Clinical Genetics Laboratories Research Articles

The current landscape of clinical exome and genome reanalysis in the U.S.

The majority of patients undergoing exome or genome sequencing receive a nondiagnostic result. Periodic reanalysis is known to increase diagnostic yield from exome sequencing, yet laboratory reanalysis practices are obscure. We sought to define the landscape of exome and genome reanalysis across clinical laboratories. Genetic testing registries were queried to identify eligible clinical genetic laboratories offering exome and/or genome sequencing in the United States. A survey administered to lab representatives investigated reanalysis offerings, policies, perceived uptake, bioinformatic steps, and billing options. The analysis consisted of descriptive statistics. Survey data were collected from 30 of 32 eligible laboratories (93%), comprising 28 exome products and 13 genome products. Reanalysis was widely available for both exomes (n = 27/28, 96%) and genomes (n = 12/13, 92%). Most participating laboratories required ordering providers to initiate reanalysis (n = 24/28, 86%). Most respondents estimated providers initiated reanalysis in less than 10% of all exomes (n = 12/22) or genomes (n = 6/9) sequenced. The approach to reanalysis varied greatly by laboratory. Laboratory approaches to exome and genome reanalysis are highly variable and typically require provider initiation. This could contribute to low reanalysis uptake and increased administrative burden on providers. Further work should emphasize development of clinical exome and genome reanalysis standards.

Generating Clinical-Grade Gene-Disease Validity Classifications Through the ClinGen Data Platforms.

Clinical genetic laboratories must have access to clinically validated biomedical data for precision medicine. A lack of accessibility, normalized structure, and consistency in evaluation complicates interpretation of disease causality, resulting in confusion in assessing the clinical validity of genes and genetic variants for diagnosis. A key goal of the Clinical Genome Resource (ClinGen) is to fill the knowledge gap concerning the strength of evidence supporting the role of a gene in a monogenic disease, which is achieved through a process known as Gene-Disease Validity curation. Here we review the work of ClinGen in developing a curation infrastructure that supports the standardization, harmonization, and dissemination of Gene-Disease Validity data through the creation of frameworks and the utilization of common data standards. This infrastructure is based on several applications, including the ClinGen GeneTracker, Gene Curation Interface, Data Exchange, GeneGraph, and website.

Pediatric cardiomyopathy illustrates the importance of reinterpreting the significance of genetic variants

BackgroundClinical genetic testing is increasingly being utilized to establish a molecular diagnosis to help manage children with cardiomyopathy and to assess the risk of cardiomyopathy among family members. However, as evidence and guidelines evolve, variant classification can change with the potential to impact counseling and family screening. ObjectivesThe main purpose of this study was to investigate whether variants in cardiomyopathy genes previously interpreted by clinical genetic testing laboratories would be reclassified under current guidelines for the interpretation of sequence variants. MethodsIn 211 children enrolled in the Pediatric Cardiomyopathy Registry, we compared the results of previous clinical genetic testing with the results of research testing in 37 cardiomyopathy genes. ResultsThe mean time difference between initial testing and reinterpretation was 7 years. Using the 2015 American College of Medical Genetics and Genomics guidelines for the interpretation of sequence variants, we found that 18 % of the tested population had a change in variant classification. Ninety-two percent of the initial classifications were performed before the publication of the guidelines, with 82 % of reclassifications resulting in a variant downgrade. Most of these were changes from the pathogenic or likely pathogenic category to a variant of uncertain significance. Reclassification frequency was similar across types of cardiomyopathy. ConclusionOur results highlight that a portion of variants get downgraded, and periodic reinterpretation of genetic testing results is necessary for all types of cardiomyopathy—particularly for variant interpretations prior to 2015. Importantly, variant reclassification has potential impact on the clinical management of at-risk patients.

Cost-effectiveness of genetic testing of endocrine tumor patients using a comprehensive hereditary cancer gene panel.

