Variants Of Unknown Clinical Significance Research Articles

Clinical characteristics and genetic analysis of six children with carnitine palmitoyltransferase 2 deficiency.

To investigate the clinical characteristic and genetic variants of children with carnitine palmitoyltransferase 2 (CPT2) deficiency. The clinical and genetic data of 6 children with CPT2 deficiency were retrospectively analyzed. The blood acylcarnitines and genetic variants were detected with tandem mass spectrometry and whole-exon gene sequencing, respectively. There were 4 males and 2 females with a mean age of 32 months (15 d-9 years) at diagnosis. One case was asymptomatic and with normal laboratory test results, 2 had delayed onset, and 3 were of infantile type. Three cases were diagnosed at neonatal screening, and 3 cases presented with clinical manifestations of fever, muscle weakness, and increased muscle enzymes. Five children presented with decreased free carnitine and elevated levels of palmitoyl and octadecenoyl carnitines. CPT2 gene variants were detected at 8 loci in 6 children (4 harboring biallelic mutations and 2 harboring single locus mutations), including 3 known variants (p.R631C, p.T589M, and p.D255G) and 5 newly reported variants (p.F352L, p.R498L, p.F434S, p.A515P, and c.153-2A>G). It was predicted by PolyPhen2 and SIFT software that c.153-2A>G and p.F352L were suspected pathogenic variants, while p.R498L, p.F434S and p.A515P were variants of unknown clinical significance. The clinical phenotypes of CPT2 deficiency are diverse. An early diagnosis can be facilitated by neonatal blood tandem mass spectrometry screening and genetic testing, and most patients have good prognosis after a timely diagnosis and treatment.

Abstract 1735: DNA demethylating agents have cell type-specific effects on viability and BRCA2 alternative splicing

Abstract Introduction: BRCA2 is one of two principal tumor suppressors responsible for hereditary breast/ovarian cancer syndrome (HBOC). Patients with strong family histories of breast/ovarian cancer may carry BRCA2 DNA sequence variants of unknown clinical significance (VUSs). To evaluate which of these VUSs may contribute to cancer risk by altering splicing patterns, naturally occurring BRCA2 mRNA alternate splicing events have been extensively characterized, but it is not yet known which if any of these alternate splicing events plays a role in BRCA2 function. One variant lacking exon 3 (∆3), which maintains the full length translational reading frame, lacks sequence encoding EMSY and PALB binding domains as well as transactivation function. Previous work has shown that, while some VUSs associated with increased levels of ∆3 in lymphoblastoid cell lines are not pathogenic, germline deletions that eliminate BRCA2 exon 3 are associated with increased breast cancer risk. It is therefore of interest to characterize the factors that influence the frequency of naturally occurring BRCA2 exon 3-skipping, including cell types and therapies. DNA demethylating agents are used as cancer therapy to promote expression of tumor suppressor genes that may be epigenetically silenced in tumors. However, DNA methylation has been shown to be more frequent in exonic than intronic regions of protein-coding genes, suggesting that methylation may play a role in recruiting spliceosomal components to nascent pre-mRNA. It is therefore of interest to determine whether genomic demethylation affects alternative splicing patterns. Here, we explore whether BRCA2 exon 3 alternative splicing patterns are altered by demethylating agents. Methods: To determine whether DNA demethylating agents can alter the levels of ∆3, MCF7 and/or the non-cancer breast cell line MCF 10A was treated with 5-aza 2’-deoxycytidine (5-AzadC) or 5-Azacytidine (5-AzaC), and isoform-specific RT-PCR was used to compare relative levels of splice junctions containing or skipping exon 3. Results and Conclusions: 1) While the IC50 for both 5-AzadC and 5-AzaC in MCF 10A was similar (less than 1 μM), MCF7 showed considerably more resistance to 5-AzaC than 5-AzadC (IC50 of ≥ 5 μM vs ≤ 0.2 μM). 2) 5-AzaC treatment reduces the proportion of MCF 10A cultures in apoptosis but does not increase the proportion of viable cells, indicating it causes cell death by some other means. 3) While both 5-AzaC and 5-AzadC reduce relative levels of ∆3 in MCF7, 5-azadC does not reduce relative levels of ∆3 in MCF 10A, suggesting there may be a cell type-specific splicing response to genomic demethylation therapies. Citation Format: Jordan Werner, Hiba Siddiqui, Samiha Syed, Osman Khan, Servando Casillas Garabito, James D. Fackenthal. DNA demethylating agents have cell type-specific effects on viability and BRCA2 alternative splicing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1735.

