Rapid whole-genome sequencing for genetic disease diagnosis in neonatal intensive care units

Fast and accurate DNASeq variant calling workflow composed of LUSH toolkit

BACKGROUND

Whole genome sequencing (WGS) is becoming increasingly prevalent for molecular diagnosis, staging and prognosis because of its declining costs and the ability to detect nearly all genes associated with a patient's disease. The currently widely accepted variant calling pipeline, GATK, is limited in terms of its computational speed and efficiency, which cannot meet the growing analysis needs.

RESULTS

Here, we propose a fast and accurate DNASeq variant calling workflow that is purely composed of tools from LUSH toolkit. The precision and recall measurements indicate that both the LUSH and GATK pipelines exhibit high levels of consistency, with precision and recall rates exceeding 99% on the 30x NA12878 dataset. In terms of processing speed, the LUSH pipeline outperforms the GATK pipeline, completing 30x WGS data analysis in just 1.6 h, which is approximately 17 times faster than GATK. Notably, the LUSH_HC tool completes the processing from BAM to VCF in just 12 min, which is around 76 times faster than GATK.

CONCLUSION

These findings suggest that the LUSH pipeline is a highly promising alternative to the GATK pipeline for WGS data analysis, with the potential to significantly improve bedside analysis of acutely ill patients, large-scale cohort data analysis, and high-throughput variant calling in crop breeding programs. Furthermore, the LUSH pipeline is highly scalable and easily deployable, allowing it to be readily applied to various scenarios such as clinical diagnosis and genomic research.

Genetic disorders and their association with morbidity and mortality in early preterm small for gestational age infants

BACKGROUND

Early preterm (<34 weeks of gestation) small for gestational age infants (<10th percentile birth weight for sex and gestational age) experience high rates of morbidity and mortality, the causes of which are poorly understood. Mounting evidence suggests that genetic disorders contribute. Scarce data exist regarding the prevalence of genetic disorders and their contribution to morbidity and mortality.

OBJECTIVE

This study aimed to determine the proportion of genetic disorders in early preterm small for gestational age infants (with and without congenital anomalies) compared to early preterm appropriate for gestational age infants and the association of genetic disorders with morbidity or mortality.

STUDY DESIGN

This is a retrospective cohort study of infants delivered at 23 and 0/7 to 33 and 6/7 weeks of gestation from 2000 to 2020 from the Pediatrix Clinical Data Warehouse. Data included diagnosed genetic disorders and congenital anomalies, baseline characteristics, and morbidity or mortality. We excluded cases of death in the delivery room before neonatal intensive care unit admission, multiple gestations, and cases transferred after birth or before death or discharge.

RESULTS

We identified 223,431 early preterm infants, including 21,180 small for gestational age. Genetic disorders were present in 441 (2.3%) of small for gestational age infants without congenital anomalies, in 194 (10.8%) of small for gestational age infants with congenital anomalies, and in 304 (4.5%) of small for gestational age infants that experienced morbidity or mortality (with or without congenital anomalies). Trisomies 13, 18, and 21 were the most prevalent genetic disorders in these groups, together accounting for 145 small for gestational age infants without congenital anomalies, 117 small for gestational age infants with congenital anomalies, and 166 small for gestational age infants with morbidity or mortality (with or without congenital anomalies). Less prevalent genetic disorders consisted of other aneuploidy (45, X and 47, XXY), copy number variants (13q14 deletion syndrome, cri du chat syndrome, DiGeorge syndrome), and single gene disorders (cystic fibrosis, Fanconi anemia, glucose-6-phosphate dehydrogenase deficiency, hemophilia, hypophosphatasia, sickle cell disease, and thalassemia). Comparatively, genetic disorders were found in 1792 (1.0%) appropriate for gestational age infants without congenital anomalies, in 572 (5.8%) appropriate for gestational age infants with congenital anomalies, and 809 (2.0%) appropriate for gestational age infants that experienced morbidity or mortality (with or without congenital anomalies). Genetic disorders were associated with an adjusted odds ratio (95% confidence interval) of 2.10 (1.89-2.33) of isolated small for gestational age and 12.84 (11.47-14.35) of small for gestational age accompanied by congenital anomalies. Genetic disorders were associated with an adjusted odds ratio of 2.24 (1.83-2.74) of morbidity or mortality.

CONCLUSION

These findings suggest that genetic disorders are more prevalent in early preterm small for gestational age infants, particularly those with congenital anomalies. These findings also suggest that genetic disorders are associated with increased morbidity and mortality. These associations were primarily driven by trisomies 13, 18, and 21. Genetic diagnoses in this cohort were made through routine clinical care, principally via karyotype, chromosomal microarray, and single gene testing. These findings support evolving clinical guidelines for genetic testing of small for gestational age infants. Our study is limited due to the lack of prospective, genome-wide testing.

Clinical characteristics of BRAT1-related disease: a systematic literature review

BACKGROUND

BRAT1 (BRCA1-associated ataxia telangiectasia mutated activator 1) is involved in many important biological processes, including DNA damage response and maintenance of mitochondrial homeostasis. Dysfunctional BRAT1 causes variable clinical phenotypes, which hinders BRAT1-related disease from recognition and diagnosis.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement was the guideline for this systematic review. MEDLINE was searched by terms ("BAAT1" and "BRAT1") from inception until June 21, 2022.

RESULTS

Twenty-eight studies, screened out of 49 records, were included for data extraction. The data from fifty patients with mutated BRAT1 were collected. There are 3 high relevant phenotypes, 4 medium relevant phenotypes and 3 low relevant phenotypes. Eye-related abnormal features were most frequently reported: 27 abnormal features were observed. Thirty-nine kinds of pathogenic nucleotide change in BRAT1 were reported. Top three common mutations of BRAT1 were c.638_639insA (16 cases), c.1395G > A (5 cases) and c.294dupA (4 cases). Homozygous mutations in BRAT1 presented a more severe phenotype than those who are compound heterozygotes.

CONCLUSIONS

This is the first comprehensive systematic review to present quantitative data about clinical characteristics of BRAT1-related disease, which helps doctors to recognize and diagnose it easier.

An atypical form of 60S ribosomal subunit in Diamond-Blackfan anemia linked to RPL17 variants

Diamond-Blackfan anemia syndrome (DBA) is a ribosomopathy associated with loss-of-function variants in more than 20 ribosomal protein (RP) genes. Here, we report the genetic, functional, and biochemical dissection of 2 multigenerational pedigrees with variants in RPL17, a large ribosomal subunit protein-encoding gene. Affected individuals had clinical features and erythroid proliferation defects consistent with DBA. Further, RPL17/uL22 depletion resulted in anemia and micrognathia in zebrafish larvae, and in vivo complementation studies indicated that RPL17 variants were pathogenic. Lymphoblastoid cell lines (LCLs) derived from patients displayed a ribosomal RNA maturation defect reflecting haploinsufficiency of RPL17. The proteins encoded by RPL17 variants were not incorporated into ribosomes, but 10%-20% of 60S ribosomal subunits contained a short form of 5.8S rRNA (5.8SC), a species that is marginal in normal cells. These atypical 60S subunits were actively engaged in translation. Ribosome profiling showed changes of the translational profile, but those are similar to LCLs bearing RPS19 variants. These results link an additional RP gene to DBA. They show that ribosomes can be modified substantially by RPL17 haploinsufficiency but support the paradigm that translation alterations in DBA are primarily related to insufficient ribosome production rather than to changes in ribosome structure or composition.

Clinical exome sequencing uncovers genetic disorders in neonates with suspected hypoxic-ischemic encephalopathy: A retrospective analysis

Hypoxic-ischemic encephalopathy (HIE) occurs in up to 7 out of 1000 births and accounts for almost a quarter of neonatal deaths worldwide. Despite the name, many newborns with HIE have little evidence of perinatal hypoxia. We hypothesized that some infants with HIE have genetic disorders that resemble encephalopathy. We reviewed genetic results for newborns with HIE undergoing exome or genome sequencing at a clinical laboratory (2014-2022). Neonates were included if they had a diagnosis of HIE and were delivered ≥35 weeks. Neonates were excluded for cardiopulmonary pathology resulting in hypoxemia or if neuroimaging suggested postnatal hypoxic-ischemic injury. Of 24 patients meeting inclusion criteria, six (25%) were diagnosed with a genetic condition. Four neonates had variants at loci linked to conditions with phenotypic features resembling HIE, including KIF1A, GBE1, ACTA1, and a 15q13.3 deletion. Two additional neonates had variants in genes not previously associated with encephalopathy, including DUOX2 and PTPN11. Of the six neonates with a molecular diagnosis, two had isolated HIE without apparent comorbidities to suggest a genetic disorder. Genetic diagnoses were identified among neonates with and without sentinel labor events, abnormal umbilical cord gasses, and low Apgar scores. These results suggest that genetic evaluation is clinically relevant for patients with perinatal HIE.

