Polymorphism analysis of HOPA: a candidate gene for schizophrenia

Thyroid hormones in persons with schizophrenia: A systematic review and meta-analysis

There is accumulating evidence that individuals with schizophrenia show altered levels of thyroid hormones. However, a qualitative and quantitative synthesis of findings in this field has not been performed so far. Therefore, we aimed to perform a systematic review and meta-analysis of studies investigating the levels of thyroid-stimulating hormone (TSH), free thyroxine (fT4), total thyroxine (tT4), free triiodothyronine (fT3) and total triiodothyronine (tT3) in multiple-episode schizophrenia (MES) and first-episode psychosis (FEP). Electronic databases were searched from their inception until 30th May 2020 by two independent reviewers. Random-effects meta-analyses and meta-regression analyses were performed. Altogether, 19 studies were included. Persons with FEP had significantly lower TSH levels (5 studies, g = -0.26, 95%CI: -0.47 to -0.06, p = 0.013, I² = 21.3%), higher fT4 levels (3 studies, g = 0.58, 95%CI: 0.15-1.01, p = 0.008, I² = 64.6%) and lower tT3 levels (2 studies, g = -0.60, 95%CI: -0.82 to -0.37, p < 0.001, I² = 0%) compared to controls. Elevated TSH levels were found in persons with MES (13 studies, g = 0.20, 95%CI: 0.02-0.39, p = 0.031, I² = 50.0%). Our findings imply that the levels of TSH might be decreased in persons with FEP and increased in those with MES. Other alterations need to be confirmed by additional studies. These findings imply the need to monitor the levels of TSH and thyroid hormones from the onset of psychosis.

Dose-response association of acute-phase quetiapine treatment with risk of new-onset hypothyroidism in schizophrenia patients

AIMS

To assess association between quetiapine treatment and risk of new-onset hypothyroidism in schizophrenia patients.

METHODS

We conducted a retrospective cohort study in a tertiary hospital in China between January 2016 and December 2018. Schizophrenia patients with normal thyroid tests at admission were included. Hypothyroidism, which was defined as thyroid-stimulating hormone >4.20 mU/L and free thyroxine <12.00 pmol/L, or on L-thyroxine prescriptions, was the outcome measure, and quetiapine treatment between admission and subsequent thyroid test was the exposure measure of this study. Adjusted relative risks and 95% confidence intervals were used to assess the independent association of quetiapine treatment with risk of new-onset hypothyroidism. The dose-response association was further analysed by 3 quetiapine doses: low (≤<=0.2 g/d), medium (0.2-0.6 g/d), and high (>0.6 g/d).

RESULTS

A total of 2022 eligible patients were included in the final analysis. Sixty patients (15.0%) in the quetiapine group developed hypothyroidism, while 56 patients (3.5%) in the nonquetiapine group developed hypothyroidism. Relative risk (95% confidence interval) of developing hypothyroidism for quetiapine use was 4.01 (2.86-5.64) after adjusting for several potential confounding factors. A strong dose-response association between quetiapine use and risk of developing hypothyroidism was observed: adjusted relative risks (95% confidence intervals) were 1.00 (0.25-2.59), 4.22 (2.80-6.25) and 5.62 (3.66-8.38), respectively, for low-, medium- and high-dose quetiapine, as compared with no quetiapine.

CONCLUSION

Acute phase quetiapine treatment for schizophrenia patients was strongly associated with increased risk of developing new-onset hypothyroidism, with a clear dose-response association.