Algorithmic assessment reveals functional implications of GABRD gene variants linked to idiopathic generalized epilepsy

Objective The primary objective of this study is to address the challenge posed by the increasing number of variants of unknown clinical significance within the GABRD gene, which encodes the δ subunit of γ-Aminobutyric acid type A receptors. The focus is on predicting the most pathogenic GABRD VUS to enhance precision medicine and improve our understanding of relevant pathophysiology. Methods The study employs a combination of in silico algorithms to analyze 82 variants of unknown clinical significance of GABRD gene sourced from the ClinVar database. Initially, separate algorithms based on sequence homology are utilized to assess this variant set. Subsequently, consensus variants predicted as pathogenic undergo further evaluation through a web server employing an algorithm based on structural homology. The resulting 11 variants are then validated using in silico tools that assess variant effects based on genetic and molecular data. The evaluation includes consideration of disease association and protein stability due to amino acid substitutions. Results The study identifies specific variants (L111R, R114C, D123N, G150S, and L243P) in the coding region of the GABRD gene, which are predicted as deleterious by multiple algorithms. These variants are evolutionarily conserved, mapped onto the extracellular domain of the δ subunit, and associated with idiopathic generalized epilepsy. Conclusions The findings suggest structural or functional consequences that lead to pathogenicity, offering valuable insights for wet-lab experimentation. Besides, the findings contribute to the validation of clinically significant genetic variants in the GABRD gene, which is critical for epilepsy precision medicine.

Challenges in Genetic Diagnosis of Mitochondrial Diseases: What Can Functional Genomics' Studies Do?

Mitochondrial oxidative phosphorylation (OXPHOS) diseases are challenging both from clinical and therapeutic perspectives. The advent of next-generation sequencing (NGS) boosted the discovery of new genetic defects affecting OXPHOS, with pathogenic variants identified in >350 genes to date [1]. However, in many patients, novel variants of unknown clinical significance are found. Subsequent functional studies may clarify its pathogenic consequences and modify the variant's classification, establishing a genetic diagnosis [2, 3]. Analysis of data obtained from patients (P1-P5) with novel genetic causes and functional genomics' studies performed, namely OXPHOS respiratory/glycolytic rates (Seahorse XF), enzymatic activity and assembly (BN-page), protein levels (SDS-WB), single muscle fiber assay, NGS and bioinformatics. P1-Leigh syndrome (40y, male); Complex IV activity deficiency (full assembly absent), homozygous deletion (c.-11_13del, SURF1), not detected by NGS[2]. P2- Epileptic encephalopathy (8y, male); homozygous c.882-1G>A, FASTKD2; OXPHOS decrease; reduced FASTKD2 expression and abnormal respiratory/glycolytic rates. P3-Cardiomyopathy/ nephropathy (39y, male); c.29G>C, FASTKD2; OXPHOS decrease; reduced FASTKD2 levels. P4-CPEO (62y, female); multiple OXPHOS deficiency; mtDNA alterations (m.7486G>A, MTTS1; 4,977bp del); higher levels of mutant mtDNA alterations in COX-deficient fibers [3]. P5- Polyneuropathy (15y, female); heterozygous c.1437C>A, POLG; combined def. or normal OXPHOS activity/respiratory capacity (tissue variable), raised CI assembly; normal POLG levels. Also, proteins' expression levels were reduced (P1-4), confirming pathogenicity. In P5, data do not support pathogenicity. If specific functional results are similar to controls, one might inquire about the pathogenicity of the studied variant and more genetic or bioinformatics analyses and family investigations are needed. There are also limitations of NGS in mutation detection that Sanger sequencing can overcome (P1). When performed first, the OXPHOS activity may guide to genetic screening or interpretation, concordant to later assembly results. All cases were solved and data may be crucial for genetic counseling.

