Publications by authors named "Mark J Cowley"

110 Publications

Whole-genome sequencing facilitates patient-specific quantitative PCR-based minimal residual disease monitoring in acute lymphoblastic leukaemia, neuroblastoma and Ewing sarcoma.

Br J Cancer 2021 Sep 1. Epub 2021 Sep 1.

Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Sydney, Sydney, NSW, Australia.

Background: Minimal residual disease (MRD) measurement is a cornerstone of contemporary acute lymphoblastic leukaemia (ALL) treatment. The presence of immunoglobulin (Ig) and T cell receptor (TCR) gene recombinations in leukaemic clones allows widespread use of patient-specific, DNA-based MRD assays. In contrast, paediatric solid tumour MRD remains experimental and has focussed on generic assays targeting tumour-specific messenger RNA, methylated DNA or microRNA.

Methods: We examined the feasibility of using whole-genome sequencing (WGS) data to design tumour-specific polymerase chain reaction (PCR)-based MRD tests (WGS-MRD) in 18 children with high-risk relapsed cancer, including ALL, high-risk neuroblastoma (HR-NB) and Ewing sarcoma (EWS) (n = 6 each).

Results: Sensitive WGS-MRD assays were generated for each patient and allowed quantitation of 1 tumour cell per 10 (0.01%)-10 (0.001%) mononuclear cells. In ALL, WGS-MRD and Ig/TCR-MRD were highly concordant. WGS-MRD assays also showed good concordance between quantitative PCR and droplet digital PCR formats. In serial clinical samples, WGS-MRD correlated with disease course. In solid tumours, WGS-MRD assays were more sensitive than RNA-MRD assays.

Conclusions: WGS facilitated the development of patient-specific MRD tests in ALL, HR-NB and EWS with potential clinical utility in monitoring treatment response. WGS data could be used to design patient-specific MRD assays in a broad range of tumours.
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http://dx.doi.org/10.1038/s41416-021-01538-zDOI Listing
September 2021

Genome sequencing in congenital cataracts improves diagnostic yield.

Hum Mutat 2021 Sep 15;42(9):1173-1183. Epub 2021 Jun 15.

Eye Genetics Research Unit, The Children's Hospital at Westmead, Save Sight Institute, Children's Medical Research Institute, University of Sydney, Sydney, New South Wales, Australia.

Congenital cataracts are one of the major causes of childhood-onset blindness around the world. Genetic diagnosis provides benefits through avoidance of unnecessary tests, surveillance of extraocular features, and genetic family information. In this study, we demonstrate the value of genome sequencing in improving diagnostic yield in congenital cataract patients and families. We applied genome sequencing to investigate 20 probands with congenital cataracts. We examined the added value of genome sequencing across a total cohort of 52 probands, including 14 unable to be diagnosed using previous microarray and exome or panel-based approaches. Although exome or genome sequencing would have detected the variants in 35/52 (67%) of the cases, specific advantages of genome sequencing led to additional diagnoses in 10% (5/52) of the overall cohort, and we achieved an overall diagnostic rate of 77% (40/52). Specific benefits of genome sequencing were due to detection of small copy number variants (2), indels in repetitive regions (2) or single-nucleotide variants (SNVs) in GC-rich regions (1), not detectable on the previous microarray, exome sequencing, or panel-based approaches. In other cases, SNVs were identified in cataract disease genes, including those newly identified since our previous study. This study highlights the additional yield of genome sequencing in congenital cataracts.
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http://dx.doi.org/10.1002/humu.24240DOI Listing
September 2021

Spitz Melanoma of Childhood With A Novel Promoter Hijacking Anaplastic Lymphoma Kinase (C2orf42-ALK) Rearrangement.

Am J Dermatopathol 2021 Dec;43(12):972-975

Department of Anatomical Pathology, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Nedlands, Western Australia, Australia.

Abstract: We present the case of a prepubescent man of African descent who developed a spitzoid melanocytic proliferation showing evidence of a novel promoter hijacking ALK-C2orf42 rearrangement, with atypical histology, clinically apparent metastatic disease, and abnormal cytogenetic findings, representing a rare genuine case of "Spitz melanoma of childhood." As our understanding of the distinct molecular biology of different tumors traditionally grouped as spitzoid melanocytic lesions evolves, it is becoming increasingly apparent that this group encompasses morphologically and genetically distinct entities. Accurate classification with detailed molecular analysis and prolonged clinical follow-up is essential to allow meaningful conclusions regarding prognostication and prediction of response to therapy.
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http://dx.doi.org/10.1097/DAD.0000000000001972DOI Listing
December 2021

Application of Genome Sequencing from Blood to Diagnose Mitochondrial Diseases.

Genes (Basel) 2021 04 20;12(4). Epub 2021 Apr 20.

Murdoch Children's Research Institute, Melbourne, VIC 3052, Australia.

Mitochondrial diseases can be caused by pathogenic variants in nuclear or mitochondrial DNA-encoded genes that often lead to multisystemic symptoms and can have any mode of inheritance. Using a single test, Genome Sequencing (GS) can effectively identify variants in both genomes, but it has not yet been universally used as a first-line approach to diagnosing mitochondrial diseases due to related costs and challenges in data analysis. In this article, we report three patients with mitochondrial disease molecularly diagnosed through GS performed on DNA extracted from blood to demonstrate different diagnostic advantages of this technology, including the detection of a low-level heteroplasmic pathogenic variant, an intragenic nuclear DNA deletion, and a large mtDNA deletion. Current technical improvements and cost reductions are likely to lead to an expanded routine diagnostic usage of GS and of the complementary "Omic" technologies in mitochondrial diseases.
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http://dx.doi.org/10.3390/genes12040607DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8072654PMC
April 2021

Different types of disease-causing noncoding variants revealed by genomic and gene expression analyses in families with X-linked intellectual disability.

Hum Mutat 2021 Jul 3;42(7):835-847. Epub 2021 May 3.

Adelaide Medical School and Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.