NeoGx: Machine-Recommended Rapid Genome Sequencing for Neonates

Background

Genetic disease is common in the Level IV Neonatal Intensive Care Unit (NICU), but neonatology providers are not always able to identify the need for genetic evaluation. We trained a machine learning (ML) algorithm to predict the need for genetic testing within the first 18 months of life using health record phenotypes.

Methods

For a decade of NICU patients, we extracted Human Phenotype Ontology (HPO) terms from clinical text with Natural Language Processing tools. Considering multiple feature sets, classifier architectures, and hyperparameters, we selected a classifier and made predictions on a validation cohort of 2,241 Level IV NICU admits born 2020-2021.

Results

Our classifier had ROC AUC of 0.87 and PR AUC of 0.73 when making predictions during the first week in the Level IV NICU. We simulated testing policies under which subjects begin testing at the time of first ML prediction, estimating diagnostic odyssey length both with and without the additional benefit of pursuing rGS at this time. Just by using ML to accelerate initial genetic testing (without changing the tests ordered), the median time to first genetic test dropped from 10 days to 1 day, and the number of diagnostic odysseys resolved within 14 days of NICU admission increased by a factor of 1.8. By additionally requiring rGS at the time of positive ML prediction, the number of diagnostic odysseys resolved within 14 days was 3.8 times higher than the baseline.

Conclusions

ML predictions of genetic testing need, together with the application of the right rapid testing modality, can help providers accelerate genetics evaluation and bring about earlier and better outcomes for patients.

Application of whole exome sequencing in carrier screening for high-risk families without probands

Purpose

This study aimed to screen the genetic etiology for the high-risk families including those with an adverse pregnancy history, a history of consanguineous marriages, or a history of genetic diseases, but lack of proband via whole exome sequencing (WES).

Methods

128 individuals from high-risk family were tested by WES. The candidate variants were analyzed according to the ACMG criteria to screen the potential carriers. At-risk couples (ARCs) who harbored the same causative gene were provided with precise fertility guidance to avoid the birth of children with birth defects.

Results

The total detection rate was 36.72%, with pathogenic/likely pathogenic (P/LP) variants found in 47 individuals, and variants of uncertain significance (VUS) were found in 34. Among couples with adverse pregnancy history: P/LP variants were found in 38 individuals, and VUS were found in 26, for a detection rate of 34.55%; among members of family history of genetic disease or consanguineous marriages: P/LP variants were found in nine individuals, and VUS were found in 8, for a detection rate of 50.00%. Otherwise, we detected 19 ARCs who both carried P/LP variants in the same gene, with a theoretical offspring prevalence of up to 7.42%.

Conclusion

In the absence of probands, carrier screening using WES can provide an efficient tool for screening the molecular etiology of high-risk families.

Whole genome sequencing as a first-tier diagnostic test for infants in neonatal intensive care units: A pilot study in Brazil

In this pilot study, we aimed to evaluate the feasibility of whole genome sequencing (WGS) as a first-tier diagnostic test for infants hospitalized in neonatal intensive care units in the Brazilian healthcare system. The cohort presented here results from a joint collaboration between private and public hospitals in Brazil considering the initiative of a clinical laboratory to provide timely diagnosis for critically ill infants. We performed trio (proband and parents) WGS in 21 infants suspected of a genetic disease with an urgent need for diagnosis to guide medical care. Overall, the primary indication for genetic testing was dysmorphic syndromes (n = 14, 67%) followed by inborn errors of metabolism (n = 6, 29%) and skeletal dysplasias (n = 1, 5%). The diagnostic yield in our cohort was 57% (12/21) based on cases that received a definitive or likely definitive diagnostic result from WGS analysis. A total of 16 pathogenic/likely pathogenic variants and 10 variants of unknown significance were detected, and in most cases inherited from an unaffected parent. In addition, the reported variants were of different types, but mainly missense (58%) and associated with autosomal diseases (19/26); only three were associated with X-linked diseases, detected in hemizygosity in the proband an inherited from an unaffected mother. Notably, we identified 10 novel variants, absent from public genomic databases, in our cohort. Considering the entire diagnostic process, the average turnaround time from enrollment to medical report in our study was 53 days. Our findings demonstrate the remarkable utility of WGS as a diagnostic tool, elevating the potential of transformative impact since it outperforms conventional genetic tests. Here, we address the main challenges associated with implementing WGS in the medical care system in Brazil, as well as discuss the potential benefits and limitations of WGS as a diagnostic tool in the neonatal care setting.

Development and validation of a prenatal predictive nomogram for the risk of NICU admission in infants born to Chinese mothers over 35 years of age: a retrospective cohort study

BACKGROUND

The rising number of women giving birth at advanced maternal age has posed significant challenges in obstetric care in recent years, resulting in increased incidence of neonatal transfer to the Neonatal Intensive Care Unit (NICU). Therefore, identifying fetuses requiring NICU transfer before delivery is essential for guiding targeted preventive measures.

OBJECTIVE

This study aims to construct and validate a nomogram for predicting the prenatal risk of NICU admission in neonates born to mothers over 35 years of age.

STUDY DESIGN

Clinical data of 4218 mothers aged ≥ 35 years who gave birth at the Department of Obstetrics of the Second Hospital of Shandong University between January 1, 2017 and December 31, 2021 were reviewed. Independent predictors were identified by multivariable logistic regression, and a predictive nomogram was subsequently constructed for the risk of neonatal NICU admission.

RESULTS

Multivariate logistic regression demonstrated that the method of prenatal screening, number of implanted embryos, preterm premature rupture of the membranes, preeclampsia, HELLP syndrome, fetal distress, premature birth, and cause of preterm birth are independent predictors of neonatal NICU admission. Analysis of the nomogram decision curve based on these 8 independent predictors showed that the prediction model has good net benefit and clinical utility.

CONCLUSION

The nomogram demonstrates favorable performance in predicting the risk of neonatal NICU transfer after delivery by mothers older than 35 years. The model serves as an accurate and effective tool for clinicians to predict NICU admission in a timely manner.

A DFTB study on the electronic response of encapsulated DNA nucleobases onto chiral CNTs as a sequencer

Sequencing the DNA nucleobases is essential in the diagnosis and treatment of many diseases related to human genes. In this article, the encapsulation of DNA nucleobases with some of the important synthesized chiral (7, 6), (8, 6), and (10, 8) carbon nanotubes were investigated. The structures were modeled by applying density functional theory based on tight binding method (DFTB) by considering semi-empirical basis sets. Encapsulating DNA nucleobases on the inside of CNTs caused changes in the electronic properties of the selected chiral CNTs. The results confirmed that van der Waals (vdW) interactions, π-orbitals interactions, non-bonded electron pairs, and the presence of high electronegative atoms are the key factors for these changes. The result of electronic parameters showed that among the CNTs, CNT (8, 6) is a suitable choice in sequencing guanine (G) and cytosine (C) DNA nucleobases. However, they are not able to sequence adenine (A) and thymine (T). According to the band gap energy engineering approach and absorption energy, the presence of G and C DNA nucleobases decreased the band gap energy of CNTs. Hence selected CNTs suggested as biosensor substrates for sequencing G and C DNA nucleobases.

BRAT1-Associated Leukodystrophy Exacerbated by Classic Hodgkin Lymphoma-Directed Therapy

INTRODUCTION

BRCA1-associated ataxia-telangiectasia-mutated activator-1 (BRAT1) is responsible for cell cycle surveillance and mitochondrial function. The implications of adult-onset BRAT1-variant and the resulting phenotypic neurocognitive and imaging features have not been previously described.

