Publications by authors named "Nicholas Pachter"

Purpose: The Australian Genomics Cardiovascular Disorders Flagship was a national multidisciplinary collaboration. It aimed to investigate the feasibility of genome sequencing (GS) and functional genomics to resolve variants of uncertain significance (VUS) in the clinical management of patients and families with cardiomyopathies, primary arrhythmias, and congenital heart disease (CHD).

Methods: Between April 2019 and December 2021, 600 probands meeting cardiovascular disorder criteria from 17 cardiology and genetics clinics across Australia were enrolled in the Flagship and underwent GS.

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The role of genomic testing in rare disease clinical management is growing. However, geographical and socioeconomic factors contribute to inequitable uptake of testing. Geographical investigations of genomic testing across Australia have not been undertaken.

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Background: Genomic sequencing technology allows for identification of reproductive couples with an increased chance, as compared with that in the general population, of having a child with an autosomal recessive or X-linked genetic condition.

Methods: We investigated the feasibility, acceptability, and outcomes of a nationwide, couple-based genetic carrier screening program in Australia as part of the Mackenzie's Mission project. Health care providers offered screening to persons before pregnancy or early in pregnancy.

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  • Colorectal cancers (CRCs) linked to biallelic germline variants show specific mutational signatures (SBS18+SBS36 and SBS30) that could also be present in adenomas, which are precursors to CRCs.
  • A study sequenced DNA from adenomas and CRCs in biallelic cases and compared them with sporadic cases to investigate these signatures.
  • Results indicated that adenomas in biallelic cases had similar mutational signature proportions as their corresponding CRCs, suggesting testing adenomas could enhance the detection of biallelic cases and improve variant classification for better CRC prevention strategies.
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  • The study aims to establish accurate age-related penetrance figures for various cancer types linked to pathogenic germline variants, which is essential for effective clinical management and variant classification.
  • Researchers used full pedigree data from 146 families across Australia, Spain, and the U.S. to estimate cancer penetrance, adjusting for biases and background cancer risks.
  • The findings reveal high cumulative risks for core cancers associated with Li-Fraumeni syndrome and identify significant lifetime risks for additional cancers, helping refine clinical recommendations for individuals with these pathogenic variants.
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  • * A study analyzed 28 tumors from 25 patients with variants of uncertain significance (VUS) in MMR genes to evaluate how specific tumor characteristics help classify these genetic variants.
  • * The results reclassified 28% of VUS as likely pathogenic, with the majority confirming features like microsatellite instability and MMR deficiency, suggesting that recognizing these characteristics can enhance clinical decision-making.
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  • Many families show unusual cancer clusters but don't fit into known hereditary cancer syndrome categories; they may still carry harmful genetic variants that increase cancer risk.* -
  • In a study of 195 participants with suspected hereditary cancer syndromes, whole-genome sequencing identified pathogenic variants in 5.1% and additional variants with potential health implications in 9.7% of participants.* -
  • The study suggests that using whole-genome sequencing up front is more cost-effective than traditional testing, but broader implementation will hinge on funding decisions and financial perspectives of healthcare payers.*
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  • Routine screening for DNA mismatch repair (MMR) deficiency in certain tumors often results in unresolved cases labeled as suspected Lynch syndrome (SLS), with a study involving 135 such cases across Australia and New Zealand.
  • Targeted sequencing of tumors and matched blood samples revealed that 86.9% of these SLS cases could be classified into specific subtypes, primarily through the detection of double somatic MMR mutations.
  • The research indicates that implementing tumor-focused testing and MLH1 methylation assays in clinical settings can effectively clarify SLS diagnoses, leading to better surveillance and screening for patients.
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  • Routine screening for DNA mismatch repair deficiency in colorectal, endometrial, and sebaceous skin tumors has led to many unresolved cases suspected of Lynch syndrome, affecting 135 patients across Australia and New Zealand.
  • Targeted panel sequencing of tumors and matched blood DNA helped resolve 86.9% of these suspected cases by identifying various factors, including epimutations and germline MMR variants, with double somatic mutations being the most common cause.
  • The study suggests that incorporating tumor sequencing and methylation assays into clinical diagnostics could reduce unresolved cases and improve patient surveillance and screening strategies.
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Background: Truncating variants in desmoplakin (tv) are an important cause of arrhythmogenic cardiomyopathy; however the genetic architecture and genotype-specific risk factors are incompletely understood. We evaluated phenotype, risk factors for ventricular arrhythmias, and underlying genetics of tv cardiomyopathy.

Methods: Individuals with tv and any cardiac phenotype, and their gene-positive family members were included from multiple international centers.

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Reproductive genetic carrier screening (RGCS) provides people with information about their chance of having children with autosomal recessive or X-linked genetic conditions, enabling informed reproductive decision-making. RGCS is recommended to be offered to all couples during preconception or in early pregnancy. However, cost and a lack of awareness may prevent access.

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Background: To inform effective genomic medicine strategies, it is important to examine current approaches and gaps in well-established applications. Lynch syndrome (LS) causes 3-5% of colorectal cancers (CRCs). While guidelines commonly recommend LS tumour testing of all CRC patients, implementation in health systems is known to be highly variable.

