BACKGROUND: Genetic disorders often manifest as abnormal fetal or childhood development. Copy number variations (CNVs) represent a significant genetic mechanism underlying such disorders. Despite their importance, the effectiveness of clinical exome sequencing (CES) in detecting CNVs, particularly small ones, remains incompletely understood. We aimed to evaluate the detection of both large and small CNVs using CES in a substantial clinical cohort, including parent-offspring trios and proband only analysis.
METHODS: We conducted a retrospective analysis of CES data from 2428 families, collected from 2018 to 2021. Detected CNV were categorized as large or small, and various validation techniques including chromosome microarray (CMA), Multiplex ligation-dependent probe amplification assay (MLPA), and/or PCR-based methods, were employed for cross-validation.
RESULTS: Our CNV discovery pipeline identified 171 CNV events in 154 cases, resulting in an overall detection rate of 6.3%. Validation was performed on 113 CNVs from 103 cases to assess CES reliability. The overall concordance rate between CES and other validation methods was 88.49% (100/113). Specifically, CES demonstrated complete consistency in detecting large CNV. However, for small CNVs, consistency rates were 81.08% (30/37) for deletions and 73.91% (17/23) for duplications.
CONCLUSIONS: CES demonstrated high sensitivity and reliability in CNV detection. It emerges as an economical and dependable option for the clinical CNV detection in cases of developmental abnormalities, especially fetal structural abnormalities.

Non-small cell lung cancer (NSCLC) has been found to have recurrent genetic abnormalities, and novel therapies targeting these aberrations have improved patient survival. In this study, specimens from benign tissue, primary tumors, and brain metastases were obtained at autopsy from a 55-year-old White female patient diagnosed with NSCLC and were examined using next-generation sequencing (NGS) and chromosomal microarray assay (CMA). No genetic aberrations were noted in the benign tissue; however, NGS identified a mutation in the KRAS proto-oncogene, GTPase (KRAS): KRAS exon 2 p.G12D in primary and metastatic tumor specimens. We observed 7 DNA copy number aberrations (CNAs) in primary and metastatic tumor specimens; an additional 7 CNAs were exclusively detected in the metastatic tumor specimens. These DNA alterations may be genetic drivers in the pathogenesis of the tumor specimen from our patient and may serve as biomarkers for the classification and prognosis of NSCLC.

About 15% of congenital heart disease (CHD) patients have a known pathogenic copy number variant. The majority of their chromosomal microarray (CMA) tests are deemed normal. Diagnostic interpretation typically ignores microdeletions smaller than 100 kb. We hypothesized that unreported microdeletions are enriched for CHD genes. We analyzed \"normal\" CMAs of 1762 patients who were evaluated at a pediatric referral center, of which 319 (18%) had CHD. Using CMAs from monozygotic twins or replicates from the same individual, we established a size threshold based on probe count for the reproducible detection of small microdeletions. Genes in the microdeletions were sequentially filtered by their nominal association with a CHD diagnosis, the expression level in the fetal heart, and the deleteriousness of a loss-of-function mutation. The subsequent enrichment for CHD genes was assessed using the presence of known or potentially novel genes implicated by a large whole-exome sequencing study of CHD. The unreported microdeletions were modestly enriched for both known CHD genes and those of unknown significance identified using their de novo mutation in CHD patients. Our results show that readily available \"normal\" CMA data can be a fruitful resource for genetic discovery and that smaller deletions should receive more attention in clinical evaluation.

Single nucleotide polymorphism (SNP) chromosome microarray is well established for investigation of children with intellectual deficit/development delay and prenatal diagnosis of fetal malformation but has also emerged for uniparental disomy (UPD) genotyping. Despite published guidelines on clinical indications for testing there are no laboratory guidelines published for performing SNP microarray UPD genotyping. We evaluated SNP microarray UPD genotyping using Illumina beadchips on family trios/duos within a clinical cohort (n=98) and then explored our findings in a post-study audit (n=123). UPD occurred in 18.6% and 19.5% cases, respectively, with chromosome 15 most frequent (62.5% and 25.0%). UPD was predominantly maternal in origin (87.5% and 79.2%), highest in suspected genomic imprinting disorder cases (56.3% and 41.7%) but absent amongst children of translocation carriers. We assessed regions of homozygosity among UPD cases. The smallest interstitial and terminal regions were 2.5 Mb and 9.3 Mb, respectively. We found regions of homozygosity confounded genotyping in a consanguineous case with UPD15 and another with segmental UPD due to non-informative probes. In a unique case with chromosome 15q UPD mosaicism, we established the detection limit of mosaicism as ∼5%. From the benefits and pitfalls identified in this study, we propose a testing model and recommendations for UPD genotyping by SNP microarray.

