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At least 19 recordsLinked to original sources

A complete diploid human genome benchmark for personalized genomics.

Human genome resequencing typically involves mapping reads to a reference genome to call variants; however, this approach suffers from both technical and reference biases, leaving many duplicated and structurally polymorphic regions of the genome unmapped. Consequently, existing variant benchmarks, generated by the same methods, fail to assess these complex regions. To address this limitation, we present a telomere-to-telomere genome benchmark that achieves near-perfect accuracy (i.e. no detectable errors) across 99.4% of the complete, diploid HG002 genome. This benchmark adds 701.4 Mb of autosomal sequence and both sex chromosomes (216.8 Mb), totaling 15.3% of the genome that was absent from prior benchmarks. We also provide a diploid annotation of genes, transposable elements, segmental duplications, and satellite repeats, including 39,144 protein-coding genes across both haplotypes. To facilitate application of the benchmark, we developed tools for measuring the accuracy of sequencing reads, phased variant call sets, and genome assemblies against a diploid reference. Genome-wide analyses show that state-of-the-art de novo assembly methods resolve 2-7% more sequence and outperform variant calling accuracy by an order of magnitude, yielding just one error per 100 kb across 99.9% of the benchmark regions. Adoption of genome-based benchmarking is expected to accelerate the development of cost-effective methods for complete genome sequencing, expanding the reach of genomic medicine to the entire genome and enabling a new era of personalized genomics.

Journal Article

Nuclear-lamin-guided plastic positioning and folding of the human genome.

The human genome exhibits a highly ordered hierarchical architecture, yet the mechanisms governing its large-scale organization remain poorly understood. Here, we generate lamin single-, double-, and triple-knockout human embryonic and mesenchymal stem cells (hESCs and hMSCs) to investigate the role of lamins in the spatial organization of the human genome. Complete lamin depletion in hMSCs triggers extensive genome repositioning, disrupts chromosome territories, and dissolves long-range compartment clustering and mega-loops. Lamin loss affects both the nuclear periphery and interior, causing partial inversion and dispersion of nuclear speckles, accompanied by reduced global transcription and impaired stem cell homeostasis. Re-expression of wild-type lamin A, which interacts with the speckle scaffold protein SON, partially restores the organizational and transcriptional defects, while the disease-associated E161K mutant disrupts SON binding and shows limited recovery. Our results elucidate the multifaceted roles of lamins in nuclear organization and link their dysfunction to the pathogenesis of laminopathies.

Humans

Retrotransposon-based mechanisms for transgene addition to the human genome.

When human disease arises from a loss of function caused by diverse mutant alleles of the same gene, the patient population could be best served by a clinical therapy that achieves genome safe-harbor supplementation with a functional transgene. Until recently, transgene delivery strategies have shared the disadvantages of induced immune responses and/or genome mutagenesis from untargeted DNA insertion. As a different strategy, several groups recently described the use of retrotransposon proteins to accomplish transgene insertion by RNA-templated cDNA synthesis directly into the genome. In some strategies, gene insertion relies on the retrotransposon protein to bring a transgene-encoding template RNA to the target site. Retrotransposon protein positioning of template RNA for cDNA synthesis minimizes the requirement for RNA base-pairing to target-site DNA. This review presents an overview of RNA-templated DNA synthesis in cells as backdrop for describing recent uses of retrotransposon reverse transcriptases to supplement the human genome.

Journal Article

Nonhomologous recombination in the human genome: deletions in the human factor VIII gene.

Four deletions in the human factor VIII gene have been characterized at the sequence level in patients with hemophilia A. Deletion JH 1 extends 57 kb from IVS 10 to IVS 18. Intron 13 and exon 14 are partially deleted in patients JH 7 and JH 37, with a loss of 3.2 and 2.4 kb of DNA, respectively. The 3' deletion breakpoint of the JH 21 event resides in intron 3 and extends 5' into intron 1, resulting in the loss of exons 2 and 3. Seven of the eight breakpoints sequenced (5' and 3' for each of the four deletions) occur in nonrepetitive sequence, while the 3' breakpoint of the JH 1 resides in an Alu repetitive element. All of the deletions are the result of nonhomologous recombination. The 5' and 3' breakpoints of JH 1, JH 7, and JH 37 share 2- to 3-bp homologies at the deletion junctions. In contrast, two nucleotides have been inserted at the JH 21 deletion junction. Short sequence homologies may facilitate end-joining reactions in nonhomologous recombination events.

Base Sequence

Vacuolar type H(+)-ATPase genes: presence of four genes including pseudogenes for the 16-kDa proteolipid subunit in the human genome.