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Purpose: Tubo-ovarian cancer (TOC) is a sentinel cancer for and pathogenic variants (PVs). Identification of a PV in the first member of a family at increased genetic risk (the proband) provides opportunities for cancer prevention in other at-risk family members. Although Australian testing rates are now high, PVs in patients with TOC whose diagnosis predated revised testing guidelines might have been missed.

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  • The study emphasizes the need for population-based estimates of breast cancer risk for women carrying pathogenic variants found through gene-panel testing, moving beyond high-risk selections.
  • Researchers tested 2,326 women (1,464 diagnosed with breast cancer and 862 controls) and 6,549 older healthy women for rare genetic variants to assess breast cancer risk.
  • The results revealed that certain gene variants, such as BRCA1 and BRCA2, significantly increased breast cancer risk, highlighting the importance of improving identification methods for women at risk.
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This study aimed to describe the acceptability and perceived barriers and enablers to establish a national registry targeting carriers of pathogenic variants in cancer susceptibility genes from stakeholders' perspectives. Such a registry may effectively target carriers to translate existing research findings into optimised clinical care and provide a population-level resource for further clinical research and new gene and therapy discovery. In-depth interviews were conducted with individuals from four stakeholder groups: carriers of pathogenic variants, healthcare professionals, data custodians from the field of familial cancer, and heads of molecular pathology laboratories.

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Background: The rapid increase in demand for cancer genetic testing in Australia led to the establishment of private Familial Cancer Clinics (FCCs) as alternatives to public sector FCCs. Australian studies conducted in the public sector have shown high patient satisfaction with genetic counselling. No study has investigated patient satisfaction with genetic counselling in the private sector in Australia.

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  • Lynch syndrome is a hereditary cancer syndrome linked to mutations in mismatch repair genes, increasing the risk for various cancers, especially colorectal and endometrial cancer, and recently identified as a risk factor for early-onset aggressive prostate cancer.
  • The IMPACT study, an international research project, is evaluating the effectiveness of prostate-specific antigen (PSA) screening among men aged 40-69 with and without these genetic variants to determine the incidence and characteristics of prostate cancer.
  • Initial findings from the first round of PSA screenings indicate differences in prostate cancer detection and characteristics between men with pathogenic variants compared to age-matched controls who do not carry these variants.
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Background: In 2016 universal screening with mismatch repair protein immunohistochemistry in all newly diagnosed endometrial carcinomas was introduced in Western Australia.

Objective: To compare the prevalence of Lynch syndrome associated endometrial carcinomas between 2016 and 2019 with a historical control (2015). Additionally, to compare the number of cases appropriately referred for genetic assessment.

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  • - The MCM2-7 helicase complex is crucial for DNA replication, and disruptions to it are linked to conditions like Meier-Gorlin syndrome and immune deficiencies, often involving variants in genes like MCM4, MCM5, and others involved in the replication process.
  • - Recent studies identified harmful genetic variants in MCM7 and MCM3 that affect how well the MCM complex forms, impacting DNA replication efficiency and leading to diverse health issues in affected patients.
  • - The findings highlight that even with similar genetic variants in MCM7, patients can exhibit very different symptoms, illustrating the complex relationship between DNA replication disruptions and various clinical outcomes.
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Exome sequencing has enabled molecular diagnoses for rare disease patients but often with initial diagnostic rates of ~25-30%. Here we develop a robust computational pipeline to rank variants for reassessment of unsolved rare disease patients. A comprehensive web-based patient report is generated in which all deleterious variants can be filtered by gene, variant characteristics, OMIM disease and Phenolyzer scores, and all are annotated with an ACMG classification and links to ClinVar.

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Background: The strength of evidence supporting the validity of gene-disease relationships is variable. Hereditary cancer has the additional complexity of low or moderate penetrance for some confirmed disease-associated alleles.

Methods: To promote national consistency in interpretation of hereditary cancer/tumour gene test results, we requested opinions of representatives from Australian Family Cancer Clinics regarding the clinical utility of 157 genes initially collated for a national research project.

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Genetic risk information is relevant to individual patients and also their blood relatives. Health practitioners (HPs) routinely advise patients of the importance of sharing genetic information with family members, especially for clinically actionable conditions where prevention is possible. However, some patients refuse to share genetic results with at-risk relatives, and HPs must choose whether to use or disclose genetic information without consent.

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Reproductive genetic carrier screening aims to offer couples information about their chance of having children with certain autosomal recessive and X-linked genetic conditions. We developed a gene list for use in "Mackenzie's Mission", a research project in which 10,000 couples will undergo screening. Criteria for selecting genes were: the condition should be life-limiting or disabling, with childhood onset, such that couples would be likely to take steps to avoid having an affected child; and/or be one for which early diagnosis and intervention would substantially change outcome.

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In the context of the current global COVID-19 pandemic, this Consensus Statement provides current recommendations for patients with, or at risk of developing, genetic heart disease, and for their health care management and service provision in Australia and New Zealand. Apart from general recommendations, there are specific recommendations for the following conditions: cardiomyopathy, Brugada syndrome (including in children), long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT). Other recommendations are relevant to patient self-care and primary health care.

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Objective: To develop, test, and iterate a comprehensive neuromuscular targeted gene panel in a national referral center.

Methods: We designed two iterations of a comprehensive targeted gene panel for neuromuscular disorders. Version 1 included 336 genes, which was increased to 464 genes in Version 2.

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