CASE REPORT

A 66-year-old man with a recent diagnosis of classic Hodgkin lymphoma was referred to neuro-oncology for cognitive and motor decline, and progressive cerebral white matter changes noted on magnetic resonance imaging (MRI). A neurological examination revealed global weakness, broad-based gait, and bilateral extensor plantar responses. Brain MRI demonstrated periventricular, deep, and subcortical white matter T2/FLAIR hyperintensities without contrast enhancement. Cerebral spinal fluid studies were unremarkable. A GeneDX genetic leukodystrophy panel conduction revealed a pathogenic variant (c.294dupA; p.L99TfsX92) resulting in a truncated protein of BRAT1, along with a variant of uncertain significance (c.746A>G;p.E249G). A presumptive diagnosis of late-onset leukoencephalopathy secondary to the BRAT1 variant was made. In an attempt to combat his mitochondrial dysfunction, he was initiated on a mitochondrial cocktail, including B-100 complex and coenzyme Q10. He began lymphoma-directed combination chemotherapy and developed precipitous functional decline after 2 cycles of therapy. Compared with prechemotherapy imaging, repeat positron emission tomography/computed tomography metabolic imaging showed a response after 3 cycles of chemotherapy; however, repeat brain MRI showed worsening diffuse white matter hyperintensities and cerebral atrophy.

CONCLUSION

Given the variability in phenotypes and clinical onset, leukodystrophies can be a diagnostic challenge. This case demonstrated progressive BRAT1-associated leukodystrophy exacerbated by chemotherapy-induced toxic leukoencephalopathy. Mitochondrial energy deficiency in the context of multiple metabolic insults was likely underlying the progressive neurological decline observed in this case of genetic leukodystrophy.

Whole-genome sequencing analysis in fetal structural anomalies: novel phenotype-genotype discoveries

OBJECTIVES

The identification of structural variants and single-nucleotide variants is essential in finding molecular etiologies of monogenic genetic disorders. Whole-genome sequencing (WGS) is becoming more widespread in genetic disease diagnosis. However, data on its clinical utility remain limited in prenatal practice. We aimed to expand our understanding of implementing WGS in the genetic diagnosis of fetal structural anomalies.

METHODS

We employed trio WGS with a minimum coverage of 40× on the MGI DNBSEQ-T7 platform in a cohort of 17 fetuses presenting with aberrations detected by ultrasound, but uninformative findings of standard chromosomal microarray analysis (CMA) and exome sequencing (ES).

RESULTS

Causative genetic variants were identified in two families, with an increased diagnostic yield of 11.8% (2/17). Both were exon-level copy-number variants of small size (3.03 kb and 5.16 kb) and beyond the detection thresholds of CMA and ES. Moreover, to the best of our knowledge, we have described the first prenatal instance of the association of FGF8 with holoprosencephaly and facial deformities.

CONCLUSIONS

Our analysis demonstrates the clinical value of WGS in the diagnosis of the underlying etiology of fetuses with structural abnormalities, when routine genetic tests have failed to provide a diagnosis. Additionally, the novel variants and new fetal manifestations have expanded the mutational and phenotypic spectrums of BBS9 and FGF8. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

D-Bifunctional Protein Deficiency Diagnosis-A Challenge in Low Resource Settings: Case Report and Review of the Literature

D-bifunctional protein deficiency (D-BPD) is a rare, autosomal recessive peroxisomal disorder that affects the breakdown of long-chain fatty acids. Patients with D-BPD typically present during the neonatal period with hypotonia, seizures, and facial dysmorphism, followed by severe developmental delay and early mortality. While some patients have survived past two years of age, the detectable enzyme activity in these rare cases was likely a contributing factor. We report a D-BPD case and comment on challenges faced in diagnosis based on a narrative literature review. An overview of Romania's first patient diagnosed with D-BPD is provided, including clinical presentation, imaging, biochemical, molecular data, and clinical course. Establishing a diagnosis can be challenging, as the clinical picture is often incomplete or similar to many other conditions. Our patient was diagnosed with type I D-BPD based on whole-exome sequencing (WES) results revealing a pathogenic frameshift variant of the HSD17B4 gene, c788del, p(Pro263GInfs*2), previously identified in another D-BPD patient. WES also identified a variant of the SUOX gene with unclear significance. We advocate for using molecular diagnosis in critically ill newborns and infants to improve care, reduce healthcare costs, and allow for familial counseling.

Wales Infants' and childreN's Genome Service (WINGS): providing rapid genetic diagnoses for unwell children

INTRODUCTION

This study reviews the first 3 years of delivery of the first National Health Service (NHS)-commissioned trio rapid whole genome sequencing (rWGS) service for acutely unwell infants and children in Wales.

METHODS

Demographic and phenotypic data were prospectively collected as patients and their families were enrolled in the Wales Infants' and childreN's Genome Service (WINGS). These data were reviewed alongside trio rWGS results.

RESULTS

From April 2020 to March 2023, 82 families underwent WINGS, with a diagnostic yield of 34.1%. The highest diagnostic yields were noted in skeletal dysplasias, neurological or metabolic phenotypes. Mean time to reporting was 9 days.

CONCLUSION

This study demonstrates that trio rWGS is having a positive impact on the care of acutely unwell infants and children in an NHS setting. In particular, the study shows that rWGS can be applied in an NHS setting, achieving a diagnostic yield comparable with the previously published diagnostic yields achieved in research settings, while also helping to improve patient care and management.

The use of next-generation sequencing in personalized medicine

The revolutionary progress in development of next-generation sequencing (NGS) technologies has made it possible to deliver accurate genomic information in a timely manner. Over the past several years, NGS has transformed biomedical and clinical research and found its application in the field of personalized medicine. Here we discuss the rise of personalized medicine and the history of NGS. We discuss current applications and uses of NGS in medicine, including infectious diseases, oncology, genomic medicine, and dermatology. We provide a brief discussion of selected studies where NGS was used to respond to wide variety of questions in biomedical research and clinical medicine. Finally, we discuss the challenges of implementing NGS into routine clinical use.

Rapid genomic sequencing for genetic disease diagnosis and therapy in intensive care units: a review

Single locus (Mendelian) diseases are a leading cause of childhood hospitalization, intensive care unit (ICU) admission, mortality, and healthcare cost. Rapid genome sequencing (RGS), ultra-rapid genome sequencing (URGS), and rapid exome sequencing (RES) are diagnostic tests for genetic diseases for ICU patients. In 44 studies of children in ICUs with diseases of unknown etiology, 37% received a genetic diagnosis, 26% had consequent changes in management, and net healthcare costs were reduced by $14,265 per child tested by URGS, RGS, or RES. URGS outperformed RGS and RES with faster time to diagnosis, and higher rate of diagnosis and clinical utility. Diagnostic and clinical outcomes will improve as methods evolve, costs decrease, and testing is implemented within precision medicine delivery systems attuned to ICU needs. URGS, RGS, and RES are currently performed in <5% of the ~200,000 children likely to benefit annually due to lack of payor coverage, inadequate reimbursement, hospital policies, hospitalist unfamiliarity, under-recognition of possible genetic diseases, and current formatting as tests rather than as a rapid precision medicine delivery system. The gap between actual and optimal outcomes in children in ICUs is currently increasing since expanded use of URGS, RGS, and RES lags growth in those likely to benefit through new therapies. There is sufficient evidence to conclude that URGS, RGS, or RES should be considered in all children with diseases of uncertain etiology at ICU admission. Minimally, diagnostic URGS, RGS, or RES should be ordered early during admissions of critically ill infants and children with suspected genetic diseases.

3-hour genome sequencing and targeted analysis to rapidly assess genetic risk

Purpose

Rapid genetic testing in the critical care setting may guide diagnostic evaluation, direct therapies, and help families and care providers make informed decisions about goals of care. We tested whether a simplified DNA extraction and library preparation process would enable us to perform ultra-rapid assessment of genetic risk for a Mendelian condition, based on information from an affected sibling, using long-read genome sequencing and targeted analysis.

Methods

Following extraction of DNA from cord blood and rapid library preparation, genome sequencing was performed on an Oxford Nanopore PromethION. FASTQ files were generated from original sequencing data in near real-time and aligned to a reference genome. Variant calling and analysis were performed at timed intervals.

Results

We optimized the DNA extraction and library preparation methods to create sufficient library for sequencing from 500 μL of blood. Real-time, targeted analysis was performed to determine that the newborn was neither affected nor a heterozygote for variants underlying a Mendelian condition. Phasing of the target region and prior knowledge of the affected haplotypes supported our interpretation despite a low level of coverage at 3 hours of life.

