Copy number variants at Williams–Beuren syndrome 7q11.23 region

Copy number variants (CNVs) of the Williams–Beuren syndrome (WBS) 7q11.23 region are responsible for neurodevelopmental disorders with multi-system involvement and variable expressivity. Typical features of WBS microdeletion comprise a recognizable pattern of facial dysmorphisms, supravalvular aortic stenosis, connective tissue abnormalities, hypercalcemia, and a distinctive neurobehavioral phenotype. Conversely, the phenotype of patients carrying the 7q11.23 reciprocal duplications includes less distinctive facial dysmorphisms and prominent speech delay. The common deletion/duplication ranges in size from 1.5 to 1.8 Mb and encompasses approximately 28 genes. This region is flanked by low copy repeats (LCRs) with greater than ~97% identity, which can mediate non-allelic homologous recombination resulting from misalignment of LCRs during meiosis. A clear genotype–phenotype correlation has been established in WBS only for the elastin gene, which is responsible for the vascular and connective tissue abnormalities. The molecular substrates underlying the other clinical features of 7q11.23 CNVs, including the neurocognitive phenotypes, are still debated. Recent studies suggest that besides the role of the genes in the deleted/duplicated interval, multiple factors such as regulatory sequences, epigenetic mechanisms, parental origin of the CNV, and nucleotide variations in the non-deleted/duplicated allele may be important in determining the variable expressivity of 7q11.23 CNV phenotypes. Here, we review the clinical and molecular findings and the recent insights on genomic disorders associated with CNVs involving the 7q11.23 region.     

Application of high resolution SNP arrays in patients with congenital oral clefts in south China

Chromosome microarray analysis (CMA) has proven to be a powerful tool in postnatal patients with intellectual disabilities. However, the diagnostic capability of CMA in patients with congenital oral clefts remain mysterious. Here, we present our clinical experience in implementing whole-genome high-resolution SNP arrays to investigate 33 patients with syndromic and nonsyndromic oral clefts in whom standard karyotyping analyses showed normal karyotypes. We aim to identify the genomic aetiology and candidate genes in patients with congenital oral clefts. CMA revealed copy number variants (CNVs) in every patient, which ranged from 2 to 9 per sample. The size of detected CNVs varied from 100 to 3.2 Mb. In 33 patients, we identified six clinically significant CNVs. The incidence of clinically significant CNVs was 18.2% (6/33). Three of these six CNVs were detected in patients with nonsyndromic clefts, including one who presented with isolated cleft lip with cleft palate (CLP) and two with cleft palate only (CPO). The remaining three CNVs were detected in patients with syndromic clefts. However, no CNV was detected in patients with cleft lip only (CLO). The six clinically significant CNVs were as follows: 8p23.1 microduplication (198 kb); 10q22.2-q22.3 microdeletion (1766 kb); 18q12.3 microduplication (638 kb); 20p12.1 microdeletion (184 kb); 6q26 microdeletion (389 kb); and 22q11.21-q11.23 microdeletion (3163 kb). In addition, two novel candidate genes for oral clefts, KAT6B and MACROD2, were putatively identified. We also found a CNV of unknown clinical significance with a detection rate of 3.0% (1/33). Our results further support the notion that CNVs significantly contributed to the genetic aetiology of oral clefts and emphasize the efficacy of whole-genome high-resolution SNP arrays to detect novel candidate genes in patients with syndromic and nonsyndromic clefts.     

Array CGH analysis of a cohort of Russian patients with intellectual disability

The use of array comparative genomic hybridization (array CGH) as a diagnostic tool in molecular genetics has facilitated the identification of many new microdeletion/microduplication syndromes (MMSs). Furthermore, this method has allowed for the identification of copy number variations (CNVs) whose pathogenic role has yet to be uncovered. Here, we report on our application of array CGH for the identification of pathogenic CNVs in 79 Russian children with intellectual disability (ID). Twenty-six pathogenic or likely pathogenic changes in copy number were detected in 22 patients (28%): 8 CNVs corresponded to known MMSs, and 17 were not associated with previously described syndromes. In this report, we describe our findings and comment on genes potentially associated with ID that are located within the CNV regions.     

