Copy Number Variations Carriers Research Articles

Using rare genetic mutations to revisit structural brain asymmetry

Asymmetry between the left and right hemisphere is a key feature of brain organization. Hemispheric functional specialization underlies some of the most advanced human-defining cognitive operations, such as articulated language, perspective taking, or rapid detection of facial cues. Yet, genetic investigations into brain asymmetry have mostly relied on common variants, which typically exert small effects on brain-related phenotypes. Here, we leverage rare genomic deletions and duplications to study how genetic alterations reverberate in human brain and behavior. We designed a pattern-learning approach to dissect the impact of eight high-effect-size copy number variations (CNVs) on brain asymmetry in a multi-site cohort of 552 CNV carriers and 290 non-carriers. Isolated multivariate brain asymmetry patterns spotlighted regions typically thought to subserve lateralized functions, including language, hearing, as well as visual, face and word recognition. Planum temporale asymmetry emerged as especially susceptible to deletions and duplications of specific gene sets. Targeted analysis of common variants through genome-wide association study (GWAS) consolidated partly diverging genetic influences on the right versus left planum temporale structure. In conclusion, our gene-brain-behavior data fusion highlights the consequences of genetically controlled brain lateralization on uniquely human cognitive capacities.

Effects of gene dosage and development on subcortical nuclei volumes in individuals with 22q11.2 copy number variations.

The 22q11.2 locus contains genes critical for brain development. Reciprocal Copy Number Variations (CNVs) at this locus impact risk for neurodevelopmental and psychiatric disorders. Both 22q11.2 deletions (22qDel) and duplications (22qDup) are associated with autism, but 22qDel uniquely elevates schizophrenia risk. Understanding brain phenotypes associated with these highly penetrant CNVs can provide insights into genetic pathways underlying neuropsychiatric disorders. Human neuroimaging and animal models indicate subcortical brain alterations in 22qDel, yet little is known about developmental differences across specific nuclei between reciprocal 22q11.2 CNV carriers and typically developing (TD) controls. We conducted a longitudinal MRI study in a total of 385 scans from 22qDel (n = 96, scans = 191, 53.1% female), 22qDup (n = 37, scans = 64, 45.9% female), and TD controls (n = 80, scans = 130, 51.2% female), across a wide age range (5.5-49.5 years). Volumes of the thalamus, hippocampus, amygdala, and anatomical subregions were estimated using FreeSurfer, and the linear effects of 22q11.2 gene dosage and non-linear effects of age were characterized with generalized additive mixed models (GAMMs). Positive gene dosage effects (volume increasing with copy number) were observed for total intracranial and whole hippocampus volumes, but not whole thalamus or amygdala volumes. Several amygdala subregions exhibited similar positive effects, with bi-directional effects found across thalamic nuclei. Distinct age-related trajectories were observed across the three groups. Notably, both 22qDel and 22qDup carriers exhibited flattened development of hippocampal CA2/3 subfields relative to TD controls. This study provides novel insights into the impact of 22q11.2 CNVs on subcortical brain structures and their developmental trajectories.

Rare CNVs and phenome-wide profiling highlight brain structural divergence and phenotypical convergence.

Copy number variations (CNVs) are rare genomic deletions and duplications that can affect brain and behaviour. Previous reports of CNV pleiotropy imply that they converge on shared mechanisms at some level of pathway cascades, from genes to large-scale neural circuits to the phenome. However, existing studies have primarily examined single CNV loci in small clinical cohorts. It remains unknown, for example, how distinct CNVs escalate vulnerability for the same developmental and psychiatric disorders. Here we quantitatively dissect the associations between brain organization and behavioural differentiation across 8 key CNVs. In 534 CNV carriers, we explored CNV-specific brain morphology patterns. CNVs were characteristic of disparate morphological changes involving multiple large-scale networks. We extensively annotated these CNV-associated patterns with ~1,000 lifestyle indicators through the UK Biobank resource. The resulting phenotypic profiles largely overlap and have body-wide implications, including the cardiovascular, endocrine, skeletal and nervous systems. Our population-level investigation established brain structural divergences and phenotypical convergences of CNVs, with direct relevance to major brain disorders.