Conclusion

This proof-of-concept experiment demonstrates how prior knowledge of haplotype structure or familial variants can be used to rapidly evaluate an individual at risk for a genetic disease. While ultra-rapid sequencing remains both complex and cost prohibitive, our method is more easily automated than prior approaches and uses smaller volumes of blood, thus may be more easily adopted for future studies of ultra-rapid genome sequencing in the clinical setting.

Clinical utility of early rapid genome sequencing in the evaluation of patients with differences of sex development

Establishing an early and accurate genetic diagnosis among patients with differences of sex development (DSD) is crucial in guiding the complex medical and psychosocial care they require. Genetic testing routinely utilized in clinical practice for this population is predicated upon physical exam findings and biochemical and endocrine profiling. This approach, however, is inefficient and unstandardized. Many patients with DSD, particularly those with 46,XY DSD, never receive a molecular genetic diagnosis. Rapid genome sequencing (rGS) is gaining momentum as a first-tier diagnostic instrument in the evaluation of patients with DSD given its ability to provide greater diagnostic yield and timely results. We present the case of a patient with nonbinary genitalia and systemic findings for whom rGS identified a novel variant of the WT1 gene and resulted in a molecular diagnosis within two weeks of life. This timeframe of diagnosis for syndromic DSD is largely unprecedented at our institution. Rapid GS expedited mobilization of a multidisciplinary medical team; enabled early understanding of clinical trajectory; informed planning of medical and surgical interventions; and guided individualized psychosocial support provided to the family. This case highlights the potential of early rGS in transforming the evaluation and care of patients with DSD.

Lessons learned from rapid exome sequencing for 575 critically ill patients across the broad spectrum of rare disease

Introduction: Rapid exome sequencing (rES) has become the first-choice genetic test for critically ill patients, mostly neonates, young infants, or fetuses in prenatal care, in time-sensitive situations and when it is expected that the genetic test result may guide clinical decision making. The implementation of rES has revolutionized medicine by enabling timely identification of genetic causes for various rare diseases. The utilization of rES has increasingly been recognized as an essential diagnostic tool for the identification of complex and undiagnosed genetic disorders. Methods: We conducted a retrospective evaluation of our experiences with rES performed on 575 critically ill patients from various age groups (prenatal to adulthood), over a four-year period (2016-2019). These patients presented with a wide spectrum of rare diseases, including but not limited to neurological disorders, severe combined immune deficiency, and cancer. Results: During the study period, there was a significant increase in rES referrals, with a rise from a total of two referrals in Q1-2016 to 10 referrals per week in Q4-2019. The median turnaround time (TAT) decreased from 17 to 11 days in the period 2016-2019, with an overall median TAT of 11 days (IQR 8-15 days). The overall diagnostic yield for this cohort was 30.4%, and did not significantly differ between the different age groups (e.g. adults 22.2% vs children 31.0%; p-value 0.35). However, variability in yield was observed between clinical entities: craniofacial anomalies yielded 58.3%, while for three clinical entities (severe combined immune deficiency, aneurysm, and hypogonadotropic hypogonadism) no diagnoses were obtained. Discussion: Importantly, whereas clinical significance is often only attributed to a conclusive diagnosis, we also observed impact on clinical decision-making for individuals in whom no genetic diagnosis was established. Hence, our experience shows that rES has an important role for patients of all ages and across the broad spectrum of rare diseases to impact clinical outcomes.

Genetic counselling considerations with genetic/genomic testing in Neonatal and Pediatric Intensive Care Units: A scoping review

Genetic and genomic technologies can effectively diagnose numerous genetic disorders. Patients benefit when genetic counselling accompanies genetic testing and international guidelines recommend pre- and post-test genetic counselling with genome-wide sequencing. However, there is a gap in knowledge regarding the unique genetic counselling considerations with different types of genetic testing in the Neonatal Intensive Care Unit (NICU) and the Pediatric Intensive Care Unit (PICU). This scoping review was conducted to identify the gaps in care with respect to genetic counselling for infants/pediatric patients undergoing genetic and genomic testing in NICUs and PICUs and understand areas in need of improvement in order to optimize clinical care for patients, caregivers, and healthcare providers. Five databases (MEDLINE [Ovid], Embase [Ovid], PsycINFO [Ebsco], CENTRAL [Ovid], and CINHAL [Ebsco]) and grey literature were searched. A total of 170 studies were included and used for data extraction and analysis. This scoping review includes descriptive analysis, followed by a narrative account of the extracted data. Results were divided into three groups: pre-test, post-test, and comprehensive (both pre- and post-test) genetic counselling considerations based on indication for testing. More studies were conducted in the NICU than the PICU. Comprehensive genetic counselling was discussed in only 31% of all the included studies demonstrating the need for both pre-test and post-test genetic counselling for different clinical indications in addition to the need to account for different cultural aspects based on ethnicity and geographic factors.

The future of commercial genetic testing

PURPOSE OF REVIEW

There are thousands of different clinical genetic tests currently available. Genetic testing and its applications continue to change rapidly for multiple reasons. These reasons include technological advances, accruing evidence about the impact and effects of testing, and many complex financial and regulatory factors.

RECENT FINDINGS

This article considers a number of key issues and axes related to the current and future state of clinical genetic testing, including targeted versus broad testing, simple/Mendelian versus polygenic and multifactorial testing models, genetic testing for individuals with high suspicion of genetic conditions versus ascertainment through population screening, the rise of artificial intelligence in multiple aspects of the genetic testing process, and how developments such as rapid genetic testing and the growing availability of new therapies for genetic conditions may affect the field.

SUMMARY

Genetic testing is expanding and evolving, including into new clinical applications. Developments in the field of genetics will likely result in genetic testing becoming increasingly in the purview of a very broad range of clinicians, including general paediatricians as well as paediatric subspecialists.

Genomic medicine in neonatal care: progress and challenges

During the neonatal period, many genetic disorders present and contribute to neonatal morbidity and mortality. Genomic medicine-the use of genomic information in clinical care- has the potential to significantly reduce morbidity and mortality in the neonatal period and improve outcomes for this population. Diagnostic genomic testing for symptomatic newborns, especially rapid testing, has been shown to be feasible and have diagnostic and clinical utility, particularly in the short-term. Ongoing studies are assessing the feasibility and utility, including personal utility, of implementation in diverse populations. Genomic screening for asymptomatic newborns has also been studied, and the acceptability and feasibility of such an approach remains an active area of investigation. Emerging precision therapies, with examples even at the "n-of-1" level, highlight the promise of precision diagnostics to lead to early intervention and improve outcomes. To sustainably implement genomic medicine in neonatal care in an ethical, effective, and equitable manner, we need to ensure access to genetics and genomics knowledge, access to genomic tests, which is currently limited by payors, feasible processes for ordering these tests, and access to follow up in the clinical and research realms. Future studies will provide further insight into enablers and barriers to optimize implementation strategies.

Prenatal whole-exome sequencing in fetuses with increased nuchal translucency

BACKGROUND

Increased nuchal translucency (NT) is associated with an increased risk for genetic disorders. The aim of this study was to investigate the value of whole-exome sequencing (WES) in detecting genetic abnormalities for fetuses with isolated first-trimester increased NT.

METHODS

After the exclusion of aneuploidies and pathogenic copy number variants (CNVs) by quantitative fluorescent polymerase chain reaction (QF-PCR) and chromosomal microarray analysis (CMA), WES was performed on 63 fetuses with isolated first-trimester increased NT (≥3.5 mm).

RESULTS

Overall, WES yielded a 4.8% (3/63) diagnostic rate for fetuses with isolated increased NT. Pathogenic variants were identified in 37.5% (3/8) fetuses that developed additional structural anomalies later in gestation, and no pathogenic variants were detected in increased NT that resolved or remained isolated throughout the pregnancy.

CONCLUSION

This study provides powerful evidence to offer prenatal WES for increased NT only when additional abnormalities are present. Early detailed ultrasound to detect emerging anomalies can help physicians offer prenatal WES to fetuses with a greater likelihood of diagnosis.

