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Ridha Joober

Publications and source records attributed to Ridha Joober.

At least 19 recordsLinked to original sources
PubMed2007

Informative phenotypes for genetic studies of psychiatric disorders.

Despite its initial promise, there has been both progress and some set backs in genetic studies of the major psychiatric disorders of childhood and adulthood. Finding true susceptibility genes may be delayed because the most genetically informative phenotypes are not being used on a regular basis in linkage analysis and association studies. It is highly likely that using alternative phenotypes instead of DSM diagnostic categories will lead more rapid success in the search for these susceptibility genes. The objective of this paper is to describe the different types of informative phenotypes that can be employed in psychiatric genetic studies, to clarify their uses, to identify several methodologic issues the design and conduct of linkage and association studies that use alternative phenotypes and finally to suggest possible solutions to those difficulties. This is a conceptual review with a focus on methodological issues that may arise in psychiatric genetics and examples are taken from the literature on autism, schizophrenia, bipolar disorder, and alcoholism.

Diagnostic and Statistical Manual of Mental Disord↗
PubMed2006

Dopamine transporter 3'-UTR VNTR genotype and ADHD: a pharmaco-behavioural genetic study with methylphenidate.

We sought to test the hypothesis that the variable number of tandem repeat (VNTR) polymorphism in the 3'-untranslated region (3'-UTR) of the SLC6A3 gene modulates behavior in children with ADHD and/or behavioral response to methylphenidate (MPH). One hundred and fifty-nine children with AHDH (6-12 years) were assessed with regard to the Conners' Global Index for parents (CGI-Parents) and teachers (CGI-Teachers) and the response of these behaviors to MPH (0.5 mg/kg/day) using a 2-week prospective within-subject (crossover) trial. Based on CGI-Parents, the profile of behavioral response to MPH as compared to placebo was not parallel in the three groups of children separated according to their genotype in the 3'-UTR VNTR polymorphism of SLC6A3, as indicated by a significant (p=0.017) genotype by treatment two-way interaction. Individuals having the 9/10 and 10/10 genotypes displayed a significant positive response to MPH as opposed to those homozygous for the 9-repeat allele. No genotype or genotype by treatment interaction was observed for CGI-Teachers. These findings support a role for the DAT gene 3'-UTR VNTR polymorphism in modulating the response of some behavioral dimensions to MPH in children with ADHD. They also suggest the presence of genetic heterogeneity that could be indexed by the quality of behavioral response to MPH.

3' Untranslated Regions↗
PubMed2006

Association study of the trinucleotide repeat polymorphism within SMARCA2 and schizophrenia.

BACKGROUND: Brahma (BRM) is a key component of the multisubunit SWI/SNF complex, a complex which uses the energy of ATP hydrolysis to remodel chromatin. BRM contains an N-terminal polyglutamine domain, encoded by a polymorphic trinucleotide (CAA/CAG) repeat, the only known polymorphism in the coding region of the gene (SMARCA2). We have examined the association of this polymorphism with schizophrenia in a family-based and case/control study. SMARCA2 was chosen as a candidate gene because of its specific role in developmental pathways, its high expression level in the brain and some evidence of its association with schizophrenia spectrum disorder from genome-wide linkage analysis. RESULTS: Family-based analysis with 281 complete and incomplete triads showed that there is no significant preferential transmission of any of the alleles to the affected offspring. Also, in the case/control analysis, similar allele and genotype distributions were observed between affected cases (n = 289) and unaffected controls (n = 273) in each of three Caucasian populations studied: French Canadian, Tunisian and other Caucasians of European origin. CONCLUSION: Results from our family-based and case-control association study suggest that there is no association between the trinucleotide repeat polymorphism within SMARCA2 and schizophrenia.

Case-Control Studies↗
PubMed2006

Identification of informative strains and provisional QTL mapping of amphetamine (AMPH)-induced locomotion in recombinant congenic strains (RCS) of mice.

Amphetamine (AMPH)-induced locomotor activity is a rodent behavioral trait that reflects mesolimbic dopaminergic activity. To identify potential quantitative trait loci (QTL) associated with this behavior, we used 34 recombinant congenic strains (RCSs) of mice derived from A/J (A strains) and C57BL/6J (B strains) and measured AMPH-induced total distance traveled (AMPH-TDIST). Two strains in the A panel (A52 and A63) showed significantly elevated AMPH-TDIST compared to the parental A/J strain and behaved similarly to C57BL/6J. Simple sequence length polymorphism (SSLP) markers on chromosomes 1, 2, 3, 5, 6, 8, 9, 10 and 20 were significantly associated with AMPH-TDIST in the A strains. Within the B panel, two strains (B81 and B74) had significantly higher and two strains (B69 and B75) had significantly lower AMPH-TDIST than C57BL/6J. Markers associated with AMPH-TDIST in the B strains appeared on chromosomes 5, 17 and 20. Combining data from this approach and other genetic (mapping data in humans) and functional (cDNA expression) sources may help to identify suitable candidate genes relevant to human disorders where mesolimbic dopamine dysregulation has been postulated.

