Pathogenic Copy Number Variants Research Articles

A novel compound heterozygous mutation in the DYNC2H1 gene in a Chinese family with Jeune syndrome

BackgroundThe dynein cytoplasmic two heavy chain 1 (DYNC2H1) gene encodes a cytoplasmic dynein subunit. Cytoplasmic dyneins transport cargo towards the minus end of microtubules and are thus termed the “retrograde” cellular motor. Mutations in DYNC2H1 are the main causative mutations of short rib-thoracic dysplasia syndrome type III with or without polydactyly (SRTD3). Early diagnosis of SRTD3 prenatally by ultrasound alone is difficult. In this case, a couple who gave birth to three consecutive babies with SRTD3 requested fertility guidance to avoid having another baby with SRTD3.MethodsCytogenetic and molecular genetic analyses of amniotic fluid via whole-genome sequencing (WGS), routine G-banded karyotype analysis, fluorescent quantitative polymerase chain reaction, and whole-exome sequencing (WES) were performed at 19 weeks. Peripheral blood samples from the parents were also screened by Sanger sequencing for SRTD3-related mutations.ResultsTwo compound heterozygous mutations, c.10,594 C > T and c.7720G > A, in the DYNC2H1 gene were identified, which were inherited from the mother and father, respectively. The foetus’s mother is heterozygous for the c.10,594 C > T variant, and the foetus’s father is heterozygous for the c.7720G > A variant. The mutation c.10,594 C > T, which is a nonsense mutation believed to be pathogenic, has been previously reported. The mutation c.7720G > A, which is a missense mutation, has yet to be reported. Moreover, no chromosomal abnormalities or pathogenic copy number variations (CNVs) were detected in the foetus. The patient did not become pregnant after PGT-M and IVF-ET. This family subsequently accepted donated eggs; a successful pregnancy occurred, and a healthy girl was born.ConclusionThe compound heterogeneous mutations in DYNC2H1 ultimately accounts for the diversity of disease phenotypes reported in this study and can be used to guide future pregnancies. Our findings expand the mutation spectrum of DYNC2H1 in this rare disease and highlight the value of WES in the diagnosis of skeletal dysplasia with unclear prenatal indications.

DNA copy number variations and craniofacial abnormalities in 1,457 children with neurodevelopmental disorders

BackgroundThis study aimed to investigate deoxyribonucleic acid (DNA) copy number variations (CNVs) in children with neurodevelopmental disorders and their association with craniofacial abnormalities.MethodsA total of 1,457 children who visited the Child Health Department of our hospital for unexplained Neurodevelopmental disorders (NDDs) between November 2019 and December 2022 were enrolled. Peripheral venous blood samples (2 mL) were collected from the children and their parents for whole-exome sequencing. Positive results were verified through Sanger sequencing for locus and pedigree validation. Simultaneously, a specific sign-scoring scale was created to evaluate characteristics related to the developments of eyes, nose, ears, eyebrows, head, mouth, face, trunk, limbs, and reproductive, urinary, and cardiovascular systems.ResultsA total of 536 children (36.78%, 536/1,457) were found to have genetic variations, with 379 (70.71%, 379/536) exhibiting pathogenic monogenic mutations. Furthermore, 157 children (29.29%, 157/536) harbored DNA copy number variants, encompassing microdeletions (68.15%, 107/157) and microduplications (31.85%, 50/157). Regarding the pathogenicity of CNVs, 91 (57.96%, 91/157) were identified as pathogenic, 28 (17.83%, 28/157) as variants of uncertain clinical significance (VOUS), and 38 (24.20%, 38/157) as benign according to the American College of Medical Genetics and Genomics (ACMG).Using a specific sign-scoring scale, the proportion of pathogenic CNVs in children graded 1 point or higher (64%, 58/91) was significantly higher than that of non-pathogenic CNVs (43%, 29/66) (P < 0.05). Furthermore, the proportion of microdeletions in children graded 1 point or higher (60.75%, 65/107) was significantly higher than those carrying microduplications (44%, 22/50) (P < 0.05). The proportion of pathogenic microdeletions in children graded 1 point or higher (73.43%,47/64) was significantly higher than those carrying pathogenic microduplications (40.74%, 11/27) (P < 0.05).ConclusionThe positive rate of whole-exome sequencing for children with combined craniofacial abnormalities and NDDs exceeds the international average in our study cohort. Thus, whole-exome sequencing may be recommended for precise diagnosis of neurogenetic diseases in such cases.