ADHD-associated PARK2 copy number variants: A pilot study on gene expression and effects of supplementary deprivation in patient-derived cell lines.

Recent studies show an association of Parkin RBR E3 ubiquitin protein ligase (PARK2) copy number variations (CNVs) with attention deficit hyperactivity disorder (ADHD). The aim of our pilot study to investigate gene expression associated with PARK2 CNVs in human-derived cellular models. We investigated gene expression in fibroblasts, hiPSC and dopaminergic neurons (DNs) of ADHD PARK2 deletion and duplication carriers by qRT PCR compared with healthy and ADHD cell lines without PARK2 CNVs. The selected 10genes of interest were associated with oxidative stress response (TP53, NQO1, and NFE2L2), ubiquitin pathway (UBE3A, UBB, UBC, and ATXN3) and with a function in mitochondrial quality control (PINK1, MFN2, and ATG5). Additionally, an exploratory RNA bulk sequencing analysis in DNs was conducted. Nutrient deprivation as a supplementary deprivation stress paradigm was used to enhance potential genotype effects. At baseline, in fibroblasts, hiPSC, and DNs, there was no significant difference in gene expression after correction for multiple testing. After nutrient deprivation in fibroblasts NAD(P)H-quinone-dehydrogenase 1 (NQO1) expression was significantly increased in PARK2 CNV carriers. In a multivariate analysis, ubiquitin C (UBC) was significantly upregulated in fibroblasts of PARK2 CNV carriers. RNA sequencing analysis of DNs showed the strongest significant differential regulation in Neurontin (NNAT) at baseline and after nutrient deprivation. Our preliminary results suggest differential gene expression in pathways associated with oxidative stress, ubiquitine-proteasome, immunity, inflammation, cell growth, and differentiation, excitation/inhibition modulation, and energy metabolism in PARK2 CNV carriers compared to wildtype healthy controls and ADHD patients.

Longitudinal trajectories of cortical development in 22q11.2 copy number variants and typically developing controls

Probing naturally-occurring, reciprocal genomic copy number variations (CNVs) may help us understand mechanisms that underlie deviations from typical brain development. Cross-sectional studies have identified prominent reductions in cortical surface area (SA) and increased cortical thickness (CT) in 22q11.2 deletion carriers (22qDel), with the opposite pattern in duplication carriers (22qDup), but the longitudinal trajectories of these anomalies—and their relationship to clinical symptomatology—are unknown. Here, we examined neuroanatomic changes within a longitudinal cohort of 261 22q11.2 CNV carriers and demographically-matched typically developing (TD) controls (84 22qDel, 34 22qDup, and 143 TD; mean age 18.35, ±10.67 years; 50.47% female). A total of 431 magnetic resonance imaging scans (164 22qDel, 59 22qDup, and 208 TD control scans; mean interscan interval = 20.27 months) were examined. Longitudinal FreeSurfer analysis pipelines were used to parcellate the cortex and calculate average CT and SA for each region. First, general additive mixed models (GAMMs) were used to identify regions with between-group differences in developmental trajectories. Secondly, we investigated whether these trajectories were associated with clinical outcomes. Developmental trajectories of CT were more protracted in 22qDel relative to TD and 22qDup. 22qDup failed to show normative age-related SA decreases. 22qDel individuals with psychosis spectrum symptoms showed two distinct periods of altered CT trajectories relative to 22qDel without psychotic symptoms. In contrast, 22q11.2 CNV carriers with autism spectrum diagnoses showed early alterations in SA trajectories. Collectively, these results provide new insights into altered neurodevelopment in 22q11.2 CNV carriers, which may shed light on neural mechanisms underlying distinct clinical outcomes.

