To systematically investigate the longer-term clinical and health economic impacts of genomic sequencing for rare-disease diagnoses.
We collected information on continuing diagnostic investigation, ...changes in management, cascade testing, and parental reproductive outcomes in 80 infants who underwent singleton whole-exome sequencing (WES).
The median duration of follow-up following result disclosure was 473 days. Changes in clinical management due to diagnostic WES results led to a cost saving of AU$1,578 per quality-adjusted life year gained, without increased hospital service use. Uninformative WES results contributed to the diagnosis of non-Mendelian conditions in seven infants. Further usual diagnostic investigations in those with ongoing suspicion of a genetic condition yielded no new diagnoses, while WES data reanalysis yielded four. Reanalysis at 18 months was more cost-effective than every 6 months. The parents of diagnosed children had eight more ongoing pregnancies than those without a diagnosis. Taking the costs and benefits of cascade testing and reproductive service use into account, there was an additional cost of AU$8,118 per quality-adjusted life year gained due to genomic sequencing.
These data strengthen the case for the early use of genomic testing in the diagnostic trajectory, and can guide laboratory policy on periodic WES data reanalysis.
ClinGen provides gene-specific guidance for interpretation of sequence variants in MYH7. We assessed laboratory and clinical impact of reclassification by the American College of Medical Genetics and ...Genomics-Association for Molecular Pathology (ACMG-AMP) and ClinGen recommendations in 43 MYH7 variants reported by a diagnostic laboratory between 2013 and 2017.
Fifty-two proband reports containing MYH7 variants were reinterpreted by original ACMG-AMP and ClinGen guidelines. Evidence items were compared across schemes and reasons for classification differences recorded. Laboratory impact was assessed by number of recommended report reissues, and reclassifications coded as clinically “actionable” or “equivalent.” Available pedigrees were reviewed to describe projected cascade impact.
ClinGen produced a higher proportion of diagnostic classifications (65% of variants) compared with ACMG-AMP (54%) and fewer variants of uncertain significance (30% versus 42%). ClinGen classification resulted in actionable changes in 18% of variants with equal upgrades and downgrades from original report. ClinGen’s revisions to PM1 and PS4 contributed to classification differences in 21% and 19% of variants respectively. Each classification change per proband report impacted, on average, 3.1 cascade reports with a further 6.3 first- and second-degree relatives potentially available for genotyping per family.
ClinGen’s gene-specific criteria provide expert-informed guidance for interpretation of MYH7 sequence variants. Periodic re-evaluation improves diagnostic confidence and should be considered by clinical and laboratory teams.
Tumour heterogeneity in primary prostate cancer is a well-established phenomenon. However, how the subclonal diversity of tumours changes during metastasis and progression to lethality is poorly ...understood. Here we reveal the precise direction of metastatic spread across four lethal prostate cancer patients using whole-genome and ultra-deep targeted sequencing of longitudinally collected primary and metastatic tumours. We find one case of metastatic spread to the surgical bed causing local recurrence, and another case of cross-metastatic site seeding combining with dynamic remoulding of subclonal mixtures in response to therapy. By ultra-deep sequencing end-stage blood, we detect both metastatic and primary tumour clones, even years after removal of the prostate. Analysis of mutations associated with metastasis reveals an enrichment of TP53 mutations, and additional sequencing of metastases from 19 patients demonstrates that acquisition of TP53 mutations is linked with the expansion of subclones with metastatic potential which we can detect in the blood.
To determine the diagnostic yield and clinical impact of exome sequencing (ES) in patients with suspected monogenic kidney disease.
We performed clinically accredited singleton ES in a prospectively ...ascertained cohort of 204 patients assessed in multidisciplinary renal genetics clinics at four tertiary hospitals in Melbourne, Australia.
ES identified a molecular diagnosis in 80 (39%) patients, encompassing 35 distinct genetic disorders. Younger age at presentation was independently associated with an ES diagnosis (p < 0.001). Of those diagnosed, 31/80 (39%) had a change in their clinical diagnosis. ES diagnosis was considered to have contributed to management in 47/80 (59%), including negating the need for diagnostic renal biopsy in 10/80 (13%), changing surveillance in 35/80 (44%), and changing the treatment plan in 16/80 (20%). In cases with no change to management in the proband, the ES result had implications for the management of family members in 26/33 (79%). Cascade testing was subsequently offered to 40/80 families (50%).
In this pragmatic pediatric and adult cohort with suspected monogenic kidney disease, ES had high diagnostic and clinical utility. Our findings, including predictors of positive diagnosis, can be used to guide clinical practice and health service design.
Congenital hearing impairment (HI) is the most common sensory impairment and can be isolated or part of a syndrome. Diagnosis through newborn hearing screening and management through early ...intervention, hearing aids and cochlear implantation is well established in the Australian setting; however understanding the genetic basis of congenital HI has been missing. This population-derived cohort comprised infants with moderate-profound bilateral HI born in the 2016-2017 calendar years, detected through newborn hearing screening. Participants were recruited through an integrated paediatric, otolaryngology and genetics HI clinic and offered whole exome sequencing (WES) on a HiSeq4000 or NextSeq500 (Illumina) platform with a targeted average sequencing depth of 100x and chromosome microarray on the Illumina Infinium core exome-24v1.2 platform. Of those approached, 68% (106/156) consented to participate. The rate of genetic diagnosis was 56% (59/106), significantly higher than standard of care (GJB2/6 sequencing only), 21% (22/106). There were clinical implications for the 106 participants: 36% required no further screening, 9% had tailored screening initiated, 2% were offered treatment and 4% had informed care for a complex neurodevelopmental syndrome. WES in this cohort demonstrates the range of diagnoses associated with congenital HI and confirms the genetic heterogeneity of congenital HI. The high diagnostic yield and clinical implications emphasises the need for genomic sequencing to become standard of care.