The pioneering discovery research of X-linked intellectual disability (XLID) genes has benefitted thousands of individuals worldwide; however, approximately 30% of XLID families still remain unresolved. We postulated that noncoding variants that affect gene regulation or splicing may account for the lack of a genetic diagnosis in some cases. Detecting pathogenic, gene-regulatory variants with the same sensitivity and specificity as structural and coding variants is a major challenge for Mendelian disorders. Here, we describe three pedigrees with suggestive XLID where distinctive phenotypes associated with known genes guided the identification of three different noncoding variants. We used comprehensive structural, single-nucleotide, and repeat expansion analyses of genome sequencing. RNA-Seq from patient-derived cell lines, reverse-transcription polymerase chain reactions, Western blots, and reporter gene assays were used to confirm the functional effect of three fundamentally different classes of pathogenic noncoding variants: a retrotransposon insertion, a novel intronic splice donor, and a canonical splice variant of an untranslated exon. In one family, we excluded a rare coding variant in ARX, a known XLID gene, in favor of a regulatory noncoding variant in OFD1 that correlated with the clinical phenotype. Our results underscore the value of genomic research on unresolved XLID families to aid novel, pathogenic noncoding variant discovery.
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http://dx.doi.org/10.1002/humu.24207DOI Listing
July 2021

ClinSV: clinical grade structural and copy number variant detection from whole genome sequencing data.

Genome Med 2021 02 25;13(1):32. Epub 2021 Feb 25.

Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, 370 Victoria Street, Darlinghurst, NSW, Australia.

Whole genome sequencing (WGS) has the potential to outperform clinical microarrays for the detection of structural variants (SV) including copy number variants (CNVs), but has been challenged by high false positive rates. Here we present ClinSV, a WGS based SV integration, annotation, prioritization, and visualization framework, which identified 99.8% of simulated pathogenic ClinVar CNVs > 10 kb and 11/11 pathogenic variants from matched microarrays. The false positive rate was low (1.5-4.5%) and reproducibility high (95-99%). In clinical practice, ClinSV identified reportable variants in 22 of 485 patients (4.7%) of which 35-63% were not detectable by current clinical microarray designs. ClinSV is available at https://github.com/KCCG/ClinSV .
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http://dx.doi.org/10.1186/s13073-021-00841-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7908648PMC
February 2021

Efficacy of MEK inhibition in a recurrent malignant peripheral nerve sheath tumor.

NPJ Precis Oncol 2021 Feb 12;5(1). Epub 2021 Feb 12.

Kids Cancer Centre, Sydney Children's Hospital, Randwick, NSW, Australia.

The prognosis of recurrent malignant peripheral nerve sheath tumors (MPNST) is dismal, with surgical resection being the only definitive salvage therapy. Treatment with chemoradiation approaches has not significantly improved patient outcomes. Similarly, trials of therapies targeting MPNST genomic drivers have thus far been unsuccessful. Improved understanding of the molecular pathogenesis of MPNST indicates frequent activation of the mitogen-activated protein kinase (MAPK) cell signaling pathway. MEK inhibitors have shown activity in preclinical studies; however, their clinical efficacy has not been reported to date. We describe here a case of sustained complete response to MEK inhibition in an adolescent patient with a recurrent metastatic MPNST with multiple alterations in the MAPK pathway, guided by a precision oncology approach.
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http://dx.doi.org/10.1038/s41698-021-00145-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7881142PMC
February 2021

Fatal perinatal mitochondrial cardiac failure caused by recurrent duplications in the locus.

Med (N Y) 2021 Jan 9;2(1):49-73. Epub 2020 Jul 9.

Genetic Metabolic Disorders Service, Sydney Children's Hospital Network, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia.

Background: In about half of all patients with a suspected monogenic disease, genomic investigations fail to identify the diagnosis. A contributing factor is the difficulty with repetitive regions of the genome, such as those generated by segmental duplications. The locus is one such region, in which recessive deletions and dominant duplications have recently been reported to cause lethal perinatal mitochondrial diseases characterized by pontocerebellar hypoplasia or cardiomyopathy, respectively.

Methods: Whole exome, whole genome and long-read DNA sequencing techniques combined with studies of RNA and quantitative proteomics were used to investigate 17 subjects from 16 unrelated families with suspected mitochondrial disease.

Findings: We report six different duplications in the gene locus causing a distinctive presentation including lethal perinatal cardiomyopathy, persistent hyperlactacidemia, and frequently corneal clouding or cataracts and encephalopathy. The recurrent 68 Kb duplications are identifiable from genome and exome sequencing but usually missed by microarrays. The duplications result in the formation of identical chimeric ATAD3A/ATAD3C proteins, altered ATAD3 complexes and a striking reduction in mitochondrial oxidative phosphorylation complex I and its activity in heart tissue.

Conclusions: duplications appear to act in a dominant-negative manner and the inheritance infers a low recurrence risk for families, unlike most pediatric mitochondrial diseases. More than 350 genes underlie mitochondrial diseases. In our experience the locus is now one of the five most common causes of nuclear-encoded pediatric mitochondrial disease but the repetitive nature of the locus means diagnoses may be frequently missed by current genomic strategies.

Funding: Australian NHMRC, US Department of Defense, Japanese AMED and JSPS agencies, Australian Genomics Health Alliance and Australian Mito Foundation.
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http://dx.doi.org/10.1016/j.medj.2020.06.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7875323PMC
January 2021

Diagnostic Yield of Whole Genome Sequencing After Nondiagnostic Exome Sequencing or Gene Panel in Developmental and Epileptic Encephalopathies.

Neurology 2021 03 10;96(13):e1770-e1782. Epub 2021 Feb 10.

From the School of Women's and Children's Health (E.E.P., R.S., S.R., T.K., H.S., P.I.A., J.L., M.C., D.M., M.J.C., A.B., E.K.), The School of Biotechnology and Biomolecular Sciences (M.E.D.), Childrens Cancer Institute (M.J.C.), and NeuRA (T.R.), University of New South Wales; Sydney Childrens Hospital Randwick (E.E.P., R.S., R.M., S.R., T.K., H.S., P.I.A., J.L., M.C., D.M., A.B., E.K.), Sydney Childrens Hospital Network; GOLD Service (E.E.P.), Hunter Genetics; Kinghorn Centre for Clinical Genomics (E.E.P., A.E.M., C.P., V.G., L.H., S.I., R.L.D., A.P.D., S.K., M.J.C.), Garvan Institute of Medical Research, Sydney, Australia; RG Development & Disease (U.S.M., S.M.), Max Planck Institute for Molecular Genetics; Institute for Medical Genetics and Human Genetics (U.S.M., S.M.), Charité-Universitätsmedizin, Berlin, Germany; Faculty of Medicine, Prince of Wales Clinical School (L.H.), and Faculty of Medicine, St Vincents Clinical School (S.K.), UNSW Sydney, Randwick; Adelaide Medical School (C.S., M.H.N.T.), University of Adelaide; Kolling Institute (R.L.D.), University of Sydney; SWSLHD Liverpool Hospital (A.C.), Liverpool; and New South Wales Health Pathology Randwick Genomics Laboratory (T.R., E.K.), Australia.