Ab Initio investigation for DNA nucleotide bases sequencing using chiral carbon nanobelts and nanotubes

Understanding the interaction mechanism between DNA nucleotide bases and carbon nanomaterials is an important issue in the field of identifying nucleotide molecules sequencing. In this article, the adsorption behavior of DNA nucleotide bases on the external surface of chiral carbon nanobelts (CNBs) (6, 5), (7, 6) and (8, 6), was comprehensively investigated from electronic and optical perspectives. As a result, it was determined that the DNA nucleotide bases have optical absorption in the ultraviolet region. When bases are adsorbed on the surface of CNBs, the optical absorption peak of the new complex structure shifted to the visible region. The study of the optical properties of selected CNBs showed that CNB (6,5) performs better in detecting Cytosine and the red shift in the absorption spectrum of complex structure is noticeable. Also, the effect of infinite length for chiral CNTs in DNA nucleotide base sequencing was investigated using DFTB approach. Our investigations based on electronic properties showed that CNTs have better performance than CNBs in DNA nucleotide base sequencing.

Implementation of Rapid Genome Sequencing for Critically Ill Infants With Complex Congenital Heart Disease

BACKGROUND

Rapid genome sequencing (rGS) has been shown to improve care of critically ill infants. Congenital heart disease (CHD) is a leading cause of infant mortality and is often caused by genetic disorders, yet the utility of rGS has not been prospectively studied in this population.

METHODS

We conducted a prospective evaluation of rGS to improve the care of infants with complex CHD in our cardiac neonatal intensive care unit.

RESULTS

In a cohort of 48 infants with complex CHD, rGS diagnosed 14 genetic disorders in 13 (27%) individuals and led to changes in clinical management in 8 (62%) cases with diagnostic results. These included 2 cases in whom genetic diagnoses helped avert intensive, futile interventions before cardiac neonatal intensive care unit discharge, and 3 cases in whom eye disease was diagnosed and treated in early childhood.

CONCLUSIONS

Our study provides the first prospective evaluation of rGS for infants with complex CHD to our knowledge. We found that rGS diagnosed genetic disorders in 27% of cases and led to changes in management in 62% of cases with diagnostic results. Our model of care depended on coordination between neonatologists, cardiologists, surgeons, geneticists, and genetic counselors. These findings highlight the important role of rGS in CHD and demonstrate the need for expanded study of how to implement this resource to a broader population of infants with CHD.

Whole-Genome Sequencing Can Identify Clinically Relevant Variants from a Single Sub-Punch of a Dried Blood Spot Specimen

The collection of dried blood spots (DBS) facilitates newborn screening for a variety of rare, but very serious conditions in healthcare systems around the world. Sub-punches of varying sizes (1.5-6 mm) can be taken from DBS specimens to use as inputs for a range of biochemical assays. Advances in DNA sequencing workflows allow whole-genome sequencing (WGS) libraries to be generated directly from inputs such as peripheral blood, saliva, and DBS. We compared WGS metrics obtained from libraries generated directly from DBS to those generated from DNA extracted from peripheral blood, the standard input for this type of assay. We explored the flexibility of DBS as an input for WGS by altering the punch number and size as inputs to the assay. We showed that WGS libraries can be successfully generated from a variety of DBS inputs, including a single 3 mm or 6 mm diameter punch, with equivalent data quality observed across a number of key metrics of importance in the detection of gene variants. We observed no difference in the performance of DBS and peripheral-blood-extracted DNA in the detection of likely pathogenic gene variants in samples taken from individuals with cystic fibrosis or phenylketonuria. WGS can be performed directly from DBS and is a powerful method for the rapid discovery of clinically relevant, disease-causing gene variants.

Whole genome sequencing vs chromosomal microarray analysis in prenatal diagnosis

BACKGROUND

Emerging studies suggest that whole genome sequencing provides additional diagnostic yield of genomic variants when compared with chromosomal microarray analysis in the etiologic diagnosis of infants and children with suspected genetic diseases. However, the application and evaluation of whole genome sequencing in prenatal diagnosis remain limited.

OBJECTIVE

This study aimed to evaluate the accuracy, efficacy, and incremental yield of whole genome sequencing in comparison with chromosomal microarray analysis for routine prenatal diagnosis.

STUDY DESIGN

In this prospective study, a total of 185 unselected singleton fetuses with ultrasound-detected structural anomalies were enrolled. In parallel, each sample was subjected to whole genome sequencing and chromosomal microarray analysis. Aneuploidies and copy number variations were detected and analyzed in a blinded fashion. Single nucleotide variations and insertions and deletions were confirmed by Sanger sequencing, and trinucleotide repeats expansion variants were verified using polymerase chain reaction plus fragment-length analysis.

RESULTS

Overall, genetic diagnoses using whole genome sequencing were obtained for 28 (15.1%) cases. Whole genome sequencing not only detected all these aneuploidies and copy number variations in the 20 (10.8%) diagnosed cases identified by chromosomal microarray analysis, but also detected 1 case with an exonic deletion of COL4A2 and 7 (3.8%) cases with single nucleotide variations or insertions and deletions. In addition, 3 incidental findings were detected including an expansion of the trinucleotide repeat in ATXN3, a splice-sites variant in ATRX, and an ANXA11 missense mutation in a case of trisomy 21.

CONCLUSION

Compared with chromosomal microarray analysis, whole genome sequencing increased the additional detection rate by 5.9% (11/185). Using whole genome sequencing, we detected not only aneuploidies and copy number variations, but also single nucleotide variations and insertions and deletions, trinucleotide repeat expansions, and exonic copy number variations with high accuracy in an acceptable turnaround time (3-4 weeks). Our results suggest that whole genome sequencing has the potential to be a new promising prenatal diagnostic test for fetal structural anomalies.

BRAT1-related disorders: phenotypic spectrum and phenotype-genotype correlations from 97 patients

BRAT1 biallelic variants are associated with rigidity and multifocal seizure syndrome, lethal neonatal (RMFSL), and neurodevelopmental disorder associating cerebellar atrophy with or without seizures syndrome (NEDCAS). To date, forty individuals have been reported in the literature. We collected clinical and molecular data from 57 additional cases allowing us to study a large cohort of 97 individuals and draw phenotype-genotype correlations. Fifty-nine individuals presented with BRAT1-related RMFSL phenotype. Most of them had no psychomotor acquisition (100%), epilepsy (100%), microcephaly (91%), limb rigidity (93%), and died prematurely (93%). Thirty-eight individuals presented a non-lethal phenotype of BRAT1-related NEDCAS phenotype. Seventy-six percent of the patients in this group were able to walk and 68% were able to say at least a few words. Most of them had cerebellar ataxia (82%), axial hypotonia (79%) and cerebellar atrophy (100%). Genotype-phenotype correlations in our cohort revealed that biallelic nonsense, frameshift or inframe deletion/insertion variants result in the severe BRAT1-related RMFSL phenotype (46/46; 100%). In contrast, genotypes with at least one missense were more likely associated with NEDCAS (28/34; 82%). The phenotype of patients carrying splice variants was variable: 41% presented with RMFSL (7/17) and 59% with NEDCAS (10/17).

Genetic Testing Guidelines Impact Care in Newborns with Congenital Heart Defects

OBJECTIVE

To evaluate genetic evaluation practices in newborns with the most common birth defect, congenital heart defects (CHD), we determined the prevalence and the yield of genetic evaluation across time and across patient subtypes, before and after implementation of institutional genetic testing guidelines.

STUDY DESIGN

This was a retrospective, cross-sectional study of 664 hospitalized newborns with CHD using multivariate analyses of genetic evaluation practices across time and patient subtypes.

RESULTS

Genetic testing guidelines for hospitalized newborns with CHD were implemented in 2014, and subsequently genetic testing increased (40% in 2013 and 75% in 2018, OR 5.02, 95% CI 2.84-8.88, P < .001) as did medical geneticists' involvement (24% in 2013 and 64% in 2018, P < .001). In 2018, there was an increased use of chromosomal microarray (P < .001), gene panels (P = .016), and exome sequencing (P = .001). The testing yield was high (42%) and consistent across years and patient subtypes analyzed. Increased testing prevalence (P < .001) concomitant with consistent testing yield (P = .139) added an estimated 10 additional genetic diagnoses per year, reflecting a 29% increase.

CONCLUSIONS

In patients with CHD, yield of genetic testing was high. After implementing guidelines, genetic testing increased significantly and shifted to newer sequence-based methods. Increased use of genetic testing identified more patients with clinically important results with potential to impact patient care.