Copy number variation (CNV) identification,interpretation, and database from Brazilian patients

Copy number variations (CNVs) constitute an important class of variation in the human genome and the interpretation of their pathogenicity considering different frequencies across populations is still a challenge for geneticists. Since the CNV databases are predominantly composed of European and non-admixed individuals, and Brazilian genetic constitution is admixed and ethnically diverse, diagnostic screenings on Brazilian variants are greatly difficulted by the lack of populational references. We analyzed a clinical sample of 268 Brazilian individuals, including patients with neurodevelopment disorders and/or congenital malformations. The pathogenicity of CNVs was classified according to their gene content and overlap with known benign and pathogenic variants. A total of 1,504 autosomal CNVs (1,207 gains and 297 losses) were classified as benign (92.9%), likely benign (1.6%), VUS (2.6%), likely pathogenic (0.2%) and pathogenic (2.7%). Some of the CNVs were recurrent and with frequency increased in our sample, when compared to populational open resources of structural variants: 14q32.33, 22q11.22, 1q21.1, and 1p36.32 gains. Thus, these highly recurrent CNVs classified as likely benign or VUS were considered non-pathogenic in our Brazilian sample. This study shows the relevance of introducing CNV data from diverse cohorts to improve on the interpretation of clinical impact of genomic variations.     

Microdeletion and Microduplication Analysis of Chinese Conotruncal Defects Patients with Targeted Array Comparative Genomic Hybridization

Objective

The current study aimed to develop a reliable targeted array comparative genomic hybridization (aCGH) to detect microdeletions and microduplications in congenital conotruncal defects (CTDs), especially on 22q11.2 region, and for some other chromosomal aberrations, such as 5p15-5p, 7q11.23 and 4p16.3.

Methods

Twenty-seven patients with CTDs, including 12 pulmonary atresia (PA), 10 double-outlet right ventricle (DORV), 3 transposition of great arteries (TGA), 1 tetralogy of Fallot (TOF) and one ventricular septal defect (VSD), were enrolled in this study and screened for pathogenic copy number variations (CNVs), using Agilent 8 x 15K targeted aCGH. Real-time quantitative polymerase chain reaction (qPCR) was performed to test the molecular results of targeted aCGH.

Results

Four of 27 patients (14.8%) had 22q11.2 CNVs, 1 microdeletion and 3 microduplications. qPCR test confirmed the microdeletion and microduplication detected by the targeted aCGH.

Conclusion

Chromosomal abnormalities were a well-known cause of multiple congenital anomalies (MCA). This aCGH using arrays with high-density coverage in the targeted regions can detect genomic imbalances including 22q11.2 and other 10 kinds CNVs effectively and quickly. This approach has the potential to be applied to detect aneuploidy and common microdeletion/microduplication syndromes on a single microarray.     

Genome‐wide mapping of copy number variations in patients with both anorectal malformations and central nervous system abnormalities

Background: Anorectal malformations (ARM) have a prevalence of around 1 in 2500 live births. In around 50% of patients, the malformation is isolated, while in the remainder it arises within the context of complex genetic abnormalities or a defined genetic syndrome. Recent studies have implicated rare copy number variations (CNVs) in both isolated and nonisolated ARM, and identified plausible candidate genes. Methods: In the present study, array‐based molecular karyotyping was performed to identify causative CNVs in 32 sporadic ARM patients with comorbid abnormalities of the central nervous system (CNS). This phenotype was selected to enrich for rare CNVs, since previous research has implicated rare CNVs in both CNS abnormalities and ARM. Results: In five patients, a probable disease‐causing CNV was identified (del6q14.3q16.3, del14q32.2, del17q12q21.2, and two patients with del22q11.21). In three of these patients, the CNVs were de novo. For the remaining two patients, no parental DNA was available. Deletions at 22q11.21 and 6q14.3 have been associated with both CNS abnormalities and ARM. In contrast, deletions at 14q32.2 have only been described in patients with CNS abnormalities, and the del17q12q21.2 is a novel CNV. Expression studies in mice suggest that NEUROD2 and RARA, which reside within the newly identified del17q12q21.2 region, are candidate genes for the formation of microcephaly and ARM. Conclusion: The present data suggest that CNVs are a frequent cause of the ARM with CNS abnormalities phenotype, and that array‐analysis is indicated in such patients. Birth Defects Research (Part A) 103:235–242, 2015. © 2014 Wiley Periodicals, Inc.     