Chromosomal Microarray Analysis as a Diagnostic Tool in Congenital Heart Diseases

Introduction: Congenital heart diseases are a group of diseases present at birth, including anatomical and physiological abnormalities of the heart. They are the most common birth defects observed in the populations. The etiology is quite diverse. Although they mostly shows a multifactorial inheritance pattern, chromosome abnormalities, copy number variations, single gene diseases and environmental factors are involved in the etiology. Even though the etiology can be detected at a higher rate in syndromic cases, it has not been elucidated in most syndromic and non-syndromic cases. Our study aimed to detect copy number variations in syndromic and non-syndromic cases through chromosomal microarray analysis, to reveal the diagnostic value of the method, and to determine possible new loci. Methods: Patient files, photographs, and laboratory results of 85 cases (55 syndromic and 30 non-syndromic) who had congenital heart disease and chromosomal microarray analysis were retrospectively evaluated. The differences between the groups were analyzed with Chi-Square and Mann Whitney-U tests. Results: Pathogenic/likely pathogenic copy number variations were detected in 32.7% (18/55) of the syndromic case group and 6,7% (2/30) of the non-syndromic case group. The diagnostic efficacy of chromosomal microarray analysis in the diagnosis and the age at the time of admission were statistically significant between groups. Conclusions: Our study suggest that the chromosomal microarray analysis is a valuable diagnostic tool to elucidate the etiology of congenital heart diseases.

Diagnostic efficiency of exome-based sequencing in pediatric patients with epilepsy.

Epilepsy, a prevalent neurological disorder, has multifaceted etiologies. Next-generation sequencing (NGS) has emerged as a robust diagnostic tool for this condition. This study aims to evaluate the detection efficiencies of different exome-based sequencing techniques. Exome-based epilepsy panel tests, clinical exome sequencing (CES), and whole exome sequencing (WES) were conducted on 259 pediatric patients diagnosed with epilepsy. Single-nucleotide variants (SNVs) and copy number variants (CNVs) were interpreted based on each patient's phenotypic presentation. Additionally, data concerning clinical symptoms, neuroimaging findings, treatment responses, and prognostic outcomes were collected and analyzed. The overall diagnostic yield was 32.8% (85/259), with a diagnostic yield of 40.0% for exome-based epilepsy panels, 30.1% for CES, and 27.8% for WES. We identified 82 cases with pathogenic or likely pathogenic SNVs and 4 cases with pathogenic CNVs, of which one case with both SNV and CNV. The most frequently detected gene was PRRT2, present in 10.0% (9/82) of cases. Epileptic syndromes were diagnosed in 66 patients, predominantly West Syndrome, Dravet Syndrome and Genetic Epilepsy with Febrile Seizures plus. NGS is an effective method for uncovering the genetic foundations of pediatric epilepsy, with diagnostic yields varying based on the sequencing approach used. The growing preference for WES underscores its utility in complex cases, pointing to a trend towards more tailored diagnostic strategies.

Incidental Findings Identified by Prenatal Microarray Analysis and Consensus Reporting Criteria of the Catalan Public Health Network XIGENICS.

The study aimed to evaluate the frequency of pathogenic copy number variants (CNVs) classified as incidental findings (IFs) in prenatal diagnosis and to develop consensus recommendations for standardizing their reporting across six centers within the Catalan public health system (XIGENICS network). A retrospective review of 4219 consecutive prenatal microarrays performed within the network from 2018 to 2023 was conducted, including all referral reasons. To develop consensus recommendations, several discussion meetings were held along with an extensive review of the existing literature. A total of 69 IFs were identified in 68 samples, revealing a detection rate of 1.6%. They included: 5 CNVs associated with neurodevelopmental disorders and/or congenital defects with complete penetrance, 41 CNVs for neurodevelopmental disorders and/or congenital defects with incomplete penetrance, 4 disorders that can potentially be prevented or treated, 5 non-childhood onset neurological disorders, 13 X-linked disorders (mainly STS and DMD deletions), and 1 deletion of the SHOX gene. Long-term follow-up revealed that newborns with high penetrance neurosusceptibility CNVs exhibited clinical manifestations more frequently than those with low penetrance CNVs. At the time of reporting, 52 IFs were disclosed, while 17 were not. According to the new consensus criteria, 43 IFs would now be reported, 17 would not, and 9 would depend on parental decision. CNVs consistent with the referral reason were identified in 4% of cases. This study represents the largest series rigorously documenting all identified IFs in consecutive pregnancies evaluated by microarray, including both reported and unreported findings. IFs were found at a higher frequency than previously recognized, underscoring the need for specific clinical attention. Comprehensive consensus reporting recommendations were developed to ensure uniformity of criteria, and an ad hoc committee was established to manage complex cases.