Heterogenous clinical manifestations, overlapping phenotypes and complex genetic backgrounds are common in patients with endocrine tumors. There are no comprehensive recommendations for genetic testing and counselling of these patients compared to other hereditary cancer syndromes. The application of multigene panel testing is common in clinical genetic laboratories, but their performance for patients with endocrine tumors has not been assessed. As a national reference center, we prospectively tested the diagnostic utility and cost-efficiency of a multigene panel covering 113 genes representing genetic susceptibility for solid tumors. 1279 patients (including 96 cases with endocrine tumors) were evaluated between October 2021 and December 2022 who were suspected to have hereditary tumor syndromes. The analytical performance of the hereditary cancer panel was suitable for diagnostic testing. Clinical diagnosis was confirmed in 24% (23/96); incidental findings in genes not associated with the patient's phenotype were identified in 5% (5/96). A further 7% of pathogenic/likely pathogenic variants were detected in genes with potential genetic susceptibility roles but currently no clear clinical consequence. Cost-benefit analysis showed that the application of a more comprehensive gene panel in a diagnostic laboratory yielded a shorter turnaround time and provided additional genetic results with the same cost and workload. Using comprehensive multigene panel results in faster turnaround time and cost-efficiently identifies genetic alterations in hereditary endocrine tumor syndromes. Incidentally identified variants in patients with poor prognoses may serve as a potential therapeutic target in tumors where therapeutic possibilities are limited.

Clinical application of next generation sequencing for Mendelian disease diagnosis in the Iranian population

Next-generation sequencing (NGS) has been proven to be one of the most powerful diagnostic tools for rare Mendelian disorders. Several studies on the clinical application of NGS in unselected cohorts of Middle Eastern patients have reported a high diagnostic yield of up to 48%, correlated with a high level of consanguinity in these populations. We evaluated the diagnostic utility of NGS-based testing across different clinical indications in 1436 patients from Iran, representing the first study of its kind in this highly consanguineous population. A total of 1075 exome sequencing and 361 targeted gene panel sequencing were performed over 8 years at a single clinical genetics laboratory, with the majority of cases tested as proband-only (91.6%). The overall diagnostic rate was 46.7%, ranging from 24% in patients with an abnormality of prenatal development to over 67% in patients with an abnormality of the skin. We identified 660 pathogenic or likely pathogenic variants, including 241 novel variants, associated with over 342 known genetic conditions. The highly consanguineous nature of this cohort led to the diagnosis of autosomal recessive disorders in the majority of patients (79.1%) and allowed us to determine the shared carrier status of couples for suspected recessive phenotypes in their deceased child(ren) when direct testing was not possible. We also highlight the observations of recessive inheritance of genes previously associated only with dominant disorders and provide an expanded genotype–phenotype spectrum for multiple less-characterized genes. We present the largest mutational spectrum of known Mendelian disease, including possible founder variants, throughout the Iranian population, which can serve as a unique resource for clinical genomic studies locally and beyond.

Detection of a novel gross deletion in the UNC13D gene ends the diagnostic odyssey for a family with familial hemophagocytic lymphohistiocytosis 3

BackgroundFamilial hemophagocytic lymphohistiocytosis (FHL) is an immunological disorder characterized by overactivation of macrophages and T lymphocytes. This autosomal recessive condition has been characterized into multiple types depending on the genetic etiology. FHL type 3 is associated with bi-allelic pathogenic variants in the UNC13D gene.Case presentationWe present a 12-year diagnostic odyssey for a family with FHL that signifies the advances of FHL genetic testing in a clinical genetic diagnostic laboratory setting. We describe the first case of a large UNC13D gross deletion in trans to a nonsense variant in a family with FHL3, which may have been mediated by Alu elements within introns 12 and 25 of the UNC13D gene.ConclusionsThis case highlights the importance of re-evaluating past genetic testing for a patient and family as test technology evolves in order to end a diagnostic odyssey.

A taxonomic schema of potential pitfalls in clinical variant analysis based on real-world evidence.

The classification and interpretation of genetic variants associated with genetic diseases have been shown to vary between clinical genetic laboratories. This can lead to errors introduced in the interpretation and public presentation of genetic findings in the literature and available databases. This qualitative study utilizes real-world evidence to introduce a taxonomic schema of potential pitfalls associated with public and commercial resources commonly used for sequence variant analysis. Databases, articles and other resources continue to evolve over time. A modified and expanded version of Reason's Model of Human Error with respect to variant analysis is proposed and discussed. This study complements professional standards and published recommendations of interpretive considerations associated with variant analysis and expands the scope of professional competency.

Clinical and functional analysis of the germline TP53 p.K164E acetylation site variant.