Objective: To assess the benefits and limitations of whole genome sequencing (WGS) compared to exome sequencing (ES) or multigene panel (MGP) in the molecular diagnosis of developmental and epileptic encephalopathies (DEE).

Methods: We performed WGS of 30 comprehensively phenotyped DEE patient trios that were undiagnosed after first-tier testing, including chromosomal microarray and either research ES (n = 15) or diagnostic MGP (n = 15).

Results: Eight diagnoses were made in the 15 individuals who received prior ES (53%): 3 individuals had complex structural variants; 5 had ES-detectable variants, which now had additional evidence for pathogenicity. Eleven diagnoses were made in the 15 MGP-negative individuals (68%); the majority (n = 10) involved genes not included in the panel, particularly in individuals with postneonatal onset of seizures and those with more complex presentations including movement disorders, dysmorphic features, or multiorgan involvement. A total of 42% of diagnoses were autosomal recessive or X-chromosome linked.

Conclusion: WGS was able to improve diagnostic yield over ES primarily through the detection of complex structural variants (n = 3). The higher diagnostic yield was otherwise better attributed to the power of re-analysis rather than inherent advantages of the WGS platform. Additional research is required to assist in the assessment of pathogenicity of novel noncoding and complex structural variants and further improve diagnostic yield for patients with DEE and other neurogenetic disorders.
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http://dx.doi.org/10.1212/WNL.0000000000011655DOI Listing
March 2021

Genomic diagnostics in polycystic kidney disease: an assessment of real-world use of whole-genome sequencing.

Eur J Hum Genet 2021 05 12;29(5):760-770. Epub 2021 Jan 12.

Division of Genomics and Epigenetics, Garvan Institute of Medical Research, Sydney, NSW, Australia.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is common, with a prevalence of 1/1000 and predominantly caused by disease-causing variants in PKD1 or PKD2. Clinical diagnosis is usually by age-dependent imaging criteria, which is challenging in patients with atypical clinical features, without family history, or younger age. However, there is increasing need for definitive diagnosis of ADPKD with new treatments available. Sequencing is complicated by six pseudogenes that share 97% homology to PKD1 and by recently identified phenocopy genes. Whole-genome sequencing can definitively diagnose ADPKD, but requires validation for clinical use. We initially performed a validation study, in which 42 ADPKD patients underwent sequencing of PKD1 and PKD2 by both whole-genome and Sanger sequencing, using a blinded, cross-over method. Whole-genome sequencing identified all PKD1 and PKD2 germline pathogenic variants in the validation study (sensitivity and specificity 100%). Two mosaic variants outside pipeline thresholds were not detected. We then examined the first 144 samples referred to a clinically-accredited diagnostic laboratory for clinical whole-genome sequencing, with targeted-analysis to a polycystic kidney disease gene-panel. In this unselected, diagnostic cohort (71 males :73 females), the diagnostic rate was 70%, including a diagnostic rate of 81% in patients with typical ADPKD (98% with PKD1/PKD2 variants) and 60% in those with atypical features (56% PKD1/PKD2; 44% PKHD1/HNF1B/GANAB/ DNAJB11/PRKCSH/TSC2). Most patients with atypical disease did not have clinical features that predicted likelihood of a genetic diagnosis. These results suggest clinicians should consider diagnostic genomics as part of their assessment in polycystic kidney disease, particularly in atypical disease.
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http://dx.doi.org/10.1038/s41431-020-00796-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8110527PMC
May 2021

Targeted Therapy of -Rearranged Neuroblastoma with BET Bromodomain Inhibitor and Proteasome Inhibitor Combination Therapy.

Clin Cancer Res 2021 03 11;27(5):1438-1451. Epub 2020 Dec 11.

Department of Pathology, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia.

Purpose: gene rearrangement with transcriptional superenhancers leads to overexpression and neuroblastoma. No targeted therapy is available for clinical trials in patients with -rearranged neuroblastoma.

Experimental Design: Anticancer agents exerting the best synergistic anticancer effects with BET bromodomain inhibitors were identified by screening an FDA-approved oncology drug library. The synergistic effects of the BET bromodomain inhibitor OTX015 and the proteasome inhibitor carfilzomib were examined by immunoblot and flow cytometry analysis. The anticancer efficacy of OTX015 and carfilzomib combination therapy was investigated in mice xenografted with -rearranged neuroblastoma cell lines or patient-derived xenograft (PDX) tumor cells, and the role of TERT reduction in the anticancer efficacy was examined through rescue experiments in mice.

Results: The BET bromodomain protein BRD4 promoted -rearranged neuroblastoma cell proliferation through upregulating TERT expression. Screening of an approved oncology drug library identified the proteasome inhibitor carfilzomib as the agent exerting the best synergistic anticancer effects with BET bromodomain inhibitors including OTX015. OTX015 and carfilzomib synergistically reduced TERT protein expression, induced endoplasmic reticulum stress, and induced -rearranged neuroblastoma cell apoptosis which was blocked by TERT overexpression and endoplasmic reticulum stress antagonists. In mice xenografted with -rearranged neuroblastoma cell lines or PDX tumor cells, OTX015 and carfilzomib synergistically blocked TERT expression, induced tumor cell apoptosis, suppressed tumor progression, and improved mouse survival, which was largely reversed by forced TERT overexpression.

Conclusions: OTX015 and carfilzomib combination therapy is likely to be translated into the first clinical trial of a targeted therapy in patients with -rearranged neuroblastoma.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-3044DOI Listing
March 2021

RLIM Is a Candidate Dosage-Sensitive Gene for Individuals with Varying Duplications of Xq13, Intellectual Disability, and Distinct Facial Features.

