Mapping of gene loci in the Q13–Q15 region of chromosome 12

The gene loci CDK4, GLI, CHOP and MDM2 have been mapped to the q13–q15 region of chromosome 12. Using fluorescencein situ hybridization onto simultaneously DAPI-banded metaphase chromosomes and interphase nuclei, we have more precisely mapped and ordered these loci, together with a number of Genethon microsatellite markers. GLI and CHOP localize to 12q13.3–14.1, CDK4 to 12q14 and MDM2 to 12q14.3–q15, and the gene order is cen-GLI/CHOP-CDK4-MDM2. The Genethon microsatellites D12S80 and D12S83 flank MDM2.     

14-3-3 protein η chain gene (YWHAH) polymorphism and its genetic association with schizophrenia

Recent genetic analyses have suggested a linkage between schizophrenia and the chromosomal region 22q12–q13. 14-3-3 protein, abundant in the brain, mediates interactions between diverse molecules of biological activities; its gene was recently mapped to chromosome 22q12.1–q13.1. We therefore investigated allele frequencies of a variable number of tandem repeat (VNTR) in the 5′-noncoding region of the 14-3-3 η chain gene in controls and schizophrenics. The frequencies of the two-repeat allele were significantly higher (P < 0.05) in the schizophrenics, and particularly in those with onset before age 22 (early-onset schizophrenics, P < 0.02), than in the controls. The odds ratio was significantly increased in the early-onset schizophrenics homozygous for the two-repeat allele (OR = 3.3, 95% CI = 1.1—9.7). The 14-3-3 η chain gene is a potential susceptibility gene for schizophrenia, and particularly for early-onset schizophrenia. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:164–167, 1999. © 1999 Wiley-Liss, Inc.     

Velo‐cardio‐facial syndrome: Implications of microdeletion 22q11 for schizophrenia and mood disorders

Velo‐cardio‐facial syndrome (VCFS) is a congenital malformation syndrome with variable phenotypic features that has been associated with chromosomal microdeletion 22q11.2. Psychiatric disorders have been reported to be highly prevalent in individuals with this syndrome, and the objective of this study was to assess the nature and extent of psychopathology among individuals with VCFS. We studied 20 children and adolescents with 22q11 deletions determined by fluorescence in situ hybridization (FISH). Control subjects were 11 nondeleted siblings who were the closest age match to the affected subjects. Both affected and control subjects were assessed using two standardized psychiatric research instruments. The results of this study confirmed the high rate of psychiatric disorders among VCFS subjects (60% of our subjects). Of the specific types of disorders, only mood disorders were significantly more common among VCFS subjects compared to sibling controls, with eight VCFS subjects having mood disorders compared with none of the control subjects (P<0.02). Three affected subjects had schizotypal traits comorbid with a mood disorder. In addition, disruptive behavior disorders were frequently diagnosed among VCFS subjects. Using a dimensional measure of psychopathology, significant differences between VCFS subjects and sibling controls were found on three scales: ADHD (P<0.02), separation anxiety (P<0.02), and depression (P<0.01). VCFS subjects were achieving significantly less well academically and requiring significantly more special educational assistance than sibling controls. Follow‐up data were available on two subjects, both of whom had been diagnosed with schizophrenia. Further research on psychopathology in VCFS may provide a model of how a specific genetic defect can lead to the development of psychiatric disorders. © 2001 Wiley‐Liss, Inc.     

Polymorphisms of the σ1 receptor gene in schizophrenia: An association study

Possible involvement of σ receptors in the pathogenesis of schizophrenia has been suggested. In this study we searched systematically for polymorphisms in the 5′‐franking region of the σ₁ receptor. Genetic variation in this region could reduce the expression of the gene, and this suggestion is compatible with findings of reduced σ binding sites in several cortical regions of schizophrenia. We confirmed G−241T and G−240T polymorphisms; these two consecutive polymorphisms were resolved to be in complete linkage disequilibrium with each other by single‐strand conformation polymorphism (SSCP) analysis. We also identified the A61C (Gln2Pro) polymorphism, which was in almost complete linkage disequilibrium with G−241T/G−240T. There was no significant difference in the distribution of alleles or overall genotypes of the polymorphisms between schizophrenic patients (n = 129) and controls (n = 140). We found slight increased homozygosity for T−241/T−240 and C61 in patients compared with controls using multiple comparison (p = 0.045). However, the significance did not remain when a Bonferroni correction was made (p = 0.135). These results do not support that the σ₁ receptor gene plays a major role in the pathogenesis of schizophrenia. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:118–122, 2000. © 2000 Wiley‐Liss, Inc.     