TP53 plays a critical role as a tumor suppressor by controlling cell cycle progression, DNA repair, and apoptosis. Post-translational modifications such as acetylation of specific lysine residues in the DNA binding and carboxy-terminus regulatory domains modulate its tumor suppressor activities. In this study, we addressed the functional consequences of the germline TP53 p.K164E (NM_000546.5: c.490A>G) variant identified in a patient with early-onset breast cancer and a significant family history of cancer. K164 is a conserved residue located in the L2 loop of the p53 DNA binding domain that is post-translationally modified by acetylation. In silico, in vitro, and in vivo analyses demonstrated that the glutamate substitution at K164 marginally destabilizes the p53 protein structure but significantly impairs sequence-specific DNA binding, transactivation, and tumor cell growth inhibition. Although p.K164E is currently considered a variant of unknown significance by different clinical genetic testing laboratories, the clinical and laboratory-based findings presented here provide strong evidence to reclassify TP53 p.K164E as a likely pathogenic variant.

National clinical Genetic Networks - GENets - Establishment of expert collaborations in Denmark

Genetic conditions are often familial, but not all relatives receive counseling from the same institution. It is therefore necessary to ensure consistency in variant interpretation, counseling practices, and clinical follow up across health care providers. Furthermore, as new possibilities for gene-specific treatments emerge and whole genome sequencing becomes more widely available, efficient data handling and knowledge sharing between clinical laboratory geneticists and medical specialists in clinical genetics are increasingly important.In Denmark, these needs have been addressed through the establishment of collaborative national networks called Genetic Expert Networks or "GENets". These networks have enhanced patient and family care significantly by bringing together groups of experts in national collaborations. This promotes coordinated clinical care, the dissemination of best clinical practices, and facilitates the exchange of new knowledge.

Molecular characterization of 13 patients with PIK3CA-related overgrowth spectrum using a targeted deep sequencing approach.

Activating variants in the PIK3CA gene cause a heterogeneous spectrum of disorders that involve congenital or early-onset segmental/focal overgrowth, now referred to as PIK3CA-related overgrowth spectrum (PROS). Historically, the clinical diagnoses of patients with PROS included a range of distinct syndromes, including CLOVES syndrome, dysplastic megalencephaly, hemimegalencephaly, focal cortical dysplasia, Klippel-Trenaunay syndrome, CLAPO syndrome, fibroadipose hyperplasia or overgrowth, hemihyperplasia multiple lipomatosis, and megalencephaly capillary malformation-polymicrogyria (MCAP) syndrome. MCAP is a sporadic overgrowth disorder that exhibits core features of progressive megalencephaly, vascular malformations, distal limb malformations, cortical brain malformations, and connective tissue dysplasia. In 2012, our research group contributed to the identification of predominantly mosaic, gain-of-function variants in PIK3CA as an underlying genetic cause of the syndrome. Mosaic variants are technically more difficult to detect and require implementation of more sensitive sequencing technologies and less stringent variant calling algorithms. In this study, we demonstrated the utility of deep sequencing using the Illumina TruSight Oncology 500 (TSO500) sequencing panel in identifying variants with low allele fractions in a series of patients with PROS and suspected mosaicism: pathogenic, mosaic PIK3CA variants were identified in all 13 individuals, including 6 positive controls. This study highlights the importance of screening for low-level mosaic variants in PROS patients. The use of targeted panels with deep sequencing in clinical genetic testing laboratories would improve diagnostic yield and accuracy within this patient population.

Rates and Classification of Variants of Uncertain Significance in Hereditary Disease Genetic Testing