Possible association of 16p11.2 copy number variation with altered lymphocyte and neutrophil counts

Recurrent copy-number variations (CNVs) at chromosome 16p11.2 are associated with neurodevelopmental diseases, skeletal system abnormalities, anemia, and genitourinary defects. Among the 40 protein-coding genes encompassed within the rearrangement, some have roles in leukocyte biology and immunodeficiency, like SPN and CORO1A. We therefore investigated leukocyte differential counts and disease in 16p11.2 CNV carriers. In our clinically-recruited cohort, we identified three deletion carriers from two families (out of 32 families assessed) with neutropenia and lymphopenia. They had no deleterious single-nucleotide or indel variant in known cytopenia genes, suggesting a possible causative role of the deletion. Noticeably, all three individuals had the lowest copy number of the human-specific BOLA2 duplicon (copy-number range: 3–8). Consistent with the lymphopenia and in contrast with the neutropenia associations, adult deletion carriers from UK biobank (n = 74) showed lower lymphocyte (Padj = 0.04) and increased neutrophil (Padj = 8.31e-05) counts. Mendelian randomization studies pinpointed to reduced CORO1A, KIF22, and BOLA2-SMG1P6 expressions being causative for the lower lymphocyte counts. In conclusion, our data suggest that 16p11.2 deletion, and possibly also the lowest dosage of the BOLA2 duplicon, are associated with low lymphocyte counts. There is a trend between 16p11.2 deletion with lower copy-number of the BOLA2 duplicon and higher susceptibility to moderate neutropenia. Higher numbers of cases are warranted to confirm the association with neutropenia and to resolve the involvement of the deletion coupled with deleterious variants in other genes and/or with the structure and copy number of segments in the CNV breakpoint regions.

16.5 CARVING CLINICAL HETEROGENEITY AT ITS JOINTS: THE POTENTIAL ROLE OF COPY NUMBER VARIATION IN UNDERSTANDING AUTISM SPECTRUM DISORDER

Autism spectrum disorder (ASD) is characterized by marked clinical heterogeneity. Copy number variation (CNV), a type of structural genetic variation involving the deletion or duplication of a DNA segment, may help parse this heterogeneity by defining ASD subtypes. Several CNV-associated ASD syndromes have been described with characteristic phenotypes. This presentation will focus on 1 such syndrome, 16p11.2 CNV, and will include a discussion of recent unpublished work that we have conducted with this population. We will discuss what is known about the 16p11.2 CNV. We will then describe the results and implications of the recent work we conducted with a small (n = 19) pilot sample of 16p11.2 CNV carriers. 16p11.2 duplication and 16p11.2 deletion are both associated with ASD, but their clinical phenotypes otherwise diverge in notable ways. 16p11.2 duplication is associated with microcephaly, thinness, and a variable degree of intellectual impairment (from mild to severe). 16p11.2 deletion is associated with macrocephaly, obesity, and consistently severe intellectual impairment. Notably, 16p11.2 duplication, but not the deletion, is also associated with schizophrenia. In a small pilot study, we conducted in-depth interviews with 16p11.2 duplication and deletion carriers and assessed them for formal thought disorder. We found a suggestion of quantitative differences in thought process between the 2 groups. Given the small size of our pilot sample, our findings are not definitive. However, they represent a proof of concept that CNVs represent a way to identify subtle, detectable differences between people with ASD that would otherwise be obscured by the disorder’s overall heterogeneity and that may have clinical meaning.

Modeling familial predictors of proband outcomes in neurogenetic disorders: initial application in XYY syndrome

BackgroundDisorders of gene dosage can significantly increase risk for psychopathology, but outcomes vary greatly amongst carriers of any given chromosomal aneuploidy or sub-chromosomal copy number variation (CNV). One potential path to advance precision medicine for neurogenetic disorders is modeling penetrance in probands relative to observed phenotypes in their non-carrier relatives. Here, we seek to advance this general analytic framework by developing new methods in application to XYY syndrome—a sex chromosome aneuploidy that is known to increase risk for psychopathology.MethodsWe analyzed a range of cognitive and behavioral domains in XYY probands and their non-carrier family members (n = 58 families), including general cognitive ability (FSIQ), as well as continuous measures of traits related to autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Proband and relative scores were compared using covariance, regression and cluster analysis. Comparisons were made both within and across traits.ResultsProband scores were shifted away from family scores with effect sizes varying between 0.9 and 2.4 across traits. Only FSIQ and vocabulary scores showed a significant positive correlation between probands and their non-carrier relatives across families (R2 ~ 0.4). Variability in family FSIQ also cross-predicted variability in proband ASD trait severity. Cluster analysis across all trait-relative pairings revealed that variability in parental psychopathology was more weakly coupled to their XYY versus their euploid offspring.ConclusionsWe present a suite of generalizable methods for modeling variable penetrance in aneuploidy and CNV carriers using family data. These methods update estimates of phenotypic penetrance for XYY and suggest that the predictive utility of family data is likely to vary for different traits and different gene dosage disorders.Trial registrationsClinicalTrials.govNCT00001246, “89-M-0006: Brain Imaging of Childhood Onset Psychiatric Disorders, Endocrine Disorders and Healthy Controls.” Date of registry: 01 October 1989.

