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Combined family trio and case-control analysis of the COMT Val158Met polymorphism in European patients with anorexia nervosa.

The high activity Val158 (H) allele of the dopamine-metabolizing enzyme catechol-O-methyltransferase (COMT) was associated with anorexia nervosa (AN) in a recent family trio-based study of patients from Israel. In an attempt to replicate this finding, we performed a combined family trio and case-control study in an European population from seven centers in six different countries (Austria, Germany, Great Britain, Italy [Milan], Italy [Florence], Slovenia, and Spain), together contributing a total of 372 family trios, 684 controls and 266 cases. TDT analyses of high (H) and low (L) alleles in family trios showed that H allele and L allele were each transmitted 101 times (chi(2) = 0, ns). Allele-wise case-control analysis using separate samples simply combined from the centers was also not significant, with the frequencies of the H allele 50% in cases and same in controls. Stratified analysis of data from all centers gave an odds ratio of 0.98 (Cornfield 95% confidence limits 0.78-1.24). Analysis by genotype was likewise not significant (overall chi(2) = 0.42). Because we were not able to support the primary hypothesis that Val158Met is a risk factor for AN, we did not perform secondary analysis of minimum body mass index (mBMI), age at onset or illness subtype (restricting or binge purging anorexia). Overall we found no support for the hypothesis that the Val158 allele of COMT gene is associated with AN in our combined European sample.

Alleles↗

Haplotype analysis of the COMT-ARVCF gene region in Israeli anorexia nervosa family trios.

Anorexia nervosa (AN) is a severe and complex psychiatric disorder with a significant genetic contribution. Previously, we found an association between AN and the 158Val/Met polymorphism of the catechol-O-methyltransferase (COMT) gene in a family-based study of 51 Israeli AN trios. In the present study, we extended the original sample to include 85 family trios [66 AN restricting (AN-R) and 19 bingeing/purging (AN-BP) subtype] and performed a family-based transmission disequilibrium test (TDT) analysis for five SNPs in the COMT and two in the adjacent ARVCF gene. Association was found between AN-R and several SNPs in the COMT-ARVCF region including the 158Val/Met polymorphism. TDT analysis of 5-SNP haplotypes in AN-R trios revealed an overall statistically significant transmission disequilibrium (P < 0.001). Specifically, haplotype B [COMT-186C-408G-472G(158Val)-ARVCF-659C(220Pro)-524T(175Val)] was preferentially transmitted (P < 0.001) from parents of AN-R patients to their affected daughters, while haplotype A [COMT-186T-408C-472A(158Met)-ARVCF-659T(220Leu)-524C(175Ala)] was preferentially (P = 0.01) not transmitted. Haplotype B was associated with increased risk (RR 3.38; 0.95CI 1.98-6.43) while haplotype A exhibited a protective effect (RR 0.40; 0.95CI 0.21-0.70) for AN-R. Preferential transmission of the risk alleles and haplotypes from the parents was mostly contributed by the fathers. No significant transmission disequilibrium of alleles or haplotypes was found for AN-BP trios. The risk and protective haplotypes may carry molecular variations in the COMT gene or its vicinity that are relevant to the pathophysiology of restrictive anorexia nervosa in the Israeli-Jewish population.

Adolescent↗

The combination of SOX5, SOX6, and SOX9 (the SOX trio) provides signals sufficient for induction of permanent cartilage.

OBJECTIVE: To regenerate permanent cartilage, it is crucial to know not only the necessary conditions for chondrogenesis, but also the sufficient conditions. The objective of this study was to determine the signal sufficient for chondrogenesis. METHODS: Embryonic stem cells that had been engineered to fluoresce upon chondrocyte differentiation were treated with combinations of factors necessary for chondrogenesis, and chondrocyte differentiation was detected as fluorescence. We screened for the combination that could induce fluorescence within 3 days. Then, primary mesenchymal stem cells, nonchondrogenic immortalized cell lines, and primary dermal fibroblasts were treated with the combination, and the induction of chondrocyte differentiation was assessed by detecting the expression of the cartilage marker genes and the accumulation of proteoglycan-rich matrix. The effects of monolayer, spheroid, and 3-dimensional culture systems on induction by combinations of transcription factors were compared. The effects of the combination on hypertrophic and osteoblastic differentiation were evaluated by detecting the expression of the characteristic marker genes. RESULTS: No single factor induced fluorescence. Among various combinations examined, only the SOX5, SOX6, and SOX9 combination (the SOX trio) induced fluorescence within 3 days. The SOX trio successfully induced chondrocyte differentiation in all cell types tested, including nonchondrogenic types, and the induction occurred regardless of the culture system used. Contrary to the conventional chondrogenic techniques, the SOX trio suppressed hypertrophic and osteogenic differentiation at the same time. CONCLUSION: These data strongly suggest that the SOX trio provides signals sufficient for the induction of permanent cartilage.