Perspective of artificial intelligence in healthcare data management: A journey towards precision medicine

Mounting evidence has highlighted the implementation of big data handling and management in the healthcare industry to improve the clinical services. Various private and public companies have generated, stored, and analyzed different types of big healthcare data, such as omics data, clinical data, electronic health records, personal health records, and sensing data with the aim to move in the direction of precision medicine. Additionally, with the advancement in technologies, researchers are curious to extract the potential involvement of artificial intelligence and machine learning on big healthcare data to enhance the quality of patient's lives. However, seeking solutions from big healthcare data requires proper management, storage, and analysis, which imposes hinderances associated with big data handling. Herein, we briefly discuss the implication of big data handling and the role of artificial intelligence in precision medicine. Further, we also highlighted the potential of artificial intelligence in integrating and analyzing the big data that offer personalized treatment. In addition, we briefly discuss the applications of artificial intelligence in personalized treatment, especially in neurological diseases. Lastly, we discuss the challenges and limitations imposed by artificial intelligence in big data management and analysis to hinder precision medicine.

Parents' Perspectives on Secondary Genetic Ancestry Findings in Pediatric Genomic Medicine

PURPOSE

With advances in genome sequencing technologies, large-scale genome-wide sequencing has advanced our understanding of disease risk and etiology and contributes to the rapidly expanding genomic health services in pediatric settings. Because it is possible to return ancestry estimates following clinical genomic sequencing, it is important to understand the interest in ancestry results among families who may have the option of receiving these results.

METHODS

We conducted 26 semi-structured qualitative telephone interviews of parents with children/newborns with likely genetic conditions from two studies of clinical genome sequencing. Using a purposive sampling approach, we selected parents from the SouthSeq cohort, Clinical Sequencing Evidence-Generating Research (CSER Phase 2) project active in Alabama, Mississippi, and Louisiana, or an earlier Clinical Sequencing Exploratory Research (CSER Phase 1) initiative based in the same region. Our interviews focused on parental knowledge about, attitudes on, interest in, and preferences for receiving genetic ancestry results following clinical genome sequencing in the neonatal intensive care unit or in pediatric clinics.

FINDINGS

Overall, parents prioritized clinical results or results that would help guide the diagnosis and treatment of their child, but they were also interested in any genetic result, including genetic ancestry, that potentially could enhance the meaning of information on disease risk, prevention and screening guidance, or family planning. While parents thought that ancestry results would help them learn about themselves and their heritage, the had concerns over the privacy, security, and accuracy of genetic ancestry information, although parents indicated that they had greater trust in ancestry findings provided as part of clinical care compared with those offered commercially. Parents also wanted ancestry results to be returned in a timely manner by knowledgeable staff, with kid-friendly materials and online tools available to aid, as needed, in the understanding of their results.

IMPLICATIONS

Taken together, our results highlight that despite being in high-stress situations, such as having a newborn in the neonatal intensive care unit, parents were interested in receiving genetic ancestry results along with their clinically relevant findings.

Hypomyelination caused by a novel homozygous pathogenic variant in FOLR1: complete clinical and radiological recovery with oral folinic acid therapy and review of the literature

BACKGROUND

Neurodegeneration due to cerebral folate transport deficiency is a rare autosomal recessive disorder caused by biallelic pathogenic variants in FOLR1. Onset typically occurs in late infancy and is characterized by psychomotor regression, epilepsy, and a hypomyelinating leukodystrophy on magnetic resonance imaging. If left untreated, progressive neurodegeneration occurs. However, early treatment with folinic acid has been shown to stabilize or reverse neurological features. Approximately thirty patients have been described worldwide. Here, we report the first two cases with genetically proven cerebral folate transport deficiency from South-Eastern Europe, describe the effect of oral folinic acid therapy on clinical and neuroradiological features and review the literature.

RESULTS

Two siblings presented in childhood with clinical and radiological findings consistent with a hypomyelinating leukodystrophy. Exome sequencing revealed a novel homozygous pathogenic variant in FOLR1 (c.465_466delinsTG; p.W156G), confirming the diagnosis of neurodegeneration due to cerebral folate transport deficiency. Folinic acid treatment was promptly initiated in both patients. The younger sibling was treated early in disease course at 2 years of age, and demonstrated complete recovery in clinical and MRI features. The older sibling, who was 8 years of age at the time of diagnosis and treatment, demonstrated partial but substantial improvements.

CONCLUSION

We present the first account in the literature that early treatment initiation with oral folinic acid alone can result in complete neurological recovery of both clinical and radiological abnormalities in neurodegeneration due to cerebral folate deficiency. Moreover, through the report of these patients along with review of the literature, we provide information about the natural history of the disease with comparison of treatment effects at different stages of disease progression. This report also reinforces the importance of universal access to genetic testing to ensure prompt diagnoses for treatable disorders.

The clinical utility of rapid exome sequencing in a consanguineous population

BACKGROUND

The clinical utility of exome sequencing is now well documented. Rapid exome sequencing (RES) is more resource-intensive than regular exome sequencing and is typically employed in specialized clinical settings wherein urgent molecular diagnosis is thought to influence acute management. Studies on the clinical utility of RES have been largely limited to outbred populations.

METHODS

Here, we describe our experience with rapid exome sequencing (RES) in a highly consanguineous population. Clinical settings included intensive care units, prenatal cases approaching the legal cutoff for termination, and urgent transplant decisions.

RESULTS

A positive molecular finding (a pathogenic or likely pathogenic variant that explains the phenotype) was observed in 80 of 189 cases (42%), while 15 (8%) and 94 (50%) received ambiguous (variant of uncertain significance (VUS)) and negative results, respectively. The consanguineous nature of the study population gave us an opportunity to observe highly unusual and severe phenotypic expressions of previously reported genes. Clinical utility was observed in nearly all (79/80) cases with positive molecular findings and included management decisions, prognostication, and reproductive counseling. Reproductive counseling is a particularly important utility in this population where the overwhelming majority (86%) of identified variants are autosomal recessive, which are more actionable in this regard than the de novo variants typically reported by RES elsewhere. Indeed, our cost-effectiveness analysis shows compelling cost savings in the study population.

CONCLUSIONS

This work expands the diversity of environments in which RES has a demonstrable clinical utility.

Diagnostic genomic sequencing in critically ill children

Rare genetic diseases are a major cause of severe illnesses and deaths in new-borns and infants. Disease manifestation in critically ill children may be atypical or incomplete, making a monogenetic disease difficult to diagnose clinically. Rapid exome or genome ("genomic") sequencing in critically ill children demonstrated profound diagnostic and clinical value, and there is growing evidence that the faster a molecular diagnosis is established in such children, the more likely clinical management is influenced positively. An early molecular diagnosis enables treatment of critically ill children with precision medicine, has the potential to improve patient outcome and leads to healthcare cost savings. In this review, we outline the status quo of rapid genomic sequencing and possible future implications.

Whole genome sequencing diagnostic yield for paediatric patients with suspected genetic disorders: systematic review, meta-analysis, and GRADE assessment

BACKGROUND

About 80% of the roughly 7,000 known rare diseases are single gene disorders, about 85% of which are ultra-rare, affecting less than one in one million individuals. NGS technologies, in particular whole genome sequencing (WGS) in paediatric patients suffering from severe disorders of likely genetic origin improve the diagnostic yield allowing targeted, effective care and management. The aim of this study is to perform a systematic review and meta-analysis to assess the effectiveness of WGS, with respect to whole exome sequencing (WES) and/or usual care, for the diagnosis of suspected genetic disorders among the paediatric population.

METHODS

A systematic review of the literature was conducted querying relevant electronic databases, including MEDLINE, EMBASE, ISI Web of Science, and Scopus from January 2010 to June 2022. A random-effect meta-analysis was run to inspect the diagnostic yield of different techniques. A network meta-analysis was also performed to directly assess the comparison between WGS and WES.

RESULTS

Of the 4,927 initially retrieved articles, thirty-nine met the inclusion criteria. Overall results highlighted a significantly higher pooled diagnostic yield for WGS, 38.6% (95% CI: [32.6 - 45.0]), in respect to WES, 37.8% (95% CI: [32.9 - 42.9]) and usual care, 7.8% (95% CI: [4.4 - 13.2]). The meta-regression output suggested a higher diagnostic yield of the WGS compared to WES after controlling for the type of disease (monogenic vs non-monogenic), with a tendency to better diagnostic performances for Mendelian diseases. The network meta-analysis showed a higher diagnostic yield for WGS compared to WES (OR = 1.54, 95%CI: [1.11 - 2.12]).