Variants of uncertain significance (VUSs) are rampant in clinical genetic testing, frustrating clinicians, patients, and laboratories because the uncertainty hinders diagnoses and clinical management. A comprehensive assessment of VUSs across many disease genes is needed to guide efforts to reduce uncertainty. To describe the sources, gene distribution, and population-level attributes of VUSs and to evaluate the impact of the different types of evidence used to reclassify them. This cohort study used germline DNA variant data from individuals referred by clinicians for diagnostic genetic testing for hereditary disorders. Participants included individuals for whom gene panel testing was conducted between September 9, 2014, and September 7, 2022. Data were analyzed from September 1, 2022, to April 1, 2023. The outcomes of interest were VUS rates (stratified by age; clinician-reported race, ethnicity, and ancestry groups; types of gene panels; and variant attributes), percentage of VUSs reclassified as benign or likely benign vs pathogenic or likely pathogenic, and enrichment of evidence types used for reclassifying VUSs. The study cohort included 1 689 845 individuals ranging in age from 0 to 89 years at time of testing (median age, 50 years), with 1 203 210 (71.2%) female individuals. There were 39 150 Ashkenazi Jewish individuals (2.3%), 64 730 Asian individuals (3.8%), 126 739 Black individuals (7.5%), 5539 French Canadian individuals (0.3%), 169 714 Hispanic individuals (10.0%), 5058 Native American individuals (0.3%), 2696 Pacific Islander individuals (0.2%), 4842 Sephardic Jewish individuals (0.3%), and 974 383 White individuals (57.7%). Among all individuals tested, 692 227 (41.0%) had at least 1 VUS and 535 385 (31.7%) had only VUS results. The number of VUSs per individual increased as more genes were tested, and most VUSs were missense changes (86.6%). More VUSs were observed per sequenced gene in individuals who were not from a European White population, in middle-aged and older adults, and in individuals who underwent testing for disorders with incomplete penetrance. Of 37 699 unique VUSs that were reclassified, 30 239 (80.2%) were ultimately categorized as benign or likely benign. A mean (SD) of 30.7 (20.0) months elapsed for VUSs to be reclassified to benign or likely benign, and a mean (SD) of 22.4 (18.9) months elapsed for VUSs to be reclassified to pathogenic or likely pathogenic. Clinical evidence contributed most to reclassification. This cohort study of approximately 1.6 million individuals highlighted the need for better methods for interpreting missense variants, increased availability of clinical and experimental evidence for variant classification, and more diverse representation of race, ethnicity, and ancestry groups in genomic databases. Data from this study could provide a sound basis for understanding the sources and resolution of VUSs and navigating appropriate next steps in patient care.

Assessing the pharmacy students' knowledge of genetic counseling with genetic variants that are associated with inherited disease

Background and purposeTo assess pharmacy students' understanding of the importance of genetic counseling through a didactic lecture and active in-class learning exercise in a required pharmacogenomics course. Educational activity and settingDuring the second year, students are enrolled in a two-credit hour pharmacogenomics course which is taught by multiple faculty members from various disciplines. The pharmacy students were taught the clinical importance of genetic results and counseling patients on their individualized reports by a clinical laboratory geneticist and a clinical genetic counselor. After completion of the didactic portion of the class, students practiced genetic counseling skills through role playing with clinical cases involving genetic reports. Students' knowledge of clinical applications of pharmacogenomic data was assessed prior to and following the counseling experience. FindingsA paired sample t-test was chosen to analyze the data to determine if there was a difference in mean scores upon the completion of the lecture. There was a statistically significant mean difference between the total scores for the pretest (mean (M) = 37.89, SD = 6.66) and the total scores for the posttest (M = 48.33, SD = 5.24); t(140) = 17.53, P < .001, α = 0.05. The effect size for this analysis (d = 1.74) surpassed Cohen's determination for large effect (d = 0.8). SummaryThe genetic counseling lecture and activity increased the students' overall awareness of the importance of how sensitive genetic information is reported and delivered to patients.

O-196 Evidence-based management of mosaic embryos - a single Centre experience from prospective transfer and birth outcomes of 565 mosaic embryos