Amphetamine↗
PubMed2006

Intrafamilial correspondences on platelet [3H-]paroxetine-binding indices in bulimic probands and their unaffected first-degree relatives.

Reduced brain serotonin (5-hydroxytryptamine: 5-HT) transporter activity has been associated with susceptibility to various forms of psychopathology, including bulimia nervosa (BN) and related syndromes characterized by appetitive or behavioural dysregulation. We applied density (Bmax) of platelet [3H-]paroxetine binding as a proxy for central 5-HT reuptake activity in two groups of women (33 with BN-spectrum disorders and 19 with no apparent eating or psychiatric disorders), most of these individuals' mothers (31 and 18, respectively), and a small sampling of their sisters (seven and eight, respectively). Hierarchical linear modeling techniques were used to account for nesting of individuals within families and diagnostic groupings. Bulimic probands, their mothers, and their sisters all displayed significantly lower density (Bmax) of platelet-paroxetine binding than did 'control' probands, mothers, or sisters-even when relatives showing apparent eating or psychiatric disturbances were excluded. In addition, in bulimic probands and mothers, significant within-family correlations were obtained on Bmax. These findings imply a heritable trait (or endophenotype), linked to 5-HT activity, and carried by BN sufferers and their first-degree relatives (even when asymptomatic). We propose that, under conducive circumstances, such a trait may increase risk of binge-eating behavior, or associated symptoms of affective or behavioral dysregulation.

Adolescent↗
PubMed2006

Relationship between response to methylphenidate treatment in children with ADHD and psychopathology in their families.

OBJECTIVE: To compare the pattern of familial aggregation of psychopathology in children who are good responders (GR) to methylphenidate (MPH) versus those who are poor responders (PR). METHOD: A total of 118 clinically referred children ages 6 to 12 years, diagnosed with ADHD participated in a double-blind, placebo-controlled, randomized 2-week crossover trial of MPH from 1999 to 2004. A low dose of 0.5 mg/kg of body weight of MPH divided in two equal doses was used. Family history was obtained by interviewing at least one key historian relative of each subject using Family Interview for Genetic Studies. Information was collected on 342 first-degree and 1,151 second-degree relatives of children with attention-deficit/hyperactivity disorder. RESULTS: Forty-four subjects showed mild or no improvement (PR) and 74 showed moderate or very much improvement (GR) on MPH over placebo. First-degree relatives of GR subjects were at significantly higher risk of attention-deficit/hyperactivity disorder than the relatives of PR subjects (p<.05). Second-degree relatives of the GR were at significantly higher risk of antisocial personality disorder compared to the relatives of PR subjects (p<.05). CONCLUSIONS: The significantly higher presence of attention-deficit/hyperactivity disorder in the first-degree relatives and of antisocial personality disorder in the second-degree relatives of GR children suggests that this group may, at least partially, be distinct from the PR group on the basis of genetic determinants.

Attention Deficit Disorder with Hyperactivity↗
PubMed2006

Sleep and COMT polymorphism in ADHD children: preliminary actigraphic data.

OBJECTIVE: To examine whether COMT (catechol-O-methyltransferase) polymorphism modulates aspects of sleep in children diagnosed with attention-deficit/hyperactivity disorder (ADHD). METHOD: Nightly sleep actigraphic recordings during a double-blind, placebo-controlled, crossover clinical study (1 week of 0.5 mg/kg MPH; 1 week of placebo) were obtained for 34 children, 7.4 to 12 years old, diagnosed with ADHD (DSM-IV). Diagnosis was generated by the Diagnostic Interview Schedule for Children and was confirmed by multidisciplinary consensus. RESULTS: Children who were Val allele carriers had poorer sleep continuity compared with children with the Met-Met genotype while receiving a placebo and while receiving methylphenidate. CONCLUSIONS: The findings of the present study support the hypothesis that sleep disturbances in children with ADHD are related to the underlying pathophysiology of the disorder.

Attention Deficit Disorder with Hyperactivity↗
PubMed2006

COMT Val108/158Met gene variant, birth weight, and conduct disorder in children with ADHD.