The Sex Chromosome Hypothesis of Schizophrenia: Alive, Dead, or Forgotten? A Commentary and Review

The X chromosome has long been an intriguing site for harboring genes that have importance in brain development and function. It has received the most attention for having specific genes underlying the X-linked inherited intellectual disabilities, but has also been associated with schizophrenia in a number of early studies. An X chromosome hypothesis for a genetic predisposition for schizophrenia initially came from the X chromosome anomaly population data showing an excess of schizophrenia in Klinefelter's (XXY) males and triple X (XXX) females. Crow and colleagues later expanded the X chromosome hypothesis to include the possibility of a locus on the Y chromosome and, specifically, genes on X that escaped inactivation and are X-Y homologous loci. Some new information about possible risk loci on these chromosomes has come from the current large genetic consortia genome-wide association studies, suggesting that perhaps this hypothesis needs to be revisited for some schizophrenias. The following commentary reviews the early and more recent literature supporting or refuting this dormant hypothesis and emphasizes the possible candidate genes still of interest that could be explored in further studies.

JMJD6 Licenses ERα-Dependent Enhancer and Coding Gene Activation by Modulating the Recruitment of the CARM1/MED12 Co-activator Complex

Whereas the actions of enhancers in gene transcriptional regulation are well established, roles of JmjC-domain-containing proteins in mediating enhancer activation remain poorly understood. Here, we report that recruitment of the JmjC-domain-containing protein 6 (JMJD6) to estrogen receptor alpha (ERα)-bound active enhancers is required for RNA polymerase II recruitment and enhancer RNA production on enhancers, resulting in transcriptional pause release of cognate estrogen target genes. JMJD6 is found to interact with MED12 in the mediator complex to regulate its recruitment. Unexpectedly, JMJD6 is necessary for MED12 to interact with CARM1, which methylates MED12 at multiple arginine sites and regulates its chromatin binding. Consistent with its role in transcriptional activation, JMJD6 is required for estrogen/ERα-induced breast cancer cell growth and tumorigenesis. Our data have uncovered a critical regulator of estrogen/ERα-induced enhancer coding gene activation and breast cancer cell potency, providing a potential therapeutic target of ER-positive breast cancers.

Sex chromosome abnormalities and psychiatric diseases

Excesses of sex chromosome abnormalities in patients with psychiatric diseases have recently been observed. It remains unclear whether sex chromosome abnormalities are related to sex differences in some psychiatric diseases. While studies showed evidence of susceptibility loci over many sex chromosomal regions related to various mental diseases, others demonstrated that the sex chromosome aneuploidies may be the key to exploring the pathogenesis of psychiatric disease. In this review, we will outline the current evidence on the interaction of sex chromosome abnormalities with schizophrenia, autism, ADHD and mood disorders.

Sex differences in the genetic risk for schizophrenia: history of the evidence for sex-specific and sex-dependent effects

Although there is a long history to examinations of sex differences in the familial (and specifically, genetic) transmission of schizophrenia, there have been few investigators who have systematically and rigorously studied this issue. This is true even in light of population and clinical studies identifying significant sex differences in incidence, expression, neuroanatomic and functional brain abnormalities, and course of schizophrenia. This review highlights the history of work in this arena from studies of family transmission patterns, linkage and twin studies to the current molecular genetic strategies of large genome-wide association studies. Taken as a whole, the evidence supports the presence of genetic risks of which some are sex-specific (i.e., presence in one sex and not the other) or sex-dependent (i.e., quantitative differences in risk between the sexes). Thus, a concerted effort to systematically investigate these questions is warranted and, as we argue here, necessary in order to fully understand the etiology of schizophrenia.

The C. elegans CDK8 Mediator module regulates axon guidance decisions in the ventral nerve cord and during dorsal axon navigation

Receptors expressed on the growth cone of outgrowing axons detect cues required for proper navigation. The pathway choices available to an axon are in part defined by the set of guidance receptors present on the growth cone. Regulated expression of receptors and genes controlling the localization and activity of receptors ensures that axons respond only to guidance cues relevant for reaching their targets. In genetic screens for axon guidance mutants, we isolated an allele of let-19/mdt-13, a component of the Mediator, a large ~30 subunit protein complex essential for gene transcription by RNA polymerase II. LET-19/MDT-13 is part of the CDK8 module of the Mediator. By testing other Mediator components, we found that all subunits of the CDK8 module as well as some other Mediator components are required for specific axon navigation decisions in a subset of neurons. Expression profiling demonstrated that let-19/mdt-13 regulates the expression of a large number of genes in interneurons. A mutation in the sax-3 gene, encoding a receptor for the repulsive guidance cue SLT-1, suppresses the commissure navigation defects found in cdk-8 mutants. This suggests that the CDK8 module specifically represses the SAX-3/ROBO pathway to ensure proper commissure navigation.