Improving prenatal diagnosis with combined karyotyping, CNV-seq and QF-PCR: a comprehensive analysis of chromosomal abnormalities in high-risk pregnancies.

This study aims to assess the diagnostic efficacy of a combined approach integrating chromosomal karyotyping, copy number variation sequencing (CNV-seq), and quantitative fluorescence polymerase chain reaction (QF-PCR) in detecting chromosomal abnormalities in high-risk pregnancies. This retrospective study analyzed 617 high-risk pregnancies undergoing prenatal diagnosis from February 2023 to August 2024, with amniotic fluid samples concurrently analyzed using karyotyping, CNV-seq, and QF-PCR. We evaluated clinical characteristics, diagnostic yields, and inter-method concordance rates. Longitudinal follow-up assessed pregnancy outcomes and neonatal phenotypes, with particular emphasis on cases demonstrating diagnostic discrepancies or variants of uncertain clinical significance. The integrated approach detected chromosomal abnormalities in 12.5% (77/617) of cases, significantly higher than the rates achieved by karyotyping alone (9.7%) and CNV-seq/QF-PCR alone (8.3%) (p < 0.05). Karyotyping showed full concordance with CNV-seq and QF-PCR in detecting major chromosomal aneuploidies, identifying 21 cases of trisomy 21 and 4 cases of trisomy 18. CNV-seq uniquely identified additional pathogenic copy number variations in 2.1% of cases and variants of uncertain significance (VUS) in 3.2% of cases, both undetectable by conventional karyotyping. Subjects with high-risk non-invasive prenatal testing (NIPT) results had the highest abnormality detection rate (57.6%, p < 0.05). Follow-up data revealed pregnancy termination in 44 of 97 cases with chromosomal abnormalities. Notably, neonates carrying pathogenic CNVs inherited from asymptomatic parents demonstrated normal phenotypes. The integration of karyotyping, CNV-seq, and QF-PCR provides superior diagnostic yield compared to individual testing strategies in high-risk pregnancies. Although karyotyping remains the gold standard for detecting major chromosomal aberrations, CNV-seq and QF-PCR enhance diagnostic precision through detection of submicroscopic variations. Multi-center studies with larger cohorts are needed to confirm these findings and clarify the clinical significance of uncertain variants.

Role of copy number variation analysis in prenatally diagnosed Blake’s pouch cyst

BackgroundBlake’s pouch cyst (BPC) is a midline cystic anomaly of the posterior fossa. BPC has been shown to have a risk of aneuploidy prenatally. Copy number variation (CNV) and/or genetic syndromes have been reported in a few prenatal/postnatal cases with BPC. The purpose of this study is to determine the additional value of CNV analysis for prenatal diagnosis and prognosis evaluation of BPC.MethodsWe reviewed the sonographic findings and genetic results of BPC diagnosed within 6 years at our center. Patients were classified into the isolated and non-isolated groups based on the prenatal and postnatal imaging. We analyzed the chromosomal abnormalities by conventional karyotype analysis combined with chromosomal microarray analysis (CMA) or CNV sequencing (CNV-seq).ResultsWe recruited 467 low-risk fetuses as the control group to establish normal references of vermian area and brainstem-vermis (BV) angle. Prenatal/postnatal MRI or neonatal neurosonography was used as diagnostic criteria. 34 patients were diagnosed as BPC, including 21 (61.8%) patients with non-isolated and 13 (38.2%) with isolated. Twenty-two patients underwent CMA/CNV-seq, among them 14 patients were performed both CMA/CNV-seq and karyotype analysis. Seven (7/22, 31.8%) patients with BPC had chromosomal abnormalities, including 3 (3/22, 13.6%) patients with chromosomal aneuploidy - trisomy 21, 18 and 13, and 4 (4/22, 18.2%) patients had pathogenic CNVs located at 3p, 9p, Xp/Xq and 7p. Anomalies in fetal heart (35.3%), central nervous system (CNS) (26.5%) and limb (14.7%) were the three top anomalies accompanying BPC.ConclusionsCNV analysis could provide some additional information for prenatal diagnosis and prognosis counseling for patients with non-isolated BPC. And, it adds less value for patients with isolated BPC, however, isolated BPC can be a soft marker for aneuploidy.