Am J Hum Genet 2020 12 6;107(6):1157-1169. Epub 2020 Nov 6.

Genetics of Learning Disability Service, Waratah, NSW 2298, Australia.

Interpretation of the significance of maternally inherited X chromosome variants in males with neurocognitive phenotypes continues to present a challenge to clinical geneticists and diagnostic laboratories. Here we report 14 males from 9 families with duplications at the Xq13.2-q13.3 locus with a common facial phenotype, intellectual disability (ID), distinctive behavioral features, and a seizure disorder in two cases. All tested carrier mothers had normal intelligence. The duplication arose de novo in three mothers where grandparental testing was possible. In one family the duplication segregated with ID across three generations. RLIM is the only gene common to our duplications. However, flanking genes duplicated in some but not all the affected individuals included the brain-expressed genes NEXMIF, SLC16A2, and the long non-coding RNA gene FTX. The contribution of the RLIM-flanking genes to the phenotypes of individuals with different size duplications has not been fully resolved. Missense variants in RLIM have recently been identified to cause X-linked ID in males, with heterozygous females typically having normal intelligence and highly skewed X chromosome inactivation. We detected consistent and significant increase of RLIM mRNA and protein levels in cells derived from seven affected males from five families with the duplication. Subsequent analysis of MDM2, one of the targets of the RLIM E3 ligase activity, showed consistent downregulation in cells from the affected males. All the carrier mothers displayed normal RLIM mRNA levels and had highly skewed X chromosome inactivation. We propose that duplications at Xq13.2-13.3 including RLIM cause a recognizable but mild neurocognitive phenotype in hemizygous males.
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http://dx.doi.org/10.1016/j.ajhg.2020.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7820564PMC
December 2020

Recurrent fusions in pediatric sarcoma and brain tumors.

Cold Spring Harb Mol Case Stud 2020 12 17;6(6). Epub 2020 Dec 17.

Children's Cancer Institute, University of New South Wales, Randwick, 2031, Australia.

The identification of rearrangements driving expression of neurotrophic receptor tyrosine kinase () family kinases in tumors has become critically important because of the availability of effective, specific inhibitor drugs. Whole-genome sequencing (WGS) combined with RNA sequencing (RNA-seq) can identify novel and recurrent expressed fusions. Here we describe three fusions identified in two pediatric central nervous system cancers and an extracranial solid tumor using WGS and RNA-seq. These fusions arose either through a simple balanced rearrangement or in the context of a complex chromoplexy event. We cloned the fusion directly from a patient sample and showed that enforced expression of this fusion is sufficient to promote cytokine-independent survival and proliferation. Cells transformed by expression are sensitive to a TRK inhibitor drug. We report here that fusions can arise in a range of pediatric cancers. Although WGS and RNA-seq are not required to detect fusions, these techniques may be of benefit when fusions are not suspected on clinical grounds or not identified by other methods.
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http://dx.doi.org/10.1101/mcs.a005710DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7784491PMC
December 2020

A Novel Orthotopic Patient-Derived Xenograft Model of Radiation-Induced Glioma Following Medulloblastoma.

Cancers (Basel) 2020 Oct 12;12(10). Epub 2020 Oct 12.

Brain Tumour Research Program, Telethon Kids Institute, Nedlands, WA 6009, Australia.

Radiation-induced glioma (RIG) is a highly aggressive brain cancer arising as a consequence of radiation therapy. We report a case of RIG that arose in the brain stem following treatment for paediatric medulloblastoma, and the development and characterisation of a matched orthotopic patient-derived xenograft (PDX) model (TK-RIG915). Patient and PDX tumours were analysed using DNA methylation profiling, whole genome sequencing (WGS) and RNA sequencing. While initially thought to be a diffuse intrinsic pontine glioma (DIPG) based on disease location, results from methylation profiling and WGS were not consistent with this diagnosis. Furthermore, clustering analyses based on RNA expression suggested the tumours were distinct from primary DIPG. Additional gene expression analysis demonstrated concordance with a published RIG expression profile. Multiple genetic alterations that enhance PI3K/AKT and Ras/Raf/MEK/ERK signalling were discovered in TK-RIG915 including an activating mutation in , upregulation of and , inactivating mutations in , and a gain-of-function mutation in . Additionally, deletion of , increased expression, and decreased expression were observed. Detection of phosphorylated S6, 4EBP1 and ERK via immunohistochemistry confirmed PI3K pathway and ERK activation. Here, we report one of the first PDX models for RIG, which recapitulates the patient disease and is molecularly distinct from primary brain stem glioma. Genetic interrogation of this model has enabled the identification of potential therapeutic vulnerabilities in this currently incurable disease.
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http://dx.doi.org/10.3390/cancers12102937DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600047PMC
October 2020

Whole genome, transcriptome and methylome profiling enhances actionable target discovery in high-risk pediatric cancer.

Nat Med 2020 11 5;26(11):1742-1753. Epub 2020 Oct 5.

Hereditary Cancer Centre, Prince of Wales Hospital, Randwick, NSW, Australia.

The Zero Childhood Cancer Program is a precision medicine program to benefit children with poor-outcome, rare, relapsed or refractory cancer. Using tumor and germline whole genome sequencing (WGS) and RNA sequencing (RNAseq) across 252 tumors from high-risk pediatric patients with cancer, we identified 968 reportable molecular aberrations (39.9% in WGS and RNAseq, 35.1% in WGS only and 25.0% in RNAseq only). Of these patients, 93.7% had at least one germline or somatic aberration, 71.4% had therapeutic targets and 5.2% had a change in diagnosis. WGS identified pathogenic cancer-predisposing variants in 16.2% of patients. In 76 central nervous system tumors, methylome analysis confirmed diagnosis in 71.1% of patients and contributed to a change of diagnosis in two patients (2.6%). To date, 43 patients have received a recommended therapy, 38 of whom could be evaluated, with 31% showing objective evidence of clinical benefit. Comprehensive molecular profiling resolved the molecular basis of virtually all high-risk cancers, leading to clinical benefit in some patients.
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http://dx.doi.org/10.1038/s41591-020-1072-4DOI Listing
November 2020

Precision Oncology in Surgery: Patient Selection for Operable Pancreatic Cancer.