Abstract Study question What are the pregnancy and neonatal outcomes of prospective transfer of 565 mosaic embryos and what are the key determinants influencing the outcome? Summary answer Mosaic (diploid/aneuploid) embryos have a significant developmental potential with good neonatal outcomes allowing personalized management and evidence based prioritization of embryos for transfer. What is known already Since the first report of healthy babies born after mosaic transfer, the gradual accumulation of knowledge on mosaic embryo transfers in the International Registry of Mosaic Embryo Transfers provided the necessary reassurance for clinical management of mosaic embryos. Large and comprehensive data from single centres with consistent clinical genetic counselling and laboratory practices for preimplantation and prenatal testing offer valuable contribution to the current practices. The aim of this study was to evaluate the pregnancy and neonatal outcomes after mosaic embryo transfers and to evaluate for associations between embryo genetic aberrations, static morphology and specific outcomes. Study design, size, duration This is a retrospective cohort study that took place in a single academic IVF centre (The CReATe Fertility Centre, Toronto, Canada), where we analysed the results from high resolution PGT-A, embryo morphologic features and pregnancy outcomes of 3529 frozen embryo transfers from 2016-2022. Associated patient demographic data, transfer outcome and neonatal outcome of 2964 euploid and 565 mosaic embryo transfers were analyzed. Participants/materials, setting, methods All patients received genetic counselling prior to frozen embryo transfer. High resolution NGS PGT-A was performed using the Illumina platform and BluGnome and NxClinical for data analysis. Clinically relevant findings were aberrations &amp;gt;10Mb and mosaicism from 25%-75%. Comparison of clinical and morphological characteristics of euploid, low-level mosaic (25%-&amp;lt;50% aneuploid cells in trophectoderm biopsy), and high-level mosaics (50% -75%) was performed with R-statistical package, Mathlab and SSPS software. p &amp;lt; 0.05 with CI 95% was considered significant. Main results and the role of chance Of the total 565 mosaic embryos transferred 77.1% had mosaicism levels ≥25%-&amp;lt;50% (Group1-n=436): 54.8% had segmental chromosome mosaic (SCM)gain/loss, 45.2% had whole chromosome mosaicism(WCM)(trisomy/monosomy); and 22.9% had mosaic levels of ≥ 50-&amp;lt;70% (Group2-n=129)(50.4% with SCM and 49.6% with WCM). The overall ongoing pregnancy rate(OPR) for mosaic embryos was 33% and the miscarriage rate was 6%. Compared with euploid embryos, mosaic embryos have significantly lower implantation (p = 0,OD0.62-CI[0.5-0.7]) and OPR(p = 0,OD0.5-CI[0.4-0.6]). Pregnancy outcomes are determined by level of mosaicism: Group1 have better implantation(p = 0.005,OD1.8-CI[1.18-2.78]) and OPR compared to Group2. High level of mosaicism independently affected the OPR of SCM(p = 0.003) and WCM(p = 0.02) embryos. WCM had lower implantation rates compared to SCM (p = 0.005,OD1.6-CI[1.15-2.27]). Mosaic monosomies had the lowest impanation and OPR of all mosaic embryos (14% and 8%,respectively). Within Group1 and Group2 good static morphology was associated with higher OPR for SCM and WCM embryos. Birth outcomes were available for 118 babies from mosaic-FET and from 802 euploid-FET. There is no difference in duration of pregnancy and birth weight between mosaic and euploid-FET. No gross-fetal anomalies were reported in the mosaic group at birth. There was one termination&amp;lt;20GW due to fetal anomalies and one stillbirth. For euploid transfers, 11 had fetal anomalies, there were 7-terminations and 2-stillbirths. Limitations, reasons for caution Although this is the largest single centre study to date that evaluated genomic, morphology and outcome data of mosaic transfers, the numbers are still low to analyze the impact of specific chromosomal aberrations on pregnancy outcome. Wider implications of the findings Mosaic embryos should be considered for transfer and prioritized based on the level of mosaicism, type of chromosomal aberration and static morphology. The implantation potential is lower than euploid embryos however established pregnancies result in healthy babies born at term and normal birth weight. Trial registration number CReATe Fertility Centre, Toronto, Canada

Consensus Recommendations to Optimize the Detection and Reporting of NTRK Gene Fusions by RNA-Based Next-Generation Sequencing.

The detection of gene fusions by RNA-based next-generation sequencing (NGS) is an emerging method in clinical genetic laboratories for oncology biomarker testing to direct targeted therapy selections. A recent Canadian study (CANTRK study) comparing the detection of NTRK gene fusions on different NGS assays to determine subjects' eligibility for tyrosine kinase TRK inhibitor therapy identified the need for recommendations for best practices for laboratory testing to optimize RNA-based NGS gene fusion detection. To develop consensus recommendations, representatives from 17 Canadian genetic laboratories participated in working group discussions and the completion of survey questions about RNA-based NGS. Consensus recommendations are presented for pre-analytic, analytic and reporting aspects of gene fusion detection by RNA-based NGS.