Findings in Chromosomal Microarray Analysis during Prenatal Diagnosis in High-Risk Individuals

Introduction: Chromosomal microarray analysis (CMA) allows the detection of submicroscopic chromosomal abnormalities such as unbalanced translocations and inversions. In recent years, its use in prenatal diagnosis has been implemented when certain ultrasound findings are detected. The purpose of this study was to analyze and describe the imbalances detected in prenatal samples collected from pregnancies followed in our center for having the indication to perform diagnosis using CMA. Material and Method: On a population of pregnant women of 13,685, 216 CMAs were performed on chorionic villi and amniotic fluids during the period 2019–2023. The inclusion criteria were normal screening of common aneuploidies and at least one of the following features: nuchal translucency higher than percentile 99, fetal abnormalities, early-onset fetal growth restriction, parents’ history of chromosomal imbalances, or cases with chromosomal imbalances. When a relevant variant was detected, it was analyzed in the parents’ fetus and when available, the phenotype of the born children was collected. Results: Pathogenic copy number variations (CNVs) were detected in 13 of 216 samples (6%). In a single sample, two concurrent CNVs were detected. Isolated CNVs had OMIM numbers and corresponded to already reported syndromes. Seven variants of unknown significance (3.7%) were observed. The study of the parents showed that 14 of 21 variants identified had arisen de novo (one pathogenic and five unknown CNVs had been inherited from an apparently healthy parent). Three microduplications specially drew our attention: duplication 5q35.2 which encompassed MSX2 gene (because the reported phenotype is not consistent with what is expected for the genomic region) and duplications 1q21.1 and 16p11.2 (due to the ultrasound findings detected in fetuses had recently been postulated to be associated with these CNVs). Conclusion: The phenotype of CNVs identified in prenatal samples is highly variable prenatally, like postnatally. Some findings may be part of the syndromes to which they give rise and some phenotypes may be pending to define. Further studies are needed to better define these variants and to understand how haploinsufficiency or over-expression of genes included in these regions can cause such complex phenotypes.

Unveiling genetic insights: Array-CGH and WES discoveries in a cohort of 122 children with essential autism spectrum disorder

BackgroundAutistic Spectrum Disorder (ASD) is a neurodevelopmental disorder with a strong genetic component and high heterogeneity. Essential ASD refers to patients who do not have other comorbidities. This study aimed to investigate the genetic basis of essential ASD using whole exome sequencing (WES) and array-comparative genomic hybridization (array-CGH).ResultsIn a cohort of 122 children with essential ASD, WES detected 382 variants across 223 genes, while array-CGH identified 46 copy number variants (CNVs). The combined use of WES and array-CGH revealed pathogenic variants in four patients (3.1% detection rate) and likely pathogenic variants in 34 patients (27.8% detection rate). Only one patient had a pathogenic CNV (0.8% detection rate). Including likely pathogenic variants, the overall detection rate was 31.2%. Additionally, 33 de novo heterozygous sequence variants were identified by WES, with three classified as pathogenic and 13 as likely pathogenic. Sequence variants were found in 85 genes already associated with ASD, and 138 genes not previously included in the SFARI dataset were identified as potential new candidate genes.ConclusionsThe study enhances genetic understanding of essential ASD and identifies new candidate genes of interest. The findings suggest that using both array-CGH and WES in patients with essential ASD can improve the detection of pathogenic and likely pathogenic genetic variants, contributing to better diagnosis and potentially guiding future research and treatment strategies.

Complete genomic profiles of 1,496 Taiwanese reveal curated medical insights

IntroductionThe population of Taiwan has a long history of ethno-cultural evolution. The Taiwanese population was isolated from other large populations such as the European, Han Chinese, and Japanese population. The Taiwan Biobank (TWB) project has built a nationwide database, particularly for personal whole-genome sequence (WGS) to facilitate basic and clinical collaboration nationally and internationally, making it one of the most valuable public datasets of the East Asian population. ObjectivesThis study provides comprehensive medical genomic findings from TWB WGS data, for better characterization of disease susceptibility and the choice of ideal treatment regimens in Taiwanese population. MethodsWe reanalyzed 1,496 WGS using a PrecisionFDA Truth challenge winner method Sentieon DNAscope. Single nucleotide variants (SNV) and small insertions/deletions (INDEL) were benchmarked. We also analyzed pharmacogenomic (PGx) drug-associated alleles, and copy number variants (CNV). Multiple practicing clinicians reviewed and curated the clinically significant variants. Variant annotations can be browsed at TaiwanGenomes (https://genomes.tw). ResultsWe found that each participant had an average of 6,870.7 globally novel variants and 75.3% (831/1103) of the participants harbored at least one PharmGKB-selected high evidence level human leukocyte antigen (HLA) risk allele. 54 PharmGKB-reported high-level instances of evidence of Cytochrome P450 variant-drug pairs, with a population frequency of over 13.2%. We also identified 23 variants in the ACMG secondary finding V3 gene list from 25 participants, suggesting that 1.67% (25/1496) of the population is harboring at least one medical actionable variant. Our carrier status analyses suggest that one in 25 couples (3.94%) would risk having offspring with at least one pathogenic variant, which is in line with rates found in Japan and Singapore. For pathogenic CNV, we detected 6.88% and 2.02% carrier rates for alpha thalassemia and spinal muscular atrophy, respectively. ConclusionOur study highlights the overall medical insights of a complete Taiwanese genomic profile.