Spontaneous neural activity relates to psychiatric traits in 16p11.2 CNV carriers: An analysis of EEG spectral power and multiscale entropy

Copy number variations (CNV) at the 16p11.2 chromosomal region are rare high-risk CNVs associated with various clinical features and psychiatric disorders including intellectual disability, developmental delays, and autism spectrum disorder. No study to date has investigated whether spontaneous neural activity is altered for 16p11.2 CNV carriers and whether this relates to psychiatric traits. The aim of this study is to examine the impact of 16p11.2 deletions (del) and duplications (dup) on spontaneous neural activity and its relationship to psychiatric problems. EEG was previously collected as part of the Simons Searchlight initiative. Using spectral power (delta, theta, alpha, and beta frequency bands), complexity index (CI), and multiscale entropy analysis techniques, we analyzed frontal resting-state EEG data collected from 22 16p11.2 del carriers, 14 dup carriers, and 13 controls. We then examined associations between neural activity and psychiatric traits, measured with the Child Behavior Checklist. Results indicated that EEG entropy was higher for del and dup compared to controls, respectively, at all timescales. CI was also higher for del and dup compared to controls. Theta power of 16p11.2 dup carriers was higher than controls. A strong association was found between entropy at higher timescales and anxiety problems. In addition, a strong correlation was found between theta power and pervasive developmental problems. Atypical spontaneous neural activity is implicated in 16p11.2 CNVs. With higher entropy or theta power, psychiatric traits increase in severity. Our findings provide evidence of the link between genotype, neural activity, and phenotypes in 16p11.2 CNVs.

Reciprocal Copy Number Variations at 22q11.2 Produce Distinct and Convergent Neurobehavioral Impairments Relevant for Schizophrenia and Autism Spectrum Disorder

Background22q11.2 deletions and duplications are copy number variations (CNVs) that predispose to developmental neuropsychiatric disorders. Both CNVs are associated with autism spectrum disorder (ASD), while the deletion confers disproportionate risk for schizophrenia. Neurobehavioral profiles associated with these reciprocal CNVs in conjunction with brain imaging measures have not been reported. MethodsWe profiled the impact of 22q11.2 CNVs on neurobehavioral measures relevant to ASD and psychosis in 106 22q11.2 deletion carriers, 38 22q11.2 duplication carriers, and 82 demographically matched healthy control subjects. To determine whether brain–behavior relationships were altered in CNV carriers, we further tested for interactions between group and regional brain structure on neurobehavioral domains. ResultsCognitive deficits were observed in both CNV groups, with the lowest IQs in deletion carriers. ASD and dimensionally measured ASD traits were elevated in both CNV groups; however, duplication carriers exhibited increased stereotypies compared to deletion carriers. Moreover, discriminant analysis using ASD subdomains distinguished between CNV cases with 76% accuracy. Both psychotic disorder diagnosis and dimensionally measured positive and negative symptoms were elevated in deletion carriers. Finally, healthy control subjects showed an inverse relationship between processing speed and cortical thickness in heteromodal association areas, which was absent in both CNV groups. Conclusions22q11.2 CNVs differentially modulate intellectual functioning and psychosis-related symptomatology but converge on broad ASD-related symptomatology. However, subtle differences in ASD profiles distinguish CNV groups. Processing speed impairments, coupled with the lack of normative relationship between processing speed and cortical thickness in CNV carriers, implicate aberrant development of the cortical mantle in the pathology underlying impaired processing speed ability.

Psychotic symptoms in 16p11.2 copy-number variant carriers.