BACKGROUND: Double trisomies are rare findings among products of conception and are often lethal to the developing embryo or fetus.
METHODS: Here we describe a double trisomy case with symptoms of threatened miscarriage at 9 weeks gestation. Ultrasound revealed an anembryonic pregnancy. Pregnancy was terminated by dilation and curettage at gestational age 11 weeks and 6 days. Histologic examination and chromosome microarray were performed on a formalin-fixed product of conception (POC) sample to identify the cause of the anembryonic pregnancy.
RESULTS: Chromosome microarray analysis revealed a female chromosome complement with double trisomies 10 and 20, arr(10,20)x3, consistent with a karyotype of 48,XX,+10,+20.
CONCLUSIONS: To the best of our knowledge, this is the first reported case of double trisomy 10 and 20 in a POC. Due to nonspecific histopathological findings, chromosomal microarray is a powerful tool in identifying and differentiating chromosomal aneuploidies.

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Structural variation in genomes, such as copy number variants (CNVs), is under scrutiny for its contribution to phenotypic expression and evolution. Regions of homozygosity (ROH) are ripe for phenotype-gene discovery. Determining the genes and related phenotypes within genomic regions is key to studying potential functional and phenotypic consequences. Because individuals have multiple CNVs and ROHs in their genome, identifying genomic regions that are phenotypically significant is challenging. GeneScout is a web-based tool that can be used to search genomic regions to display and filter the genes and their associated phenotypes within regions of interest. Phenotypes and their associated gene(s) can then be filtered to show only the genes with phenotypes that have a particular inheritance pattern and/or specific clinical feature(s). Phenotypes can then be selected to compare the clinical synopses side-by-side in Online Mendelian Inheritance in Man (OMIM® ). Additionally, two coordinate sets can be compared to determine either the regions of overlap or the unique regions (subtraction). The resulting coordinate ranges are displayed on the results page, and the results table displays only the genes and phenotypes present within the coordinate ranges. The interactive table includes gene-specific links to external resources such as ClinVar, ClinGen validity, ClinGen dosage, and gnomAD, and a diamond symbol next to the gene name indicates a gene that spans the start or end of a coordinate range. Searches and comparisons may be performed for coordinates in assemblies GRCh37 (hg19) and GRCh38 (hg38). The results page offers the option to liftover coordinates entered in GRCh37 to GRCh38 and updates the results table to display the gene content based on assembly GRCh38. The search coordinates and results table can be downloaded in a tab-delimited or Excel file. © 2022 Wiley Periodicals LLC. Basic Protocol: Searching GeneScout.

Fetal cervical teratoma is a rare congenital neck tumor. Here, we report a case of a fetus with an anterior solid neck tumor that was confirmed to have an immature teratoma by histology. A duplication was found at chromosome 14q24.1-q24.3 of the fetus in chromosome microarray (CMA) and whole exome sequencing (WES), which was a copy number variation (CNV) and a probably new-onset. Ultrasound coupled with magnetic resonance imaging (MRI) can be considered to be a relatively reliable diagnostic tool, whereas ex-utero intrapartum therapy or resection of the tumor mass on placental support may improve the chances of the newborn\'s survival. Strangely, the same duplication occurred on her next fetus that was found with complex congenital heart malformations. CNV at chromosome 14q24.1-q24.3 needs to be paid more attention.

Patients with chromosome 22q11.2 deletion syndromes classically present with variable cardiac defects, parathyroid and thyroid gland hypoplasia, immunodeficiency and velopharyngeal insufficiency, developmental delay, intellectual disability, cognitive impairment, and psychiatric disorders. New technologies including chromosome microarray have identified smaller deletions in the 22q11.2 region. An increasing number of studies have reported patients presenting with various features harboring smaller 22q11.2 deletions, suggesting a need to better elucidate 22q11.2 deletions and their phenotypic contributions so that clinicians may better guide prognosis for families. We identified 16 pediatric patients at our institution harboring various 22q11.2 deletions detected by chromosomal microarray and report their clinical presentations. Findings include various neurodevelopmental delays with the most common one being attention deficit hyperactivity disorder (ADHD), one reported case of infant lethality, four cases of preterm birth, one case with dual diagnoses of 22q11.2 microdeletion and Down syndrome. We examined potential genotypic contributions of the deleted regions.

MEIS2 (Meis homeobox 2) encodes a homeobox protein in the three amino acid loop extension (TALE) family of highly conserved homeodomain-containing transcription regulators important for development. MEIS2 deletions/mutations have been associated with cleft lip/palate, dysmorphic facial features, cardiac defects, as well as intellectual disability at a variable severity. Here we report on one familial case that two affected siblings carry the same non-mosaic ~ 423 kb genomic deletion at 15q14 encompassing the entirety of CDIN1 and the last three exons (ex. 10, 11, 12) of the MEIS2 gene, while their unaffected father is mosaic for the same deletion in about 10% lymphocytes. Both siblings presented with mild developmental delay and bifid uvula, while no congenital cardiac abnormalities were identified. The elder sister also showed syncopal episodes and mild speech delay and the father had atrial septal defects. This is the first report showing multiple family members inherit a genomic deletion resulting in a MEIS2 partial truncation from a mosaic parent. Taken all together, this study has important implications for genetic counseling regarding recurrence risk and also points to the importance of offering MEIS2 gene tests covering both point mutations and microdeletions to individuals with milder bifid uvula and developmental delay.