OBJECTIVE: To re-analyze a likely pathogenic variant in the Xq28 region identified by copy number variation sequencing (CNV-seq) through whole genome sequencing (WGS). METHODS: A fetus found to harbor a duplication in the Xq28 region by CNV-seq at Shengjing Hospital Affiliated to China Medical University in May 2023 was selected as the study subject. WGS was carried out for the fetus and its parents. Bioinformatic software was used to analyze the chromosomal structure and CNVs. Quantitative PCR (qPCR) was applied to determine the expression level of the MECP2 gene. This study has been approved by the Ethics Committee of Shengjing Hospital (Ethic No. 2013PS33K). RESULTS: A duplication (ChrX:153302641_153503563) and four breakpoints were identified on the X chromosome of the fetus' father. Bioinformatic analysis revealed that the duplicated region has involved exons 1 to 3 and part of the 5'-UTR of the MECP2 gene, which was inserted into the Xp11 region. Additionally, an inversion was detected in the Xp11 region adjacent to the duplicated segment. RT-PCR results showed normal level of MECP2 mRNA expression. The Xq28 duplication has not encompassed the entire MECP2 gene, nor disrupted its structure or altered its expression. CONCLUSION WGS has enabled more precise diagnosis of chromosomal structural variants and provided guidance for accurate genetic counseling for the affected families.
Humans ; Female ; Chromosomes, Human, X/genetics* ; DNA Copy Number Variations/genetics* ; Whole Genome Sequencing/methods* ; Methyl-CpG-Binding Protein 2/genetics* ; Pregnancy ; Male ; Adult

The exploration of pathogenic single nucleotide polymorphisms in the genome plays a pivotal role in the study of human disease-associated genetic mutations. However, there remains a lack of suitable high-throughput screening platforms to investigate the impact of point mutations on genomic structure and function. CRISPR/Cas9-mediated base editors has enabled large-scale annotation of the human genome and phenotypic characterization of monogenic disorders. Base editors, a precise gene-editing technique capable of achieving targeted base substitutions, can be employed to induce mutations at specific functional sites, thereby observing their effects on gene expression, protein function, and cellular phenotypes. Furthermore, integrating base editors with high-throughput screening technologies allows for large-scale evaluation of multiple candidate sites, accelerating the identification of functional loci and providing a powerful tool for disease research and therapeutic target discovery. This article aims to introduce the working principles of various base editors, including cytosine base editors, adenine base editors, and prime editors, and summarize recent advances in high-throughput screening of functional genomic sites using base-editing techniques.
Humans ; Gene Editing/methods* ; CRISPR-Cas Systems/genetics* ; Genome, Human ; Polymorphism, Single Nucleotide

The International System for Human Cytogenomic Nomenclature (ISCN) is a standardized international nomenclature system established by the International Standing Committee on Human Cytogenomic Nomenclature (ISCN SC). It is designed for describing chromosomal or genomic abnormalities detected by commonly used genetic and genomic techniques including but not limited to karyotyping, fluorescence in situ hybridization, microarray, genome mapping, various region-specific assays, and high-throughput sequencing. With a history spanning over six decades, the ISCN was revised by the ISCN SC in 2024 and officially published in September 2024. This article provides a summary for the updates introduced in the 2024 edition of the International System for Human Cytogenomic Nomenclature.
Humans ; Terminology as Topic ; Genomics ; Genome, Human/genetics*

ACGS Best Practice Guidelines for Variant Classification in Rare Disease 2020, a supplementary practical guidelines, is based on the Standards and Guidelines for the Interpretation of Sequence Variations issued by the American Society for Medical Genetics and Genomics (ACMG) and the Association of Molecular Pathology (AMP) in 2015 by the British Medical Genetics Society under the Clinical Genomics Society (ACGS), and has integrated the detailed rules of standards developed by the ClinGen Sequence Variant Interpretation (SVI) Working Group by 2020. The further development of the ACMG/AMP guidelines is currently undertaken by the ClinGen SVI working group in the United States, which focuses on the classification of high penetrance and protein coding variants. ClinGen has established many expert panels on variants for specific diseases which required various evidence thresholds and is currently developing disease/gene specific guidelines. The British Medical Genetics Society has collected and integrated information on the guidelines for sequence variation classification and their extended rules, forming its own "2020 ACGS Best Practice Guidelines for Rare Disease Variation Classification" and is regularly updating it. The author has translated and summarized it for the reference of Chinese Medical Genetics Practitioners.
Humans ; Genetic Testing ; Genetic Variation ; Genome, Human ; Rare Diseases/genetics* ; China

Copy number variants (CNVs) are common causes of human genetic diseases. CNVs detection has become a routine component of genetic testing, especially for pediatric neurodevelopmental disorders, multiple congenital abnormalities, prenatal evaluation of fetuses with structural anomalies detected by ultrasound. Although the technologies for CNVs detection are continuously improving, the interpretation is still challenging, with significant discordance across different laboratories. In 2020, the American College of Medical Genetics and Genomics (ACMG) and the Clinical Genome Resource (ClinGen) developed a guideline for the interpreting and reporting of constitutional copy number variants, which introduced a quantitative, evidence-based scoring framework. Here, we detailed the key points of interpreting the copy number gain based on the guideline, used six examples of different categories to illuminate the scoring process and principles. We encourage a professional understanding and application of this guideline for the detected copy number gains in China in order to further improve the clinical evaluation accuracy and consistency across different laboratories.
Child ; DNA Copy Number Variations ; Female ; Genetic Testing ; Genetics, Medical ; Genome, Human/genetics* ; Genomics ; Humans ; Pregnancy ; United States