Ann Surg 2020 08;272(2):366-376

Department of Surgery, Universitätsklinikum Erlangen, Erlangen, Germany.

Objective: We aimed to define preoperative clinical and molecular characteristics that would allow better patient selection for operative resection.

Background: Although we use molecular selection methods for systemic targeted therapies, these principles are not applied to surgical oncology. Improving patient selection is of vital importance for the operative treatment of pancreatic cancer (pancreatic ductal adenocarcinoma). Although surgery is the only chance of long-term survival, 80% still succumb to the disease and approximately 30% die within 1 year, often sooner than those that have unresected local disease.

Method: In 3 independent pancreatic ductal adenocarcinoma cohorts (total participants = 1184) the relationship between aberrant expression of prometastatic proteins S100A2 and S100A4 and survival was assessed. A preoperative nomogram based on clinical variables available before surgery and expression of these proteins was constructed and compared to traditional measures, and a postoperative nomogram.

Results: High expression of either S100A2 or S100A4 was independent poor prognostic factors in a training cohort of 518 participants. These results were validated in 2 independent patient cohorts (Glasgow, n = 198; Germany, n = 468). Aberrant biomarker expression stratified the cohorts into 3 distinct prognostic groups. A preoperative nomogram incorporating S100A2 and S100A4 expression predicted survival and nomograms derived using postoperative clinicopathological variables.

Conclusions: Of those patients with a poor preoperative nomogram score, approximately 50% of patients died within a year of resection. Nomograms have the potential to improve selection for surgery and neoadjuvant therapy, avoiding surgery in aggressive disease, and justifying more extensive resections in biologically favorable disease.
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http://dx.doi.org/10.1097/SLA.0000000000003143DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7373491PMC
August 2020

Expansion of the phenotypic spectrum of de novo missense variants in kinesin family member 1A (KIF1A).

Hum Mutat 2020 Oct 22;41(10):1761-1774. Epub 2020 Jul 22.

Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.

Defects in the motor domain of kinesin family member 1A (KIF1A), a neuron-specific ATP-dependent anterograde axonal transporter of synaptic cargo, are well-recognized to cause a spectrum of neurological conditions, commonly known as KIF1A-associated neurological disorders (KAND). Here, we report one mutation-negative female with classic Rett syndrome (RTT) harboring a de novo heterozygous novel variant [NP_001230937.1:p.(Asp248Glu)] in the highly conserved motor domain of KIF1A. In addition, three individuals with severe neurodevelopmental disorder along with clinical features overlapping with KAND are also reported carrying de novo heterozygous novel [NP_001230937.1:p.(Cys92Arg) and p.(Pro305Leu)] or previously reported [NP_001230937.1:p.(Thr99Met)] variants in KIF1A. In silico tools predicted these variants to be likely pathogenic, and 3D molecular modeling predicted defective ATP hydrolysis and/or microtubule binding. Using the neurite tip accumulation assay, we demonstrated that all novel KIF1A variants significantly reduced the ability of the motor domain of KIF1A to accumulate along the neurite lengths of differentiated SH-SY5Y cells. In vitro microtubule gliding assays showed significantly reduced velocities for the variant p.(Asp248Glu) and reduced microtubule binding for the p.(Cys92Arg) and p.(Pro305Leu) variants, suggesting a decreased ability of KIF1A to move along microtubules. Thus, this study further expanded the phenotypic characteristics of KAND individuals with pathogenic variants in the KIF1A motor domain to include clinical features commonly seen in RTT individuals.
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http://dx.doi.org/10.1002/humu.24079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7908811PMC
October 2020

Proteogenomic analysis of Inhibitor of Differentiation 4 (ID4) in basal-like breast cancer.

Breast Cancer Res 2020 06 11;22(1):63. Epub 2020 Jun 11.

The Kinghorn Cancer Centre and Cancer Research Division, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia.

Background: Basal-like breast cancer (BLBC) is a poorly characterised, heterogeneous disease. Patients are diagnosed with aggressive, high-grade tumours and often relapse with chemotherapy resistance. Detailed understanding of the molecular underpinnings of this disease is essential to the development of personalised therapeutic strategies. Inhibitor of differentiation 4 (ID4) is a helix-loop-helix transcriptional regulator required for mammary gland development. ID4 is overexpressed in a subset of BLBC patients, associating with a stem-like poor prognosis phenotype, and is necessary for the growth of cell line models of BLBC through unknown mechanisms.

Methods: Here, we have defined unique molecular insights into the function of ID4 in BLBC and the related disease high-grade serous ovarian cancer (HGSOC), by combining RIME proteomic analysis, ChIP-seq mapping of genomic binding sites and RNA-seq.

Results: These studies reveal novel interactions with DNA damage response proteins, in particular, mediator of DNA damage checkpoint protein 1 (MDC1). Through MDC1, ID4 interacts with other DNA repair proteins (γH2AX and BRCA1) at fragile chromatin sites. ID4 does not affect transcription at these sites, instead binding to chromatin following DNA damage. Analysis of clinical samples demonstrates that ID4 is amplified and overexpressed at a higher frequency in BRCA1-mutant BLBC compared with sporadic BLBC, providing genetic evidence for an interaction between ID4 and DNA damage repair deficiency.

Conclusions: These data link the interactions of ID4 with MDC1 to DNA damage repair in the aetiology of BLBC and HGSOC.
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http://dx.doi.org/10.1186/s13058-020-01306-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7291584PMC
June 2020

Revealing hidden genetic diagnoses in the ocular anterior segment disorders.

Genet Med 2020 10 5;22(10):1623-1632. Epub 2020 Jun 5.

Eye Genetics Research Unit, The Children's Hospital at Westmead, Save Sight Institute, Children's Medical Research Institute, University of Sydney, Sydney, NSW, Australia.

Purpose: Ocular anterior segment disorders (ASDs) are clinically and genetically heterogeneous, and genetic diagnosis often remains elusive. In this study, we demonstrate the value of a combined analysis protocol using phenotypic, genomic, and pedigree structure data to achieve a genetic conclusion.

Methods: We utilized a combination of chromosome microarray, exome sequencing, and genome sequencing with structural variant and trio analysis to investigate a cohort of 41 predominantly sporadic cases.

