Australian public perspectives on genomic newborn screening: which conditions should be included?

BACKGROUND: Implementing genomic sequencing into newborn screening programs allows for significant expansion in the number and scope of conditions detected. We sought to explore public preferences and perspectives on which conditions to include in genomic newborn screening (gNBS). METHODS: We recruited English-speaking members of the Australian public over 18 years of age, using social media, and invited them to participate in online focus groups. RESULTS: Seventy-five members of the public aged 23-72 participated in one of fifteen focus groups. Participants agreed that if prioritisation of conditions was necessary, childhood-onset conditions were more important to include than later-onset conditions. Despite the purpose of the focus groups being to elicit public preferences, participants wanted to defer to others, such as health professionals or those with a lived experience of each condition, to make decisions about which conditions to include. Many participants saw benefit in including conditions with no available treatment. Participants agreed that gNBS should be fully publicly funded. CONCLUSION: How many and which conditions are included in a gNBS program will be a complex decision requiring detailed assessment of benefits and costs alongside public and professional engagement. Our study provides support for implementing gNBS for treatable childhood-onset conditions.

Scaling national and international improvement in virtual gene panel curation via a collaborative approach to discordance resolution.

Clinical validity assessments of gene-disease associations underpin analysis and reporting in diagnostic genomics, and yet wide variability exists in practice, particularly in use of these assessments for virtual gene panel design and maintenance. Harmonization efforts are hampered by the lack of agreed terminology, agreed gene curation standards, and platforms that can be used to identify and resolve discrepancies at scale. We undertook a systematic comparison of the content of 80 virtual gene panels used in two healthcare systems by multiple diagnostic providers in the United Kingdom and Australia. The process was enabled by a shared curation platform, PanelApp, and resulted in the identification and review of 2,144 discordant gene ratings, demonstrating the utility of sharing structured gene-disease validity assessments and collaborative discordance resolution in establishing national and international consensus.

Gene selection for genomic newborn screening: Moving toward consensus?

PURPOSE: Gene selection for genomic newborn screening (gNBS) underpins the validity, acceptability, and ethical application of this technology. Existing gNBS gene lists are highly variable despite being based on shared principles of gene-disease validity, treatability, and age of onset. This study aimed to curate a gNBS gene list that builds upon existing efforts and provide a core consensus list of gene-disease pairs assessed by multiple expert groups worldwide. METHODS: Our multidisciplinary expert team curated a gene list using an open platform and multiple existing curated resources. We included severe treatable disorders with age of disease onset <5 years with established gene-disease associations and reliable variant detection. We compared the final list with published lists from 5 other gNBS projects to determine consensus genes and to identify areas of discrepancy. RESULTS: We reviewed 1279 genes and 604 met our inclusion criteria. Metabolic conditions comprised the largest group (25%), followed by immunodeficiencies (21%) and endocrine disorders (15%). We identified 55 consensus genes included by all 6 gNBS research projects. Common reasons for discrepancy included variable definitions of treatability and strength of gene-disease association. CONCLUSION: We have identified a consensus gene list for gNBS that can be used as a basis for systematic harmonization efforts internationally.

Genetic aetiologies for childhood speech disorder: novel pathways co-expressed during brain development.

Childhood apraxia of speech (CAS), the prototypic severe childhood speech disorder, is characterized by motor programming and planning deficits. Genetic factors make substantive contributions to CAS aetiology, with a monogenic pathogenic variant identified in a third of cases, implicating around 20 single genes to date. Here we aimed to identify molecular causation in 70 unrelated probands ascertained with CAS. We performed trio genome sequencing. Our bioinformatic analysis examined single nucleotide, indel, copy number, structural and short tandem repeat variants. We prioritised appropriate variants arising de novo or inherited that were expected to be damaging based on in silico predictions. We identified high confidence variants in 18/70 (26%) probands, almost doubling the current number of candidate genes for CAS. Three of the 18 variants affected SETBP1, SETD1A and DDX3X, thus confirming their roles in CAS, while the remaining 15 occurred in genes not previously associated with this disorder. Fifteen variants arose de novo and three were inherited. We provide further novel insights into the biology of child speech disorder, highlighting the roles of chromatin organization and gene regulation in CAS, and confirm that genes involved in CAS are co-expressed during brain development. Our findings confirm a diagnostic yield comparable to, or even higher, than other neurodevelopmental disorders with substantial de novo variant burden. Data also support the increasingly recognised overlaps between genes conferring risk for a range of neurodevelopmental disorders. Understanding the aetiological basis of CAS is critical to end the diagnostic odyssey and ensure affected individuals are poised for precision medicine trials.