Retinoic Acid Induced 1, RAI1: A Dosage Sensitive Gene Related to Neurobehavioral Alterations Including Autistic Behavior

Genomic structural changes, such as gene Copy Number Variations (CNVs) are extremely abundant in the human genome. An enormous effort is currently ongoing to recognize and catalogue human CNVs and their associations with abnormal phenotypic outcomes. Recently, several reports related neuropsychiatric diseases (i.e. autism spectrum disorders, schizophrenia, mental retardation, behavioral problems, epilepsy) with specific CNV. Moreover, for some conditions, both the deletion and duplication of the same genomic segment are related to the phenotype. Syndromes associated with CNVs (microdeletion and microduplication) have long been known to display specific neurobehavioral traits. It is important to note that not every gene is susceptible to gene dosage changes and there are only a few dosage sensitive genes. Smith-Magenis (SMS) and Potocki-Lupski (PTLS) syndromes are associated with a reciprocal microdeletion and microduplication within chromosome 17p11.2. in humans. The dosage sensitive gene responsible for most phenotypes in SMS has been identified: the Retinoic Acid Induced 1 (RAI1). Studies on mouse models and humans suggest that RAI1 is likely the dosage sensitive gene responsible for clinical features in PTLS. In addition, the human RAI1 gene has been implicated in several neurobehavioral traits as spinocerebellar ataxia (SCA2), schizophrenia and non syndromic autism. In this review we discuss the evidence of RAI1 as a dosage sensitive gene, its relationship with different neurobehavioral traits, gene structure and mutations, and what is known about its molecular and cellular function, as a first step in the elucidation of the mechanisms that relate dosage sensitive genes with abnormal neurobehavioral outcomes.     

Copy number polymorphism in plant genomes

Copy number variants (CNVs) are genomic rearrangements resulting from gains or losses of DNA segments. Typically, the term refers to rearrangements of sequences larger than 1 kb. This type of polymorphism has recently been shown to be a key contributor to intra-species genetic variation, along with single-nucleotide polymorphisms and short insertion-deletion polymorphisms. Over the last decade, a growing number of studies have highlighted the importance of copy number variation (CNV) as a factor affecting human phenotype and individual CNVs have been linked to risks for severe diseases. In plants, the exploration of the extent and role of CNV is still just beginning. Initial genomic analyses indicate that CNVs are prevalent in plants and have greatly affected plant genome evolution. Many CNV events have been observed in outcrossing and autogamous species. CNVs are usually found on all chromosomes, with CNV hotspots interspersed with regions of very low genetic variation. Although CNV is mainly associated with intergenic regions, many CNVs encompass protein-coding genes. The collected data suggest that CNV mainly affects the members of large families of functionally redundant genes. Thus, the effects of individual CNV events on phenotype are usually modest. Nevertheless, there are many cases in which CNVs for specific genes have been linked to important traits such as flowering time, plant height and resistance to biotic and abiotic stress. Recent reports suggest that CNVs may form rapidly in response to stress.     

Copy number variations of obesity relevant loci associated with body mass index in young Chinese

Obesity is one of the most complex human diseases that are widely concerned and studied. More recently, copy number variations (CNVs) emerge as another important genetic marker to influence various human diseases. To elucidate the relationship between obesity and CNVs, this current study selected obesity-related candidate CNVs and analyzed their association with body mass index (BMI). Results showed that a CNV locus, 8q24.3, was significantly different (P = 0.0070) in CNV frequency between the obese and healthy controls in a young eastern Chinese cohort, while no statistical significance was observed in other seven candidate loci including well reported 10q11.22 and 16p11.2 loci. The association of 8q24.3 CNVs with BMI of the subjects only showed marginal significance, while the copy number (CN) of 5p15.33 had a significant correlation with the BMI of the subject. These results suggested that 8q24.3 CN gains was associated with obesity, and 5p15.33 might also contribute to obesity pathogenesis, highlighting the importance of these CNVs for obesity risks, as well as providing new evidence for CNVs in the pathology of common diseases.     