CONCLUSIONS

Although whole genome sequencing for the paediatric population with suspected genetic disorders provided an accurate and early genetic diagnosis in a high proportion of cases, further research is needed for evaluating costs, effectiveness, and cost-effectiveness of WGS and achieving an informed decision-making process.

TRIAL REGISTRATION

This systematic review has not been registered.

Electrical Nanobiosensors for Nucleic Acid Based Diagnostics

Recent advances in nanotechnologies have promoted the iterative updating of nucleic acid sensors. Among various sensing technologies, the electrical nanobiosensor is regarded as one of the most promising prospects to achieve rapid, precise, and point-of-care nucleic acid based diagnostics. In this Perspective, we introduce recent progresses in electrical nanobiosensors for nucleic acid detection. First, the strategies for improving detection performance are summarized, including chemical amplification and electrical amplification. Then, the detection mechanism of electrical nanobiosensors, such as electrochemical biosensors, field-effect transistors, and photoelectric enhanced biosensors, is illustrated. At the same time, their applications in cancer screening, pathogen detection, gene sequencing, and genetic disease diagnosis are introduced. Finally, challenges and future prospects in clinical application are discussed.

Test development, optimization and validation of a WGS pipeline for genetic disorders

BACKGROUND

With advances in massive parallel sequencing (MPS) technology, whole-genome sequencing (WGS) has gradually evolved into the first-tier diagnostic test for genetic disorders. However, deployment practice and pipeline testing for clinical WGS are lacking.

METHODS

In this study, we introduced a whole WGS pipeline for genetic disorders, which included the entire process from obtaining a sample to clinical reporting. All samples that underwent WGS were constructed using polymerase chain reaction (PCR)-free library preparation protocols and sequenced on the MGISEQ-2000 platform. Bioinformatics pipelines were developed for the simultaneous detection of various types of variants, including single nucleotide variants (SNVs), insertions and deletions (indels), copy number variants (CNVs) and balanced rearrangements, mitochondrial (MT) variants, and other complex variants such as repeat expansion, pseudogenes and absence of heterozygosity (AOH). A semiautomatic pipeline was developed for the interpretation of potential SNVs and CNVs. Forty-five samples (including 14 positive commercially available samples, 23 laboratory-held positive cell lines and 8 clinical cases) with known variants were used to validate the whole pipeline.

RESULTS

In this study, a whole WGS pipeline for genetic disorders was developed and optimized. Forty-five samples with known variants (6 with SNVs and Indels, 3 with MT variants, 5 with aneuploidies, 1 with triploidy, 23 with CNVs, 5 with balanced rearrangements, 2 with repeat expansions, 1 with AOHs, and 1 with exon 7-8 deletion of SMN1 gene) validated the effectiveness of our pipeline.

CONCLUSIONS

This study has been piloted in test development, optimization, and validation of the WGS pipeline for genetic disorders. A set of best practices were recommended using our pipeline, along with a dataset of positive samples for benchmarking.

Clinical and Neurophysiologic Phenotypes in Neonates With BRAT1 Encephalopathy

BACKGROUND AND OBJECTIVES

BRAT1 encephalopathy is an ultra-rare autosomal recessive neonatal encephalopathy. We delineate the neonatal electroclinical phenotype at presentation and provide insights for early diagnosis.

METHODS

Through a multinational collaborative, we studied a cohort of neonates with encephalopathy associated with biallelic pathogenic variants in BRAT1 for whom detailed clinical, neurophysiologic, and neuroimaging information was available from the onset of symptoms. Neuropathologic changes were also analyzed.

RESULTS

We included 19 neonates. Most neonates were born at term (16/19) from nonconsanguineous parents. 15/19 (79%) were admitted soon after birth to a neonatal intensive care unit, exhibiting multifocal myoclonus, both spontaneous and exacerbated by stimulation. 7/19 (37%) had arthrogryposis at birth, and all except 1 progressively developed hypertonia in the first week of life. Multifocal myoclonus, which was present in all but 1 infant, was the most prominent manifestation and did not show any EEG correlate in 16/19 (84%). Video-EEG at onset was unremarkable in 14/19 (74%) infants, and 6 (33%) had initially been misdiagnosed with hyperekplexia. Multifocal seizures were observed at a median age of 14 days (range: 1-29). During the first months of life, all infants developed progressive encephalopathy, acquired microcephaly, prolonged bouts of apnea, and bradycardia, leading to cardiac arrest and death at a median age of 3.5 months (range: 20 days to 30 months). Only 7 infants (37%) received a definite diagnosis before death, at a median age of 34 days (range: 25-126), and almost two-thirds (12/19, 63%) were diagnosed 8 days to 12 years postmortem (median: 6.5 years). Neuropathology examination, performed in 3 patients, revealed severely delayed myelination and diffuse astrogliosis, sparing the upper cortical layers.

DISCUSSION

BRAT1 encephalopathy is a neonatal-onset, rapidly progressive neurologic disorder. Neonates are often misdiagnosed as having hyperekplexia, and many die undiagnosed. The key phenotypic features are multifocal myoclonus, an organized EEG, progressive, persistent, and diffuse hypertonia, and an evolution into refractory multifocal seizures, prolonged bouts of apnea, bradycardia, and early death. Early recognition of BRAT1 encephalopathy allows for prompt workup, appropriate management, and genetic counseling.

An Integrated Pipeline for Trio-Rapid Genome Sequencing in Critically Ill Infants

Trio-rapid genome sequencing (trio-rGS) can assist the genetic diagnosis of critically ill infants given its ability to detect a broad range of pathogenic variants, as well as microbes, simultaneously with high efficiency. To achieve more comprehensive clinical diagnoses, it is essential to propose a recommended protocol in clinical practice. Here, we introduced an integrated pipeline to detect germline variants and microorganisms simultaneously from trio-RGS in critically ill infants, which provides step-by-step criteria for the semi-automatic processing procedures. With this pipeline in clinical application, only 1 ml of peripheral blood is needed for clinicians to provide both genetic and infectious causal information to a patient. The establishment and clinical practice of the method is of great significance for further mining of high-throughput sequencing data and for assisting clinicians in promoting diagnosis efficiency and accuracy. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Experimental pipeline for rapid whole-genome sequencing for the simultaneous detection of germline variants and microorganisms Basic Protocol 2: Computational pipeline for rapid whole-genome sequencing for the simultaneous detection of germline variants and microorganisms.

BRAT1 Mutation Retrospective Diagnosis: A Case Report

Biallelic mutations in the BRAT1 gene have been reported in cases with Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL), since 2012. Clinical features include progressive encephalopathy, dysmorphic features, microcephaly, hypertonia, developmental delay, refractory epilepsy, episodic apnea, and bradycardia. More recently, biallelic BRAT1 mutations have been associated with a milder phenotype in patients with migrating focal seizures in the absence of rigidity or with nonprogressive congenital ataxia with or without epilepsy (NEDCAS). It has been proposed that the loss of function caused by BRAT1 mutations may decrease cell proliferation and migration and cause neuronal atrophy through impairment of mitochondrial homeostasis. We here report a female infant with a phenotype, electroencephalogram (EEG), and brain magnetic resonance imaging (MRI) consistent with RMFSL, whose diagnosis was indirectly formulated three years after death upon the identification in both parents of a known pathogenetic variant in the BRAT1 gene. Our report emphasizes the remarkable potential of novel genetic technologies for the diagnosis of past unsolved clinical cases.

Novel blended SNRPE-related spliceosomopathy phenotype characterized by microcephaly and congenital atrichia

Variants in genes encoding core components of the spliceosomes are associated with craniofacial syndromes, collectively called craniofacial spliceosomopathies. SNRPE encodes a core component of pre-mRNA processing U-rich small nuclear ribonuclear proteins (UsnRNPs). Heterozygous variants in SNRPE have been reported in six families with isolated hypotrichosis simplex in addition to one case of isolated non syndromic congenital microcephaly. Here, we report a patient with a novel blended phenotype of microcephaly and congenital atrichia with multiple congenital anomalies due to a de novo intronic SNRPE deletion, c.82-28_82-16del, which results in exon skipping. As discussed within, this phenotype, which we propose be named SNRPE-related syndromic microcephaly and hypotrichosis, overlaps other craniofacial splicesosomopathies.