In silico analysis of TRPM4 variants of unknown clinical significance

Background TRPM4 is a calcium-activated channel that selectively permeates monovalent cations. Genetic variants of the channel in cardiomyocytes are associated with various heart disorders, such as progressive familial heart block and Brugada syndrome. About97% of all known TRPM4 missense variants are classified as variants of unknown clinical significance (VUSs). The very large number of VUSs is a serious problem in diagnostics and treatment of inherited heart diseases. Methods and results We collected 233 benign or pathogenic missense variants in the superfamily of TRP channels from databases ClinVar, Humsavar and Ensembl Variation to compare performance of 22 algorithms that predict damaging variants. We found that ClinPred is the best-performing tool for TRP channels. We also used the paralogue annotation method to identify disease variants across the TRP family. In the set of 565 VUSs of hTRPM4, ClinPred predicted pathogenicity of 299 variants. Among these, 12 variants are also categorized as LP/P variants in at least one paralogue of hTRPM4. We further used the cryo-EM structure of hTRPM4 to find scores of contact pairs between parental (wild type) residues of VUSs for which ClinPred predicts a high probability of pathogenicity of variants for both contact partners. We propose that 68 respective missense VUSs are also likely pathogenic variants. Conclusions ClinPred outperformed other in-silico tools in predicting damaging variants of TRP channels. ClinPred, the paralogue annotation method, and analysis of residue contacts the hTRPM4 cryo-EM structure collectively suggest pathogenicity of 80 TRPM4 VUSs.

Whole exome sequencing identifies novel pathogenic variants in TGM1 and ALOX12B in patients with hereditary ichthyosis.

Hereditary ichthyosis is a clinically and genetically heterogeneous disorder associated with more than 50 genes with TGM1, ALOX12B, and ALOXE3 being the most prevalent. Establishing an accurate diagnosis is important for effective genetic counseling and optimal patient management. We studied the diagnostic value of whole exome sequencing (WES) in a small case series with hereditary ichthyosis. During a 1-year period, index cases of 5 unrelated families clinically diagnosed with hereditary ichthyosis went through WES, followed by extensive segregation analysis. Prenatal diagnosis (PND) was conducted where indicated. We identified 4 homozygous variants-2 in TGM1 (c.655A>G and c.797A>G) and 2 in ALOX12B (c.527+2T>G and c.1654G>T)-alongside a heterozygous variant in TGM1 (c.428G>A) in 5 families. The variants were all pathogenic/likely pathogenic according to the ACMG classification and segregation analysis, except for c.797A>G in TGM1 which remained a variant of unknown clinical significance. Four variants were novel. All families were referred either during pregnancy or before reproductive planning; 4 benefited from WES as it identified the mutation in the probands and enabled carrier detection in at-risk relatives; PND was conducted in 2 families. Our findings further support WES is a powerful tool for the comprehensive, accurate, and rapid molecular diagnosis of hereditary ichthyosis and can offer opportunities for reproductive planning, carrier screening and prenatal diagnosis to at-risk families.

Genomic characterization of an esthesioneuroblastoma with spinal metastases: illustrative case.

Esthesioneuroblastoma (ENB) is a rare neoplasm of the sinonasal tract. Currently, the optimal treatment includes maximal resection combined with radiotherapy and/or chemotherapy. Although ENBs often recur and have an aggressive clinical course, spinal metastases are extremely rare and the underlying molecular mechanisms are poorly understood. Here, the authors describe a 50-year-old male with an aggressive ENB, initially treated with resection and chemotherapy/radiation, who developed multiple thoracic and lumbar spinal metastases. The authors performed targeted exome sequencing on both the resected primary tumor and biopsied spinal metastases, which revealed 12 total variants of unknown clinical significance in genes associated with the PI3K/AKT/mTOR pathway, chromatin remodeling, DNA repair, and cell proliferation. Six of these variants were restricted to the metastatic lesion and included missense mutations with predicted functional effects in GRM3, DNMT3B, PLCG2, and SPEN. This report discusses the potential impact of these variants on tumor progression and metastasis, as well as the implications for identifying potential new biomarkers and therapies.