Obesity and metabolic syndrome in adults with a 22q11.2 microdeletion.

Copy number variations (CNVs) may contribute to medical conditions. However, research on the impact of individual CNVs on endocrine disease is limited. This study aimed to provide new data on obesity and metabolic syndrome (MetS) in adults with microdeletion 22q11.2, the pathogenic CNV associated with 22q11.2 deletion syndrome. We examined prevalence rates of obesity and MetS in 103 adults with a typical 22q11.2 deletion (45.2% male, at median age 30.0 (range 17-71) years) and compared these rates with population-based data. Generalized obesity was defined by a body mass index (BMI) ≥ 30 kg/m2, abdominal obesity by a waist circumference (WC) of ≥102 cm in males and ≥88 cm in females, and MetS by standard Joint Interim Statement criteria. General linear models were used to examine the independent associations of age, sex, congenital heart defect, smoking, and antipsychotic use with BMI, WC, and the presence of MetS. Prevalence rates of generalized obesity (32.0%), abdominal obesity (51.5%), and MetS (33.0%) were significantly higher compared to a population-based cohort (15.7% (P < 0.0001), 36.1% (P = 0.002), and 15.2% (P < 0.0001), respectively). In antipsychotic naïve subjects, significant correlations were observed between age and BMI (r = 0.54, P < 0.001), and age and WC (r = 0.60, P < 0.001). These correlations were not present in individuals taking antipsychotic medication. The models predicting BMI (F(5, 97) = 3.083, R2 = 0.137, P = 0.01) and WC (F(5, 92) = 5.985, R2 = 0.245, P < 0.001) were significant. Only age was individually predictive of outcomes (P < 0.05 and P < 0.001). The model predicting MetS was also significant (P < 0.001), with higher age being the only factor associated with MetS (OR = 1.07, 95% CI = 1.03-1.12, P < 0.001). Generalized and abdominal obesity, as well as MetS, appear to be common in adults with 22q11.2 deletion syndrome, emphasizing the importance of careful monitoring from a young age. These findings contribute to the limited knowledge about the association between pathogenic CNVs, obesity, and MetS.

Investigation of chromosomal anomalies and copy number variations in children diagnosed with autism spectrum disorder by array CGH method.

This study aimed to identify the chromosomal anomalies and copy number variations (CNVs) in autism spectrum disorder (ASD) and to provide genotype/phenotype correlations. Fifty-four patients diagnosed with ASD between March 2021 and June 2022 were included in the study. Patients were evaluated by cytogenetic analysis and array comparative genomic hybridisation analysis (aCGH). The structural and numerical chromosomal anomaly was detected in 3.7%, and the CNVs were identified in 18.52% of patients. Of the CNVs detected, 27.3% were identified as pathogenic, 18.2% as likely pathogenic and 54.5% as VUS. The copy number gain rate of the detected CNVs was higher than the copy number losses rate, 70% and 30% respectively. As an important finding in the study, a new pathogenic CNV with a 6.3-mb copy number gain in the 3p22.3p22.2 region, whose gene region had not been previously defined in OMIM, was detected. Identifying a genetic aetiology may provide clinicians with more information about disease prognosis and risk of recurrence.

Genetic analysis of 280 children with unexplained developmental delay or intellectual disability using whole exome sequencing

IntroductionDevelopmental delay (DD) and intellectual disability (ID) are key manifestations of neurodevelopmental disorders (NDDs), characterized by considerable clinical and genetic variability, which complicates genetic diagnosis. Whole exome sequencing (WES) has become an effective method for uncovering genetic causes in patients with unexplained DD/ID.MethodsWe retrospectively analyzed WES data from 280 patients diagnosed with unexplained DD/ID. Demographic information and genetic variants identified through WES were assessed, along with an evaluation of clinical factors that might influence the detection of genetic causes.ResultsPathogenic variants were detected in 73 cases (36.07%), including 25 cases involving pathogenic chromosomal copy number variations. Clinical factors such as age, sex, gestational age, birth weight, anoxia, jaundice, associated symptoms, family history, muscle strength, muscle tone, epilepsy, brain MRI findings, EEG results, and the severity of DD/ID did not significantly impact the WES outcomes. However, a significant correlation was observed between delivery mode and positive WES results, with a higher diagnostic yield among patients delivered via caesarean section.ConclusionsWES is a valuable approach for identifying genetic causes in patients with unexplained DD/ID, providing benefits for patient management, family genetic counseling, and long-term prognosis assessment.Clinical trial numberNot applicable.