Systematic molecular and cytogenetic screening of 100 patients with marfanoid syndromes and intellectual disability

The association of marfanoid habitus (MH) and intellectual disability (ID) has been reported in the literature, with overlapping presentations and genetic heterogeneity. A hundred patients (71 males and 29 females) with a MH and ID were recruited. Custom-designed 244K array-CGH (Agilent®; Agilent Technologies Inc., Santa Clara, CA) and MED12, ZDHHC9, UPF3B, FBN1, TGFBR1 and TGFBR2 sequencing analyses were performed. Eighty patients could be classified as isolated MH and ID: 12 chromosomal imbalances, 1 FBN1 mutation and 1 possibly pathogenic MED12 mutation were found (17%). Twenty patients could be classified as ID with other extra-skeletal features of the Marfan syndrome (MFS) spectrum: 4 pathogenic FBN1 mutations and 4 chromosomal imbalances were found (2 patients with both FBN1 mutation and chromosomal rearrangement) (29%). These results suggest either that there are more loci with genes yet to be discovered or that MH can also be a relatively non-specific feature of patients with ID. The search for aortic complications is mandatory even if MH is associated with ID since FBN1 mutations or rearrangements were found in some patients. The excess of males is in favour of the involvement of other X-linked genes. Although it was impossible to make a diagnosis in 80% of patients, these results will improve genetic counselling in families.

Sex-specific rates of transmission of psychosis in the New England high-risk family study

Recent molecular genetic studies have demonstrated X-chromosome abnormalities in the transmission of psychosis, a finding that may contribute to understanding sex differences in the disorder. Using our family high risk paradigm, we tested the hypothesis that there are sex-specific patterns of transmission of psychosis and whether there is specificity comparing nonaffective- with affective-type psychoses. We identified 159 parents with psychoses (schizophrenia psychosis spectrum disorders (SPS, n=59) and affective (AP, n=100)) and 114 comparable, healthy control parents. 203 high risk (HR) and 147 control offspring were diagnostically assessed (185 females; 165 males). We compared the proportion of male:female offspring with psychoses by affected parent sex and the consistency for SPS compared to AP parents, and tested (using exact logistic regression) whether the male:female ratio for affected offspring differed significantly between affected mothers and affected fathers. Risk of psychosis in offspring was a function of the sex of the parent and offspring. Among ill mothers, 18.8% of their male offspring developed psychosis compared with 9.5% of their daughters. In contrast, among ill fathers, 3.1% of their male offspring developed psychosis compared with 15.2% of their daughters. The male:female ratio for affected offspring differed significantly (p < 0.05) between affected mothers and fathers. Similar patterns held for SPS and AP. Results demonstrated sex-specific transmission of psychosis regardless of psychosis-type and suggest X-linked inheritance. This has important implications for molecular genetic studies of psychoses underscoring the impact of one's gender on gene-brain-behavior phenotypes of SCZ.

