Genetics in Medicine最新文献

The Clinical Genome Resource (ClinGen) is a National Institutes of Health-funded program founded 10 years ago that defines the clinical relevance of genes and variants for medical and research use. ClinGen working groups develop standards for data sharing and curating genomic knowledge. Expert panels, with >2500 active members from 67 countries, curate the validity of monogenic disease relationships, pathogenicity of genetic variation, dosage sensitivity of genes, and actionability of gene-disease interventions using ClinGen standards, infrastructure, and curation interfaces. Results are available on clinicalgenome.org and classified variants are also submitted to ClinVar, a publicly available database hosted by the National Institutes of Health. As of January 2024, over 2700 genes have been curated (2420 gene-disease relationships for validity, 1557 genes for dosage sensitivity, and 447 gene-condition pairs for actionability), and 5161 unique variants have been classified for pathogenicity. New efforts are underway in somatic cancer, complex disease and pharmacogenomics, and a systematic approach to addressing justice, equity, diversity, and inclusion. ClinGen's knowledge can be used to build evidence-based genetic testing panels, interpret copy-number variation, resolve discrepancies in variant classification, guide disclosure of genomic findings to patients, and assess new predictive algorithms. To get involved in ClinGen activities go to https://www.clinicalgenome.org/start.

Purpose: Clinically significant copy-number variants (CNVs) occur in 1% to 2% of pregnancies and are difficult to detect via prenatal cell-free DNA (cfDNA) screening because of the low fraction of fetal-derived cfDNA in maternal plasma. Here, we use fetal fraction amplification (FFA) and improved computational algorithms to enhance the resolution and sensitivity of CNV detection.

Methods: We implemented and characterized the performance of a hidden Markov model that identifies fetal CNVs. This CNV caller was analytically validated on 117 FFA samples, including 57 fetal-CNV-containing samples, and applied retrospectively to a cohort of more than 300k patient samples.

Results: Our assay was concordant with orthogonal testing and detected fetal CNVs ≥5 Mb with estimated aggregate sensitivity and specificity of >95.1% and >99.7%, respectively. The resolution of CNV detection was fetal fraction dependent, but 97.2% of samples reached ≥5-Mb resolution. Overall, CNVs ≥5 Mb were found in 1 in 500 pregnancies.

Conclusion: FFA improves the sensitivity and resolution of CNV detection in prenatal cfDNA screening, allowing accurate detection of fetal CNVs as small as 1 Mb. Using our approach, we found that clinically significant fetal CNVs were detected more frequently than the common trisomies 13 and 18 that are recommended as part of guideline-based screening.

Purpose: This study details a novel syndromic form of autosomal recessive intellectual disability resulting from recessive variants in GTF3C3, encoding a key component of the DNA-binding transcription factor IIIC, which has a conserved role in RNA polymerase III-mediated transcription.

Methods: Exome sequencing, minigene analysis, molecular modeling, RNA polymerase III reporter gene assays, and Drosophila knockdown models were utilized to characterize GTF3C3 variants.

Results: Twelve affected individuals from 7 unrelated families were identified with homozygous or compound heterozygous missense variants in GTF3C3 including c.503C>T p.(Ala168Val), c.1268T>C p.(Leu423Pro), c.1436A>G p.(Tyr479Cys), c.2419C>T p.(Arg807Cys), and c.2420G>A p.(Arg807His). The cohort presented with intellectual disability, variable nonfamilial facial features, motor impairments, seizures, and cerebellar/corpus callosum malformations. Consistent with disruptions in intra- and intermolecular interactions observed in molecular modeling, RNA polymerase III reporter assays confirmed that the majority of missense variants resulted in a loss of function. Minigene analysis of the recurrent c.503C>T p.(Ala168Val) variant confirmed the introduction of a cryptic donor site into exon 4, resulting in mRNA missplicing. Consistent with the clinical features of this cohort, neuronal loss of Gtf3c3 in Drosophila induced seizure-like behavior, motor impairment, and learning deficits.

Conclusion: These findings confirm that GTF3C3 variants result in an autosomal recessive form of syndromic intellectual disability.