De novo PHF5A variants are associated with craniofacial abnormalities, developmental delay, and hypospadias.

PURPOSE: The SF3B splicing complex is composed of SF3B1-6 and PHF5A. We report a developmental disorder caused by de novo variants in PHF5A. METHODS: Clinical, genomic, and functional studies using subject-derived fibroblasts and a heterologous cellular system were performed. RESULTS: We studied 9 subjects with congenital malformations, including preauricular tags and hypospadias, growth abnormalities, and developmental delay who had de novo heterozygous PHF5A variants, including 4 loss-of-function (LOF), 3 missense, 1 splice, and 1 start-loss variant. In subject-derived fibroblasts with PHF5A LOF variants, wild-type and variant PHF5A mRNAs had a 1:1 ratio, and PHF5A mRNA levels were normal. Transcriptome sequencing revealed alternative promoter use and downregulated genes involved in cell-cycle regulation. Subject and control fibroblasts had similar amounts of PHF5A with the predicted wild-type molecular weight and of SF3B1-3 and SF3B6. SF3B complex formation was unaffected in 2 subject cell lines. CONCLUSION: Our data suggest the existence of feedback mechanisms in fibroblasts with PHF5A LOF variants to maintain normal levels of SF3B components. These compensatory mechanisms in subject fibroblasts with PHF5A or SF3B4 LOF variants suggest disturbed autoregulation of mutated splicing factor genes in specific cell types, that is, neural crest cells, during embryonic development rather than haploinsufficiency as pathomechanism.

Feasibility of Targeted Next-Generation DNA Sequencing for Expanding Population Newborn Screening.

BACKGROUND: Newborn screening (NBS) is an effective public health intervention that reduces death and disability from treatable genetic diseases, but many conditions are not screened due to a lack of a suitable assay. Whole genome and whole exome sequencing can potentially expand NBS but there remain many technical challenges preventing their use in population NBS. We investigated if targeted gene sequencing (TGS) is a feasible methodology for expanding NBS. METHODS: We constructed a TGS panel of 164 genes which screens for a broad range of inherited conditions. We designed a high-volume, low-turnaround laboratory and bioinformatics workflow that avoids the technical and data interpretation challenges associated with whole genome and whole exome sequencing. A methods-based analytical validation of the assay was completed and test performance in 2552 newborns examined. We calculated annual birth estimates for each condition to assess cost-effectiveness. RESULTS: Assay analytical sensitivity was >99% and specificity was 100%. Of the newborns screened, 1.3% tested positive for a condition. On average, each individual had 225 variants to interpret and 1.8% were variants of uncertain significance (VUS). The turnaround time was 7 to 10 days. Maximum batch size was 1536 samples. CONCLUSIONS: We demonstrate that a TGS assay could be incorporated into an NBS program soon to increase the number of conditions screened. Additionally, we conclude that NBS using TGS may be cost-effective.

An incidental finding in prenatal exome sequencing-A case study and review of the clinical and ethical considerations.

The introduction of genomic testing into prenatal care has come at a rapid pace and has been met with significant clinical and ethical challenges, specifically when dealing with incidental findings. We present the case of a couple in their first pregnancy who were referred to our institution with isolated fetal cataracts on morphology scan. After an unremarkable infectious disease workup and microarray on an amniocentesis sample, the couple opted for fetal whole-exome sequencing to investigate the cataracts further. This investigation did not find any cause for the cataracts but yielded an incidental finding of a de novo pathogenic variant in the SCN1A gene unrelated to the cataracts. Pathogenic variants in the SCN1A gene are strongly associated with severe myoclonic epilepsy of infancy, or Dravet syndrome. After extensive genetic counseling, the couple decided to terminate the pregnancy at 28 weeks' gestation based on this finding. This case highlights some of the important clinical and ethical considerations in prenatal genetic diagnosis, particularly in the group of patients in which there is no phenotypic evidence in-utero of the incidental finding. The case demonstrates the value of frameworks and guidelines to guide management decisions for both clinicians and patients.

Prenatal diagnosis of cleft lip and/or palate: What do we tell prospective parents?

Cleft lip and/or palate (CL/CP) is the most common congenital craniofacial anomaly and parents often ask, "how did this happen?" Patients and families may benefit from access to a multidisciplinary team (MDT) from prenatal diagnosis into early adulthood. Multiple factors can contribute to the development of a cleft. We discuss the epidemiology and risk factors that increase the likelihood of having a newborn with a cleft. The purpose of this article is to review the prenatal investigations involved in the diagnosis and workup of these patients in addition to postpartum treatment, prognostic factors, and counseling families regarding future recurrence risk.