The incorporation of next-generation sequencing into pediatric care

Genetic condition is one of the major etiologies causing morbidity and mortality in infants and children. More and more etiologies can be solved using next-generation sequencing (NGS) as it develops. Currently, whole-exome sequencing (WES) and whole-genome sequencing (WGS) have been highly integrated into clinical practice. The average diagnostic yield of WES/WGS in pediatric patients with genetic condition was around 40% (range: 21%-80%), with acceptable turnaround time and cost. The higher diagnostic yield categories are deafness, ophthalmic, neurological, skeletal conditions, and inborn error of metabolism. Positive results provide benefit with those for actionable diseases, next pregnancy planning, and family members. For those in critical condition, with the emergence of sequencing technology and bioinformatics analysis tools, provisional diagnosis can be made as short as 13.5 h using ultrarapid WGS. We believe this powerful tool has changed pediatric daily practice.

Exome/Genome Sequencing in Undiagnosed Syndromes

Exome sequencing (ES) and genome sequencing (GS) have radically transformed the diagnostic approach to undiagnosed rare/ultrarare Mendelian diseases. Next-generation sequencing (NGS), the technology integral for ES, GS, and most large (100+) gene panels, has enabled previously unimaginable diagnoses, changes in medical management, new treatments, and accurate reproductive risk assessments for patients, as well as new disease gene discoveries. Yet, challenges remain, as most individuals remain undiagnosed with current NGS. Improved NGS technology has resulted in long-read sequencing, which may resolve diagnoses in some patients who do not obtain a diagnosis with current short-read ES and GS, but its effectiveness is unclear, and it is expensive. Other challenges that persist include the resolution of variants of uncertain significance, the urgent need for patients with ultrarare disorders to have access to therapeutics, the need for equity in patient access to NGS-based testing, and the study of ethical concerns. However, the outlook for undiagnosed disease resolution is bright, due to continual advancements in the field.

Rapid Whole Genome Sequencing for Diagnosis of Single Locus Genetic Diseases in Critically Ill Children

Upon admission to intensive care units (ICU), the differential diagnosis of almost all infants with diseases of unclear etiology includes single locus genetic diseases. Rapid whole genome sequencing (rWGS), including sample preparation, short-read sequencing-by-synthesis, informatics pipelining, and semiautomated interpretation, can now identify nucleotide and structural variants associated with most genetic diseases with robust analytic and diagnostic performance in as little as 13.5 h. Early diagnosis of genetic diseases transforms medical and surgical management of infants in ICUs, minimizing both the duration of empiric treatment and the delay to start of specific treatment. Both positive and negative rWGS tests have clinical utility and can improve outcomes. Since first described 10 years ago, rWGS has evolved considerably. Here we describe our current methods for routine diagnostic testing for genetic diseases by rWGS in as little as 18 h.

Recurrent FOXP4 nonsense variant in two unrelated patients: Association with neurodevelopmental disease and congenital diaphragmatic hernia

De novo variants in FOXP4 were recently associated with a neurodevelopmental disorder characterized by speech and language delay, growth abnormalities, hypotonia, and variable congenital abnormalities, including congenital diaphragmatic hernia, cervical spine abnormalities, strabismus, cryptorchidism, and ptosis. The variant spectrum in this small cohort was limited to de novo missense except for one frameshift, the inheritance of which was unknown. Variants tested in vitro exhibited reduced repressor transcriptional activity, indicating loss of function is the likely mechanism of disease, but only one frameshift variant was reported. Here, we report four affected individuals from two unrelated families heterozygous for a nonsense variant, c.1893C > G, p.Tyr631*, in FOXP4. The phenotype of the affected children includes developmental delay, feeding difficulties in infancy, and similar facial features. In both cases, the variant was inherited from a parent with mild or even subclinical features. Interestingly, one patient presented with congenital diaphragmatic hernia, as reported in two other FOXP4 patients. This report implicates FOXP4 truncating variants in human disease and highlights the wide phenotypic spectrum and variable expressivity.

Accuracy benchmark of the GeneMind GenoLab M sequencing platform for WGS and WES analysis

Background

GenoLab M is a recently developed next-generation sequencing (NGS) platform from GeneMind Biosciences. To establish the performance of GenoLab M, we present the first report to benchmark and compare the WGS and WES sequencing data of the GenoLab M sequencer to NovaSeq 6000 and NextSeq 550 platform in various types of analysis. For WGS, thirty-fold sequencing from Illumina NovaSeq platform and processed by GATK pipeline is currently considered as the golden standard. Thus this dataset is generated as a benchmark reference in this study.

Results

GenoLab M showed an average of 94.62% of Q20 percentage for base quality, while the NovaSeq was slightly higher at 96.97%. However, GenoLab M outperformed NovaSeq or NextSeq at a duplication rate, suggesting more usable data after deduplication. For WGS short variant calling, GenoLab M showed significant accuracy improvement over the same depth dataset from NovaSeq, and reached similar accuracy to NovaSeq 33X dataset with 22x depth. For 100X WES, the F-score and Precision in GenoLab M were higher than NovaSeq or NextSeq, especially for InDel calling.

Conclusions

GenoLab M is a promising NGS platform for high-performance WGS and WES applications. For WGS, 22X depth in the GenoLab M sequencing platform offers a cost-effective alternative to the current mainstream 33X depth on Illumina.

First Successful Application of Preimplantation Genetic Diagnosis for Lethal Neonatal Rigidity and Multifocal Seizure Syndrome in Korea: A Case Report

Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL) is a severe autosomal recessive epileptic encephalopathy characterized by rigidity, intractable multifocal seizures, microcephaly, apnea, and bradycardia immediately after birth. RMFSL is related to a mutation in breast cancer 1-associated ataxia telangiectasia mutated activation-1 protein (BRAT1). We report a case of a female infant born to non-consanguineous Korean parents who developed hypertonia, dysmorphic features, progressive encephalopathy with refractory seizures at birth, and worsening intermittent apnea, leading to intubation and death at 137 days of age. The initial repeated electroencephalographic findings were normal; however, a pattern of focal seizures emerged at 35 days of life. Rapid trio whole-exome sequencing revealed heterozygous mutations c.1313_1314delAG p.(Gln438Argfs*51) and c.1276C>T p. (Gln426*) in BRAT1. After genetic counseling for pregnancy planning, a preimplantation genetic diagnosis for targeted BRAT1 mutations was successfully performed, and a healthy baby was born. To our knowledge, this is the first reported case of a Korean patient with compound heterozygous mutations in BRAT1. An early and accurate genetic diagnosis can help provide timely treatment to patients and indicate the need for reproductive counseling for parents for family planning.

Compound heterozygous loss-of-function variants in BRAT1 cause lethal neonatal rigidity and multifocal seizure syndrome

BACKGROUND

Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL, OMIM 614498) is a rare autosomal recessive disease characterized by the onset of rigidity and intractable seizures at or soon after birth. The BRAT1 has been identified to be the disease-causing gene for RMFSL. This study aimed to determine the underlying pathogenic mutations of a Chinese family with RMFSL and to confirm the effect of the splice-site mutation by reverse transcription analysis.

METHODS

Detailed family history and clinical data were recorded, and peripheral blood samples were collected from all available family members. Whole exome sequencing (WES), Sanger sequencing, and bioinformatics analysis were performed to investigate the causative variants. The impact of the intronic variant on splicing was subsequently analyzed by RT-PCR analysis.

RESULTS

We identified two compound heterozygous variants in the BRAT1, c.431-2A>G in intron 3 and c.1359_1361del(p.Leu454del) in exon 9 in the proband, one inherited from each parent. Furthermore, the 3'-splice site acceptor (c.431-2A>G) variant was found to activate a cryptic acceptor splice site, which resulted in the loss of 29 nucleotides and generation of a premature stop codon at code 180, producing a truncated BRAT1 (c.432_460del; p.Ala145Argfs*36).

CONCLUSIONS

This research identified two mutations in the BRAT1 of one Chinese family with RMFSL. These data can aid in developing clinical diagnoses as well as providing genetic counseling and prenatal interventions to the family. These findings also expand our knowledge of the spectrum of BRAT1 pathogenic variants in RMFSL syndrome.