Results: We identified likely causative variants in 54% (22/41) of cases, including 51% (19/37) of sporadic cases and 75% (3/4) of cases initially referred as familial ASD. Two-thirds of sporadic cases were found to have heterozygous variants, which in most cases were de novo. Approximately one-third (7/22) of genetic diagnoses were found in rarely reported or recently identified ASD genes including PXDN, GJA8, COL4A1, ITPR1, CPAMD8, as well as the new phenotypic association of Axenfeld-Rieger anomaly with a homozygous ADAMTS17 variant. The remainder of the variants were in key ASD genes including FOXC1, PITX2, CYP1B1, FOXE3, and PAX6.

Conclusions: We demonstrate the benefit of detailed phenotypic, genomic, variant, and segregation analysis to uncover some of the previously "hidden" heritable answers in several rarely reported and newly identified ocular ASD-related disease genes.
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http://dx.doi.org/10.1038/s41436-020-0854-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7521990PMC
October 2020

Molecular patterns in salivary duct carcinoma identify prognostic subgroups.

Mod Pathol 2020 10 26;33(10):1896-1909. Epub 2020 May 26.

Kinghorn Cancer Centre and Garvan Institute of Medical Research, Sydney, NSW, Australia.

Salivary duct carcinoma (SDCa) is a rare cancer with high rate of metastases and poor survival despite aggressive multimodality treatment. This study analyzes the genetic changes in SDCa, their impact on cancer pathways, and evaluates whether molecular patterns can identify subgroups with distinct clinical characteristics and outcome. Clinicopathologic details and tissue samples from 66 patients (48 males, 18 females) treated between 1995 and 2018 were obtained from multiple institutions. Androgen receptor (AR) was assessed by immunohistochemistry, and the Illumina TruSight 170 gene panel was used for DNA sequencing. Male gender, lympho-vascular invasion, lymph node metastasis, and smoking were significant predictors of disease-free survival. AR was present in 79%. Frequently encountered alterations were mutations in TP53 (51%), PIK3CA (32%) and HRAS (22%), as well as amplifications of CDK4/6 (22%), ERBB2 (21%), MYC (16%), and deletions of CDKN2A (13%). TP53 mutation and MYC amplifications were associated with decreased disease-free survival. Analysis of cancer pathways revealed that the PI3K pathway was most commonly affected. Alterations in the cell cycle pathway were associated with impaired disease-free survival (HR 2.6, P = 0.038). Three subgroups based on AR and ERBB2 status were identified, which featured distinct molecular patterns and outcome. Among AR positive SDCa, HRAS mutations were restricted to AR positive tumors without ERBB2 amplification and HRAS mutations featured high co-occurrence with PIK3CA alterations, which seems specific to SDCa. AR negative SDCa were associated with poor disease-free survival in multivariate analysis (HR 4.5, P = 0.010) and none of these tumors exhibited ERBB2 amplification or HRAS mutations. AR and ERBB2 status in SDCa thus classifies tumors with distinct molecular profiles relevant to future targeted therapy. Furthermore, clinical factors such as smoking and molecular features such as MYC amplification may serve as markers of poor prognosis of SDCa.
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http://dx.doi.org/10.1038/s41379-020-0576-2DOI Listing
October 2020

The diagnostic utility of genome sequencing in a pediatric cohort with suspected mitochondrial disease.

Genet Med 2020 07 21;22(7):1254-1261. Epub 2020 Apr 21.

Genetic Metabolic Disorders Research Unit, The Children's Hospital at Westmead, Sydney, Australia.

Purpose: The utility of genome sequencing (GS) in the diagnosis of suspected pediatric mitochondrial disease (MD) was investigated.

Methods: An Australian cohort of 40 pediatric patients with clinical features suggestive of MD were classified using the modified Nijmegen mitochondrial disease severity scoring into definite (17), probable (17), and possible (6) MD groups. Trio GS was performed using DNA extracted from patient and parent blood. Data were analyzed for single-nucleotide variants, indels, mitochondrial DNA variants, and structural variants.

Results: A definitive MD gene molecular diagnosis was made in 15 cases and a likely MD molecular diagnosis in a further five cases. Causative mitochondrial DNA (mtDNA) variants were identified in four of these cases. Three potential novel MD genes were identified. In seven cases, causative variants were identified in known disease genes with no previous evidence of causing a primary MD. Diagnostic rates were higher in patients classified as having definite MD.

Conclusion: GS efficiently identifies variants in MD genes of both nuclear and mitochondrial origin. A likely molecular diagnosis was identified in 67% of cases and a definitive molecular diagnosis achieved in 55% of cases. This study highlights the value of GS for a phenotypically and genetically heterogeneous disorder like MD.
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http://dx.doi.org/10.1038/s41436-020-0793-6DOI Listing
July 2020

Infant High-Grade Gliomas Comprise Multiple Subgroups Characterized by Novel Targetable Gene Fusions and Favorable Outcomes.

Cancer Discov 2020 07 1;10(7):942-963. Epub 2020 Apr 1.

Department of Neuropathology, University Hospital Hamburg-Eppendorf, and Research Institute Children's Cancer Center, Hamburg, Germany.

Infant high-grade gliomas appear clinically distinct from their counterparts in older children, indicating that histopathologic grading may not accurately reflect the biology of these tumors. We have collected 241 cases under 4 years of age, and carried out histologic review, methylation profiling, and custom panel, genome, or exome sequencing. After excluding tumors representing other established entities or subgroups, we identified 130 cases to be part of an "intrinsic" spectrum of disease specific to the infant population. These included those with targetable MAPK alterations, and a large proportion of remaining cases harboring gene fusions targeting ( = 31), ( = 21), ( = 9), and ( = 4) as their driving alterations, with evidence of efficacy of targeted agents in the clinic. These data strongly support the concept that infant gliomas require a change in diagnostic practice and management. SIGNIFICANCE: Infant high-grade gliomas in the cerebral hemispheres comprise novel subgroups, with a prevalence of , or gene fusions. Kinase fusion-positive tumors have better outcome and respond to targeted therapy clinically. Other subgroups have poor outcome, with fusion-negative cases possibly representing an epigenetically driven pluripotent stem cell phenotype...
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http://dx.doi.org/10.1158/2159-8290.CD-19-1030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8313225PMC
July 2020

The Medical Genome Reference Bank contains whole genome and phenotype data of 2570 healthy elderly.