Branchioma: immunohistochemical and molecular genetic study of 23 cases highlighting frequent loss of retinoblastoma 1 immunoexpression.

Branchioma is an uncommon benign neoplasm with an adult male predominance, typically occurring in the lower neck region. Different names have been used for this entity in the past (ectopic hamartomatous thymoma, branchial anlage mixed tumor, thymic anlage tumor, biphenotypic branchioma), but currently, the term branchioma has been widely accepted. Branchioma is composed of endodermal and mesodermal lineage derivatives, in particular epithelial islands, spindle cells, and mature adipose tissue without preexistent thymic tissue or evidence of thymic differentiation. Twenty-three branchiomas were evaluated morphologically. Eighteen cases with sufficient tissue were assessed by immunohistochemistry, next-generation sequencing (NGS) using the Illumina Oncology TS500 panel, and fluorescence in situ hybridization (FISH) using an RB1 dual-color probe. All cases showed a biphasic morphology of epithelial and spindle cells with intermingled fatty tissue. Carcinoma arising in branchioma was detected in three cases. The neoplastic cells showed strong AE1/3 immunolabeling (100%), while the spindle cells expressed CD34, p63, and SMA (100%); AR was detected in 40-100% of nuclei (mean, 47%) in 14 cases. Rb1 showed nuclear loss in ≥ 95% of neoplastic cells in 16 cases (89%), while two cases revealed retained expression in 10-20% of tumor cell nuclei. NGS revealed a variable spectrum of likely pathogenic variants (n = 5) or variants of unknown clinical significance (n = 6). Loss of Rb1 was detected by FISH in two cases. Recent developments support branchioma as a true neoplasm, most likely derived from the rudimental embryological structures of endoderm and mesoderm. Frequent Rb1 loss by immunohistochemistry and heterozygous deletion by FISH is a real pitfall and potential confusion with other Rb1-deficient head and neck neoplasms (i.e., spindle cell lipoma), especially in small biopsy specimens.

Diagnostic pitfalls in a young adult with new diabetes.

A 20-year-old South Asian male presented with polyuria, polydipsia, HbA1c 81 mmol/mol, BMI 28.8 and family history of both type 1 and type 2 diabetes mellitus. As autoantibody testing was negative and c-peptide level demonstrated significant endogenous insulin secretion, type 1 diabetes was excluded. Given his age and family history, the differential diagnosis included maturity-onset diabetes of the young (MODY), a rare form of diabetes caused by a single-gene variant. A high probability of MODY was calculated and he was subsequently referred for genetic testing. Although a useful tool, the pre-test probability calculator for MODY is only validated in White Europeans. A heterogenous variant of unknown clinical significance of the NEUROD1 gene was detected, leading to gliclazide use with poor response. The patient responded well to metformin. Type 2 diabetes was considered the most likely diagnosis. This case highlights the diagnostic challenges in young patients of Asian ethnicity and the importance of interpreting genetic results of unknown significance within the clinical context. Ethnicity-specific BMI thresholds should be used when classifying patients as overweight or obese. Variants of unknown significance detected by genetic sequencing should be interpreted within the context of the patient's other clinical parameters. It is important to use ethnicity-specific BMI thresholds for obesity. Diagnosis of type 2 diabetes mellitus at younger ages is becoming increasingly common. The pre-test probability calculator for MODY is only validated in White Europeans; although a useful guide, results should be interpreted with caution in patients of other ethnicities.

Pathogenic variants of human GABRA1 gene associated with epilepsy: A computational approach