Consensus ; Genetic Diseases, Inborn ; diagnosis ; genetics ; Genome, Human ; genetics ; High-Throughput Nucleotide Sequencing ; Humans ; Practice Guidelines as Topic ; Sequence Analysis, DNA ; Whole Genome Sequencing

As next-generation sequencing (NGS) technology has become widely used to identify genetic causal variants for various diseases and traits, a number of packages for checking NGS data quality have sprung up in public domains. In addition to the quality of sequencing data, sample quality issues, such as gender mismatch, abnormal inbreeding coefficient, cryptic relatedness, and population outliers, can also have fundamental impact on downstream analysis. However, there is a lack of tools specialized in identifying problematic samples from NGS data, often due to the limitation of sample size and variant counts. We developed SeqSQC, a Bioconductor package, to automate and accelerate sample cleaning in NGS data of any scale. SeqSQC is designed for efficient data storage and access, and equipped with interactive plots for intuitive data visualization to expedite the identification of problematic samples. SeqSQC is available at http://bioconductor.org/packages/SeqSQC.
Breast Neoplasms ; genetics ; Cohort Studies ; Continental Population Groups ; genetics ; Female ; Genome, Human ; High-Throughput Nucleotide Sequencing ; methods ; standards ; Humans ; Software ; Whole Exome Sequencing

Adult ; Azoospermia/pathology* ; Carbonic Anhydrases/genetics* ; Congenital Abnormalities/genetics* ; Epithelial Sodium Channels/genetics* ; Gene Expression Regulation/genetics* ; Genome, Human ; Humans ; Infertility, Male/genetics* ; Male ; Male Urogenital Diseases/genetics* ; Mutation ; Vas Deferens/abnormalities*

To further enrich the genetic data of the Chinese Xinjiang Mongolian group, the genetic distribution and forensic parameters of 19 autosomal short tandem repeats (STRs) were investigated. Altogether, 249 alleles were observed in these 19 STRs. The mean values of the polymorphism information content (PIC), match probability (MP), discrimination power (DP), and probability of exclusion (PE) for these 19 STRs were 0.7775, 0.0699, 0.9301, and 0.6085, respectively. Additionally, the cumulative DP and PE values obtained in the Mongolian group were 0.999 999 999 999 999 999 999 995 67 and 0.999 999 992 163, respectively. Furthermore, population genetic analysis of the Mongolian group and 20 published populations was conducted based on the population data of 15 overlapping STRs. Genetic distances indicated that the Mongolian group had closer genetic similarities with the Uyghur, Xibe, and other Chinese populations rather than the other continental populations. Multidimensional scaling analysis further revealed that the Mongolian group possessed similar genetic distributions as most Chinese populations. To sum it all up, these STRs could be used as an extremely efficient tool for forensic applications in the Xinjiang Mongolian group.
Alleles ; Asian People/genetics* ; China ; DNA Fingerprinting ; Databases, Genetic ; Ethnicity/genetics* ; Gene Frequency ; Genetic Markers ; Genetics, Population ; Genome, Human ; Humans ; Linkage Disequilibrium ; Microsatellite Repeats ; Mongolia ; Polymorphism, Genetic ; Principal Component Analysis ; Probability ; Software

OBJECTIVE: This study aimed to investigate DNA sequences that are substantially homologous to the corresponding RNA sequence sections of the hepatitis C virus (HCV). These DNA sequences are present in the whole DNA extracted from peripheral blood mononuclear cells (PBMCs) of HCV-negative subjects. We presumed that these experimentally proven 5'-noncoding region (5'-NCR) homologous DNA sequences could be contained in the extrachromosomal circular DNA (eccDNA) fraction as part of the whole cellular DNA. METHODS: Home-made polymerase chain reaction (PCR) with whole cellular and isolated eccDNA, nucleotide basic local alignment search tool (BLASTn) alignments, and tests for patterns of methylation in selected sequence sections were performed. RESULTS: The PCR tests revealed DNA sequences of up to 320 bp that broadly matched the corresponding sequence sections of known HCV genotypes. In contrast, BLASTn alignment searches of published HCV 5'-NCR sequences with human genome databases revealed only sequence segments of up to 36 bp of the 5'-NCR. The composition of these sequences shows missing base pairs, base pair mismatches as well as complete homology with HCV reference sequences. These short sequence sections are present in numerous copies on both the same and different chromosomes. The selected sequence region within the DNA sequences of the 5'-NCR revealed a broad diversity of individual patterns of methylation. CONCLUSIONS The experimental results confirm our assumption that parts of the HCV 5'-NCR genomic RNA sequences are present at the DNA level in the eccDNA fraction of PBMCs. The tests for methylation patterns therein revealed individual methylomes which could represent an epigenetic feature. The respective sequence section might be subject to genetic regulation.
Computational Biology ; DNA Methylation ; DNA, Circular/genetics* ; DNA, Viral/genetics* ; Genome, Human ; Genomics ; Genotype ; Hepacivirus/genetics* ; Hepatitis C/virology* ; Humans ; Leukocytes, Mononuclear/virology* ; Polymerase Chain Reaction ; RNA, Viral/genetics* ; Sequence Alignment