Stephen A. Haddad

Corticotrophin-releasing hormone type 1 receptor gene (CRHR1) variants predict posttraumatic stress disorder onset and course in pediatric injury patients

Posttraumatic stress disorder (PTSD) is a common and disabling anxiety disorder that may occur in the aftermath of exposure to potentially traumatic life events. PTSD is moderately heritable, but few specific molecular variants accounting for this heritability have been identified. Genes regulating the hypothalamic-pituitary-adrenal (HPA) axis, such as corticotrophin-releasing hormone type 1 receptor gene (CRHR1), have been implicated in traumatic-stress related phenotypes but have yet to be studied in relation to PTSD. The present study sought to examine the relation between 9 single nucleotide polymorphisms (SNPs) in the CRHR1 gene and posttraumatic stress symptoms in a prospective study of pediatric injury patients (n = 103) who were first assessed in the acute aftermath of their injury at the hospital. Results indicated that multiple SNPs were associated with acute symptoms at a univariate level, and after correction for multiple testing, rs12944712 was significantly related to acute PTSD symptoms. Longitudinal latent growth curve analyses suggest that rs12944712 is also related to both acute symptom level and trajectory of symptoms over time. The present study adds support for the role of CRHR1 in the stress response following potentially traumatic event exposure in youth. It should be noted that the sample size in this study was small, and therefore statistical power was low; following, results from this study should be considered preliminary. Although results are not definitive, the findings from this study warrant future replication studies on how variation in this gene relates to response to traumatic event exposure in youth.

Predictors of Family Accommodation in Obsessive-Compulsive Disorder

BACKGROUND Obsessive-compulsive disorder (OCD) is a serious, disabling illness. Family members are frequently involved by attempting to stop rituals or by performing rituals for their relative. Factors associated with family accommodation of OCD have been largely overlooked in the literature. This study aims to identify the frequency and clinical predictors of OCD family accommodation behaviors. METHODS Participants include those with a first admission to the McLean/Massachusetts General Hospital OCD Institute (N = 110). The Family Accommodation Scale was completed independently by family members. Univariate relationships between factors and family accommodation were assessed via graphs, parametric and non-parametric testing. Multiple regression analyses modeled relationships between family accommodation and predictor variables. RESULTS Family accommodation was reported in 96.9% of cases, and predominantly occurred at least daily (59.1% of cases). Most common behaviors included providing reassurance and waiting for ritual completion. Two of 13 potential predictors were significantly correlated with family accommodation both in univariate regression analysis and in the final regression model (F = 10.15; p < 0.0001; R-square = 0.17; adjusted R-Square = 0.15). These include OCD severity (p = 0.0007) and the cleaning/contamination symptom dimension (p = 0.03). CONCLUSIONS Family accommodation is ubiquitous in OCD. Psychoeducation regarding potential deleterious effects of accommodation must not be overlooked in management of this illness.

Paternal age increases the risk for autism in an Iranian population sample

BackgroundAutism is a neurodevelopmental disorder which is known to have a strong genetic component and is most likely oligogenic. However, the necessary role of environmental factors has been well documented. Prior research suggests that parental characteristics, such as age and level of education, may be associated with a risk of autism. Parental age has been shown to be associated with many disorders, such as schizophrenia, childhood cancer and fetal death. However, results from studies of parental age and autism are inconsistent.MethodsIn the present study, we investigated the association of autism with parental age in 179 autism cases and 1611 matched cohort children from Iran. Each case was matched with nine cohort controls on parental education, sex, order of birth, consanguineous marriage, urbanism and province of residence. The Cox regression model was used to carry out conditional logistic regression on the matched data.ResultsThere was a significant association between higher paternal age, but not maternal age, and an increasing risk of autism. An analysis of the combined effect of parental age and education also revealed that parents with higher education had an increased risk of having autistic children, with a dose-response effect of parental age.ConclusionsThis study, which is the first epidemiological study of autism in Iran, provides evidence of the association of paternal age and risk of autism.