Critical for brain development, neurodevelopmental and network disorders, the GABRA1 gene encodes for the α1 subunit, an abundantly and developmentally expressed subunit of heteropentameric gamma-aminobutyric acid A receptors (GABAARs) mediating primary inhibition in the brain. Mutations of the GABAAR subunit genes including GABRA1 gene are associated with epilepsy, a group of syndromes, characterized by unprovoked seizures and diagnosed by integrative approach, that involves genetic testing. Despite the diagnostic use of genetic testing, a large fraction of the GABAAR subunit gene variants including the variants of GABRA1 gene is not known in terms of their molecular consequence, a challenge for precision and personalized medicine. Addressing this, one hundred thirty-seven GABRA1 gene variants of unknown clinical significance have been extracted from the ClinVar database and computationally analyzed for pathogenicity. Eight variants (L49H, P59L, W97R, D99G, G152S, V270G, T294R, P305L) are predicted as pathogenic and mapped to the α1 subunit's extracellular domain (ECD), transmembrane domains (TMDs) and extracellular linker. This is followed by the integration with relevant data for cellular pathology and severity of the epilepsy syndromes retrieved from the literature. Our results suggest that the pathogenic variants in the ECD of GABRA1 (L49H, P59L, W97R, D99G, G152S) will probably manifest decreased surface expression and reduced current with mild epilepsy phenotypes while V270G, T294R in the TMDs and P305L in the linker between the second and the third TMDs will likely cause reduced cell current with severe epilepsy phenotypes. The results presented in this study provides insights for clinical genetics and wet lab experimentation.

Screening of Fabry Disease of patients in renal replacement therapy in a population from Lazio (Italy).

Fabry's disease (FD) is a genetic disorder of lysosomal storage characterized by the intralysosomal accumulation of globotriaosylceramide (Gb3). This genetic mutation causes a total or partial deficit of the α-galactosidase (GAL) enzyme activity. FD has an incidence of 1:40000-60000 born alive. Its prevalence is higher in specific pathological conditions like chronic kidney disease (CKD). The aim of this study was to evaluate the FD prevalence in Italian renal replacement therapy (RRT) patients from Lazio region. 485 patients in RRT (hemodialysis, peritoneal dialysis, and kidney transplantation) were recruited. The screening test was performed on venous blood sample. The latter was analyzed using specific FD diagnostic kit, based on the analysis of dried blood spots on filter paper. We found 3 cases of positivity to FD (1 female and 2 males). In addition, 1 male patient was identified with biochemical alteration indicative of GAL enzyme deficiency with a genetic variant of the GLA gene of unknown clinical significance. The FD prevalence in our population was 0.60% (1 case out 163), it rises to 0.80% (1 case out of 122) if the genetic variant of unknown clinical significance is considered. Comparing the three subpopulations, we observed a statistically significant difference in GAL activity in transplanted patients compared to dialysis patients (p<0.001). Considering the presence of an enzyme replacement therapy able to modify FD clinical history, it is essential to try to implement FD early diagnoses. However, the screening is too expensive to be extended on large scale, due to the low prevalence of the pathology. The screening should be performed on high-risk populations.

Array Comparative Genomic Hybridization Analysis of Products of Conception in Recurrent Pregnancy Loss for specific anomalies detected by USG.

To evaluate the proportion of chromosomal abnormalities in recurrent pregnancy loss (RPL) assisted by array comparative genomic hybridization (aCGH) bright out with higher detection rate, more accuracy, and less sample failure as compared with conventional cytogenetic analysis. In this study, product of conception samples with abnormal USG findings of the fetus and clinical history of RPL were first processed for karyotyping and Fluorescence In Situ Hybridization analysis. Normal results given by Karyotype and FISH samples with major anomalies detected by Ultrasound with RPL were divided into six groups and aCGH was performed to detect the gain or loss and copy number variations (CNVs) of a particular gene present in chromosomal segments. Among a total of 300 POC samples, 100 abnormal samples were identified either by karyotype (n=70) or by FISH (n=30). From the remaining 200 samples, 5 showed the presence of maternal cell contamination excluded. aCGH analysis revealed (n=195) that 74 (38%) samples with copy number variations (CNVs) and two samples with variants of unknown clinical significance (VOUS) were clinically associated with the clinical findings and 121(62%) samples showed no change in CNVs. The most frequent CNVs were loss of chromosome regions at 2q33.1, 7q11.21, 15q11.1, 16p11.2, Xp22.33, and Yp11.32. CNVs at arr[GRCh37]7p22.3,p21.2(830852-15124702)×1,7q34q36.3(141464180_158909738)×3, 14.2Mbp deletion of 7p22.3p21.2 (SUN1 gene) and 17.4Mbp duplication of 7q34q36.3 (KCNH2, CNTNAP2, and SHH genes) in one sample, CNVs at arr[GRCh37]8p22.2q22.3 (86326349_105509986)×1, 2.48Mbp deletion of 8p22.2q22.3 (GRHL1 gene) were found in another sample.