Genetic correlation between fetal nuchal translucency thickening and cystic hygroma and exploration of pregnancy outcome

Chromosome microarray analysis (CMA) and whole exome sequencing (WES) are increasingly utilized in prenatal diagnosis of abnormal ultrasound findings, but studies on correlation between pathogenic copy number variations (pCNVs) and single-gene mutations in fetuses with nuchal translucency (NT) thickening/cystic hygroma (CH), and pregnancy outcomes, are rare. This study aimed to investigate clinical value of CMA and WES for NT thickening/CH in fetuses, explore genetic correlation between fetal NT thickening and CH, and analyze pregnancy outcomes. We retrospectively selected 215 pregnant women diagnosed with fetal NT thickening (NT > 95th)/CH who underwent invasive prenatal diagnosis at our hospital from January 2020 to June 2022. With negative chromosomal karyotype analysis (KA) and CMA results, patients voluntarily underwent WES. Patients were grouped by NT thickening/CH, and application value of KA, CMA, and WES examined. Ultrasound findings, pregnancy outcomes, and fetal growth post-birth were followed during mid/late pregnancy and post-delivery. Abnormalities in chromosomal number were detected in 28 of 215 samples, with a detection rate of 13.0%, and pCNVs were detected in 12 cases, with a detection rate of 5.6%. The most common abnormality in fetuses from both groups suggested by CMA was 22q11.21 microdeletion-microduplication syndrome. 35 patients with negative KA and CMA results underwent WES, and single gene variants were detected in 12 fetuses, with an abnormality rate of 34.3%. The incidence of adverse pregnancy outcomes was 28.2% in the NT thickening group and 82.9% in the CH group (P < 0.05). Overall, fetal NT thickening/CH was associated with genetic abnormalities, WES further improved the diagnosis of abnormal fetuses after negative KA and CMA results in both groups, and the incidence of adverse pregnancy outcomes was lower in the NT thickening group than in the CH group. The management of pregnancy outcomes could guide clinical genetic counselling.

Looks Can Be Deceiving: Diagnostic Power of Exome Sequencing in Debunking 15q11.2 Copy Number Variations.

Background/Objectives: The pathogenetic role of 15q11.2 Copy Number Variations (CNVs) remains contentious in the scientific community, as microdeletions and microduplications in this region are linked to neurodevelopmental disorders with variable expressivity. This study aims to explore the diagnostic utility of Exome Sequencing (ES) in a cohort of pediatric patients with 15q11.2 CNVs. Methods: We enrolled 35 probands with 15q11.2 microdeletions or microduplications from two genetic centers between January 2021 and January 2023. Chromosomal Microarray Analysis (CMA) and ES were performed with written consent obtained from all parents. Pathogenic variants were classified according to ACMG guidelines. Results: CMA identified additional pathogenic CNVs in 3 of 35 children (9%). Subsequent ES revealed likely pathogenic or pathogenic variants in 11 of 32 children (34%). Notably, a higher percentage of isolated autism spectrum disorder (ASD) diagnoses was observed in patients without other CNVs or point mutations (p = 0.019). Conclusions: The ES analysis provided a diagnostic yield of 34% in this pediatric cohort with 15q11.2 CNVs. While the study does not dismiss the contribution of the CNV to the clinical phenotype, the findings suggest that ES may uncover the underlying causes of neurodevelopmental disorders. Continuous monitoring and further genetic testing are recommended for all 15q11.2 CNV carriers to optimize clinical management and familial counseling.