16p11.2 copy-number variation (CNV) is implicated in neurodevelopmental disorders, with the duplication and deletion associated with autism spectrum disorder (ASD) and the duplication associated with schizophrenia (SCZ). The 16p11.2 CNV may therefore provide insight into the relationship between ASD and SCZ, distinct disorders that co-occur at an elevated rate, and are difficult to distinguish from each other and from common co-occurring diagnoses such as obsessive compulsive disorder (OCD), itself a potential risk factor for SCZ. As psychotic symptoms are core to SCZ but distinct from ASD, we sought to examine their predictors in a population (n = 546) of 16p11.2 CNV carriers and their noncarrier siblings recruited by the Simons Variation in Individuals Project. We hypothesized that psychotic symptoms would be most common in duplication carriers followed by deletion carriers and noncarriers, that an ASD diagnosis would predict psychotic symptoms among CNV carriers, and that OCD symptoms would predict psychotic symptoms among all participants. Using data collected across multiple measures, we identified 19 participants with psychotic symptoms. Logistic regression models adjusting for biological sex, age, and IQ found that 16p11.2 duplication and ASD diagnosis predicted psychotic symptom presence. Our findings suggest that the association between 16p11.2 duplication and psychotic symptoms is independent of ASD diagnosis and that ASD diagnosis and psychotic symptoms may be associated in 16p11.2 CNV carriers. Autism Res 2020, 13: 187-198. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Either deletion or duplication at chromosome 16p11.2 raises the risk of autism spectrum disorder, and duplication, but not deletion, has been reported in schizophrenia (SCZ). In a sample of 16p11.2 deletion and duplication carriers, we found that having the duplication or having an autism diagnosis may increase the risk of psychosis, a key feature of SCZ.

Dosage sensitivity intolerance of VIPR2 microduplication is disease causative to manifest schizophrenia-like phenotypes in a novel BAC transgenic mouse model.

Recent genome-wide association studies (GWAS) have identified copy number variations (CNVs) at chromosomal locus 7q36.3 that significantly contribute to the risk of schizophrenia, with all of the microduplications occurring within a single gene: vasoactive intestinal peptide receptor 2 (VIPR2). To confirm disease causality and translate such a genetic vulnerability into mechanistic and pathophysiological insights, we have developed a series of conditional VIPR2 bacterial artificial chromosome (BAC) transgenic mouse models of VIPR2 CNV. VIPR2 CNV mouse model recapitulates gene expression and signaling deficits seen in human CNV carriers. VIPR2 microduplication in mice elicits prominent dorsal striatal dopamine dysfunction, cognitive, sensorimotor gating, and social behavioral deficits preceded by an increase of striatal cAMP/PKA signaling and the disrupted early postnatal striatal development. Genetic removal of VIPR2 transgene expression via crossing with Drd1a-Cre BAC transgenic mice rescued the dopamine D2 receptor abnormality and multiple behavioral deficits, implicating a pathogenic role of VIPR2 overexpression in dopaminoceptive neurons. Thus, our results provide further evidence to support the GWAS studies that the dosage sensitivity intolerance of VIPR2 is disease causative to manifest schizophrenia-like dopamine, cognitive, and social behavioral deficits in mice. The conditional BAC transgenesis offers a novel strategy to model CNVs with a gain-of -copies and facilitate the genetic dissection of when/where/how the genetic vulnerabilities affect development, structure, and function of neural circuits. Our findings have important implications for therapeutic development, and the etiology-relevant mouse model provides a useful preclinical platform for drug discovery.

Atypical neural variability in carriers of 16p11.2 copy number variants.

Copy number variations (CNVs) at the 16p11.2 chromosomal region are associated with myriad clinical features including intellectual disability and autism spectrum disorder. The aim of this study is to determine whether 16p11.2 deletion (DEL) and duplication (DUP) carriers demonstrate a distinct and reciprocal pattern of electroencephalography (EEG) activity as represented by neural variability measures. EEG data were previously collected as part of the Simons Variation in Individuals Project. Variability measures, as estimated by single-trial ERP and spectral power analyses in the alpha and beta frequency bands, in addition to signal-to-noise ratios (SNRs), were analyzed in DEL (n = 20), DUP (n = 8), and typical (n = 11) groups. We also analyzed mean visual evoked potentials and spectral power (alpha and beta power) to facilitate comparisons with other studies of associated disorders and CNVs. From measures of single-trial variability, we found higher intraparticipant variability in P1 amplitude and timecourse amplitude in DEL compared to controls. Compared to DUP, DEL showed higher variability in absolute alpha and absolute beta power but lower variability in P1 latency. SNRs did not differ between the groups. From measures of amplitude, latency, and spectral power, DUP showed lower relative alpha power compared to controls. Although it is yet unclear whether 16p11.2 CNV dosage impacts neural activity in an opposing manner, findings suggest that 16p11.2 DEL impacts the level of variability of neural responses. Higher neural variability may play a role in a range of cognitive processes in 16p11.2 CNV carriers. Autism Res 2019, 12: 1322-1333. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: The study analyzed the consistency of patterns of brain waves and rhythms in those affected with a loss or gain of DNA material in the 16p11.2 region. Compared with typical individuals, 16p11.2 deletion carriers showed greater inconsistency in the way the brain responds to the same visual event. This high inconsistency in brain activity may play a role in some core symptoms in 16p11.2 copy number variation carriers.