Effects of bisphenol-A and other endocrine disruptors compared with abnormalities of schizophrenia: an endocrine-disruption theory of schizophrenia

In recent years, numerous substances have been identified as so-called "endocrine disruptors" because exposure to them results in disruption of normal endocrine function with possible adverse health outcomes. The pathologic and behavioral abnormalities attributed to exposure to endocrine disruptors like bisphenol-A (BPA) have been studied in animals. Mental conditions ranging from cognitive impairment to autism have been linked to BPA exposure by more than one investigation. Concurrent with these developments in BPA research, schizophrenia research has continued to find evidence of possible endocrine or neuroendocrine involvement in the disease. Sufficient information now exists for a comparison of the neurotoxicological and behavioral pathology associated with exposure to BPA and other endocrine disruptors to the abnormalities observed in schizophrenia. This review summarizes these findings and proposes a theory of endocrine disruption, like that observed from BPA exposure, as a pathway of schizophrenia pathogenesis. The review shows similarities exist between the effects of exposure to BPA and other related chemicals with schizophrenia. These similarities can be observed in 11 broad categories of abnormality: physical development, brain anatomy, cellular anatomy, hormone function, neurotransmitters and receptors, proteins and factors, processes and substances, immunology, sexual development, social behaviors or physiological responses, and other behaviors. Some of these similarities are sexually dimorphic and support theories that sexual dimorphisms may be important to schizophrenia pathogenesis. Research recommendations for further elaboration of the theory are proposed.

The association of the HOPA(12bp) polymorphism with schizophrenia in the NIMH Genetics Initiative for Schizophrenia sample

HOPA (MED12) is an X-chromosome gene that codes for a critical member of the Mediator Complex, a group of proteins that regulates transcription via the nuclear receptor, Wnt and Receptor Tyrosine Kinase pathways. In prior association and meta-analyses, we have shown that the presence of an evolutionarily conserved, 12 bp (4 amino acid) insertional polymorphism in exon 43 of this gene is associated with increased risk for an endophenotype of schizophrenia. In this communication, we describe the results of our work with subjects and data from the National Institutes of Mental Health (NIMH) Genetics Initiative for Schizophrenia. We report that the presence of the HOPA(12bp) polymorphism is associated with increased risk for schizophrenia in subjects of European ancestry. In the light of this new study and the prior wealth of clinical and basic science data, we conclude that the HOPA(12bp) allele is a risk factor for schizophrenia in subjects of European ancestry and suggest that further studies to define the endophenotype and mechanisms of illness associated with this polymorphism are indicated.

A meta-analysis of the association of the HOPA12bp polymorphism and schizophrenia

Uncommon polymorphisms, particularly balanced uncommon polymorphisms, present a significant challenge to our understanding of their role in behavior. We have recently demonstrated that an uncommon candidate gene polymorphism for schizophrenia, known as HOPA12bp, is the defining polymorphism for a large X-chromosome haplotype in population disequilibrium and that it is associated with a positive syndrome of psychosis. Not all studies, however, have shown this effect. In this report, we reviewed prior studies and conducted meta-analysis of studies using probands of northern European extraction. We found that the presence of the HOPA12bp is a significant risk factor for psychosis for both men and women and suggest that differences in the case definition of schizophrenia may affect the strength of the association.

An association study of PCQAP polymorphisms and schizophrenia

INTRODUCTION

PCQAP is a member of the mediator family of transcription co-activators that is found in the region of 22q11, which is consistently deleted in DiGeorges/velocranialfacial (VCF) syndrome. As such, it is a gene of interest to behavioral geneticists because VCF is also associated with a high rate of psychosis and because defects in other mediator genes have been linked to psychosis and abnormal neurodevelopmental abnormalities. Recently, DeLuca and colleagues reported that polymorphisms in a trinucleotide repeat in exon 7 of PCQAP were associated with schizophrenia in a case-control study of Italian schizophrenics.

OBJECTIVE AND METHODS

To confirm and extend the prior findings, we conducted a case-control association analysis using DNA from 233 schizophrenics and 371 random controls.

RESULTS

Unfortunately, we did not find any significant differences in the distribution of CAG repeat alleles between subjects and controls.

CONCLUSIONS

These findings limit the role of exon 7 PCQAP polymorphisms in the pathogenesis of schizophrenia.