Evaluation of an automated genome interpretation model for rare disease routinely used in a clinical genetic laboratory

PurposeThe analysis of exome and genome sequencing data for the diagnosis of rare diseases is challenging and time-consuming. In this study, we evaluated an artificial intelligence model, based on machine learning for automating variant prioritization for diagnosing rare genetic diseases in the Baylor Genetics clinical laboratory. MethodsThe automated analysis model was developed using a supervised learning approach based on thousands of manually curated variants. The model was evaluated on 2 cohorts. The model accuracy was determined using a retrospective cohort comprising 180 randomly selected exome cases (57 singletons, 123 trios); all of which were previously diagnosed and solved through manual interpretation. Diagnostic yield with the modified workflow was estimated using a prospective “production” cohort of 334 consecutive clinical cases. ResultsThe model accurately pinpointed all manually reported variants as candidates. The reported variants were ranked in top 10 candidate variants in 98.4% (121/123) of trio cases, in 93.0% (53/57) of single proband cases, and 96.7% (174/180) of all cases. The accuracy of the model was reduced in some cases because of incomplete variant calling (eg, copy number variants) or incomplete phenotypic description. ConclusionThe automated model for case analysis assists clinical genetic laboratories in prioritizing candidate variants effectively. The use of such technology may facilitate the interpretation of genomic data for a large number of patients in the era of precision medicine.

Synthesis of positive plasmas with known chromosomal abnormalities for validation of non-invasive prenatal screening.

Non-invasive prenatal screening (NIPS) is a DNA sequencing-based screening test for fetal aneuploidies and possibly other pathogenic genomic abnormalities, such as large deletions and duplications. Validation and quality assurance (QA) of this clinical test using plasmas with and without targeted chromosomal abnormalities from pregnant women as negative and positive controls are required. However, the positive plasma controls may not be available for many laboratories that are planning to establish NIPS. Limited synthetic positive plasmas are commercially available, but the types of abnormalities and the number/quantity of synthetic plasmas for each abnormality are insufficient to meet the minimal requirements for the initial validation. We report here a method of making synthetic positive plasmas by adding cell-free DNA (cfDNA) isolated from culture media of prenatal cells with chromosomal abnormalities to the plasmas from non-pregnant women. Thirty-eight positive plasmas with various chromosomal abnormalities, including autosomal and sex chromosomal aneuploidies, large deletions and duplications, were synthesized. The synthetic plasmas were characterized side-by-side with real positive plasmas from pregnant women and commercially available synthetic positive plasmas using the Illumina VeriSeq NIPT v2 system. All chromosomal abnormalities in the synthetic plasmas were correctly identified with the same testing sensitivity and specificity as in the real and commercial synthetic plasmas. The findings demonstrate that the synthetic positive plasmas are excellent alternatives of real positive plasmas for validation and QA of NIPS. The method described here is simple and straightforward, and can be readily used in clinical genetics laboratories with accessibility to prenatal cultures.

The practice of genomic medicine: A delineation of the process and its governing principles.

Genomic medicine, an emerging medical discipline, applies the principles of evolution, developmental biology, functional genomics, and structural genomics within clinical care. Enabling widespread adoption and integration of genomic medicine into clinical practice is key to achieving precision medicine. We delineate a biological framework defining diagnostic utility of genomic testing and map the process of genomic medicine to inform integration into clinical practice. This process leverages collaboration and collective cognition of patients, principal care providers, clinical genomic specialists, laboratory geneticists, and payers. We detail considerations for referral, triage, patient intake, phenotyping, testing eligibility, variant analysis and interpretation, counseling, and management within the utilitarian limitations of health care systems. To reduce barriers for clinician engagement in genomic medicine, we provide several decision-making frameworks and tools and describe the implementation of the proposed workflow in a prototyped electronic platform that facilitates genomic care. Finally, we discuss a vision for the future of genomic medicine and comment on areas for continued efforts.

Distinct gastric phenotype in patients with pathogenic variants in SMAD4: A nationwide cross-sectional study.