Genes for the human vacuolar type H(+)-ATPase proteolipid (16-kDa) subunit were cloned and their nucleotide sequences were determined. Comparison of the deduced sequences indicated that at least four genes including pseudogenes are present in the human genome. One of them corresponded to that for the 16-kDa subunit expressed in HeLa cells. The coding sequence was separated by two introns. The second intron was located in the DNA segment giving a loop between the second and third transmembrane helices, supporting the idea that the 16-kDa subunit was evolved by gene duplication. The primary sequence determined from the second clone had a termination codon behind the third transmembrane helix. Possible translation products from the other two clones had no putative acidic residues essential for proton transport function of the 16-kDa subunit. Thus, it is interesting to know whether these genes are transcribed, since they may have unique cellular functions.

Base Sequence

The implications of the Human Genome Project for family practice.

The Human Genome Project is an international effort to map and sequence the human genome. The information it will generate has been referred to by some as the "new anatomy," and may play an important role in the future of medicine. However, as with any new technological advancement, the outcome of the Human Genome Project and the subsequent availability of new technology will raise a myriad of ethical, legal, and social concerns. The fear is that this technology will be applied in the clinical setting before the appropriate infrastructure is in place to deal with the issues it will raise. The family physician, far from being merely an interested observer in this process, will be responsible for the delivery of much of this technology as it becomes available. As an intermediary between the technology and the individual patient, the physician has a unique obligation to join in the thoughtful consideration and debate of these issues.

Abortion, Induced

A second-generation linkage map of the human genome.

A linkage map of the human genome has been constructed based on the segregation analysis of 814 newly characterized polymorphic loci containing short tracts of (C-A)n repeats in a panel of DNAs from eight large families. Statistical linkage analysis placed 813 of the markers into 23 linkage groups corresponding to the 22 autosomes and the X chromosome; 605 show a heterozygosity above 0.7 and 553 could be ordered with odds ratios above 1,000:1. The distance spanned corresponds to approximately 90% of the estimated length of the human genome.

Chromosome Mapping

[Ethical and social issues on the human genome analysis].

The modern technologies for human genome analysis raise a variety of ethical and social questions. The pre-symptomatic diagnostic of diseases of late expression is becoming possible for a rapidly increasing number of situations. The use of that knowledge by employers, insurance companies, schools, and society in general, could lead to discriminations and stigmatizations, in addition to adverse psychological reactions. DNA fingerprinting raises questions of privacy and personal autonomy in its applications to paternity proof, criminal proceedings, and establishment of data banks. The project of the immediate and complete sequencing of the human genome will lead to questions of economical ethics, as well as of access, commercialization and property rights of scientific information and materials obtained. It also favours a reducionistic mentality and international unbalances. The molecular biology of humans, which will follow the complete sequencing of the genome, may foster a rethinking of the concepts of freedom of self-determination (basic for moral responsibility) and of equality. The gene therapy and its possible extension to the betterment of the human species, pose questions of ethical limits to this technology. All these problems will have to be answered in terms of the application of the principle of ethical freedom for self-fulfillment, as a right of the human person, as well as of science and society. Scientific, economic and social interests have to be subordinated to the dignity of the human person.

DNA Fingerprinting

Archaic ancestry inference in imputed ancient human genomes.

When modern humans expanded from Africa into Eurasia, they interbred with archaic hominins such as Neanderthals and Denisovans. This introgression shaped human evolution, yet most insights have been gained from present-day genomes, leaving little known about how archaic variants evolved after interbreeding. Ancient genomes offer a direct view of this process, but low coverage and poor quality have limited their use. Recent advances in genotype imputation offer a way to overcome these challenges by reconstructing missing information from reference panels and recovering evolutionary signals from low-coverage data. Here, we show that imputation enables accurate detection and quantification of archaic introgression in ancient genomes, improves local archaic ancestry inference, and that regions of archaic ancestry are imputed with especially high accuracy. We further demonstrate that imputed genomes can reconstruct the trajectories of introgressed haplotypes, distinguish populations across time and geography, and identify both known and additional candidates for adaptive introgression.

Humans

Medium reiteration frequency repetitive sequences in the human genome.

Fourteen novel medium reiteration frequency (MER) families were found, in the human genome, by using two different methods. Repetition frequencies per haploid human genome were estimated for each of these families as well as for six previously described MER DNA families. By these measurements, the families were found to contain variable numbers of elements, ranging from 200 to 10,000 copies per haploid human genome.

Base Sequence