Purpose: Families living with mitochondrial diseases (MD) often endure prolonged diagnostic journeys and invasive testing, yet many remain without a molecular diagnosis. The Australian Genomics Mitochondrial Flagship, comprising clinicians, diagnostic, and research scientists, conducted a prospective national study to identify the diagnostic utility of singleton genomic sequencing using blood samples.

Methods: A total of 140 children and adults living with suspected MD were recruited using modified Nijmegen criteria (MNC) and randomized to either exome + mitochondrial DNA (mtDNA) sequencing or genome sequencing.

Results: Diagnostic yield was 55% (n = 77) with variants in nuclear (n = 37) and mtDNA (n = 18) MD genes, as well as phenocopy genes (n = 22). A nuclear gene etiology was identified in 77% of diagnoses, irrespective of disease onset. Diagnostic rates were higher in pediatric-onset (71%) than adult-onset (31%) cases and comparable in children with non-European (78%) vs European (67%) ancestry. For children, higher MNC scores correlated with increased diagnostic yield and fewer diagnoses in phenocopy genes. Additionally, 3 adult patients had a mtDNA deletion discovered in skeletal muscle that was not initially identified in blood.

Conclusion: Genomic sequencing from blood can simplify the diagnostic pathway for individuals living with suspected MD, especially those with childhood onset diseases and high MNC scores.

Purpose: To characterize the diagnostic and clinical outcomes of a cohort of critically ill infants and children with suspected mitochondrial disorders (MD) undergoing ultrarapid genomic testing as part of a national program.

Methods: Ultrarapid genomic sequencing was performed in 454 families (genome sequencing: n = 290, exome sequencing +/- mitochondrial DNA sequencing: n = 164). In 91 individuals, MD was considered, prompting analysis using an MD virtual gene panel. These individuals were reviewed retrospectively and scored according to modified Nijmegen Mitochondrial Disease Criteria.

Results: A diagnosis was achieved in 47% (43/91) of individuals, 40% (17/43) of whom had an MD. Seven additional individuals in whom an MD was not suspected were diagnosed with an MD after broader analysis. Gene-agnostic analysis led to the discovery of 2 novel disease genes, with pathogenicity validated through targeted functional studies (CRLS1 and MRPL39). Functional studies enabled diagnosis in another 4 individuals. Of the 24 individuals ultimately diagnosed with an MD, 79% had a change in management, which included 53% whose care was redirected to palliation.

Conclusion: Ultrarapid genetic diagnosis of MD in acutely unwell infants and children is critical for guiding decisions about the need for additional investigations and clinical management.

Measurement of lysosomal disease (LD) biomarkers can reveal valuable information about disease status. Lyso-globotriaosylceramide (lyso-Gb₃), glucosylsphingosine (lyso-Gb₁), galactosylsphingosine (psychosine), and glucose tetrasaccharide (Glca1-6Glca1-4Glca1-4Glc, Glc₄) are biomarkers associated with Fabry, Gaucher, Krabbe, and Pompe disease, respectively. Clinical biomarker testing is performed to guide patient management, including monitoring disease progression and initiating treatment, and in diagnostic evaluations of either symptomatic patients or asymptomatic individuals with a positive family history or abnormal newborn screen. Biomarker analysis can be performed through independent analysis of a single analyte or as a multiplex assay measuring analytes for more than one disorder utilizing liquid chromatographic separation and tandem mass spectrometric detection. These guidelines were developed to provide technical standards for biomarker analysis, results interpretation, and results reporting, highlighting Fabry, Gaucher, Krabbe, and Pompe diseases as examples.

Purpose: The TAOK proteins are a group of serine/threonine-protein kinases involved in signalling pathways, cytoskeleton regulation, and neuronal development. TAOK1 variants are associated with a neurodevelopmental disorder (NDD) characterized by distinctive facial features, hypotonia and feeding difficulties. TAOK2 variants have been reported to be associated with autism and early-onset obesity. However, a distinct TAOK2-NDD has not yet been delineated.

Methods: We retrospectively studied the clinical and genetic data of individuals recruited from several centres with TAOK1 and TAOK2 variants that were detected through exome and genome sequencing.