Maternal Modifiers and Parent-of-Origin Bias of the Autism-Associated 16p11.2 CNV

Recurrent deletions and duplications at chromosomal region 16p11.2 are a major genetic contributor to autism but also associate with a wider range of pediatric diagnoses, including intellectual disability, coordination disorder, and language disorder. In order to investigate the potential genetic basis for phenotype variability, we assessed the parent of origin of the 16p11.2 copy-number variant (CNV) and the presence of additional CNVs in 126 families for which detailed phenotype data were available. Among de novo cases, we found a strong maternal bias for the origin of deletions (59/66, 89.4% of cases, p = 2.38 × 10⁻¹¹), the strongest such effect so far observed for a CNV associated with a microdeletion syndrome. In contrast to de novo events, we observed no transmission bias for inherited 16p11.2 CNVs, consistent with a female meiotic hotspot of unequal crossover driving this maternal bias. We analyzed this 16p11.2 CNV cohort for the presence of secondary CNVs and found a significant maternal transmission bias for secondary deletions (32 maternal versus 14 paternal, p = 1.14 × 10⁻²). Of the secondary deletions that disrupted a gene, 82% were either maternally inherited or de novo (p = 4.3 × 10⁻³). Nine probands carry secondary CNVs that disrupt genes associated with autism and/or intellectual disability risk variants. Our findings demonstrate a strong bias toward maternal origin of 16p11.2 de novo deletions as well as a maternal transmission bias for secondary deletions that contribute to the clinical outcome on a background sensitized by the 16p11.2 CNV.     

Disentangling the myriad genomics of complex disorders, specifically focusing on autism, epilepsy, and schizophrenia

Analyses of structural genome variation by array-CGH have dramatically enhanced our ability to detect copy number variations (CNVs). De novo CNVs and those co-segregating with disease in a family are generally interpreted as pathogenic. Yet, often CNVs, such as recurrent microdeletions in region 15q13.3, are not so clearly pathogenic. Here we discuss potential confounding mechanisms that may lead to the phenotypic pleiotropy of CNVs, such as unmasking of recessive alleles by hemizygous deletions, interaction of CNVs with other loci and genes, genetic epistasis, allelic exclusion, and somatic mosaicism. We illustrate some of these mechanisms with a detailed analysis of recent studies of CNVs involving MCPH1, AUTS2, CNTNAP2, and mutations in GRIN2B. Next we discuss the clinical ramifications of these findings and urge workers to avoid 'diagnostic fatalism' (i.e., halting all genetic investigation after the detection of a single CNV) and address some of the future challenges likely to result from implementations of next generation sequencing techniques.     

Identification of copy number variants on human chromosome 22 in patients with a variety of clinical findings

The aims of this study were to create a copy number variant (CNV) profile of human chromosome 22 and to establish a genotype-phenotype correlation for patients with genomic abnormalities on chromosome 22. Thus, 1,654 consecutive pediatric patients with a diversity of clinical findings were evaluated by high-resolution chromosomal microarray analysis (CMA). We identified 25 individuals with abnormal CNVs on chromosome 22, representing 1.5% of the cases analyzed in this cohort. Meanwhile, we detected 1,298 benign CNVs on this chromosome in these individuals. Twenty-one of the 25 abnormal CNVs and the majority of the benign CNVs occurred through involvement of the 8 unstable genomic regions enriched with low copy repeats (LCR22A-H). The highly dynamic status of LCR22s within the 22q11 region facilitates the formation of diverse genomic abnormalities. This CNV profile provides a general perspective of the spectrum of chromosome 22 genomic imbalances and subsequently improves the CNV-phenotype correlations.     

Diagnostic efficacy and new variants in isolated and complex autism spectrum disorder using molecular karyotyping

Autism spectrum disorder (ASD) is a group of the neurodevelopment disorders presenting as an isolated ASD or more complex forms, where a broader clinical phenotype comprised of developmental delay and intellectual disability is present. Both the isolated and complex forms have a significant causal genetic component and submicroscopic genomic copy number variations (CNV) are the most common identifiable genetic factor in these patients. The data on microarray testing in ASD cohorts are still accumulating and novel loci are often identified; therefore, we aimed to evaluate the diagnostic efficacy of the method and the relevance of implementing it into routine genetic testing in ASD patients. A genome-wide CNV analysis using the Agilent microarrays was performed in a group of 150 individuals with an isolated or complex ASD. Altogether, 11 (7.3%) pathogenic CNVs and 15 (10.0%) variants of unknown significance (VOUS) were identified, with the highest proportion of pathogenic CNVs in the subgroup of the complex ASD patients (14.3%). An interesting case of previously unreported partial UPF3B gene deletion was identified among the pathogenic CNVs. Among the CNVs with unknown significance, four VOUS involved genes with possible correlation to ASD, namely genes SNTG2, PARK2, CADPS2 and NLGN4X. The diagnostic efficacy of aCGH in our cohort was comparable with those of the previously reported and identified an important proportion of genetic ASD cases. Despite the continuum of published studies on the CNV testing in ASD cohorts, a considerable number of VOUS CNVs is still being identified, namely 10.0% in our study.     