Adult↗

Frequent amplifications and abundant expression of TRIO, NKD2, and IRX2 in soft tissue sarcomas.

Copy number gains and high-level amplifications of the short arm of chromosome 5 are frequently observed in soft tissue sarcomas. To identify genes from this region possibly involved in tumor progression, we analyzed 34 soft tissue sarcomas (10 pleomorphic and 8 dedifferentiated liposarcomas, 6 malignant fibrous histiocytomas, and 10 malignant peripheral nerve sheath tumors (MPNST)) using a DNA microarray including 418 BAC clones representing 99% of chromosome arm 5p. In seven tumors, distinct high-level amplifications were identified affecting four different subregions. From these regions, genes TERT, TRIO, SKP2, FBXO32, NKD2, SLC6A3, IRX2, POLS, FYB, PTGER4, and FGF10 were selected for detailed quantitative expression analysis (RQ-PCR) based on their potential tumorigenic function. Of these, TRIO, coding for a guanidine nucleotide exchange factor, was consistently overexpressed in all cases, while IRX2 and NKD2, both involved in the regulation of developmental processes via the WNT pathway, showed a characteristic expression only in MPNSTs. Detailed nonparametric multidimensional scaling analysis further showed that the expression of TRIO, IRX2, and NKD2 strongly correlated with the gene copy number. In conclusion, we found TRIO, IRX2, and NKD2 frequently affected by high-level amplifications as well as up-regulated in a gene-dosage dependent manner. Thus, these genes represent candidate targets of 5p amplifications in soft tissue sarcomas and might play a crucial role during the progression of this disease.

Adaptor Proteins, Signal Transducing↗

Clinical Utility of Trio Exome Sequencing in Rwandan Children With Autism Spectrum Disorder.

INTRODUCTION: Autism spectrum disorder (ASD) is a neurodevelopmental condition with substantial genetic and phenotypic heterogeneity. However, populations of African ancestry remain underrepresented in genomic studies, limiting understanding of ASD genetic architecture. This study aimed to characterize rare, clinically relevant genetic variants in a Rwandan pediatric ASD cohort using trio-based whole-exome sequencing (WES). METHODS: Trio-based WES was performed in 31 Rwandan pediatric patients with ASD (aged 2-18&#x2009;years) and their parents. Variants were analyzed using a trio-based workflow and classified according to American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines. RESULTS: Eleven candidate variants were identified in 9 of 31 patients, including four likely pathogenic variants and seven variants of uncertain significance. This resulted in a diagnostic yield of 12.9% (4/31), expanded to 29.0% when phenotypically concordant variants of uncertain significance were considered. Most likely pathogenic variants were identified in individuals with syndromic ASD who presented with intellectual disability, epilepsy, and global developmental delay. Likely pathogenic findings included two single nucleotide variants in GABRB3, SYNGAP1, and two copy-number variants involving the GNAS locus and chromosome 1p35.3-p35.2. CONCLUSIONS: The diagnostic yield observed in this cohort is consistent with previous trio-based WES studies of ASD. The findings support the clinical utility of WES for the genetic evaluation of ASD and underscore the need for expanded genomic studies in African populations.

Humans↗

Effects of tracheal insufflation of oxygen (TRIO) on blood gases during external cardiac compressions in dogs under ventricular fibrillation.

Tracheal insufflation of oxygen (TRIO) is a form of constant-flow ventilation. We studied the effect of TRIO at a flow rate of 2 L/kg/min on arterial blood gases during external cardiac compressions in dogs with ventricular fibrillation. During the combined application of TRIO and external cardiac compressions, all animals were adequately oxygenated and hyperventilated except in cases where lung edema developed in the course of cardiopulmonary resuscitation (CPR). No pulmonary barotrauma was observed. The findings suggest that TRIO might be used as a temporary measure for emergency ventilation when CPR is performed in certain situations such as upper airway abnormalities or cardiac arrest outside the hospital setting, where intermittent positive pressure ventilation is not feasible.

