an Italian MDD patient cohort with advocacy license independence. METHODS: Our study is a prospective participant- and rater-blinded, randomized, controlled clinical observational trial enrolling 300 MDD patients who are referred to psychiatric services to receive a new antidepressant due to the failure of their current treatment and/or the onset of adverse effects. Eligible participants are randomized to the TGTG group (Treated with Genetic Test Guide) or TAU group (Treated as Usual). For all subjects, DNA is collected with a buccal brush. The primary outcome is the reduction in depressive symptomatology. The secondary outcomes involve a range of scales that assess MDD symptoms and social functioning outcomes. The assessment is performed at four timepoints: baseline and 4, 8, and 12 weeks. DISCUSSION: This project represents the first randomized controlled clinical trial to investigate whether a non-commercial PGx test improves outcomes in an MDD naturalistic cohort. Moreover, the identification of new genetic variants associated with non-response or side effects will improve the efficacy of the test, leading to further cost-saving. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov NCT04615234. Registered on November 4, 2020.

Evidence of an interaction between FXR1 and GSK3ß polymorphisms on levels of Negative Symptoms of Schizophrenia and their response to antipsychotics.

BACKGROUND: Genome-Wide Association Studies (GWASs) have identified several genes associated with Schizophrenia (SCZ) and exponentially increased knowledge on the genetic basis of the disease. In addition, products of GWAS genes interact with neuronal factors coded by genes lacking association, such that this interaction may confer risk for specific phenotypes of this brain disorder. In this regard, fragile X mental retardation syndrome-related 1 (FXR1) gene has been GWAS associated with SCZ. FXR1 protein is regulated by glycogen synthase kinase-3ß (GSK3ß), which has been implicated in pathophysiology of SCZ and response to antipsychotics (APs). rs496250 and rs12630592, two eQTLs (Expression Quantitative Trait Loci) of FXR1 and GSK3ß, respectively, interact on emotion stability and amygdala/prefrontal cortex activity during emotion processing. These two phenotypes are associated with Negative Symptoms (NSs) of SCZ suggesting that the interaction between these SNPs may also affect NS severity and responsiveness to medication. METHODS: To test this hypothesis, in two independent samples of patients with SCZ, we investigated rs496250 by rs12630592 interaction on NS severity and response to APs. We also tested a putative link between APs administration and FXR1 expression, as already reported for GSK3ß expression. RESULTS: We found that rs496250 and rs12630592 interact on NS severity. We also found evidence suggesting interaction of these polymorphisms also on response to APs. This interaction was not present when looking at positive and general psychopathology scores. Furthermore, chronic olanzapine administration led to a reduction of FXR1 expression in mouse frontal cortex. DISCUSSION: Our findings suggest that, like GSK3ß, FXR1 is affected by APs while shedding new light on the role of the FXR1/GSK3ß pathway for NSs of SCZ.

RNA Editing and Modifications in Mood Disorders.

Major depressive disorder (MDD) is a major health problem with significant limitations in functioning and well-being. The World Health Organization (WHO) evaluates MDD as one of the most disabling disorders in the world and with very high social cost. Great attention has been given to the study of the molecular mechanism underpinning MDD at the genetic, epigenetic and proteomic level. However, the importance of RNA modifications has attracted little attention until now in this field. RNA molecules are extensively and dynamically altered by a variety of mechanisms. Similar to "epigenomic" changes, which modify DNA structure or histones, RNA alterations are now termed "epitranscriptomic" changes and have been predicted to have profound consequences for gene expression and cellular functionality. Two of these modifications, adenosine to inosine (A-to-I) RNA editing and m6A methylations, have fascinated researchers over the last years, showing a new level of complexity in gene expression. In this review, we will summary the studies that focus on the role of RNA editing and m6A methylation in MDD, trying to underline their potential breakthroughs and pitfalls.

Author Correction: A novel homozygous mutation in GAD1 gene described in a schizophrenic patient impairs activity and dimerization of GAD67 enzyme.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.