Multiple recurrent de novo CNVs, including duplications of the 7q11.23 Williams syndrome region, are strongly associated with autism

We have undertaken a genome-wide analysis of rare copy-number variation (CNV) in 1124 autism spectrum disorder (ASD) families, each comprised of a single proband, unaffected parents, and, in most kindreds, an unaffected sibling. We find significant association of ASD with de novo duplications of 7q11.23, where the reciprocal deletion causes Williams-Beuren syndrome, characterized by a highly social personality. We identify rare recurrent de novo CNVs at five additional regions, including 16p13.2 (encompassing genes USP7 and C16orf72) and Cadherin 13, and implement a rigorous approach to evaluating the statistical significance of these observations. Overall, large de novo CNVs, particularly those encompassing multiple genes, confer substantial risks (OR = 5.6; CI = 2.6-12.0, p = 2.4 × 10(-7)). We estimate there are 130-234 ASD-related CNV regions in the human genome and present compelling evidence, based on cumulative data, for association of rare de novo events at 7q11.23, 15q11.2-13.1, 16p11.2, and Neurexin 1.     

Parental Imbalances Involving Chromosomes 15q and 22q May Predispose to the Formation of De Novo Pathogenic Microdeletions and Microduplications in the Offspring

Microarray-based comparative genomic hybridization (array-CGH) led to the discovery of genetic abnormalities among patients with complex phenotype and normal karyotype. Also several apparently normal individuals have been found to be carriers of cryptic imbalances, hence the importance to perform parental investigations after the identification of a deletion/duplication in a proband. Here, we report the molecular cytogenetic characterization of two individuals in which the microdeletions/duplications present in their parents could have predisposed and facilitated the formation of de novo pathogenic different copy number variations (CNVs). In family 1, a 4-year-old girl had a de novo pathogenic 10.5 Mb duplication at 15q21.2q22.2, while her mother showed a 2.262 Mb deletion at 15q13.2q13.3; in family 2, a 9-year-old boy had a de novo 1.417 Mb deletion at 22q11.21 and a second paternal deletion of 247 Kb at 22q11.23 on the same chromosome 22. Chromosome 22 at band q11.2 and chromosome 15 at band q11q13 are considered unstable regions. We could hypothesize that 15q13.2q13.3 and 22q11.21 deletions in the two respective parents might have increased the risk of rearrangements in their children. This study highlights the difficulty to make genetic counseling and predict the phenotypic consequences in these situations.     

Copy-Number Mutations on Chromosome 17q24.2-q24.3 in Congenital Generalized Hypertrichosis Terminalis with or without Gingival Hyperplasia

Congenital generalized hypertrichosis terminalis (CGHT) is a rare condition characterized by universal excessive growth of pigmented terminal hairs and often accompanied with gingival hyperplasia. In the present study, we describe three Han Chinese families with autosomal-dominant CGHT and a sporadic case with extreme CGHT and gingival hyperplasia. We first did a genome-wide linkage scan in a large four-generation family. Our parametric multipoint linkage analysis revealed a genetic locus for CGHT on chromosome 17q24.2-q24.3. Further two-point linkage and haplotyping with microsatellite markers from the same chromosome region confirmed the genetic mapping and showed in all the families a microdeletion within the critical region that was present in all affected individuals but not in unaffected family members. We then carried out copy-number analysis with the Affymetrix Genome-Wide Human SNP Array 6.0 and detected genomic microdeletions of different sizes and with different breakpoints in the three families. We validated these microdeletions by real-time quantitative PCR and confirmed their perfect cosegregation with the disease phenotype in the three families. In the sporadic case, however, we found a de novo microduplication. Two-color interphase FISH analysis demonstrated that the duplication was inverted. These copy-number variations (CNVs) shared a common genomic region in which CNV is not reported in the public database and was not detected in our 434 unrelated Han Chinese normal controls. Thus, pathogenic copy-number mutations on 17q24.2-q24.3 are responsible for CGHT with or without gingival hyperplasia. Our work identifies CGHT as a genomic disorder.     