Journal Article↗

Trio exome sequencing identifies de novo variants in novel candidate genes in 19.62% of CAKUT families.

PURPOSE: Congenital anomalies of the kidney and urinary tract (CAKUT) encompass heterogenous malformations arising from defective nephrogenesis. To date, approximately 50 monogenic genes are known to cause CAKUT if mutated. Recent studies show the impact of de novo variants in genetic disease etiology. Trio exome sequencing identifies de novo variants in novel candidate genes in 19.62% of CAKUT families. METHODS: We performed trio-based exome sequencing in 209 families with CAKUT to detect novel candidate disease genes. RESULTS: Trio analysis yielded in the identification of CAKUT candidate genes in 96 of 209 trio families (45.93%). In 41 of 209 cases, we detected strong de novo variants in 45 potential novel CAKUT candidate genes (19.62%). We developed a prioritization approach that highlights a truncating de novo variant in SOX13 (HGNC:11192) as a promising cause for CAKUT. In addition, further allele carriers for the candidate gene CHD1L (HGNC:1916) were identified, thus supporting the role of CHD1L in the pathogenesis of CAKUT. CONCLUSION: We conclude that de novo variants in potential novel CAKUT candidate genes contribute to the disease etiology and present SOX13 as a potential novel cause for CAKUT.

Humans↗

The guanine nucleotide exchange factor trio mediates axonal development in the Drosophila embryo.

Recent analysis of Rho subfamily GTPases in Drosophila revealed roles for Rac and Cdc42 during axonogenesis. Here, we describe the identification and characterization of the Drosophila counterpart of Trio, a guanine nucleotide exchange factor (GEF) that associates with the receptor phosphatase LAR and regulates GTPase activation in vertebrate cells. Mutants deficient in trio activity display defects in both central and peripheral axon pathways reminiscent of phenotypes observed in embryos deficient in small GTPase function. Double mutant analysis shows that trio interacts with Rac in a dose-sensitive manner but not with Rho. Moreover, reduction of trio activity potentiates the phenotype of mutations in the LAR homolog Dlar, suggesting that these proteins collaborate in orchestrating the cytoskeletal events that underlie normal axonogenesis.

Animals↗

Retrospective perceptions of parents' child-rearing conduct by same-sex sibling trios in African American and European American families.

Adult (M = 33 years) trios of 20 sisters and 6 brothers from 15 African American and 11 European American intact families retrospectively described their parents' child-rearing conduct on the Parent-Child Relations Questionnaire II (Siegelman & Roe, 1979). Respondents' mean education (15.1 years) and family size exceeded U.S. averages. Fitting cultural stereotypes, mothers were depicted as more loving, more attentive, and less rejecting than fathers. African American parents were described as more demanding and less lenient than European American parents, although this finding was confounded with the latter's greater education (M = 14.4 years vs. 10.9 years). Daughter trios tended to differ more than son trios on their ratings of each parent, suggesting that daughters may be more attentive to intrafamilial events. The uniqueness of the sample and the small number of brother trios limit the generalizability of these findings.

Adult↗

The affected sib method. IV. Sib trios.

The classical sib pair method uses the expected and observed HLA (human leukocyte antigen) haplotype sharing distribution in sib pairs, who are affected with an HLA associated disease, to make inferences about the inheritance of the disease. In this paper we present the expected HLA haplotype sharing distributions in affected sib trios, and sib pairs, from families with three or more affected sibs. The underlying model for both distributions, as for the classical sib pair method, is that disease predisposition is determined by a single allele at an HLA-linked locus. The sib trio tests of hypotheses (additive and recessive), and disease parameter estimates (additive, recessive and intermediate), can be compared with those obtained from the classical sib pair analysis. In addition, the sib trio data allow parameter estimation for a general disease model to be made, if the data fall within the bounds of the expectation. This study forms the basis of later investigations which show that haplotype sharing of affected sib trios for two susceptibility alleles (negative complementation) model, which appears appropriate for insulin dependent diabetes mellitus (IDDM), moves outside the bound of the single susceptibility expectations outlined here, whereas haplotype sharing values for sib pairs are bound by the single susceptibility allele expectations. Available Caucasian IDDM data have been analysed. The results support genetic heterogeneity of IDDM.

Diabetes Mellitus, Type 1↗

Cdk5 and Trio modulate endocrine cell exocytosis.