OBJECTIVE: In a recent study, Thapar and colleagues reported that COMT "gene variant and birth weight predict early-onset antisocial behavior in children" with attention-deficit/hyperactivity disorder. We have attempted to replicate these findings in a group of ADHD children using a similar research design. METHOD: Children (n=191) between 6 and 12 years of age who were diagnosed with ADHD were included in the study. Conduct disorder was diagnosed according to DSM-IV criteria based on clinical evaluation and a structured interview (Diagnostic Interview Schedule for Children-IV). The mother's report on the child's birth weight was used in the analysis. Logistic regression analysis, with genotype and birth weight as independent variables and DSM-IV conduct disorder as the dependent variable, was conducted. RESULTS: No significant main effects of genotype and birth weight or interaction effects on conduct disorder were observed. CONCLUSION: In this sample of children diagnosed with ADHD, we find no association between the COMT ValMet gene variant, birth weight, and conduct disorder. Further investigations are required before using birth weight and COMT genotype as predictors of conduct disorder in children with attention-deficit/hyperactivity disorder, especially given the societal and legal ramifications of conduct disorder.

Birth Weight↗
PubMed2006

Schizotypy, attention deficit hyperactivity disorder, and dopamine genes.

Previous research has suggested that there may be overlap between schizophrenia and attention-deficit hyperactivity disorder (ADHD). The relationship between schizotypal personality traits, ADHD features and polymorphisms was evaluated in dopamine-related genes. Thirty-one healthy, Caucasian men completed the Rust Inventory of Schizotypal Cognitions (RISC) and the ADHD Self-Report Scale (ASRS). Catechol-O-methyltransferase (COMT) Val158Met, dopamine receptors of the D3 type (DRD3) Ser9Gly, DRD4 variable number of tandem repeats (VNTR), and SLC6A3 VNTR polymorphisms were analyzed. RISC score was correlated with ASRS score (r = 0.54, P = 0.003). COMT Met homozygotes had higher ASRS scores than Val homozygotes (P = 0.005). These findings are consistent with evidence of overlap between schizophrenia and ADHD and support an involvement of COMT genotype in ADHD features.

Adult↗
PubMed2006

Efficacy of methylphenidate in children with attention-deficit hyperactivity disorder and learning disabilities: a randomized crossover trial.

OBJECTIVE: To determine whether children with attention-deficit hyperactivity disorder (ADHD) and learning disabilities respond differently to methylphenidate (MPH) compared with children with ADHD only. METHODS: We conducted a prospective, double-blind, placebo-controlled, randomized, 2-week crossover trial of MPH, during which response to MPH was assessed. Learning ability was appraised using the Wide Range Achievement Test, Revised (WRAT-R), for English-speaking students and the Test de rendement pour francophones for French-speaking students. The study was conducted at the Douglas Hospital, a McGill University-affiliated teaching hospital in Montréal. Ninety-five children, aged 6-12 years, who met the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), criteria for ADHD participated in the study, which ran from 2001 to 2004. The outcome measure used was the Consensus Clinical Response, an indicator of the degree of clinical improvement shown when taking MPH. RESULTS: The proportion of children with learning disabilities who responded to MPH (55%) was significantly smaller (chi(2)1 = 4.5, p = 0.034) than the proportion of children without learning disabilities who responded adequately to MPH (75%). This difference was mainly because of children with mathematics disability being particularly unresponsive to MPH (chi(2)1 = 4.5, p = 0.034). Children with reading disability did not show this pattern of poor response (chi(2)1 = 1.0, p = 0.33). CONCLUSION: Children with ADHD and comorbid learning disability tended to respond more poorly to MPH. In particular, children with disability in mathematics responded less to MPH than those without disability in mathematics. Additional therapy may be indicated for this group of patients.

Attention Deficit Disorder with Hyperactivity↗
PubMed2005

Chromosome 11-q24 region in Tourette syndrome: association and linkage disequilibrium study in the French Canadian population.

Previous studies have found association and linkage between Tourette syndrome (TS) and markers at the 11q24 region, mainly with markers D11S1377 and D11S933. In order to determine if these positive findings could be replicated in our sample, we undertook a family-based association study in 199 French Canadian TS nuclear families. We genotyped 572 individuals from 174 complete and 25 incomplete TS trios. TDT analysis failed to detect an association between TS and six markers from 11q24. Furthermore, no haplotype combining alleles from D11S1377, D11S933, or any of the other four markers was associated with the disorder. Linkage disequilibrium analysis showed evidence of historical recombination between every contiguous pair of markers, indicating that these genetic variants are probably in equilibrium in the French Canadian population. Further analysis in additional families, with different methodologies (linkage and association) will be required in order to determine if the 11q24 region harbors a susceptibility locus for TS. If it does, this defect may not be frequent in the French Canadian population due to locus heterogeneity.