Identification of a DNA methylation signature for Renpenning syndrome (RENS1), a spliceopathy.

The challenges and ambiguities in providing an accurate diagnosis for patients with neurodevelopmental disorders have led researchers to apply epigenetics as a technique to validate the diagnosis provided based on the clinical examination and genetic testing results. Genome-wide DNA methylation analysis has recently been adapted for clinical testing of patients with genetic neurodevelopmental disorders. In this paper, preliminary data demonstrating a DNA methylation signature for Renpenning syndrome (RENS1 - OMIM 309500), which is an X-linked recessive neurodevelopmental disorder caused by variants in polyglutamine-binding protein 1 (PQBP1) is reported. The identified episignature was then utilized to construct a highly sensitive and specific binary classification model. Besides providing evidence for the existence of a DNA methylation episignature for Renpenning syndrome, this study increases the knowledge of the molecular mechanisms related to the disease. Moreover, the availability of more subjects in future may facilitate the establishment of an episignature that can be utilized for diagnosis in a clinical setting and for reclassification of variants of unknown clinical significance.

Occurrence of variants of unknown clinical significance in genetic testing for hereditary breast and ovarian cancer syndrome and Lynch syndrome: a literature review and analytical observational retrospective cohort study

Background and purposeOver the last decade, the implementation of multigene panels for hereditary tumor syndrome has increased at our institution (Inselspital, University Hospital Berne, Switzerland). The aim of this study was to determine the prevalence of variants of unknown significance (VUS) in patients with suspected Lynch syndrome and suspected hereditary breast and ovarian cancer syndrome, the latter in connection with the trend toward ordering larger gene panels.ResultsRetrospectively collected data from 1057 patients at our institution showed at least one VUS in 126 different cases (11.9%). In patients undergoing genetic testing for BRCA1/2, the prevalence of VUS was 6%. When < 10 additional genes were tested in addition to BRCA1/2, the prevalence increased to 13.8%, and 31.8% for > 10 additional genes, respectively. The gene most frequently affected with a VUS was ATM. 6% of our patients who were tested for Lynch syndrome had a VUS result in either MLH1, MSH2 or MSH6.ConclusionsOur data demonstrate that panel testing statistically significantly increases VUS rates due to variants in non-BRCA genes. Good genetic counseling before and after obtaining results is therefore particularly important when conducting multigene panels to minimize patient uncertainty due to VUS results.

The multi-faceted nature of 15 CFTR exonic variations: Impact on their functional classification and perspectives for therapy

BackgroundThe majority of variants of unknown clinical significance (VUCS) in the CFTR gene are missense variants. While change on the CFTR protein structure or function is often suspected, impact on splicing may be neglected. Such undetected splicing default of variants may complicate the interpretation of genetic analyses and the use of an appropriate pharmacotherapy. MethodsWe selected 15 variants suspected to impact CFTR splicing after in silico predictions on 319 missense variants (214 VUCS), reported in the CFTR-France database. Six specialized laboratories assessed the impact of nucleotide substitutions on splicing (minigenes), mRNA expression levels (quantitative PCR), synthesis and maturation (western blot), cellular localization (immunofluorescence) and channel function (patch clamp) of the CFTR protein. We also studied maturation and function of the truncated protein, consecutive to in-frame aberrant splicing, on additional plasmid constructs. ResultsSix of the 15 variants had a major impact on CFTR splicing by in-frame (n = 3) or out-of-frame (n = 3) exon skipping. We reclassified variants into: splicing variants; variants causing a splicing defect and the impairment of CFTR folding and/or function related to the amino acid substitution; deleterious missense variants that impair CFTR folding and/or function; and variants with no consequence on the different processes tested. ConclusionThe 15 variants have been reclassified by our comprehensive approach of in vitro experiments that should be used to properly interpret very rare exonic variants of the CFTR gene. Targeted therapies may thus be adapted to the molecular defects regarding the results of laboratory experiments.