Lessons learnt from multifaceted diagnostic approaches to the first 150 families in Victoria's Undiagnosed Diseases Program.

BACKGROUND: Clinical exome sequencing typically achieves diagnostic yields of 30%-57.5% in individuals with monogenic rare diseases. Undiagnosed diseases programmes implement strategies to improve diagnostic outcomes for these individuals. AIM: We share the lessons learnt from the first 3 years of the Undiagnosed Diseases Program-Victoria, an Australian programme embedded within a clinical genetics service in the state of Victoria with a focus on paediatric rare diseases. METHODS: We enrolled families who remained without a diagnosis after clinical genomic (panel, exome or genome) sequencing between 2016 and 2018. We used family-based exome sequencing (family ES), family-based genome sequencing (family GS), RNA sequencing (RNA-seq) and high-resolution chromosomal microarray (CMA) with research-based analysis. RESULTS: In 150 families, we achieved a diagnosis or strong candidate in 64 (42.7%) (37 in known genes with a consistent phenotype, 3 in known genes with a novel phenotype and 24 in novel disease genes). Fifty-four diagnoses or strong candidates were made by family ES, six by family GS with RNA-seq, two by high-resolution CMA and two by data reanalysis. CONCLUSION: We share our lessons learnt from the programme. Flexible implementation of multiple strategies allowed for scalability and response to the availability of new technologies. Broad implementation of family ES with research-based analysis showed promising yields post a negative clinical singleton ES. RNA-seq offered multiple benefits in family ES-negative populations. International data sharing strategies were critical in facilitating collaborations to establish novel disease-gene associations. Finally, the integrated approach of a multiskilled, multidisciplinary team was fundamental to having diverse perspectives and strategic decision-making.

Standardized practices for RNA diagnostics using clinically accessible specimens reclassifies 75% of putative splicing variants.

PURPOSE: Genetic variants causing aberrant premessenger RNA splicing are increasingly being recognized as causal variants in genetic disorders. In this study, we devise standardized practices for polymerase chain reaction (PCR)-based RNA diagnostics using clinically accessible specimens (blood, fibroblasts, urothelia, biopsy). METHODS: A total of 74 families with diverse monogenic conditions (31% prenatal-congenital onset, 47% early childhood, and 22% teenage-adult onset) were triaged into PCR-based RNA testing, with comparative RNA sequencing for 19 cases. RESULTS: Informative RNA assay data were obtained for 96% of cases, enabling variant reclassification for 75% variants that can be used for genetic counseling (71%), to inform clinical care (32%) and prenatal counseling (41%). Variant-associated mis-splicing was highly reproducible for 28 cases with samples from ≥2 affected individuals or heterozygotes and 10 cases with ≥2 biospecimens. PCR amplicons encompassing another segregated heterozygous variant was vital for clinical interpretation of 22 of 79 variants to phase RNA splicing events and discern complete from partial mis-splicing. CONCLUSION: RNA diagnostics enabled provision of a genetic diagnosis for 64% of recruited cases. PCR-based RNA diagnostics has capacity to analyze 81.3% of clinically significant genes, with long amplicons providing an advantage over RNA sequencing to phase RNA splicing events. The Australasian Consortium for RNA Diagnostics (SpliceACORD) provide clinically-endorsed, standardized protocols and recommendations for interpreting RNA assay data.

Etiology, Comorbidities, and Health Service Use in a Clinical Cohort of Children With Hearing Loss.

