Case report of whole genome sequencing in the XY female: identification of a novel SRY mutation and revision of a misdiagnosis of androgen insensitivity syndrome

Background: The 46,XY female is characterised by a male karyotype and female phenotype arising due to any interruption in the sexual development pathways in utero. The cause is usually genetic and various genes are implicated. Case presentation: Herein we describe a 46,XY woman who was first diagnosed with androgen insensitivity syndrome (testicular feminisation) at 18 years; however, this was later questioned due to the presence of intact Müllerian structures. The clinical phenotype suggested several susceptibility genes including SRY, DHH, NR5A1, NR0B1, AR, AMH, and AMHR2. To study candidate genes simultaneously, we performed whole genome sequencing. This revealed a novel and likely pathogenic missense variant (p.Arg130Pro, c.389G>C) in SRY, one of the major genes implicated in complete gonadal dysgenesis, hence securing this condition over androgen insensitivity syndrome as the cause of the patient’s disorder of sexual development. Conclusion: This case highlights the emerging clinical utility of whole genome sequencing as a tool in differentiating disorders of sexual development.Sunita M. C. De Sousa, Karin S. Kassahn, Liam C. McIntyre, Chan-Eng Chong, Hamish S. Scott and David J. Torp

Clinical and molecular characterization of HER2 amplified-pancreatic cancer

<p>Background: Pancreatic cancer is one of the most lethal and molecularly diverse malignancies. Repurposing of therapeutics that target specific molecular mechanisms in different disease types offers potential for rapid improvements in outcome. Although HER2 amplification occurs in pancreatic cancer, it is inadequately characterized to exploit the potential of anti-HER2 therapies.</p> <p>Methods: HER2 amplification was detected and further analyzed using multiple genomic sequencing approaches. Standardized reference laboratory assays defined HER2 amplification in a large cohort of patients (n = 469) with pancreatic ductal adenocarcinoma (PDAC).</p> <p>Results: An amplified inversion event (1 MB) was identified at the HER2 locus in a patient with PDAC. Using standardized laboratory assays, we established diagnostic criteria for HER2 amplification in PDAC, and observed a prevalence of 2%. Clinically, HER2- amplified PDAC was characterized by a lack of liver metastases, and a preponderance of lung and brain metastases. Excluding breast and gastric cancer, the incidence of HER2-amplified cancers in the USA is >22,000 per annum.</p> <p>Conclusions: HER2 amplification occurs in 2% of PDAC, and has distinct features with implications for clinical practice. The molecular heterogeneity of PDAC implies that even an incidence of 2% represents an attractive target for anti-HER2 therapies, as options for PDAC are limited. Recruiting patients based on HER2 amplification, rather than organ of origin, could make trials of anti-HER2 therapies feasible in less common cancer types.</p&gt

Identification and targeted management of a neurodegenerative disorder caused by biallelic mutations in SLC5A6

We describe a sibling pair displaying an early infantile-onset, progressive neurodegenerative phenotype, with symptoms of developmental delay and epileptic encephalopathy developing from, to, months of age. Using whole exome sequencing, compound heterozygous variants were identified in SLC, A, which encodes the sodium-dependent multivitamin transporter, SMVT, protein. SMVT is an important transporter of the B-group vitamins biotin, pantothenate, and lipoate. The protein is ubiquitously expressed and has major roles in vitamin uptake in the digestive system, as well as transport of these vitamins across the blood, brain barrier. Pathogenicity of the identified variants was demonstrated by impaired biotin uptake of mutant SMVT. Identification of this vitamin transporter as the genetic basis of this disorder guided targeted therapeutic intervention, resulting clinically in improvement of the patient, s neurocognitive and neuromotor function. This is the second report of biallelic mutations in SLC, A, leading to a neurodegenerative disorder due to impaired biotin, pantothenate and lipoate uptake. The genetic and phenotypic overlap of these cases confirms mutations in SLC, A, as the genetic cause of this disease phenotype. Recognition of the genetic disorder caused by SLC, A, mutations is essential for early diagnosis and to facilitate timely intervention by triple vitamin, biotin, pantothenate, and lipoate, replacement therapy.Steven W. Polyak ... Andreas W. Schreiber ... Christopher N. Hahn ... Dylan A. Mordaunt ... Drago Bratkovic, Grant W. Booker, Nicholas J. Smith, Hamish S. Scot