Background and study aims In most patients with juvenile polyposis Syndrome, it is possible to detect a pathogenic germline variant in SMAD4 or BMPR1A . It is well known that patients with a pathogenic variant in SMAD4 have a higher risk of gastric polyposis and gastric cancer compared to BMPR1A carriers, but the natural history of gastric involvement is poorly described. We aimed to systematically review endoscopic and histopathological gastric findings in Danish patients with pathogenic variants in SMAD4. Patients and methods This was a retrospective, cross-sectional study including endoscopic and histological gastric findings in all known Danish patients with pathogenic variants in SMAD4 . The patients were identified by data from various registries as well as from clinical genetic departments and laboratories. Results We identified 41 patients (2-72 years) with a pathogenic SMAD4 variant . In 31 patients, we were able to retrieve information on upper gastrointestinal endoscopy. Eighty-seven percent had at least one gastric abnormality including erythema (72 %) and edema (72 %). Half of the patients also had vulnerability of the mucosa and 68 % had gastric polyposis. An increasing frequency of abnormalities were observed with increasing age. Gastric cancer was diagnosed in 5 % of the cases and 22 % had a gastrectomy mainly because of massive polyposis. Conclusions This study showed that most patients with pathogenic SMAD4 variants have a distinct phenotype of the gastric mucosa, and with an increasing severity in the elderly patients. These findings provide new insights into the natural history of gastric manifestations in patients with pathogenic SMAD4 variants.

Identification of Biallelic dystrophin gene variants during maternal carrier testing for Becker muscular dystrophy and review of the DMD exon 49-51 deletion phenotype.

Dystrophinopathies are X-linked recessive conditions caused by pathogenic variants in the dystrophin (DMD) gene. In a family that included two boys with Becker muscular dystrophy (BMD) due to a DMD deletion of exons 45-47, maternal carrier testing unexpectedly identified biallelic DMD deletions of exons 45-47 and 49-51. The patient's mild phenotype in the setting of biallelic DMD variants prompted further investigation of the exon 49-51 deletion in particular, via literature review and retrospective chart review of patients who have been evaluated in our institution's comprehensive neuromuscular center and/or diagnosed in our clinical genetic testing laboratory. To our knowledge, this is only the fifth case of confirmed biallelic DMD variants in a female. In males, the DMD exon 49-51 deletion appears to result in a mild BMD phenotype with low or normal creatine kinase levels. This deletion comprised 19% (4/21) of dystrophinopathies diagnosed by chromosomal microarray (CMA) in males during the past ten years in our clinical laboratory. Most individuals identified by chart review were diagnosed through CMA, despite the fact that microarray was genome-wide and not DMD-specific. This case raised important genetic counseling issues. The DMD exon 49-51 deletion appears to cause a variable but generally mild BMD phenotype. Its relatively frequent detection by CMA suggests it may be underdiagnosed.

COL4A4 variant recently identified: lessons learned in variant interpretation—a case report

BackgroundAlport syndrome is a hereditary kidney disease characterized by hematuria and proteinuria. Although there have been reports of autosomal dominant COL4A4 variants, this is likely an underdiagnosed condition. Improved access to affordable genetic testing has increased the diagnosis of Alport syndrome. As genetic testing becomes ubiquitous, it is imperative that clinical nephrologists understand the benefits and challenges associated with clinical genetic testing.Case PresentationWe present a family of Mexican descent with a heterozygous COL4A4 variant (c.5007delC, ClinVar accession numbers: SCV001580980.2, SCV001993731.1) not previously discussed in detail in the literature. The proband received a biopsy diagnosis suggestive of Fabry disease 18 years after she first developed hematuria and progressed to chronic kidney disease stage III. One year later, the proband was provisionally diagnosed with Alport syndrome after a variant of uncertain significance in the COL4A4 gene was identified following targeted family variant testing of her daughter. Upon review of the medical histories of the proband’s children and niece, all but one had the same variant. Of the four with the variant, three display clinical symptoms of hematuria, and/or proteinuria. The youngest of the four, only months old, has yet to exhibit clinical symptoms. Despite these findings there was a considerable delay in synthesizing this data, as patients were tested in different commercial genetic testing laboratories. Subsequently, understanding this family’s inheritance pattern, family history, and clinical symptoms, as well as the location of the COL4A4 variant resulted in the upgrade of the variant’s classification. Although the classification of this variant varied among different clinical genetic testing laboratories, the consensus was that this variant is likely pathogenic.ConclusionsThis COL4A4 variant (c.5007delC) not yet discussed in detail in the literature is associated with Alport syndrome. The inheritance pattern is suggestive of autosomal dominant inheritance. This report highlights the intricacies of variant interpretation and classification, the siloed nature of commercial genetic testing laboratories, and the importance of a thorough family history for proper variant interpretation. Additionally, the cases demonstrate the varied clinical presentations of Alport syndrome and suggest the utility of early screening, diagnosis, monitoring, and treatment.