Genetic burden in neonatal and pediatric-onset pulmonary hypertension: A single-center retrospective study using exome sequencing in a Chinese population

ObjectiveThis single-center retrospective study aimed to investigate the genetic factors contributing to neonatal and pediatric pulmonary hypertension in a Chinese population using trio whole-exome sequencing (trio-WES). MethodThis retrospective analysis reviewed the clinical and genetic profiles of children under 18 years of age diagnosed with pulmonary hypertension between March 2017 and March 2022. The diagnosis of pediatric pulmonary hypertension was confirmed through echocardiography and catheterization. Trio-WES was performed on the patients and their parents after obtaining informed consent. ResultsA total of 51 children with neonatal and pediatric pulmonary hypertension were included, comprising 20 with pediatric pulmonary arterial hypertension and 31 with persistent pulmonary hypertension of the newborn. Trio-WES detected 16 pathogenic or likely pathogenic variants in 14 patients across ten genes, including: BMPR2 (n = 2), CHD7 (n = 2), FOXF1 (n = 2), MED13L (n = 1), TNNI3 (n = 2), ALMS1 (n = 1), KMT2D (n = 2), NKX2-1 (n = 1), NONO (n = 1), and CACNA1E (n = 1). In addition, two patients exhibited de novo pathogenic copy number variations. ConclusionOur findings demonstrate the significant diagnostic value of trio-WES in pediatric pulmonary hypertension, supporting its recommendation for these patients.

An innovative CRISPR/Cas9 mouse model of human isolated microtia indicates the potential contribution of CNVs near HMX1 gene

BackgroundMicrotia is a prevalent congenital malformation, the precise etiology and pathogenesis of which remain elusive. Mutations in the non-coding region of the HMX1 gene have been implicated in isolated cases of microtia, emerging as a significant focus of contemporary research. Several pathogenic copy number variations (CNVs) proximal to the HMX1 gene have been documented in wild animal populations, whereas only a single large segmental duplication in this region has been identified in humans. However, the absence of a gene-edited animal model has impeded the investigation of the unclear gene function associated with HMX1 mutations in human isolated microtia. In this study, we sought to precisely identify the pathogenic mutation by analyzing three pedigrees alongside population controls. Subsequently, our objective was to develop a CRISPR/Cas9 gene-edited mouse model to elucidate the functional implications of the identified mutation. MethodsGenomic DNA was collected from 32 affected individuals across three pedigrees, as well as from 2000 control subjects. Comprehensive genomic analyses, including genome-wide linkage analysis, targeted capture, second-generation sequencing, and copy number analysis, were conducted to identify potential mutations associated with congenital auricle malformation. CRISPR/Cas9 gene-edited murine models were generated in response to the identified mutation. The auricular phenotypes of these gene-edited mice were systematically monitored. Small-animal Micro-CT scanning was employed to identify potential craniofacial or skeletal abnormalities. Furthermore, the expression of the HMX1 gene in the PA2 region of mouse embryos was quantified using RT-qPCR. ResultsA co-segregated 600 base pair duplication located on chromosome 4 (chr4:8701900-8702500, hg19) was identified in affected individuals across three pedigrees, but was absent in healthy controls. Two types of CRISPR/Cas9 gene-edited mice were subsequently generated. The knock-in (KI) mouse model was engineered by inserting one copy of the duplicated sequence directly adjacent to the mutated site, whereas the knockout (KO) mouse model was created by excising the mutation sequence. The phenotypes of different group of CRISPR/Cas9 gene-edited mice demonstrated distinct auricular deformities. Furthermore, an increase in the copy number of the mutated sequence was associated with elevated expression levels of HMX1 in the gene-edited mouse model. ConclusionsIn this study, we further narrowed down and identified a 600 base pair copy number variation (CNV) located at chr4:8701900-8702500 (hg19), which is implicated in human bilateral, isolated microtia. Utilizing CRISPR/Cas9 technology, we developed novel mouse models harboring the identified mutation. These models serve as a robust platform for the comprehensive investigation of the underlying mechanisms of the disease.