Molecular profile and clinical features of patients with gliomas using a broad targeted next generation-sequencing panel.

Gliomas are the most common malignant primary brain tumors characterized by poor prognosis. The genotyping of tumors using next generation sequencing (NGS) platforms enables the identification of genetic alterations that constitute diagnostic, prognostic and predictive biomarkers. The present study investigated the molecular profile of 32 tumor samples from 32 patients with high-grade gliomas by implementing a broad 80-gene targeted NGS panel while reporting their clinicopathological characteristics and outcomes. Subsequently, 14 of 32 tumor specimens were also genotyped using a 55-gene NGS panel to validate the diagnostic accuracy and clinical utility of the extended panel. The median follow-up was 19.2 months. In total, 129 genetic alterations including 33 structural variants were identified in 38 distinct genes. Among 96 variants (single nucleotide variants and insertions and deletions), 38 were pathogenic and 58 variants of unknown clinical significance. TP53 was the most frequently mutated gene, followed by PTEN and IDH1 genes. Glioma patients with IDH1 mutant tumors were younger and had significantly longer overall survival compared to patients with wild-type IDH1 tumors. Similarly, tumors with TP53 mutations were more likely observed in younger patients with glioma. Subsequently, a comparison of mutational profiles of samples analyzed by both panels was also performed. Implementation of the comprehensive pan-cancer and the MOL panels resulted in the identification of 37 and 15 variants, respectively. Of those, 13 were common. Comprehensive pan-cancer panel identified 24 additional variants, 22 of which were located in regions that were not targeted by the MOL panel. By contrast, the MOL panel identified two additional variants. Overall, the present study demonstrated that using an extended tumor profile assay instead of a glioma-specific tumor profile panel identified additional genetic changes that may be taken into consideration as potential therapeutic targets for glioma diagnosis and molecular classification.

Copy number variants and fetal growth in stillbirths

Fetal growth abnormalities are associated with a higher incidence of stillbirth, with small and large for gestational age infants incurring a 3 to 4- and 2 to 3-fold increased risk, respectively. Although clinical risk factors such as diabetes, hypertension, and placental insufficiency have been associated with fetal growth aberrations and stillbirth, the role of underlying genetic etiologies remains uncertain. This study aimed to assess the relationship between abnormal copy number variants and fetal growth abnormalities in stillbirths using chromosomal microarray. A secondary analysis utilizing a cohort study design of stillbirths from the Stillbirth Collaborative Research Network was performed. Exposure was defined as abnormal copy number variants including aneuploidies, pathogenic copy number variants, and variants of unknown clinical significance. The outcomes were small for gestational age and large for gestational age stillbirths, defined as a birthweight <10th percentile and greater than the 90th percentile for gestational age, respectively. Among 393 stillbirths with chromosomal microarray and birthweight data, 16% had abnormal copy number variants. The small for gestational age outcome was more common among those with abnormal copy number variants than those with a normal microarray (29.5% vs 16.5%; P=.038). This finding was consistent after adjusting for clinically important variables. In the final model, only abnormal copy number variants and maternal age remained significantly associated with small for gestational age stillbirths, with an adjusted odds ratio of 2.22 (95% confidence interval, 1.12-4.18). Although large for gestational age stillbirths were more likely to have an abnormal microarray: 6.2% vs 3.3% (P=.275), with an odds ratio of 2.35 (95% confidence interval, 0.70-7.90), this finding did not reach statistical significance. Genetic abnormalities are more common in the setting of small for gestational age stillborn fetuses. Abnormal copy number variants not detectable by traditional karyotype make up approximately 50% of the genetic abnormalities in this population.

Contribution of chromosomal microarray analysis and next-generation sequencing to genetic diagnosis in fetuses with normal karyotype.