OBJECTIVE: To examine etiology, comorbidities, and health service use in a cohort of children with permanent hearing loss. Receiving an etiological diagnosis can inform reproductive planning, rehabilitation outcomes, predict additional disabilities, and direct intervention or management decisions. DESIGN: Retrospective audit of 518 deaf/hard-of-hearing children attending a tertiary pediatric outpatient clinic (2016-2019) using descriptive statistics. We used linear regression to investigate the relationship between degree of hearing loss, comorbidities, and health service use. RESULTS: Of the 518 children who attended the clinic, 481 (92.9%) proceeded with testing for etiology. Most children (399/518, 77.0%) were diagnosed with hearing loss by 3 mo of age. Of the children tested, the cause of hearing loss was confirmed in 234/481 (48.6%), suspected in 113/481 (23.5%), and unknown in 134/481 (27.9%); 17/341 (5.0%) had congenital cytomegalovirus (CMV), 17/320 (5.3%) had enlarged vestibular aqueducts, 67/213 (31.5%) of children with bilateral hearing loss had connexin mutation, and 25/72 (34.7%) of children with unilateral loss had hypoplastic/absent cochlear nerve on imaging. The odds of having a definitive/suspected diagnosis were twice as likely for indivduals with profound hearing loss than mild hearing loss (OR 2.1; 95% CI, 1.2-3.9; P = 0.02). The majority (348/518, 67.2%) of children had medical comorbidities, and most children attended otolaryngology (453/518, 87.5%), early intervention (358/518, 69.1%), and genetic (287/518, 55.4%) services. CONCLUSIONS: Children with hearing loss have diverse etiologies, most have comorbidities, and attend multiple services. Most families elected to proceed with diagnostic testing for etiology. Current guidelines and expanded access to genetic testing identified a confirmed/suspected etiological diagnosis in 72.1% of children tested. The number of comorbidities correlated with service use, regardless of hearing loss severity.

Personal utility of genomic sequencing for infants with congenital deafness.

Decisions about genetic testing have traditionally been based on clinical utility and cost, but personal utility is increasingly recognized when assessing the value of testing. Whole exome sequencing (WES) was offered to a population cohort of 106 infants diagnosed with congenital hearing loss. Parents could choose to receive results relating to hearing loss only or also learn additional information about childhood-onset conditions (medically nonactionable and/or actionable). This study aimed to quantify the personal utility of WES for parents after a diagnosis of hearing loss in their child. Parents completed surveys pretest (63/106), after hearing loss results (52/106) and after receiving additional information (47/72). Open-ended responses from all three surveys (N = 67) were analyzed using inductive content analysis. Answers to questions regarding the value of sequencing to parents were analyzed and collated. Parents placed high value on diagnostic WES for hearing loss but had different perspectives on the personal utility of additional information. Diagnostic results provided certainty while the choice to learn additional information about childhood-onset disorders was associated with empowerment. WES also represented an opportunity to promote their child's best interests. Results provide insights into the utility of WES for the indication of congenital deafness and for genomic newborn screening broadly.

Exome sequencing in newborns with congenital deafness as a model for genomic newborn screening: the Baby Beyond Hearing project.

PURPOSE: Genomic newborn screening raises practical and ethical issues. Evidence is required to build a framework to introduce this technology safely and effectively. We investigated the choices made by a diverse group of parents with newborns when offered tiered genomic information from exome sequencing. METHODS: This population-derived cohort comprised infants with congenital deafness. Parents were offered exome sequencing and choice regarding the scope of analysis. Options were choice A, diagnostic analysis only; choice B, diagnostic analysis plus childhood-onset diseases with medical actionability; or choice C, diagnostic analysis plus childhood-onset diseases with or without medical actionability. RESULTS: Of the 106 participants, 72 (68%) consented to receive additional findings with 29 (27.4%) selecting choice B and 43 (40.6%) opting for choice C. Family size, ethnicity, and age of infant at time of recruitment were the significant predictors of choice. Parents who opted to have additional findings analysis demonstrated less anxiety and decisional conflict. CONCLUSIONS: These data provide evidence from a culturally diverse population that choice around additional findings is important and the age of the infant when this choice is offered impacts on their decision. We found no evidence that offering different levels of genomic information to parents of newborns has a negative psychological impact.

A cost-effectiveness analysis of genomic sequencing in a prospective versus historical cohort of complex pediatric patients.

PURPOSE: Cost-effectiveness evaluations of first-line genomic sequencing (GS) in the diagnosis of children with genetic conditions are limited by the lack of well-defined comparative cohorts. We sought to evaluate the cost-effectiveness of early GS in pediatric patients with complex monogenic conditions compared with a matched historical cohort. METHODS: Data, including investigation costs, were collected in a prospective cohort of 92 pediatric patients undergoing singleton GS over an 18-month period (2016-2017) with two of the following: a condition with high mortality, multisystem disease involving three or more organs, or severe limitation of daily function. Comparative data were collected in a matched historical cohort who underwent traditional investigations in the years 2012-2013. RESULTS: GS yielded a diagnosis in 42% while traditional investigations yielded a diagnosis in 23% (p = 0.003). A change in management was experienced by 74% of patients diagnosed following GS, compared with 32% diagnosed following traditional investigations. Singleton GS at a cost of AU$3100 resulted in a mean saving per person of AU$3602 (95% confidence interval [CI] AU$2520-4685). Cost savings occurred across all investigation subtypes and were only minimally offset by clinical management costs. CONCLUSION: GS in complex pediatric patients saves significant costs and doubles the diagnostic yield of traditional approaches.