Emerging evidence suggests that poor glycemic control mediates post-translational modifications to the H3 histone tail. We are only beginning to understand the dynamic role of some of the diverse ...epigenetic changes mediated by hyperglycemia at single loci, yet elevated glucose levels are thought to regulate genome-wide changes, and this still remains poorly understood. In this article we describe genome-wide histone H3K9/K14 hyperacetylation and DNA methylation maps conferred by hyperglycemia in primary human vascular cells. Chromatin immunoprecipitation (ChIP) as well as CpG methylation (CpG) assays, followed by massive parallel sequencing (ChIP-seq and CpG-seq) identified unique hyperacetylation and CpG methylation signatures with proximal and distal patterns of regionalization associative with gene expression. Ingenuity knowledge-based pathway and gene ontology analyses indicate that hyperglycemia significantly affects human vascular chromatin with the transcriptional up-regulation of genes involved in metabolic and cardiovascular disease. We have generated the first installment of a reference collection of hyperglycemia-induced chromatin modifications using robust and reproducible platforms that allow parallel sequencing-by-synthesis of immunopurified content. We uncover that hyperglycemia-mediated induction of genes and pathways associated with endothelial dysfunction occur through modulation of acetylated H3K9/K14 inversely correlated with methyl-CpG content.
We investigated the attitudes of intensive care physicians and genetics professionals towards rapid genomic testing in neonatal and paediatric intensive care units (NICU/PICU). A mixed-methods study ...(surveys and interviews) was conducted at 13 Australian hospitals and three laboratories involved in multi-center implementation of rapid genomic testing. We investigated experience and confidence with genomic tests among intensivists; perceived usefulness of genomic diagnostic results; preferences for service delivery models; and implementation readiness among genetic services. The overall survey response rate was 59%, 47% for intensivists (80/170), and 75% (91/121) for genetics professionals. Intensivists reported moderate confidence with microarray tests and lower confidence with genomic tests. The majority of intensivists (77%), clinical geneticists (87%) and genetic counsellors (82%) favoured a clinical genetics-led service delivery model of genomic testing. Perceived clinical utility of genomic results was lower in the intensivist group compared to the genetics professionals group (20 v 50%, p < 0.001). Interviews (n = 6 intensivists; n = 11 genetic counselors) demonstrated support for implementation, with concerns relating to implementation environment and organizational readiness. Overall, our findings support initial implementation of genomic testing in NICU/PICU as part of an interdisciplinary service delivery model that promotes gradual adoption of genomics by the intensive care workforce while ensuring safety, sustainability, and efficiency.
To explore parental experiences of ultrarapid genomic testing for their critically unwell infants and children.
Parents of critically unwell children who participated in a national ultrarapid genomic ...diagnosis program were surveyed >12 weeks after genomic results return. Surveys consisted of custom questions and validated scales, including the Decision Regret Scale and Genomics Outcome Scale.
With 96 survey invitations sent, the response rate was 57% (n = 55). Most parents reported receiving enough information during pretest (n = 50, 94%) and post-test (n = 44, 83%) counseling. Perceptions varied regarding benefits of testing, however most parents reported no or mild decision regret (n = 45, 82%). The majority of parents (31/52, 60%) were extremely concerned about the condition recurring in future children, regardless of actual or perceived recurrence risk. Parents whose child received a diagnostic result reported higher empowerment.
This study provides valuable insight into parental experiences of ultrarapid genomic testing in critically unwell children, including decision regret, empowerment, and post-test reproductive planning, to inform design and delivery of rapid diagnosis programs. The findings suggest considerations for pre- and post-test counseling that may influence parental experiences during the testing process and beyond, such as the importance of realistically conveying the likelihood for clinical and/or personal utility.
Intellectual disability (ID) and autism spectrum disorder (ASD) are the most common neurodevelopmental disorders and are characterized by substantial impairment in intellectual and adaptive ...functioning, with their genetic and molecular basis remaining largely unknown. Here, we identify biallelic variants in the gene encoding one of the Elongator complex subunits, ELP2, in patients with ID and ASD. Modelling the variants in mice recapitulates the patient features, with brain imaging and tractography analysis revealing microcephaly, loss of white matter tract integrity and an aberrant functional connectome. We show that the Elp2 mutations negatively impact the activity of the complex and its function in translation via tRNA modification. Further, we elucidate that the mutations perturb protein homeostasis leading to impaired neurogenesis, myelin loss and neurodegeneration. Collectively, our data demonstrate an unexpected role for tRNA modification in the pathogenesis of monogenic ID and ASD and define Elp2 as a key regulator of brain development.
PDF