Support for an association between HLA‐DR1 and schizophrenia in the Japanese population

An increase of HLA‐DR1 has been observed in schizophrenia patients from the Japanese population. A decrease of DR4, which was reported in Caucasian patients, has also been found in some of the Japanese studies. This small study further investigated frequencies of HLA‐DR1 and DR4 in unrelated Japanese patients with schizophrenia (n = 45) and healthy comparison subjects (n = 117). The number of patients possessing DR1 was higher (10 of 45, 22%) compared with the comparison group (11 of 117, 9.4%, P = 0.03). This may support the previous observation of an increased DR1 frequency in the Japanese patients. When the present data is combined with three previous studies, proportions of the Japanese subjects with DR1 were 98 of 588 schizophrenia patients (16.7%) vs. 93 of 942 comparison subjects (9.9%). However, no difference was observed in DR4 frequencies between the patients (51%) and comparison subjects (44%). Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:725–727, 2000. © 2000 Wiley‐Liss, Inc.     

A novel IL‐23p19/Ebi3 (IL‐39) cytokine mediates inflammation in Lupus‐like mice

Interleukin‐12 family cytokines have emerged as critical regulators of immunity with some members (IL‐12, IL‐23) associated with disease pathogenesis while others (IL‐27, IL‐35) mitigate autoimmune diseases. Each IL‐12 family member is comprised of an α and a β chain, and chain‐sharing is a key feature. Although four bona fide members have thus far been described, promiscuous chain‐pairing between alpha (IL‐23p19, IL‐27p28, IL‐12/IL‐35p35) and beta (IL‐12/IL‐23p40, IL‐27/IL‐35Ebi3) subunits, predicts six possible heterodimeric IL‐12 family cytokines. Here, we describe a new IL‐12 member composed of IL‐23p19 and Ebi3 heterodimer (IL‐39) that is secreted by LPS‐stimulated B cells and GL7⁺ activated B cells of lupus‐like mice. We further show that IL‐39 mediates inflammatory responses through activation of STAT1/STAT3 in lupus‐like mice. Taken together, our results show that IL‐39 might contribute to immunopathogenic mechanisms of systemic lupus erythematosus, and could be used as a possible target for its treatment.     

Systematic search for variation in the human norepinephrine transporter gene: Identification of five naturally occurring missense mutations and study of association with major psychiatric disorders

The complete coding region of the norepinephrine transporter (NET) gene was systematically screened for genetic variants in 137 unrelated individuals (including 46 probands with bipolar affective disorder and 45 schizophrenic probands, as well as 46 blood donors) using single-strand conformation analysis. We identified 13 DNA sequence variants, among them five missense substitutions. The missense substitutions Val69Ile, Thr99Ile, Val245Ile, Val449Ile, and Gly478Ser are located at putative transmembrane domains (TMD) 1, 2, 4, 9, and 10, respectively. The Thr99Ile substitution is at the 5th position of the putative leucine-zipper in TMD2. In a case-control study distribution of missense substitutions was found to be similar in 103 patients with bipolar affective disorder, in 228 schizophrenia patients and in 187 controls, indicating that presence of these variants is not causally related to major psychiatric diseases. The detection of a highly polymorphic silent 1287G/A polymorphism was utilized to demonstrate biallelic expression of the NET in adult human brain. © 1996 Wiley-Liss, Inc.     

Molecular abnormalities in liposarcoma: role of MDM2 and CDK4-containing amplicons at 12q13–22

It has recently been shown that mdm2 overexpression with stabilization of p53 represents a characteristic of retroperitoneal well-differentiated-dedifferentiated, here renamed evolved (WD-E), liposarcomas at the immunocytochemical, molecular, and cytogenetic level. This make-up appears to be confined to half the cases in non-retroperitoneal well-differentiated liposarcomas. Since in different tumours MDM2 amplification involves amplicons encompassing flanking genes, such as CDK4, the possibility was investigated that in these tumours, CDK4 could act as an alternative or additional gene involved in the transformation mechanism. Forty-one retroperitoneal (R)/non-retroperitoneal (NR) well-differentiated-dedifferentiated (WD-DD) and 33 myxoid/round cell liposarcomas were reanalysed by immunocytochemical, molecular (nine cases) and fluorescence in situ hybridization (FISH) (one case) techniques. The results showed that all but one R WD-E cases carried the mdm2+, p53+, cdk4+ immunophenotype. In NR-WD liposarcomas, this immunophenotype was shared in five cases and the remainder showed mdm2+, p53−, cdk4+ in four and mdm2−, p53−, cdk4+ in one case, showing ring chromosomes by FISH analysis. TP53 mutations are confirmed to be closely correlated with NR-DD liposarcomas and no CDK4 involvement was found in the myxoid/round cell liposarcoma group. As well as confirming the synergistic effect of MDM2 and CDK4, these results are consistent with the concept that amplicon(s) excluding MDM2 may contribute to transformation and support a role of CDK4 in opposing p53 function, particularly in NR WD liposarcoma. © 1998 John Wiley & Sons, Ltd.     