776-P: Low AMY1 Copy Number Variations Are Associated with Cardiometabolic Risk Factors in Overweight or Obese Adults

Background: Low serum amylase has been implicated in the pathogenesis of obesity and insulin resistance. Copy number variations (CNVs) in the salivary amylase gene (AMY1) correlate with serum amylase, and CNVs <4 have been associated with a higher risk of obesity and insulin resistance. However, the relationship between AMY1 and cardiometabolic risk has not been fully elucidated. Objective: To examine whether AMY1 CNVs are associated with cardiometabolic risk factors. Methods: In overweight or obese (BMI >25kg/m2), otherwise healthy adults, we measured AMY1 copy numbers (qPCR); serum amylase (commercial assay); anthropometry (BMI; body composition by dual-energy X-ray absorptiometry); cardiovascular parameters (blood pressure, plasma lipids by ELISA); fasting and 2-h glucose levels post-75g oral glucose tolerance test (glucose oxidase method), insulin sensitivity (hyperinsulinemic-euglycemic clamp), insulin secretion (intravenous glucose tolerance test), and serum inflammation markers (LEGENDplex™, Biolegend). Results: Fifty-nine adults (58% males) aged 31.27 ± 8.61 were included in the study. Based on previous studies and median values, participants were divided into low CNV and high CNV carrier groups for individuals with ≤4 and >4 AMY1 CNVs, respectively. Low AMY1 CNV carriers (n=29) had a higher BMI (32.65 ± 5.37 vs. 30.28 ± 3.51 kg/m2, p = 0.04), % fat mass (40.76 ± 12.22 vs. 33.13 ± 8.60%, p = 0.008), and LDL-c (3.25 ± 0.80 vs. 2.87 ± 0.63 mmol/L, p = 0.04) compared with the high AMY1 CNV group (n=30), as well as higher levels of interleukins [IL]-6, -1β, -10, and tumor necrosis factor-alpha (all p<0.05). Results remained significant after adjustment for age and sex. There were no differences between AMY1 CNV groups in glycaemic outcomes including insulin sensitivity or secretion as well as fasting and 2-hour glucose post-OGTT (p>0.1). Conclusions: Our results suggest that low AMY1 CNVs are associated with increased obesity, cardiovascular risk, and inflammation. Disclosure C. Marquina: None. A. Mousa: None. N. Naderpoor: None. B. de Courten: None.

Delineating the psychiatric and behavioral phenotype of recurrent 2q13 deletions and duplications.

Recurrent deletions and duplications at the 2q13 locus have been associated with developmental delay (DD) and dysmorphisms. We aimed to undertake detailed clinical characterization of individuals with 2q13 copy number variations (CNVs), with a focus on behavioral and psychiatric phenotypes. Participants were recruited via the Unique chromosomal disorder support group, U.K. National Health Service Regional Genetics Centres, and the DatabasE of genomiC varIation and Phenotype in Humans using Ensembl Resources (DECIPHER) database. A review of published 2q13 patient case reports was undertaken to enable combined phenotypic analysis. We present a new case series of 2q13 CNV carriers (21 deletion, 4 duplication) and the largest ever combined analysis with data from published studies, making a total of 54 deletion and 23 duplication carriers. DD/intellectual disabilities was identified in the majority of carriers (79% deletion, 70% duplication), although in the new cases 52% had an IQ in the borderline or normal range. Despite the median age of the new cases being only 9 years, 64% had a clinical psychiatric diagnosis. Combined analysis found attention deficit hyperactivity disorder (ADHD) to be the most frequent diagnosis (48% deletion, 60% duplication), followed by autism spectrum disorders (33% deletion, 17% duplication). Aggressive (33%) and self‐injurious behaviors (33%) were also identified in the new cases. CNVs at 2q13 are typically associated with DD with mildly impaired intelligence, and a high rate of childhood psychiatric diagnoses—particularly ADHD. We have further characterized the clinical phenotype related to imbalances of the 2q13 region and identified it as a region of interest for the neurobiological investigation of ADHD.