The aim of this study was to investigate the contribution of chromosomal microarray analysis (CMA) and next-generation sequencing (NGS) to genetic diagnosis in fetuses with normal karyotype who underwent invasive testing for different indications. The results of invasive genetic testing performed at a tertiary center between September 2020 and March 2022 were retrospectively analyzed. Indications for invasive tests were classified as fetal structural malformation, presence of soft markers, and high risk in screening tests. CMA results were classified as pathogenic or likely pathogenic (pCNVs), benign (bCNVs), and variants of unknown clinical significance (VOUS). A total of 830 invasive tests were performed and aneuploidy was detected in 11.2% of the fetuses. CMA was performed in 465 fetuses with normal karyotype, and pCNVs were detected in 6.9%. pCNVs were detected in 8.2% of fetuses with structural malformations, 6.5% in soft markers, and 4.7% in high risk in screening tests. Pathogenic variants were detected by NGS in 33.8% of fetuses with bCNVs. pCNVs can be significantly detected not only in fetuses with structural malformations, but also in invasive testing with other indications. NGS significantly contributes to genetic diagnosis in fetuses with structural malformations.

Genome Sequencing and Transcriptome Profiling in Twins Discordant for Mayer-Rokitansky-Küster-Hauser Syndrome.

To identify potential genetic causes for Mayer-Rokitansky-Küster-Hauser syndrome (MRKH), we analyzed blood and rudimentary uterine tissue of 5 MRKH discordant monozygotic twin pairs. Assuming that a variant solely identified in the affected twin or affected tissue could cause the phenotype, we identified a mosaic variant in ACTR3B with high allele frequency in the affected tissue, low allele frequency in the blood of the affected twin, and almost absent in blood of the unaffected twin. Focusing on MRKH candidate genes, we detected a pathogenic variant in GREB1L in one twin pair and their unaffected mother showing a reduced phenotypic penetrance. Furthermore, two variants of unknown clinical significance in PAX8 and WNT9B were identified. In addition, we conducted transcriptome analysis of affected tissue and observed perturbations largely similar to those in sporadic cases. These shared transcriptional changes were enriched for terms associated with estrogen and its receptors pointing at a role of estrogen in MRKH pathology. Our genome sequencing approach of blood and uterine tissue of discordant twins is the most extensive study performed on twins discordant for MRKH so far. As no clear pathogenic differences were detected, research to evaluate other regulatory layers are required to better understand the complex etiology of MRKH.

Impact of 100 LRRK2 variants linked to Parkinson's disease on kinase activity and microtubule binding.

Mutations enhancing the kinase activity of leucine-rich repeat kinase-2 (LRRK2) cause Parkinson's disease (PD) and therapies that reduce LRRK2 kinase activity are being tested in clinical trials. Numerous rare variants of unknown clinical significance have been reported, but how the vast majority impact on LRRK2 function is unknown. Here, we investigate 100 LRRK2 variants linked to PD, including previously described pathogenic mutations. We identify 23 LRRK2 variants that robustly stimulate kinase activity, including variants within the N-terminal non-catalytic regions (ARM (E334K, A419V), ANK (R767H), LRR (R1067Q, R1325Q)), as well as variants predicted to destabilize the ROC:CORB interface (ROC (A1442P, V1447M), CORA (R1628P) CORB (S1761R, L1795F)) and COR:COR dimer interface (CORB (R1728H/L)). Most activating variants decrease LRRK2 biomarker site phosphorylation (pSer935/pSer955/pSer973), consistent with the notion that the active kinase conformation blocks their phosphorylation. We conclude that the impact of variants on kinase activity is best evaluated by deploying a cellular assay of LRRK2-dependent Rab10 substrate phosphorylation, compared with a biochemical kinase assay, as only a minority of activating variants (CORB (Y1699C, R1728H/L, S1761R) and kinase (G2019S, I2020T, T2031S)), enhance in vitro kinase activity of immunoprecipitated LRRK2. Twelve variants including several that activate LRRK2 and have been linked to PD, suppress microtubule association in the presence of a Type I kinase inhibitor (ARM (M712V), LRR (R1320S), ROC (A1442P, K1468E, S1508R), CORA (A1589S), CORB (Y1699C, R1728H/L) and WD40 (R2143M, S2350I, G2385R)). Our findings will stimulate work to better understand the mechanisms by which variants impact biology and provide rationale for variant carrier inclusion or exclusion in ongoing and future LRRK2 inhibitor clinical trials.