Nat Commun 2020 01 23;11(1):435. Epub 2020 Jan 23.

Parkville Familial Cancer Centre, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.

Population health research is increasingly focused on the genetic determinants of healthy ageing, but there is no public resource of whole genome sequences and phenotype data from healthy elderly individuals. Here we describe the first release of the Medical Genome Reference Bank (MGRB), comprising whole genome sequence and phenotype of 2570 elderly Australians depleted for cancer, cardiovascular disease, and dementia. We analyse the MGRB for single-nucleotide, indel and structural variation in the nuclear and mitochondrial genomes. MGRB individuals have fewer disease-associated common and rare germline variants, relative to both cancer cases and the gnomAD and UK Biobank cohorts, consistent with risk depletion. Age-related somatic changes are correlated with grip strength in men, suggesting blood-derived whole genomes may also provide a biologic measure of age-related functional deterioration. The MGRB provides a broadly applicable reference cohort for clinical genetics and genomic association studies, and for understanding the genetics of healthy ageing.
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http://dx.doi.org/10.1038/s41467-019-14079-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978518PMC
January 2020

Clinical Spectrum and Functional Consequences Associated with Bi-Allelic Pathogenic Variants.

J Clin Med 2019 Nov 19;8(11). Epub 2019 Nov 19.

Murdoch Children's Research Institute, Melbourne, VIC 3052, Australia.

(PNPase-polynucleotide phosphorylase) is involved in multiple RNA processing functions in the mitochondria. Bi-allelic pathogenic variants cause heterogeneous clinical phenotypes affecting multiple organs without any established genotype-phenotype correlations. Defects in PNPase can cause variable combined respiratory chain complex defects. Recently, it has been suggested that PNPase can lead to activation of an innate immune response. To better understand the clinical and molecular spectrum of patients with bi-allelic variants, we captured detailed clinical and molecular phenotypes of all 17 patients reported in the literature, plus seven new patients, including a 78-year-old male with the longest reported survival. A functional follow-up of genomic sequencing by cDNA studies confirmed a splicing defect in a novel, apparently synonymous, variant. Patient fibroblasts showed an accumulation of mitochondrial unprocessed transcripts, while blood showed an increased interferon response. Our findings suggest that functional analyses of the RNA processing function of PNPase are more sensitive than testing downstream defects in oxidative phosphorylation (OXPHPOS) enzyme activities. This research extends our knowledge of the clinical and functional consequences of bi-allelic pathogenic variants that may guide management and further efforts into understanding the pathophysiological mechanisms for therapeutic development.
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http://dx.doi.org/10.3390/jcm8112020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6912252PMC
November 2019

Development and validation of a targeted gene sequencing panel for application to disparate cancers.

Sci Rep 2019 11 19;9(1):17052. Epub 2019 Nov 19.

Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.

Next generation sequencing has revolutionised genomic studies of cancer, having facilitated the development of precision oncology treatments based on a tumour's molecular profile. We aimed to develop a targeted gene sequencing panel for application to disparate cancer types with particular focus on tumours of the head and neck, plus test for utility in liquid biopsy. The final panel designed through Roche/Nimblegen combined 451 cancer-associated genes (2.01 Mb target region). 136 patient DNA samples were collected for performance and application testing. Panel sensitivity and precision were measured using well-characterised DNA controls (n = 47), and specificity by Sanger sequencing of the Aryl Hydrocarbon Receptor Interacting Protein (AIP) gene in 89 patients. Assessment of liquid biopsy application employed a pool of synthetic circulating tumour DNA (ctDNA). Library preparation and sequencing were conducted on Illumina-based platforms prior to analysis with our accredited (ISO15189) bioinformatics pipeline. We achieved a mean coverage of 395x, with sensitivity and specificity of >99% and precision of >97%. Liquid biopsy revealed detection to 1.25% variant allele frequency. Application to head and neck tumours/cancers resulted in detection of mutations aligned to published databases. In conclusion, we have developed an analytically-validated panel for application to cancers of disparate types with utility in liquid biopsy.
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http://dx.doi.org/10.1038/s41598-019-52000-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6864073PMC
November 2019

Whole genome sequencing for the genetic diagnosis of heterogenous dystonia phenotypes.

Parkinsonism Relat Disord 2019 12 7;69:111-118. Epub 2019 Nov 7.

Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW, 2010, Australia; Department of Neurogenetics, Kolling Institute, University of Sydney and Royal North Shore Hospital, St Leonards, New South Wales, 2065, Australia; Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Camperdown, 2050, Australia; Department of Neurology, Royal North Shore Hospital, St Leonards, New South Wales, 2065, Australia. Electronic address:

Introduction: Dystonia is a clinically and genetically heterogeneous disorder and a genetic cause is often difficult to elucidate. This is the first study to use whole genome sequencing (WGS) to investigate dystonia in a large sample of affected individuals.

Methods: WGS was performed on 111 probands with heterogenous dystonia phenotypes. We performed analysis for coding and non-coding variants, copy number variants (CNVs), and structural variants (SVs). We assessed for an association between dystonia and 10 known dystonia risk variants.

Results: A genetic diagnosis was obtained for 11.7% (13/111) of individuals. We found that a genetic diagnosis was more likely in those with an earlier age at onset, younger age at testing, and a combined dystonia phenotype. We identified pathogenic/likely-pathogenic variants in ADCY5 (n = 1), ATM (n = 1), GNAL (n = 2), GLB1 (n = 1), KMT2B (n = 2), PRKN (n = 2), PRRT2 (n = 1), SGCE (n = 2), and THAP1 (n = 1). CNVs were detected in 3 individuals. We found an association between the known risk variant ARSG rs11655081 and dystonia (p = 0.003).

Conclusion: A genetic diagnosis was found in 11.7% of individuals with dystonia. The diagnostic yield was higher in those with an earlier age of onset, younger age at testing, and a combined dystonia phenotype. WGS may be particularly relevant for dystonia given that it allows for the detection of CNVs, which accounted for 23% of the genetically diagnosed cases.
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http://dx.doi.org/10.1016/j.parkreldis.2019.11.004DOI Listing
December 2019

Denisovan, modern human and mouse TNFAIP3 alleles tune A20 phosphorylation and immunity.