16p11: Description of the behavioral and morphological phenotype of a “mirror” syndrome

Objective: Copy number variations (CNVs) in the 16p11.2 gene region are translated into different morphological and neurobehavioral phenotypes. The main objective of our study is to describe these differences according to the type of CNV. It is proposed as a secondary objective the design of a protocol of assessment and follow-up for these patients. Methods: Retrospective descriptive study in patients with CNVs in 16p11.2 diagnosed in a Tertiary Hospital using Array-CGH. We collected anthropometric data, dysmorphic features, and performed neuropsychological assessments (ASD, ADHD, intellectual and neurodevelopment screening). Results: A total of 9 patients with 16p11 CNVs were studied. 6 cases with a deletion, being 100% of these de novo; and 3 cases with a duplication, being 67% of the cases inherited. Patients with deletions were overweight / obese and macrocephalus, while patients with duplications present a normal BMI and microcephaly. Clinical manifestations observed in the patients studied included ophthalmological disorders (22%), psychomotor retardation (67%), mild intellectual deficit (56%), autism spectrum disorder (22%) and ADHD (78%). All of the patients that exceed cut point in SNAP -IV in the sample were carriers of a deletion, predominating in them the inattentive subtype ADHD. Conclusion: CNV carriers in the 16p11.2 gene region present mirror anthropometric phenotypes and the most frequently associated conditions were psychomotor development delay, ASD, and ADHD. Inattentive type ADHD is the most commonly observed in patients with deletions, and no significant differences in neuropsychological profile were observed at other levels depending on the type of CNVs. Taking into account the above, it is proposed to carry out an assessment and follow-up protocol that includes a standardized medical history, a comprehensive physical examination including ophthalmologic examination and complementary examinations to rule out intellectual deficit, ASD and ADHD.

Two novel copy number variations involving the α-globin gene cluster on chromosome 16 cause thalassemia in two Chinese families.

Copy number variations (CNVs) can cause many genetic disorders and the structure analysis of unknown CNVs is important for clinical diagnosis. The human α-globin gene cluster lies close to the telomere of the short arm on chromosome 16. Copy number variations of this region produce excessive or insufficient α-globin chains which imbalances the β-globin chains, resulting in thalassemia. However, these CNVs usually cannot be precisely defined by traditional methods. Here, we designed a technique strategy and applied it to identify two CNVs involving the α-globin gene cluster causing thalassemia in two Chinese families. A novel 282kb duplication (αααα(282)) was identified in family A and a novel 235kb deletion (--(235)) in family B. Proband A is a coinheritance of β(CD41-42) and αααα(282) and showed severe β-thalassemia intermedia phenotype. Proband B is a compound heterozygote of --(235)/α(CS)α genotype and was diagnosed with hemoglobin H disease. The clinical phenotypic features of the CNVs carriers were described, together with a complete picture of molecular structure of these rearrangements. Two CNVs are novel rearrangements in α-globin clusters and the αααα(282) is the first to identify the exact insert position of a duplication region from the telomere on chromosome 16. In a conclusion, successful identification and characterization of these two novel CNVs not only demonstrates the precision and effectiveness of our strategy in analyzing the structure of unknown CNVs, but also extended the spectrum of thalassemia and provide new examples for studying genomic recombination.

Relationship between M100 Auditory Evoked Response and Auditory Radiation Microstructure in 16p11.2 Deletion and Duplication Carriers.