Integrated multi-omics for rapid rare disease diagnosis on a national scale

Published online: 8 June 2023Critically ill infants and children with rare diseases need equitable access to rapid and accurate diagnosis to direct clinical management. Over 2 years, the Acute Care Genomics program provided whole-genome sequencing to 290 families whose critically ill infants and children were admitted to hospitals throughout Australia with suspected genetic conditions. The average time to result was 2.9 d and diagnostic yield was 47%. We performed additional bioinformatic analyses and transcriptome sequencing in all patients who remained undiagnosed. Long-read sequencing and functional assays, ranging from clinically accredited enzyme analysis to bespoke quantitative proteomics, were deployed in selected cases. This resulted in an additional 19 diagnoses and an overall diagnostic yield of 54%. Diagnostic variants ranged from structural chromosomal abnormalities through to an intronic retrotransposon, disrupting splicing. Critical care management changed in 120 diagnosed patients (77%). This included major impacts, such as informing precision treatments, surgical and transplant decisions and palliation, in 94 patients (60%). Our results provide preliminary evidence of the clinical utility of integrating multi-omic approaches into mainstream diagnostic practice to fully realize the potential of rare disease genomic testing in a timely manner.Sebastian Lunke ... Peer Arts ... Christopher P. Barnett ..., Chirag V. Patel ... Hamish S. Scott ... Karin S. Kassahn ... et al

Truncating Variants in NAA15 Are Associated with Variable Levels of Intellectual Disability, Autism Spectrum Disorder, and Congenital Anomalies

Genetics of disease, diagnosis and treatmen

Expanding the phenotype of DNMT3A as a cause a congenital myopathy with rhabdomyolysis

Pathogenic variants in DNMT3A are most commonly associated with Tatton-Brown-Rahman Syndrome (TBRS), but includes other phenotypes such as Heyn-Sproul-Jackson syndrome and acute myeloid leukemia (AML). We describe a patient presenting to the neuromuscular clinic with a de novo missense variant in DNMT3A where the striking clinical feature is that of a congenital myopathy with associated episodes of rhabdomyolysis, severe myalgias and chest pain along with phenotypic features associated with TBRS. Muscle biopsy showed minor myopathic features and cardiac investigations revealed mildly impaired bi-ventricular systolic function. We confirmed the DNA methylation profile matched haplo-insufficient TBRS cases, consistent with a loss of methyltransferase activity. Our report emphasizes the phenotypic overlap of patients with syndromic disorders presenting to neuromuscular clinics and limitations of gene panels in establishing a molecular diagnosis.Roula Ghaoui, Thuong T. Hac, d, Jennifer Kerkhof, Haley McConkey, Song Gao, Milena Babic, Rob King, Gianina Ravenscroftf, Barbara Koszyca, Sophia Otto, Nigel G. Laing, Hamish Scott, Bekim Sadikovic, Karin S. Kassahn

Genomic autopsy to identify underlying causes of pregnancy loss and perinatal death

Pregnancy loss and perinatal death are devastating events for families. We assessed ‘genomic autopsy’ as an adjunct to standard autopsy for 200 families who had experienced fetal or newborn death, providing a defnitive or candidate genetic diagnosis in 105 families. Our cohort provides evidence of severe atypical in utero presentations of known genetic disorders and identifes novel phenotypes and disease genes. Inheritance of 42% of defnitive diagnoses were either autosomal recessive (30.8%), X-linked recessive (3.8%) or autosomal dominant (excluding de novos, 7.7%), with risk of recurrence in future pregnancies. We report that at least ten families (5%) used their diagnosis for preimplantation (5) or prenatal diagnosis (5) of 12 pregnancies. We emphasize the clinical importance of genomic investigations of pregnancy loss and perinatal death, with short turnaround times for diagnostic reporting and followed by systematic research follow-up investigations. This approach has the potential to enable accurate counseling for future pregnancies.Alicia B. Byrne ... Peer Arts ... Christopher P. Barnett ... Thuong T. Ha ... T. Yee Khong ... David M. Lawrence ... Lynette Moore ... Andreas W. Schreiber ... Hamish S. Scott ... et al

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation; analyses timings and patterns of tumour evolution; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity; and evaluates a range of more-specialized features of cancer genomes