Systematic screening of the 14‐3‐3 eta (η) chain gene for polymorphic variants and case‐control analysis in schizophrenia

The neuronal protein 14‐3‐3 η is a candidate gene for schizophrenia because it maps chromosome 22q12, a region implicated in the disease by linkage analysis, and is involved in brain development. We systematically screened this gene for polymorphic variants by comparison of public EST sequence data (five cDNAs and 72 ESTs, 21,155 bp of sequence) in parallel with single‐stranded conformational polymorphism analysis, and we compared these methods by using a simple power calculation. Twelve potential polymorphisms were identified from EST sequence comparison, and two of these (a 5′‐VNTR and 753G/A) were confirmed by SSCP analysis and sequencing. Three additional infrequent polymorphisms (−408T/G; 177 C/G; and 989 A/G) were found by SSCP only. We next examined these variants for association with schizophrenia. One variant in untranslated region of exon 1 (−408 T/G) was found to occur more frequently in the schizophrenic subjects (8%) than the controls (3%; P = 0.01). After fivefold correction of the P value for multiple testing, marginal association was found. Haplotype analysis of pairs of polymorphisms provided no evidence for association of this gene with schizophrenia in the population studied. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:736–743, 2000. © 2000 Wiley‐Liss, Inc.     

Association between the candidate susceptibility gene ACVR2A on chromosome 2q22 and pre-eclampsia in a large Norwegian population-based study (the HUNT study)

Genome-wide scans in Icelandic, Australian/New Zealand and Finnish pedigrees have provided evidence for maternal susceptibility loci for pre-eclampsia on chromosome 2, although at different positions (Iceland: 2p13 and 2q23, Australia/New Zealand: 2p11-12 and 2q22, Finland: 2p25). In this project, a large population-based (n=65 000) nested case-control study was performed in Norway to further explore the association between positional candidate genes on chromosome 2q and pre-eclampsia, using single-nucleotide polymorphisms (SNPs). DNA samples from 1139 cases (women with one or more pre-eclamptic pregnancies) and 2269 controls (women with normal pregnancies) were genotyped using the Applied Biosystems SNPlex high-throughput genotyping assay. In total, 71 SNPs within positional candidate genes at 2q22-23 locus on chromosome 2 were genotyped in each individual. Genotype data were statistically analysed with the sequential oligogenic linkage analysis routines (SOLAR) computer package. Nominal evidence of association was found for six SNPs (rs1014064, rs17742134, rs1424941, rs2161983, rs3768687 and rs3764955) within the activin receptor type 2 gene (ACVR2A) (all P-values <0.05). The non-independence of statistical tests due to linkage disequilibrium between SNPs at a false discovery rate of 5% identifies our four best SNPs (rs1424941, rs1014064, rs2161983 and rs3768687) to remain statistically significant. The fact that populations with different ancestors (Iceland/Norway-Australia/New Zealand) demonstrate a common maternal pre-eclampsia susceptibility locus on chromosome 2q22-23, may suggest a general role of this locus, and possibly the ACVR2A gene, in pre-eclampsia pathogenesis.     

GABA‐A receptor β3 and α5 subunit gene cluster on chromosome 15q11–q13 and bipolar disorder: A genetic association study

There is accumulated evidence that the genes coding for the receptor of gamma aminobutyric acid (GABA), the most important inhibitory neurotransmitter in the CNS, may be involved in the pathogenesis of affective disorders. In a previous study, we have found a genetic association between the GABA‐A receptor α5 subunit gene locus (GABRA5) on chromosome 15q11–of 13 and bipolar affective disorder. The aim of the present study was to examine the same subjects to see if there exists a genetic association between bipolar affective disorder and the GABA receptor β3 subunit gene (GABRB3), which is located within 100 kb from GABRA5. The sample consisted of 48 bipolar patients compared to 44 controls (blood donors). All subjects were Greek, unrelated, and personally interviewed. Diagnosis was based on DSM‐IV and ICD‐10 criteria. The marker used was a dinucleotide (CA) repeat polymorphism with 12 alleles 179 to 201 bp long; genotyping was successful in all patients and 43 controls. The distribution of GABRB3 genotypes among the controls did not deviate significantly from the Hardy‐Weinberg equilibrium. No differences in allelic frequencies between bipolar patients and controls were found for GABRB3, while this locus and GABRA5 did not seem to be in significant linkage disequilibrium. In conclusion, the GABRB3 CA‐repeat polymorphism we investigated does not present the observed association between bipolar affective illness and GABRA5. This could be due to higher mutation rate in the GABRB3 CA‐repeat polymorphism, but it might also signify that GABRA5 is the gene actually associated with the disease. © 2001 Wiley‐Liss, Inc.     