Multi-locus genome-wide association analysis supports the role of glutamatergic synaptic transmission in the etiology of major depressive disorder

Major depressive disorder (MDD) is a common psychiatric illness characterized by low mood and loss of interest in pleasurable activities. Despite years of effort, recent genome-wide association studies (GWAS) have identified few susceptibility variants or genes that are robustly associated with MDD. Standard single-SNP (single nucleotide polymorphism)-based GWAS analysis typically has limited power to deal with the extensive heterogeneity and substantial polygenic contribution of individually weak genetic effects underlying the pathogenesis of MDD. Here, we report an alternative, gene-set-based association analysis of MDD in an effort to identify groups of biologically related genetic variants that are involved in the same molecular function or cellular processes and exhibit a significant level of aggregated association with MDD. In particular, we used a text-mining-based data analysis to prioritize candidate gene sets implicated in MDD and conducted a multi-locus association analysis to look for enriched signals of nominally associated MDD susceptibility loci within each of the gene sets. Our primary analysis is based on the meta-analysis of three large MDD GWAS data sets (total N=4346 cases and 4430 controls). After correction for multiple testing, we found that genes involved in glutamatergic synaptic neurotransmission were significantly associated with MDD (set-based association P=6.9 × 10−4). This result is consistent with previous studies that support a role of the glutamatergic system in synaptic plasticity and MDD and support the potential utility of targeting glutamatergic neurotransmission in the treatment of MDD.

The human ortholog of acid-sensing ion channel gene ASIC1a is associated with panic disorder and amygdala structure and function.

BACKGROUND Individuals with panic disorder (PD) exhibit a hypersensitivity to inhaled carbon dioxide, possibly reflecting a lowered threshold for sensing signals of suffocation. Animal studies have shown that carbon dioxide-mediated fear behavior depends on chemosensing of acidosis in the amygdala via the acid-sensing ion channel ASIC1a. We examined whether the human ortholog of the ASIC1a gene, ACCN2, is associated with the presence of PD and with amygdala structure and function. METHODS We conducted a case-control analysis (n = 414 PD cases and 846 healthy controls) of ACCN2 single nucleotide polymorphisms and PD. We then tested whether variants showing significant association with PD are also associated with amygdala volume (n = 1048) or task-evoked reactivity to emotional stimuli (n = 103) in healthy individuals. RESULTS Two single nucleotide polymorphisms at the ACCN2 locus showed evidence of association with PD: rs685012 (odds ratio = 1.32, gene-wise corrected p = .011) and rs10875995 (odds ratio = 1.26, gene-wise corrected p = .046). The association appeared to be stronger when early-onset (age ≤ 20 years) PD cases and when PD cases with prominent respiratory symptoms were compared with controls. The PD risk allele at rs10875995 was associated with increased amygdala volume (p = .035) as well as task-evoked amygdala reactivity to fearful and angry faces (p = .0048). CONCLUSIONS Genetic variation at ACCN2 appears to be associated with PD and with amygdala phenotypes that have been linked to proneness to anxiety. These results support the possibility that modulation of acid-sensing ion channels may have therapeutic potential for PD.

Genome-wide association studies in women of African ancestry identified 3q26.21 as a novel susceptibility locus for oestrogen receptor negative breast cancer.