Hormone secretion by pituitary cells is decreased by roscovitine, an inhibitor of cyclin-dependent kinase 5 (Cdk5). Roscovitine treatment reorganizes cortical actin and ultrastructural analysis demonstrates that roscovitine limits the ability of secretory granules to approach the plasma membrane or one another. Trio, a multifunctional RhoGEF expressed in pituitary cells, interacts with peptidylglycine alpha-amidating monooxygenase, a secretory granule membrane protein known to affect the actin cytoskeleton. Roscovitine inhibits the ability of Trio to activate Rac, and peptides corresponding to the Cdk5 consensus sites in Trio are phosphorylated by Cdk5. Together, these data suggest that control of the cortical actin cytoskeleton, long known to modulate hormone exocytosis and subsequent endocytosis, involves Cdk5-mediated activation of Trio.

Actins↗

The Trio family of guanine-nucleotide-exchange factors: regulators of axon guidance.

Axon guidance requires the integration of diverse guidance signals presented by numerous extracellular cues and cell-cell interactions. The molecular mechanisms that interpret these signals involve networks of intracellular signaling proteins that coordinate a variety of responses to the environment, including remodeling and assembly of the actin cytoskeleton. Although it has been clear for some time that Rho family GTPases play a central role in the orchestration of cytoskeletal assembly, our understanding of the components that regulate these important molecules is far more primitive. Recent functional studies of the Trio family of guanine-nucleotide-exchange factors reveal that Trio proteins play a vital role in neuronal cell migration and axon guidance. Although the molecular analysis of Trio proteins is still in its infancy, accumulated evidence suggests that Trio proteins function as integrators of multiple upstream inputs and as activators of multiple downstream pathways. Future studies of these mechanisms promise to yield insights not only into neural development but also into the ongoing function and remodeling of the adult nervous system.

Animals↗

Disentangling linkage disequilibrium and linkage from dense single-nucleotide polymorphism trio data.

Parent-offspring trios are widely collected for disease gene-mapping studies and are being extensively genotyped as part of the International HapMap Project. With dense maps of markers on trios, the effects of LD and linkage can be separated, allowing estimation of recombination rates in a model-free setting. Here we define a model-free multipoint method on the basis of dense sequence polymorphism data from parent-offspring trios to estimate intermarker recombination rates. We use simulations to show that this method has up to 92% power to detect recombination hotspots of intensity 25 times background over a region of size 10 kb typed at density 1 marker per 2.5 kb and almost 100% power to detect large hotspots of intensity >125 times background over regions of size 10 kb typed with just 1 marker per 5 kb (alpha = 0.05). We found strong agreement at megabase scales between estimates from our method applied to HapMap trio data and estimates from the genetic map. At finer scales, using Centre d'Etude du Polymorphisme Humain (CEPH) pedigree data across a 10-Mb region of chromosome 20, a comparison of population recombination rate estimates obtained from our method with estimates obtained using a coalescent-based approximate-likelihood method implemented in PHASE 2.0 shows detection of the same coldspots and most hotspots: The Spearman rank correlation between the estimates from our method and those from PHASE is 0.58 (p < 2.2(-16)).

Computer Simulation↗

Uricult trio as a screening test for bacteriuria in pregnancy.

OBJECTIVE: To establish the effectiveness in an indigent urban population of Uricult Trio as a screening test for asymptomatic bacteriuria in pregnancy and in diagnosing urinary tract infections (UTI) in symptomatic pregnant women. Likelihood ratios were established for positive and negative Uricult Trio test results. SUBJECTS: Two populations of patients from the Pretoria region were involved: (i) asymptomatic pregnant women attending the antenatal clinic for the first time or presenting in labour; and (ii) pregnant women with symptoms suggestive of UTI. METHOD: A midstream urine specimen was collected from the two populations of patients, plated onto the Uricult Trio and sent to the laboratory for culture. RESULTS: The prevalence of asymptomatic bacteriuria in this population was 23%, and for women with symptoms suggestive of UTI, 29%. The likelihood ratios for a positive test were 1.8 and 1.5 for asymptomatic and symptomatic patients respectively. The likelihood ratios for a negative test were 0.35 and 0.44 for asymptomatic and symptomatic patients respectively. Escherichia coli was the causative agent in 36% of cases. CONCLUSION: Uricult Trio is not effective as a screening test for asymptomatic bacteriuria in pregnancy or for diagnosing UTIs in women with symptoms suggestive of infection.

Bacteriuria↗

Machining efficiency of Flex-R, K-Flex, Trio-Cut, and S Files.