Deletion and duplication of chromosome 16p11.2 (BP4-BP5) have been associated with developmental disorders such as autism spectrum disorders, and deletion subjects exhibit a large (20-ms) delay of the auditory evoked cortical response as measured by magnetoencephalography (M100 latency). The purpose of this study was to use a multimodal approach to test whether changes in white matter microstructure are associated with delayed M100 latency. Thirty pediatric deletion carriers, 9 duplication carriers, and 39 control children were studied with both magnetoencephalography and diffusion MR imaging. The M100 latency and auditory system DTI measures were compared between groups and tested for correlation. In controls, white matter diffusivity significantly correlated with the speed of the M100 response. However, the relationship between structure and function appeared uncoupled in 16p11.2 copy number variation carriers. The alterations to auditory system white matter microstructure in the 16p11.2 deletion only partially accounted for the 20-ms M100 delay. Although both duplication and deletion groups exhibit abnormal white matter microstructure, only the deletion group has delayed M100 latency. These results indicate that gene dosage impacts factors other than white matter microstructure, which modulate conduction velocity.

S.11.02 Epigenetic control of stress-induced gene transcription and behaviour: relevance to PTSD

Copy number variations (CNV) at the 16p11.2 chromosomal region are rare high-risk CNVs associated with various clinical features and psychiatric disorders including intellectual disability, developmental delays, and autism spectrum disorder. No study to date has investigated whether spontaneous neural activity is altered for 16p11.2 CNV carriers and whether this relates to psychiatric traits. The aim of this study is to examine the impact of 16p11.2 deletions (del) and duplications (dup) on spontaneous neural activity and its relationship to psychiatric problems. EEG was previously collected as part of the Simons Searchlight initiative. Using spectral power (delta, theta, alpha, and beta frequency bands), complexity index (CI), and multiscale entropy analysis techniques, we analyzed frontal resting-state EEG data collected from 22 16p11.2 del carriers, 14 dup carriers, and 13 controls. We then examined associations between neural activity and psychiatric traits, measured with the Child Behavior Checklist. Results indicated that EEG entropy was higher for del and dup compared to controls, respectively, at all timescales. CI was also higher for del and dup compared to controls. Theta power of 16p11.2 dup carriers was higher than controls. A strong association was found between entropy at higher timescales and anxiety problems. In addition, a strong correlation was found between theta power and pervasive developmental problems. Atypical spontaneous neural activity is implicated in 16p11.2 CNVs. With higher entropy or theta power, psychiatric traits increase in severity. Our findings provide evidence of the link between genotype, neural activity, and phenotypes in 16p11.2 CNVs.

Copy number variations in KCNQ1 gene were frequently identified in the pediatric patients of long QT syndrome and caused exercise related QT prolongation

Purpose: More than ten genes have been reported as the cause of long QT syndrome (LQTS). However, approximately 30 percent of the patients have not been genotyped yet. Among non-genotyped LQTS patients, copy number variations (CNV) in KCNQ1 and KCNH2, the causative genes of LQTS1 and LQTS2, were recently reported, though the frequency of the CNV carriers or clinical characteristics of the carriers have not been fully elucidated yet. Therefore, we aimed to clarify the frequency of CNV in the pediatric patients with non-genotyped LQTS and to characterize their clinical symptoms. Methods: The subject of this study consisted of 172 LQTS patients (92 boys) who were less than 20-year-old (mean age was 12.3±0.3 year-old) and carried no gene mutation in LQTS1 through LQTS6. They were performed clinical evaluations including resting ECG and exercise stress test. To identify the CNV in KCNQ1 and KCNH2, we introduced multiplex ligation-dependent probe amplification (MLPA) analysis. Results: Among 172 patients, we identified 5 patients (2.9%) who carried CNV in KCNQ1 and no one in KCNH2. Table 1 summarizes the results of CNV and clinical characteristics. Two patients were asymptomatic and three patients experienced syncope while exercise. The mean QTc was prolonged from 453.6±12.9 ms½ at rest to 542.6±6.6 ms½ after exercise (p<0.01). View this table: Summary of the patients with CNV Conclusions; In the pediatric LQTS patients, especially with exercise induced QT prolongation, CNV in KCNQ1 may be the cause of the disease. Therefore screening of CNV in pediatric LQTS patients is indispensable to perform appropriate treatment and to prevent unexpected sudden cardiac death.