Coincident diabetes mellitus modulates Th1‐, Th2‐, and Th17‐cell responses in latent tuberculosis in an IL‐10‐ and TGF‐β‐dependent manner

Type 2 diabetes mellitus (DM) is a risk factor for the development of active tuberculosis (TB), although its role in the TB‐induced responses in latent TB (LTB) is not well understood. Since Th1, Th2, and Th17 responses are important in immunity to LTB, we postulated that coincident DM could alter the function of these CD4⁺ T‐cell subsets. To this end, we examined mycobacteria‐induced immune responses in the whole blood of individuals with LTB‐DM and compared them with responses of individuals without DM (LTB‐NDM). T‐cell responses from LTB‐DM are characterized by diminished frequencies of mono‐ and dual‐functional CD4⁺ Th1, Th2, and Th17 cells at baseline and following stimulation with mycobacterial antigens‐purified protein derivative, early secreted antigen‐6, and culture filtrate protein‐10. This modulation was at least partially dependent on IL‐10 and TGF‐β, since neutralization of either cytokine resulted in significantly increased frequencies of Th1 and Th2 cells but not Th17 cells in LTB‐DM but not LTB individuals. LTB‐DM is therefore characterized by diminished frequencies of Th1, Th2, and Th17 cells, indicating that DM alters the immune response in latent TB leading to a suboptimal induction of protective CD4⁺ T‐cell responses, thereby providing a potential mechanism for increased susceptibility to active disease.     

Serotonin transporter (5-HTT) and γ-aminobutyric acid receptor subunit β3 (GABRB3) gene polymorphisms are not associated with autism in the IMGSA families

Previous studies have suggested that the serotonin transporter (5-HTT) gene and the γ-aminobutyric acid receptor subunit β3 (GABRB3) gene, or other genes in the 15q11-q13 region, are possibly involved in susceptibility to autism. To test this hypothesis we performed an association study on the collection of families from the International Molecular Genetic Study of Autism (IMGSA) Consortium, using the transmission disequilibrium test. Two polymorphisms in the 5-HTT gene (a functional insertion-deletion polymorphism in the promoter and a variable number tandem repeat in the second intron) were examined in 90 families comprising 174 affected individuals. Furthermore, seven microsatellite markers spanning the 15q11-q13 region were studied in 94 families with 182 affected individuals. No significant evidence of association or linkage was found at any of the markers tested, indicating that the 5-HTT and the GABRB3 genes are unlikely to play a major role in the aetiology of autism in our family data set. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:492–496, 1999. © 1999 Wiley-Liss, Inc.     

Changes in T‐cell subsets identify responders to FcR‐nonbinding anti‐CD3 mAb (teplizumab) in patients with type 1 diabetes

The mechanisms whereby immune therapies affect progression of type 1 diabetes (T1D) are not well understood. Teplizumab, an FcR nonbinding anti‐CD3 mAb, has shown efficacy in multiple randomized clinical trials. We previously reported an increase in the frequency of circulating CD8⁺ central memory (CD8CM) T cells in clinical responders, but the generalizability of this finding and the molecular effects of teplizumab on these T cells have not been evaluated. We analyzed data from two randomized clinical studies of teplizumab in patients with new‐ and recent‐onset T1D. At the conclusion of therapy, clinical responders showed a significant reduction in circulating CD4⁺ effector memory T cells. Afterward, there was an increase in the frequency and absolute number of CD8CM T cells. In vitro, teplizumab expanded CD8CM T cells by proliferation and conversion of non‐CM T cells. Nanostring analysis of gene expression of CD8CM T cells from responders and nonresponders versus placebo‐treated control subjects identified decreases in expression of genes associated with immune activation and increases in expression of genes associated with T‐cell differentiation and regulation. We conclude that CD8CM T cells with decreased activation and regulatory gene expression are associated with clinical responses to teplizumab in patients with T1D.