Multiple breast cancer loci have been identified in previous genome-wide association studies, but they were mainly conducted in populations of European ancestry. Women of African ancestry are more likely to have young-onset and oestrogen receptor (ER) negative breast cancer for reasons that are unknown and understudied. To identify genetic risk factors for breast cancer in women of African descent, we conducted a meta-analysis of two genome-wide association studies of breast cancer; one study consists of 1,657 cases and 2,029 controls genotyped with Illumina’s HumanOmni2.5 BeadChip and the other study included 3,016 cases and 2,745 controls genotyped using Illumina Human1M-Duo BeadChip. The top 18,376 single nucleotide polymorphisms (SNP) from the meta-analysis were replicated in the third study that consists of 1,984 African Americans cases and 2,939 controls. We found that SNP rs13074711, 26.5 Kb upstream of TNFSF10 at 3q26.21, was significantly associated with risk of oestrogen receptor (ER)-negative breast cancer (odds ratio [OR]=1.29, 95% CI: 1.18-1.40; P = 1.8 × 10 − 8). Functional annotations suggest that the TNFSF10 gene may be involved in breast cancer aetiology, but further functional experiments are needed. In addition, we confirmed SNP rs10069690 was the best indicator for ER-negative breast cancer at 5p15.33 (OR = 1.30; P = 2.4 × 10 − 10) and identified rs12998806 as the best indicator for ER-positive breast cancer at 2q35 (OR = 1.34; P = 2.2 × 10 − 8) for women of African ancestry. These findings demonstrated additional susceptibility alleles for breast cancer can be revealed in diverse populations and have important public health implications in building race/ethnicity-specific risk prediction model for breast cancer.

Influence of RGS2 on Sertraline Treatment for Social Anxiety Disorder

Only a minority of patients with social anxiety disorder (SAD) has a robust therapeutic response to evidence-based serotonin reuptake inhibitor (SSRI) treatment. To help improve the personalized medicine approach to psychiatric care, we evaluated several candidate genetic predictors of SSRI response in SAD. At the start of a randomized controlled trial (NCT00282828), 346 patients with SAD at three sites received protocol-driven, open-label treatment with sertraline, up to 200. mg/d over 10 weeks. Efficacy was determined using a continuous measure of outcome (Liebowitz Social Anxiety Scale (LSAS)) and dichotomous indicators of response (LSAS ⩽50) and remission (LSAS ⩽30). Predictors of efficacy were examined in multivariate regression models that included eight polymorphic variants in four candidate genes (four in RGS2, two in HTR2A, one in SLC6A2, and one in SLC6A4). Adjusting for genetic ancestral cluster and non-genetic predictors of response, all four single-nucleotide polymorphisms (SNPs) in RGS2 predicted change in LSAS over time, at study-wise significance (p=0.00833), with the minor allele associated with less improvement over time. After adjusting for genetic ancestral cluster and non-genetic predictors of remission, two of the four RGS2 SNPs predicted likelihood of remission at or just below study-wise significance (p=0.025): rs4606 (AOR=0.49 (95% CI=0.27–0.90), p=0.022) and rs1819741 (AOR=0.50 (95% CI=0.28–0.92), p=0.027). Variation in RGS2, a gene previously shown to be associated with social anxiety phenotypes and serotonergic neurotransmission, may be a biomarker of the likelihood of substantially benefiting from sertraline among patients with SAD.

Relationship Between Genetic Variation in the Glutaminase Gene GLS1 and Brain Glutamine/Glutamate Ratio Measured In Vivo

BACKGROUND Abnormalities in glutamatergic neurotransmission are implicated in several psychiatric disorders, but in vivo neurochemical studies of the glutamate (Glu) system have been hampered by a lack of adequate probes. By contrast, glutamine (Gln) and Glu can be quantified separately in proton magnetic resonance spectroscopy studies in vivo. Accumulating evidence suggests that the Gln/Glu ratio is a putative index of glutamatergic neurotransmission but interpretation of changes in the Gln/Glu ratio depends on the conditions of the system, including ammonia levels. METHODS Here, we explored whether variation in GLS1 (the gene encoding the brain isoform of glutaminase, which catalyzes Gln-to-Glu conversion) is associated with Gln/Glu measured in vivo in two brain regions (anterior cingulate cortex, parieto-occipital cortex). RESULTS A specific haplotype of four single nucleotide polymorphisms within GLS1 was significantly associated with Gln/Glu in the parieto-occipital cortex in an magnetic resonance spectroscopy-genetics dataset optimized for Gln/Glu detection (n = 42). This finding was replicated in a second magnetic resonance spectroscopy dataset that was optimized for γ-aminobutyric acid detection where Gln and Glu measurements could still be extracted (n = 40). CONCLUSIONS These findings suggest that genetic variation in a key component of glutamatergic machinery is associated with a putative in vivo index of glutamatergic neurotransmission. Thus, GLS1 genotype might provide insight into normal brain function and into the pathophysiology of many psychiatric conditions where glutamatergic neurotransmission has been implicated. It might also serve as a biomarker for predicting response to existing and novel therapeutic interventions in psychiatry that target glutamatergic neurotransmission.