Nat Immunol 2019 10 18;20(10):1299-1310. Epub 2019 Sep 18.

Research School of Chemistry, The Australian National University, Canberra, Australian Capital Territory, Australia.

Resisting and tolerating microbes are alternative strategies to survive infection, but little is known about the evolutionary mechanisms controlling this balance. Here genomic analyses of anatomically modern humans, extinct Denisovan hominins and mice revealed a TNFAIP3 allelic series with alterations in the encoded immune response inhibitor A20. Each TNFAIP3 allele encoded substitutions at non-catalytic residues of the ubiquitin protease OTU domain that diminished IκB kinase-dependent phosphorylation and activation of A20. Two TNFAIP3 alleles encoding A20 proteins with partial phosphorylation deficits seemed to be beneficial by increasing immunity without causing spontaneous inflammatory disease: A20 T108A;I207L, originating in Denisovans and introgressed in modern humans throughout Oceania, and A20 I325N, from an N-ethyl-N-nitrosourea (ENU)-mutagenized mouse strain. By contrast, a rare human TNFAIP3 allele encoding an A20 protein with 95% loss of phosphorylation, C243Y, caused spontaneous inflammatory disease in humans and mice. Analysis of the partial-phosphorylation A20 I325N allele in mice revealed diminished tolerance of bacterial lipopolysaccharide and poxvirus inoculation as tradeoffs for enhanced immunity.
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http://dx.doi.org/10.1038/s41590-019-0492-0DOI Listing
October 2019

Biparental inheritance of mitochondrial DNA in humans is not a common phenomenon.

Genet Med 2019 12 7;21(12):2823-2826. Epub 2019 Jun 7.

Murdoch Children's Research Institute, Melbourne, Australia.

Purpose: A recent report has raised the possibility of biparental mitochondrial DNA (mtDNA) inheritance, which could lead to concerns by health-care professionals and patients regarding investigations and genetic counseling of families with pathogenic mitochondrial DNA variants. Our aim was to examine the frequency of this phenomenon by investigating a cohort of patients with suspected mitochondrial disease.

Methods: We studied genome sequencing (GS) data of DNA extracted from blood samples of 41 pediatric patients with suspected mitochondrial disease and their parents.

Results: All of the mtDNA variants in the probands segregated with their mother or were apparently de novo. There were no variants that segregated only with the father and none of these families showed evidence of biparental inheritance of their mtDNA.

Conclusion: Paternal mitochondrial transmission is unlikely to be a common occurrence and therefore at this point we would not recommend changes in clinical practice.
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http://dx.doi.org/10.1038/s41436-019-0568-0DOI Listing
December 2019

Pathogenic variants in result in a Stickler syndrome-like connective tissue disorder with vascular complications.

J Med Genet 2019 09 25;56(9):629-638. Epub 2019 May 25.

NSW Health Pathology East Laboratory, Prince of Wales Private Hospital, Randwick, New South Wales, Australia.

Background: Pathogenic variants cause a connective tissue disorder (CTD) that has been described rarely. We further characterise this CTD and propose a clinical diagnostic label to improve recognition and diagnosis of -related disease.

Methods: Reported phenotypes were compared with known CTDs utilising data from three further individuals from a consanguineous family with a homozygous c.809C>T; p.(Pro270Leu) variant. PLOD3 mRNA expression in the developing embryo was analysed for tissue-specific localisation. Mouse microarray expression data were assessed for phylogenetic gene expression similarities across CTDs with overlapping clinical features.

Results: Key clinical features included ocular abnormalities with risk for retinal detachment, sensorineural hearing loss, reduced palmar creases, finger contractures, prominent knees, scoliosis, low bone mineral density, recognisable craniofacial dysmorphisms, developmental delay and risk for vascular dissection. Collated clinical features showed most overlap with Stickler syndrome with variable features of Ehlers-Danlos syndrome (EDS) and epidermolysis bullosa (EB). Human lysyl hydroxylase 3/ expression was localised to the developing cochlea, eyes, skin, forelimbs, heart and cartilage, mirroring the clinical phenotype of this disorder.

Conclusion: These data are consistent with pathogenic variants in resulting in a clinically distinct Stickler-like syndrome with vascular complications and variable features of EDS and EB. Early identification of variants would improve monitoring for comorbidities and may avoid serious adverse ocular and vascular outcomes.
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http://dx.doi.org/10.1136/jmedgenet-2019-106019DOI Listing
September 2019

Increased Diagnostic Yield of Spastic Paraplegia with or Without Cerebellar Ataxia Through Whole-Genome Sequencing.

Cerebellum 2019 Aug;18(4):781-790

Department of Neurology, Movement Disorder Center, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, South Korea.

Inherited disorders of spasticity or ataxia exist on a spectrum with overlapping causative genes and phenotypes. We investigated the use of whole-genome sequencing (WGS) to detect a genetic cause when considering this spectrum of disorders as a single group. We recruited 18 Korean individuals with spastic paraplegia with or without cerebellar ataxia in whom common causes of hereditary cerebellar ataxia and hereditary spastic paraplegia had been excluded. We performed WGS with analysis for single nucleotide variants, small insertions and deletions, copy number variants (CNVs), structural variants (SVs) and intronic variants. Disease-relevant variants were identified in ABCD1 (n = 3), CAPN1 (n = 2), NIPA1 (n = 1) and PLA2G6 (n = 1) for 7/18 patients (38.9%). A 'reverse phenotyping' approach was used to clarify the diagnosis in individuals with PLA2G6 and ABCD1 variants. One of the ABCD1 disease-relevant variants was detected on analysis for intronic variants. No CNV or SV causes were found. The two males with ABCD1 variants were initiated on monitoring for adrenal dysfunction. This is one of only a few studies to analyse spastic-ataxias as a continuous spectrum using a single approach. The outcome was improved diagnosis of unresolved cases for which common genetic causes had been excluded. This includes the detection of ABCD1 variants which had management implications. Therefore, WGS may be particularly relevant to diagnosing spastic ataxias given the large number of genes associated with this condition and the relatively high diagnostic yield.
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http://dx.doi.org/10.1007/s12311-019-01038-0DOI Listing
August 2019
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