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This month\u2019s publications show just how versatile HiFi sequencing has become. In September, studies ranged from building the most comprehensive map yet of human genomic imprinting, to evaluating clinical whole-genome sequencing as a potential first-line diagnostic tool, to uncovering hidden hemoglobin variants in large population cohorts and tracking RNA isoforms that could open the door to new cancer immunotherapies.<\/p>\n
Across these areas HiFi sequencing is revealing layers of biology that were previously invisible to standard methods. Keep reading for a closer look at this month\u2019s featured research:<\/p>\n
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Methylation<\/a> | RID<\/a> | Population carrier screening<\/a> | Cancer immunotherapy<\/a><\/p>\n \u00a0<\/p>\n Expanded map of genomic imprinting reveals insight into human disease<\/a><\/p>\n In this preprint, researchers from Children\u2019s Mercy Kansas City (CMKC) find that \u201cHiFi genome sequencing for single-molecular profiling of 5-mC, together with pedigree-based phasing\u00a0in early developmental tissue,\u00a0provides critical insight into previously uncharted loci in the human genome.<\/p>\n Key highlights:<\/p>\n The authors first highlight the limitations of traditional methods: In\u00a0short-read bisulfite sequencing, \u201conly\u00a0~7% of reads are informative for allelic effects\u201d. In contrast, \u00a0\u201cHiFi-GS\u00a0technology generates 5-mC profiles genome-wide from standard sequencing libraries of long reads (\u223c16 kb)\u00a0increasing phasing efficiently over tenfold\u00a0as compared to WGBS. This improved haploid resolution is\u00a0\u201ccritical for POE\u00a0[parent-of-origin effect]\u00a0discovery.\u201d To address this, the team used HiFi WGS on \u201c75 samples from 25 trios\u201d and developed \u201ca\u00a010-fold enhanced map of human imprinting during development\u201d, identifying \u201c52,786 autosomal CpGs in 5852 bins showing POE of CpG methylation (POE-me) of which\u00a060% have previously not been linked to or suggestive of imprinting.\u201d Building on these results, they integrated \u201csummary statistics from population GWAS\u201d and found \u201cenrichment of common (birthweight) and rare (congenital anomalies) disease loci in\u00a0newly identified imprinting regions.\u201d The study also leveraged pedigree-based rare disease cohorts to show \u201cpreponderance of paternal inheritance of pathogenic variants mapping to autosomal dominant OMIM genes with a maternal POE-bin,\u201d identifying two genes (BNC2,\u00a0DNMT1)\u00a0as novel candidate imprinting disorder loci. The authors find that \u201cOur enhanced human map of POE of 5-mC\u00a0significantly extends the current \u201cimprintome\u201d and\u00a0uncovers previously underappreciated genes and variants that appear crucial for human development and disease.\u201d <\/p>\n \u00a0<\/p>\n Conclusion: Alle-specific methylation is often underappreciated but plays a crucial role in understanding what drives development and disease. Short reads miss most of this signal (up to 60%), proving methylation isn\u2019t just extra data, it\u2019s essential for discovery. With HiFi, you get it automatically with every genome. <\/p>\n \u00a0<\/p>\n Clinical long-read sequencing test for genetic disease diagnosis<\/a><\/p>\n In another study by CMKC, the authors, when assessing the potential implementation of long-read sequencing as a first-line clinical test, report \u201cthe comparative diagnostic yield and turnaround time and evaluate the ability to consolidate standard-of-care (SOC) approaches using a single clinical LRS test\u201d<\/p>\n Key highlights: <\/p>\n The team performed a clinical study of HiFi WGS on 235 pediatric patients (ages 0\u201318), comparing results to an age- and phenotype-matched control cohort of 513 patients. Compared to the control group, HiFi sequencing demonstrated a significantly higher diagnostic finding (37% vs. 27%) and a faster turnaround time (27 days vs. 62 days). Even among negative cases, LRS reduced the average time to report from 91 to 29 days. These improvements reflect \u201cthe integrated capability of LRS, which included aberrant methylation, rare expansion disorders, phasing of single-nucleotide variation in a singleton, and detection or refinement of SVs.\u201d The authors note, \u201cthese benefits of clinical LRS are likely only the beginnings of what may be uncovered through expanded testing and further understanding of noncoding regions.\u201d In final, the authors state that when comparing long-read sequencing case results to controls: \u201cClinical LRS offers a single, comprehensive genomic assay for diagnosing genetic disease. The advantage of LRS was explained by its expanded variant detection.\u201d <\/p>\n \u00a0<\/p>\n Conclusion: This landmark study demonstrates how HiFi sequencing can transform pediatric disease discovery by delivering 10% higher success over all prior testing methods, helping to provide families with results in <1 month vs. 3, and reducing the need for multiple stressful and costly rounds of testing. <\/p>\n \u00a0<\/p>\n The rare hemoglobin variants Hb O-Arab and Hb D-Punjab identified in population-based genetic screening throughout Guangxi, China<\/a>\u00a0<\/p>\n \u00a0In this study, researchers out of China report that \u201cSMRT sequencing enables\u00a0efficient and reliable analysis of common and complex or rare hemoglobin variants\u201d:<\/p>\n Autosomal recessive hemoglobinopathies are \u201ccharacterized by a\u00a0high degree of clinical and genetic heterogeneity\u00a0(over 1800 distinct variants involving the hemoglobin gene cluster).\u00a0The authors emphasize that \u201ccomprehensive genetic screening\u00a0for hemoglobin variants\u00a0is crucial for prevention and treatment\u00a0of these conditions\u201d.\u00a0 However, \u201cIn China, the\u00a0conventional methods\u00a0of genetic testing \u2026 typically\u00a0detect only\u00a0the\u00a024 hotspot variants\u00a0commonly found in the Chinese population.\u201d PacBio sequencing overcomes this limitation by \u201ccomprehensively encompass[ing] the full spectrum of known structural variations, single nucleotide variants (SNVs), and insertions\/deletions (InDels)\u00a0involving the HBA1, HBA2, and HBB gene clusters.\u201d The study describes a\u00a0PacBio-based population genetic screening program of 11,019 individuals in Guangxi, China. It also included and in silico\u00a0structural predictions using Alphafold2 to assess the functional impact of rare variants. In total, researchers identified 165 hemoglobin variants, including two ultra-rare (0.0045%) variants at the same genetic locus, with different impacts on hemoglobin structure. \u201cthe identification of the variant expanded the mutational spectrum of the HBB gene in the Chinese population. It should be declared that\u00a0this variant had not been included in the routine screening panels in most clinical settings in China\u201d. They conclude that \u201cSMRT sequencing has emerged as a reliable method for preconception screening and prenatal testing of hemoglobinopathies.\u201d The authors suggest that integrating this approach into screening programs for newborns in high-incidence areas \u201ccould enhance early diagnosis, enable personalized treatment, support informed decision-making, and ultimately improve public health outcomes for these conditions.\u201d <\/p>\n \u00a0<\/p>\n Conclusion: Finding these rare variants matters. Many aren\u2019t included on standard screening panels, which means families could miss crucial information about their health and risk of developing diseases like thalassemia. By uncovering what other technologies miss, PacBio sequencing can help empower answers for families in high-risk regions. <\/p>\n \u00a0<\/p>\n