Copy Number Analysis of Whole Exome Sequencing Data

Abstract Background Genetic alterations implicated in constitutional disorders range in size from single nucleotide substitutions to losses and gains of millions of bases. Whole exome sequencing (WES) captures many clinically relevant variants, but an analytic pipeline optimized for detection of small substitutions, insertions, and deletions may miss pathogenic copy number variants (CNVs). Historically, our laboratory performed separate cytogenetic tests to evaluate for larger genomic imbalances. Addition of copy number analysis to our WES pipeline could improve the assay’s diagnostic yield. This study describes part of our strategy to validate copy number analysis of our constitutional whole exome sequencing data. Methods We identified 18 CNV specimens that underwent both chromosomal microarray analysis (CMA) and WES between 2017 and 2023. Variants included 13 deletions (size range 14Kb-2Mb) and 5 duplications (size range 325Kb-10Mb). The standard method of constitutional copy number analysis in our clinical laboratory is CMA using the Affymetrix Cytoscan HD Array and analysis software. CNVs identified on CMA were reviewed with reference to the Database of Genomic Variants and multiple academic hospital databases. WES was performed on an Illumina sequencing system following capture-based library enrichment with the Integrated DNA Technologies xGen Exome Research, CNV Backbone, Human mtDNA Research, and Human ID Research Panel probes. CNVs identified on WES were called using the Broad Institute’s Genomic Analysis Toolkit (GATK) with a quality score cutoff of 120. Whole exome sequencing data was visualized on the Integrative Genomics Viewer. Results 14 out of 18 CNVs reported on CMA were also detected on WES with a quality score at or above 120 (78%). This includes 10 out of 13 deletions (77%) and 3 out of 5 duplications (60%). For both deletions and duplications, the size ranges of detected variants at or above the cutoff score and undetected variants overlapped. One duplication reported on CMA was detected on WES with a quality score below 120. Visualization of whole exome sequencing data showed variation in probe density that may have affected CNV calling. Conclusions The majority of CNVs reported after CMA (14/18, 78%) were also detected on WES data using a GATK quality score cutoff of 120. The data does not suggest an association between CNV size and detection by WES, although interpretation is limited by the small number of cases. Data visualization may be required to identify some CNVs. Future steps to characterize the limitations of copy number analysis of WES data include assessments of variance in probe density and read depth across the exome. Copy number analysis of WES data from cases with normal CMA results will also be performed for assay validation.

Copy number variations in RNF216 and postsynaptic membrane-associated genes are associated with bipolar disorder: a case-control study in the Japanese population.

Bipolar disorder (BD) is a common psychiatric disorder characterized by alterations between manic/hypomanic and depressive states. Rare pathogenic copy number variations (CNVs) that overlap with exons of synaptic genes have been associated with BD. However, no study has comprehensively explored CNVs in synaptic genes associated with BD. Here, we evaluated the relationship between BD and rare CNVs that overlap with synaptic genes, not limited to exons, in the Japanese population. Using array comparative genome hybridization, we detected CNVs in 1839 patients with BD and 2760 controls. We used the Synaptic Gene Ontology database to identify rare CNVs that overlap with synaptic genes. Using gene-based analysis, we compared their frequencies between the BD and control groups. We also searched for synaptic gene sets related to BD. The significance level was set to a false discovery rate of 10%. The RNF216 gene was significantly associated with BD (odds ratio, 4.51 [95% confidence interval, 1.66-14.89], false discovery rate < 10%). The BD-associated CNV that corresponded with RNF216 also partially overlapped with the minimal critical region of the 7p22.1 microduplication syndrome. The integral component of the postsynaptic membrane (Gene Ontology:0099055) was significantly associated with BD. The CNV overlapping with the intron region of GRM5 in this gene set showed a nominal significant association between cases and controls (P < 0.05). We provide evidence that CNVs in RNF216 and postsynaptic membrane-related genes confer a risk of BD, contributing to a better understanding of the pathogenesis of BD.

Bovine aortic arch: a potential indicator that may not serve in prenatal diagnosis - a study based on fetal anatomy, genetics, and postnatal clinical outcomes

ObjectiveTo investigate the structural abnormalities, genetic results, and postnatal clinical outcomes of fetuses with bovine aortic arch (Bovine Aortic Arch, BAA) to provide a basis for prenatal counseling and management.MethodsA retrospective analysis was conducted on 216 fetuses diagnosed with bovine aortic arch through prenatal ultrasound screening at the First Affiliated Hospital of Anhui Medical University and the No.901 Hospital of the Joint Service of the People’s Liberation Army from January 2019 to February 2023. Their family history of genetic diseases, prenatal screening results, and postnatal follow-up data were collected. The fetuses were divided into an isolated BAA group (n = 192) and a non-isolated BAA group (n = 24). Chromosomal karyotyping and copy number variation (CNV) testing were conducted, and statistical analysis was performed using SPSS 22.0 software.ResultsOf the 216 fetuses with BAA, 192 were isolated BAA (88.89%), and 24 were non-isolated BAA (11.11%). Among the isolated BAA fetuses, only 1 case (0.52%) had chromosomal karyotype and pathogenic CNV abnormalities. Among the non-isolated BAA fetuses, 4 cases (16.67%) had chromosomal or CNV abnormalities, but the overall risk was low. The postnatal outcomes of isolated BAA fetuses were good (99.48%), while 79.17% of non-isolated BAA fetuses had good postnatal outcomes.ConclusionMost BAA fetuses are isolated, with a very low incidence of chromosomal abnormalities and pathogenic CNVs, and have good postnatal outcomes. The clinical value of isolated BAA is limited, and invasive prenatal diagnosis is not recommended for low-risk populations. Prenatal screening should focus on the risk of concurrent severe structural anomalies and chromosomal abnormalities.