New copy number variations in schizophrenia

Genome-wide screenings for copy number variations (CNVs) in patients with schizophrenia have demonstrated the presence of several CNVs that increase the risk of developing the disease and a growing number of large rare CNVs; the contribution of these rare CNVs to schizophrenia remains unknown. Using Affymetrix 6.0 arrays, we undertook a systematic search for CNVs in 172 patients with schizophrenia and 160 healthy controls, all of Italian origin, with the aim of confirming previously identified loci and identifying novel schizophrenia susceptibility genes. We found five patients with a CNV occurring in one of the regions most convincingly implicated as risk factors for schizophrenia: NRXN1 and the 16p13.1 regions were found to be deleted in single patients and 15q11.2 in 2 patients, whereas the 15q13.3 region was duplicated in one patient. Furthermore, we found three distinct patients with CNVs in 2q12.2, 3q29 and 17p12 loci, respectively. These loci were previously reported to be deleted or duplicated in patients with schizophrenia but were never formally associated with the disease. We found 5 large CNVs (>900 kb) in 4q32, 5q14.3, 8q23.3, 11q25 and 17q12 in five different patients that could include some new candidate schizophrenia susceptibility genes. In conclusion, the identification of previously reported CNVs and of new, rare, large CNVs further supports a model of schizophrenia that includes the effect of multiple, rare, highly penetrant variants.     

Dosage Changes of a Segment at 17p13.1 Lead to Intellectual Disability and Microcephaly as a Result of Complex Genetic Interaction of Multiple Genes

The 17p13.1 microdeletion syndrome is a recently described genomic disorder with a core clinical phenotype of intellectual disability, poor to absent speech, dysmorphic features, and a constellation of more variable clinical features, most prominently microcephaly. We identified five subjects with copy-number variants (CNVs) on 17p13.1 for whom we performed detailed clinical and molecular studies. Breakpoint mapping and retrospective analysis of published cases refined the smallest region of overlap (SRO) for microcephaly to a genomic interval containing nine genes. Dissection of this phenotype in zebrafish embryos revealed a complex genetic architecture: dosage perturbation of four genes (ASGR1, ACADVL, DVL2, and GABARAP) impeded neurodevelopment and decreased dosage of the same loci caused a reduced mitotic index in vitro. Moreover, epistatic analyses in vivo showed that dosage perturbations of discrete gene pairings induce microcephaly. Taken together, these studies support a model in which concomitant dosage perturbation of multiple genes within the CNV drive the microcephaly and possibly other neurodevelopmental phenotypes associated with rearrangements in the 17p13.1 SRO.     

Outlier-Based Identification of Copy Number Variations Using Targeted Resequencing in a Small Cohort of Patients with Tetralogy of Fallot

Copy number variations (CNVs) are one of the main sources of variability in the human genome. Many CNVs are associated with various diseases including cardiovascular disease. In addition to hybridization-based methods, next-generation sequencing (NGS) technologies are increasingly used for CNV discovery. However, respective computational methods applicable to NGS data are still limited. We developed a novel CNV calling method based on outlier detection applicable to small cohorts, which is of particular interest for the discovery of individual CNVs within families, de novo CNVs in trios and/or small cohorts of specific phenotypes like rare diseases. Approximately 7,000 rare diseases are currently known, which collectively affect ∼6% of the population. For our method, we applied the Dixon’s Q test to detect outliers and used a Hidden Markov Model for their assessment. The method can be used for data obtained by exome and targeted resequencing. We evaluated our outlier- based method in comparison to the CNV calling tool CoNIFER using eight HapMap exome samples and subsequently applied both methods to targeted resequencing data of patients with Tetralogy of Fallot (TOF), the most common cyanotic congenital heart disease. In both the HapMap samples and the TOF cases, our method is superior to CoNIFER, such that it identifies more true positive CNVs. Called CNVs in TOF cases were validated by qPCR and HapMap CNVs were confirmed with available array-CGH data. In the TOF patients, we found four copy number gains affecting three genes, of which two are important regulators of heart development (NOTCH1, ISL1) and one is located in a region associated with cardiac malformations (PRODH at 22q11). In summary, we present a novel CNV calling method based on outlier detection, which will be of particular interest for the analysis of de novo or individual CNVs in trios or cohorts up to 30 individuals, respectively.