Many root canal instruments with several different designs have been introduced during recent years. This article evaluates the machining properties of four such instruments: the Flex-R, K-Flex, Trio-Cut, and S file. There are large variations in the machining properties of these instruments. The results are comparable to findings when evaluating conventional root canal files which show that the Hedstrom file is much more efficient when considering removal of material than the K file. The Flex-R file, K-Flex file, and Trio-Cut file are similar in design. The two former brands perform in a similar fashion, while the Trio-Cut file is less efficient than any of the evaluated K files. The S file performs as a Hedstrom file which can be expected from its similarity in design to that instrument.

Equipment Design↗

A trio family study showing association of the lymphotoxin-alpha N26 (804A) allele with coronary artery disease.

Family-based studies to map susceptibility genes through linkage disequilibrium have been successful in early-onset diseases where parental-proband trios are readily collected, but are believed to be unworkable for late-onset diseases such as coronary artery disease (CAD). PROCARDIS is a European multicentre study that was designed to identify susceptibility genes for CAD. We have tested the transmission of a putatively functional allele, lymphotoxin-alpha N26 (804A), in more than 400 PROCARDIS trio families. The present study demonstrates association of this allele with CAD in white Europeans, a different ethnic group with a heavier CAD burden than the Japanese in which the association was initially identified, which suggests a broad relevance to CAD susceptibility. The practicalities of implementing a trio-family design for late-onset diseases are discussed.

Alleles↗

Evidence to suggest biased phenotypes in children with Attention Deficit Hyperactivity Disorder from completely ascertained trios.

The transmission disequilibrium test (TDT) is widely used as a robust statistical method to test for genetic association due to linkage based upon analysis of parent-proband trios. The TDT and other family-based tests (eg haplotype relative risk method) are commonly used in association studies including those of ADHD because of concerns that the case-control design has a strong tendency for false positives due to poor matching between cases and controls. Unfortunately, it is not always possible to obtain DNA from both parents in studies of this design, even where the onset of disorder is in childhood, and usually the missing parent is the father. Despite the fact that methods exist for analysis where one parent is missing, many family-based studies are based on the collection or analysis of complete trios only. However this selection process might potentially introduce bias, particularly for studies of behavioural phenotypes like ADHD because the phenotype of proband or parents might influence family stability and therefore complete parental ascertainment. We set out to examine whether children with ADHD and for whom DNA samples from fathers were missing ('duos') differed phenotypically from children for whom genotype information was available from both parents ('trios'). Children from duos showed a significantly higher frequency of DMS-IV ADHD-combined type, significantly more co-morbid conduct disorder and conduct disorder symptoms, and a trend for higher total ADHD symptom scores. Excluding duos from sample collection and analysis may result in systematic bias. If comorbid conduct disorder and ADHD-combined type index increased genetic liability, exclusion of duos could further reduce the power of the TDT (and similar tests) to detect susceptibility genes for ADHD, or replicate effects detected by case-control analysis.

Adolescent↗

An alternative transcript derived from the trio locus encodes a guanosine nucleotide exchange factor with mouse cell-transforming potential.

By screening cDNA expression libraries derived from fresh leukemic cells of adult T-cell leukemia for the potential to transform murine fibroblasts, NIH3T3, we have identified a novel transforming gene, designated Tgat. Expression of Tgat in NIH3T3 resulted in the loss of contact inhibition, increase of saturation density, anchorage-independent growth in a semisolid medium, tumorigenicity in nude mice, and increased invasiveness. Sequence comparison revealed that an alternative RNA splicing of the Trio gene was involved in the generation of Tgat. The Tgat cDNA encoded a protein product consisting of the Rho-guanosine nucleotide exchange factor (GEF) domain of a multifunctional protein, TRIO, and a unique C-terminal 15-amino acid sequence, which were derived from the exons 38-46 of the Trio gene and a novel exon located downstream of its last exon (exon 58), respectively. A Tgat mutant cDNA lacking the C-terminal coding region preserved Rho-GEF activity but lost the transforming potential, indicating an indispensable role of the unique sequence. On the other hand, treatment of Tgat-transformed NIH3T3 cells with Y-27632, a pharmacological inhibitor of Rho-associated kinase, abrogated their transforming phenotypes, suggesting the coinvolvement of Rho-GEF activity. Thus, alternative RNA splicing, resulting in the fusion protein with the Rho-GEF domain and the unique 15 amino acids, is the mechanism generating the novel oncogene, Tgat.

3T3 Cells↗