A novel approach to offering additional genomic findings-A protocol to test a two-step approach in the healthcare system.

Internationally, the practice of offering additional findings (AFs) when undertaking a clinically indicated genomic test differs. In the USA, the recommendation is to include analysis for AFs alongside diagnostic analysis, unless a patient opts-out, whereas European and Canadian guidelines recommend opt-in models. These guidelines all consider the offer of AFs as an activity concurrent with the offer of diagnostic testing. This paper describes a novel two-step model for managing AFs within the healthcare system in Victoria, Australia and presents the study protocol for its evaluation. Adults who have received results of diagnostic whole exome sequencing undertaken within the healthcare system are invited to attend a genetic counseling appointment to consider reanalysis of their stored genomic data for AFs. The evaluation protocol addresses uptake, decision-making, understanding, counseling challenges, and explores preferences for future models of care. Recruitment commenced in November 2017 and will cease when 200 participants have been approached. When the study is concluded, the evaluation results will contribute to the evidence base guiding approaches to counseling and models of care for AFs.

Advances in genomic testing.

BACKGROUND: Advances in genomic technology and our understanding of Mendelian disease-causing genes have led to an increased use of genomic testing in clinical practice. OBJECTIVE: The aim of this paper is to outline recent advances in genetic and genomic testing and the implications for clinical practice. DISCUSSION: Next-generation genomic sequencing is improving the diagnostic yield for patients with suspected genetic disease. A molecular diagnosis for a patient with genetic disease can provide information regarding a patient's prognosis, management and reproductive risk, and identify molecular targets for treatment. However, genomic testing frequently identifies variants of uncertain significance. This is illustrated by two case examples.

A prospective evaluation of whole-exome sequencing as a first-tier molecular test in infants with suspected monogenic disorders.

PURPOSE: To prospectively evaluate the diagnostic and clinical utility of singleton whole-exome sequencing (WES) as a first-tier test in infants with suspected monogenic disease. METHODS: Singleton WES was performed as a first-tier sequencing test in infants recruited from a single pediatric tertiary center. This occurred in parallel with standard investigations, including single- or multigene panel sequencing when clinically indicated. The diagnosis rate, clinical utility, and impact on management of singleton WES were evaluated. RESULTS: Of 80 enrolled infants, 46 received a molecular genetic diagnosis through singleton WES (57.5%) compared with 11 (13.75%) who underwent standard investigations in the same patient group. Clinical management changed following exome diagnosis in 15 of 46 diagnosed participants (32.6%). Twelve relatives received a genetic diagnosis following cascade testing, and 28 couples were identified as being at high risk of recurrence in future pregnancies. CONCLUSIONS: This prospective study provides strong evidence for increased diagnostic and clinical utility of singleton WES as a first-tier sequencing test for infants with a suspected monogenic disorder. Singleton WES outperformed standard care in terms of diagnosis rate and the benefits of a diagnosis, namely, impact on management of the child and clarification of reproductive risks for the extended family in a timely manner.Genet Med 18 11, 1090-1096.

Congenital chylothorax: associations and neonatal outcomes.

AIM: Congenital chylothorax is a rare but significant neonatal entity with major morbidity and mortality. The study aims to describe the related associations, management and outcomes of this condition in neonates. METHODS: This is a retrospective case series of all cases of congenital chylothorax admitted to a tertiary neonatal centre in the last 15 years. RESULTS: Ten cases of congenital chylothorax were identified. Eight infants were diagnosed antenatally and three infants had antenatal pleural drainage. Most infants were ventilated at birth and required immediate pleurocentesis. Post-natal management included drainage of fluid, ventilation, albumin replacement, octreotide and dietary modification with medium-chain triglyceride-enriched formula. Five infants had chromosomal aberrations identified, while a further two had dysmorphic features not substantiated with routine genetic testing. Noonan's syndrome was the single most common underlying genetic diagnosis. Associated anomalies and malformations were present in 80% of the cohort. There were two deaths in the series, both in infants with multiple co-morbidities. CONCLUSIONS: Congenital chylothorax is a rare condition with overall prevalence of less than a case per year in our experience. Majority of infants had associated chromosomal anomalies and significant co-morbidities needing prolonged intensive care.