Dissociable Genetic Contributions to Error Processing: A Multimodal Neuroimaging Study

Background Neuroimaging studies reliably identify two markers of error commission: the error-related negativity (ERN), an event-related potential, and functional MRI activation of the dorsal anterior cingulate cortex (dACC). While theorized to reflect the same neural process, recent evidence suggests that the ERN arises from the posterior cingulate cortex not the dACC. Here, we tested the hypothesis that these two error markers also have different genetic mediation. Methods We measured both error markers in a sample of 92 comprised of healthy individuals and those with diagnoses of schizophrenia, obsessive-compulsive disorder or autism spectrum disorder. Participants performed the same task during functional MRI and simultaneously acquired magnetoencephalography and electroencephalography. We examined the mediation of the error markers by two single nucleotide polymorphisms: dopamine D4 receptor (DRD4) C-521T (rs1800955), which has been associated with the ERN and methylenetetrahydrofolate reductase (MTHFR) C677T (rs1801133), which has been associated with error-related dACC activation. We then compared the effects of each polymorphism on the two error markers modeled as a bivariate response. Results We replicated our previous report of a posterior cingulate source of the ERN in healthy participants in the schizophrenia and obsessive-compulsive disorder groups. The effect of genotype on error markers did not differ significantly by diagnostic group. DRD4 C-521T allele load had a significant linear effect on ERN amplitude, but not on dACC activation, and this difference was significant. MTHFR C677T allele load had a significant linear effect on dACC activation but not ERN amplitude, but the difference in effects on the two error markers was not significant. Conclusions DRD4 C-521T, but not MTHFR C677T, had a significant differential effect on two canonical error markers. Together with the anatomical dissociation between the ERN and error-related dACC activation, these findings suggest that these error markers have different neural and genetic mediation.

Polymorphisms in vitamin D-related genes and risk of uterine leiomyomata

OBJECTIVE To investigate uterine leiomyomata (UL) incidence in relation to polymorphisms in genes involved in vitamin D metabolism and skin pigmentation. Rates of UL are 2-3 times higher in African Americans than in European Americans. Recent studies suggest that vitamin D deficiency is associated with an increased risk of UL. DESIGN Nested case-control study. SETTING Not applicable. PATIENT(S) Two thousand two hundred thirty-two premenopausal women first diagnosed with UL confirmed by ultrasound or surgery during 1997-2011 (cases) and 2,432 premenopausal women never diagnosed with UL through 2011 (controls). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Self-reported UL. We used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between each polymorphism and UL, controlling for age, geographic region, and ancestry. RESULT(S) Three of 12 polymorphisms were associated with UL at the nominal significance level: rs4944957 and rs12800438 near DHCR7 and rs6058017 in ASIP. After correction for multiple hypothesis testing, two single nucleotide polymorphisms remained significantly associated with UL (rs12800438 and rs6058017). Compared with the AA genotype for rs12800438 (correlated with higher serum 25[OH]D levels), ORs were 1.09 (95% CI, 0.92, 1.29) and 1.23 (95% CI, 1.03, 1.47) for the GA and GG genotypes, respectively. Compared with the AA genotype for rs6058017 (correlated with lighter skin pigmentation), ORs were 1.01 (95% CI, 0.83, 1.22) and 1.18 (95% CI, 0.97, 1.44) for the GA and GG genotypes, respectively. CONCLUSION(S) Our data support the hypothesis that vitamin D deficiency is involved in UL etiology.