Adolescent↗
PubMed2005

Increased prevalence of schizophrenia spectrum disorders in relatives of neuroleptic-nonresponsive schizophrenic patients.

OBJECTIVE: It is suggested that schizophrenic patients who respond to neuroleptic medication and those who do not might differ with respect to their pathogenesis. In particular, it has been proposed that genetic factors may contribute to treatment response and/or outcome. In order to test this hypothesis, we compared the pattern of familial aggregation of schizophrenia related disorders in schizophrenic patients who are either responders (R) or nonresponders (NR) to typical neuroleptics. METHOD: R (n=36) or NR (n=35) patients to typical neuroleptics and healthy controls (n=63) were recruited. At least one key informant relative of each proband was interviewed blind as to the status of the proband using the Family Interview for Genetic Studies. Morbid risk for schizophrenia and cluster A personality disorders and family loading score for schizophrenia were examined in first- and second-degree relatives of these probands. RESULTS: First-degree relatives of NR patients were at a significantly higher risk for schizophrenia (MR=8.84), compared, respectively, to relatives of controls (MR=1.52) or relatives of R patients (MR=2.45). The same pattern was observed in second-degree relatives. Family loading score for schizophrenia in first- and second-degree relatives was significantly higher in NR compared to R patients. CONCLUSIONS: Schizophrenic patients who do not respond to typical neuroleptics may suffer from a more familial form of schizophrenia compared to patients who are responders.

Adult↗
PubMed2005

Association of the promoter polymorphism -1438G/A of the 5-HT2A receptor gene with behavioral impulsiveness and serotonin function in women with bulimia nervosa.

Separate lines of research suggest that the functional alterations in the serotonin (5-HT) 2A receptor are associated with 5-HT tone, behavioral impulsiveness, and bulimia nervosa (BN). We explored the effect of allelic variations within the 5-HT2A receptor gene promoter polymorphism -1438G/A on trait impulsiveness and serotonin function in women with BN. Participants included women with BN having the A allele (i.e., AA homozygotes and AG heterozygotes, BNA+, N = 21); women with BN but without the A allele (i.e., GG homozygotes, BNGG, N = 12), and normal eater control women having the A allele (NEA+, N = 19) or without the A allele (NEGG; N = 9). The women were assessed for psychopathological tendencies and eating disorder symptoms, and provided blood samples for measurement of serial prolactin responses following oral administration of the post-synaptic partial 5-HT agonist meta-chlorophenylpiperazine (m-CPP). The BNGG group had higher scores than the other groups on self-report measures of non-planning and overall impulsiveness and had blunted prolactin response following m-CPP. The bulimic groups did not differ from each other on current eating symptoms or on frequencies of other Axis I mental disorders. Findings indicate that women with BN who are GG homozygotes on the -1438G/A promoter polymorphism are characterized by increased impulsiveness and lower sensitivity to post-synaptic serotonin activation. These findings implicate the GG genotype in the co-aggregation of impulsive behaviors and alterations of post-synaptic 5-HT functioning in women with BN.

Administration, Oral↗
PubMed2005

NLGN3/NLGN4 gene mutations are not responsible for autism in the Quebec population.

Jamain [2003: Nat Genet 34:27-29] recently reported mutations in two neuroligin genes in sib-pairs affected with autism. In order to confirm these causative mutations in our autistic population and to determine their frequency we screened 96 individuals affected with autism. We found no mutations in these X-linked genes. These results indicate that mutations in NLGN3 and NLGN4 genes are responsible for at most a small fraction of autism cases and additional screenings in other autistic populations are needed to better determine the frequency with which mutations in NLGN3 and NLGN4 occur in autism.

Adolescent↗
PubMed2005

CAA insertion polymorphism in the 3'UTR of Nogo gene on 2p14 is not associated with schizophrenia.

The Nogo gene was putatively implicated in schizophrenia based on gene expression and genetic association data. In this study, we attempt to replicate the possible association of the CAA insertion and a nearby TATC deletion with schizophrenia in 204 complete and incomplete triads and in a sample of 462 unrelated cases and 153 controls, all of Caucasian origin. Our genotyping results indicated that neither the trinucleotide insertion polymorphism (CAAins; 43.4% vs. 41.8%, p>0.5) nor the polymorphism-TATC deletion (TATCdel; 49.8% vs. 49.3%, p>0.1) allele frequency is significantly different in patients compared to controls. The homozygous CAAins frequency is not significantly different between patients and controls either (18.0% vs. 15.0%, chi2=0.985, p>0.1). Furthermore, neither CAAins/TATCdel individually, nor the haplotype carrying both CAAins and TATCdel is preferentially transmitted to affected offspring.

3' Untranslated Regions↗