Results: We report 50 individuals with TAOK1 variants with associated phenotypes including neurodevelopmental abnormalities (100%), macrocephaly (83%) and hypotonia (58%). We report male genital anomalies and hypoglycaemia as novel phenotypes. Thirty-seven unique TAOK1 variants were identified. Most of the missense variants clustered in the protein kinase domain at residues that are intolerant to missense variation. We report ten patients with TAOK2 variants with associated phenotypes including neurodevelopmental abnormalities (100%), macrocephaly (75%), autism (75%), and obesity (70%).

Conclusion: We describe the largest cohort of TAOK1-NDD to date, expanding its phenotype and genotype spectrum with thirty novel variants. We delineate the phenotype of a novel TAOK2-NDD associated with neurodevelopmental abnormalities, autism, macrocephaly, and obesity.

Purpose: The value of genetic information for improving the performance of clinical risk prediction models has yielded variable conclusions. Many methodological decisions have the potential to contribute to differential results. We performed multiple modeling experiments integrating clinical and demographic data from electronic health records (EHR) with genetic data to understand which decisions may affect performance.

Methods: Clinical data in the form of structured diagnostic codes, medications, procedural codes, and demographics were extracted from two large independent health systems and polygenic risk scores (PRS) were generated across all patients of European ancestry with genetic data in the corresponding biobanks. Crohn's disease was studied based on its substantial genetic component, established EHR-based definition, and sufficient prevalence for training and testing. We investigated the impact of choices regarding PRS integration method, training sample, model complexity, and performance metrics.

Results: Overall, our results show that including PRS resulted in higher performance but this gain was only robust in situations with limited clinical information. We find consistent performance increases from more compute-intensive models such as random forest, but the impact of other decisions vary by site.

Conclusion: This work highlights the importance of considering methodological decision points in interpreting the impact of PRS on prediction performance in clinical models.

Purpose: Biallelic HPDL variants have been identified as the cause of a progressive childhood-onset movement disorder, with a broad clinical spectrum from severe neurodevelopmental disorder to juvenile-onset pure hereditary spastic paraplegia type 83. This study aims at delineating the geno- and phenotypic spectra of patients with HPDL-related disease, quantitatively modeling the natural history, and uncovering genotype-phenotype associations.

Methods: A cross-sectional analysis of 90 published and 1 novel case was performed, using a Human-Phenotype-Ontology-based approach. Unsupervised phenotypic clustering was used alongside in silico analyses to identify distinct patient subgroups.

Results: The study models the natural history of the HPDL-related disease in a global cohort, clarifying the molecular and phenotypic spectrum and identifying 3 distinct subgroups characterized by differences in onset, clinical trajectories, and survival. It establishes genotype-phenotype associations, showing that the presence of moderately pathogenic missense variants in 1 allele leads to a milder, spastic paraplegic phenotype with later disease onset, whereas biallelic, highly pathogenic missense or truncating variants are associated with a more severe phenotype and reduced life span.

Conclusion: Quantitative and unbiased natural history modeling in HPDL-related disease reveals significant genotype-phenotype associations, providing a foundation for variant interpretation, anticipatory guidance, and choice of outcome measures in future prospective and functional studies.

Purpose: Genomic sequencing of newborns can initiate disease surveillance and therapy for children and may identify at-risk relatives through reverse cascade testing. We explored genetic risk communication and reverse cascade testing among families of newborns who underwent exome sequencing and were identified as having a risk for an autosomal dominant disease.

Methods: We conducted semistructured interviews with parents of newborns enrolled in the BabySeq Project who had a pathogenic or likely pathogenic variant associated with an autosomal dominant childhood- and/or adult-onset disease returned. We used directed content analysis to derive themes.

Results: From 11 families, all first-degree relatives (n = 32, 100%), 29 second-degree relatives (76%), and 26 third-degree relatives (43%) were informed of their risk. All parents (n = 22, 69% of first-degree relatives), 4 (11%) second-degree relatives, and 1 (2%) third-degree relatives underwent cascade testing. Most parents preferred to handle risk communication themselves. Parents with positive cascade testing but no associated symptoms were less inclined to share findings with relatives but highly motivated to share results if the variant's associated disease severity was high, as perceived with adult-onset conditions. One new subtheme, family member traits, was identified and defined as a relative's propensity to anxiety/concern after risk communications but did not diminish risk communication.

Conclusion: Findings can inform more effective notification and testing practices for families of newborns at risk for hereditary genetic conditions.