Case Report: Next Generation Sequencing in Clinical Practice-A Real Tool for Ending the Protracted Diagnostic Odyssey.
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ABSTRACT:
SUBMITTER: Limonova AS
PROVIDER: S-EPMC8792487 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:MNGIE (Mitochondrial Neurogastrointestinal Encephalomyopathy) is an ultra-rare autosomal recessive disorder that leads to mutations in the nuclear genes encoding thymidine phosphorylase. Symptoms include gastrointestinal dysmotility, cachexia, ptosis, external ophthalmoplegia, sensorimotor neuropathy and asymptomatic leukoencephalopathy. We describe the first case of MNGIE with meningoencephalitis that ultimately led to a familial diagnosis ending a diagnostic odyssey. We retrospectively reviewed the electronic medical records and sent whole exome sequencing for the index case and his family members. We report the variant c.877T>C p.(Cys293Arg) found in TYMP gene in all affected siblings showed typical clinical manifestations related to MNGIE. To the best of our knowledge, this is not described in the literature nor in the population databases dbSNP (Single Nucleotide Polymorphism Database) and gnomAD (Genome Aggregation Database). Additionally, it is located in a highly conserved residue and the bioinformatic analysis suggests it is most probably deleterious. Moreover, we estimated 550 number of cases of MNGIE (including 5 cases in this study) after performing an extensive search in the literature across 3 databases from 1983-2023. In addition, we identified 44 patients with MNGIE-like phenotype in genes other than TYMP. MNGIE-like phenotype affects POLG1, RRM2B, LIG3, RRM1, MTTV1, and MT-RNR1 genes.
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Project description:BackgroundCockayne syndrome (CS) is a rare autosomal recessive disorder characterized by growth failure and multisystemic degeneration. Excision repair cross-complementation group 6 (ERCC6 OMIM: *609413) is the gene most frequently mutated in CS.MethodsA child with pre and postnatal growth failure and progressive neurologic deterioration with multisystem involvement, and with nondiagnostic whole-exome sequencing, was screened for causal variants with whole-genome sequencing (WGS).ResultsWGS identified biallelic ERCC6 variants, including a previously unreported intronic variant. Pathogenicity of these variants was established by demonstrating reduced levels of ERCC6 mRNA and protein expression, normal unscheduled DNA synthesis, and impaired recovery of RNA synthesis in patient fibroblasts following UV-irradiation.ConclusionThe study confirms the pathogenicity of a previously undescribed upstream intronic variant, highlighting the power of genome sequencing to identify noncoding variants. In addition, this report provides evidence for the utility of a combination approach of genome sequencing plus functional studies to provide diagnosis in a child for whom a lengthy diagnostic odyssey, including exome sequencing, was previously unrevealing.
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Project description:We present a patient with a unique neurological phenotype with a progressive neurodegenerative phenotype. An 18-year diagnostic odyssey for the patient ended when exome sequencing identified a homozygous PEX16 mutation suggesting an atypical peroxisomal biogenesis disorder (PBD). Interestingly, the patient's peroxisomal biochemical abnormalities were subtle, such that plasma very-long-chain fatty acids initially failed to provide a diagnosis. This case suggests next-generation sequencing may be diagnostic in some atypical peroxisomal biogenesis disorders.
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Project description:BACKGROUND:More than 100 different pathogens can cause encephalitis. Testing of all the neurological pathogens by conventional methods can be difficult. Metagenomic next-generation sequencing (NGS) could identify the infectious agents in a target-independent manner. The role of this novel method in clinical diagnostic microbiology still needs to be evaluated. In present study, we used metagenomic NGS to search for an infectious etiology in a human immunodeficiency virus (HIV)-infected patient with lethally diffuse brain lesions. Sequences mapping to Toxoplasma gondii were unexpectedly detected. CASE PRESENTATION:A 31-year-old HIV-infected patient presented to hospital in a critical ill condition with a Glasgow coma scale score of 3. Brain magnetic resonance imaging showed diffuse brain abnormalities with contrast enhancement. Metagenomic NGS was performed on DNA extract from 300 ?L patient's cerebrospinal fluid (CSF) with the BGISEQ-50 platform. The sequencing detection identified 65,357 sequence reads uniquely aligned to the Toxoplasma gondii genome. Presence of Toxoplasma gondii genome in CSF was further verified by Toxoplasma gondii-specific polymerase chain reaction and Sanger sequencing. Altogether, those results confirmed the diagnosis of toxoplasmic encephalitis. CONCLUSIONS:This study suggests that metagenomic NGS may be a useful diagnostic tool for toxoplasmic encephalitis. As metagenomic NGS is able to identify all pathogens in a single run, it may be a promising strategy to explore the clinical causative pathogens in central nervous system infections with atypical features.
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Project description:With the completion of the Human Genome Project and advances in genomic sequencing technologies, the use of clinical molecular diagnostics has grown tremendously over the last decade. Next-generation sequencing (NGS) has overcome many of the practical roadblocks that had slowed the adoption of molecular testing for routine clinical diagnosis. In endocrinology, targeted NGS now complements biochemical testing and imaging studies. The goal of this review is to provide clinicians with a guide to the application of NGS to genetic testing for endocrine conditions, by compiling a list of established gene mutations detectable by NGS, and highlighting key phenotypic features of these disorders. As we outline in this review, the clinical utility of NGS-based molecular testing for endocrine disorders is very high. Identifying an exact genetic etiology improves understanding of the disease, provides clear explanation to families about the cause, and guides decisions about screening, prevention and/or treatment. To illustrate this approach, a case of hypophosphatasia with a pathogenic mutation in the ALPL gene detected by NGS is presented.
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Project description:We present, on behalf of EuroGentest and the European Society of Human Genetics, guidelines for the evaluation and validation of next-generation sequencing (NGS) applications for the diagnosis of genetic disorders. The work was performed by a group of laboratory geneticists and bioinformaticians, and discussed with clinical geneticists, industry and patients' representatives, and other stakeholders in the field of human genetics. The statements that were written during the elaboration of the guidelines are presented here. The background document and full guidelines are available as supplementary material. They include many examples to assist the laboratories in the implementation of NGS and accreditation of this service. The work and ideas presented by others in guidelines that have emerged elsewhere in the course of the past few years were also considered and are acknowledged in the full text. Interestingly, a few new insights that have not been cited before have emerged during the preparation of the guidelines. The most important new feature is the presentation of a 'rating system' for NGS-based diagnostic tests. The guidelines and statements have been applauded by the genetic diagnostic community, and thus seem to be valuable for the harmonization and quality assurance of NGS diagnostics in Europe.
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