@article {767, title = {Recurrent De Novo NAHR Reciprocal Duplications in the ATAD3 Gene Cluster Cause a Neurogenetic Trait with Perturbed Cholesterol and Mitochondrial Metabolism.}, journal = {Am J Hum Genet}, volume = {106}, year = {2020}, month = {2020 02 06}, pages = {272-279}, abstract = {

Recent studies have identified both recessive and dominant forms of mitochondrial disease that result from ATAD3A variants. The recessive form includes subjects with biallelic deletions mediated by non-allelic homologous recombination. We report five unrelated neonates with a lethal metabolic disorder characterized by cardiomyopathy, corneal opacities, encephalopathy, hypotonia, and seizures in whom a monoallelic reciprocal duplication at the ATAD3 locus was identified. Analysis of the breakpoint junction fragment indicated that these 67 kb heterozygous duplications were likely mediated by non-allelic homologous recombination at regions of high sequence identity in ATAD3A exon 11 and ATAD3C exon 7. At the recombinant junction, the duplication allele produces a fusion gene derived from ATAD3A and ATAD3C, the protein product of which lacks key functional residues. Analysis of fibroblasts derived from two affected individuals shows that the fusion gene product is expressed and stable. These cells display perturbed cholesterol and mitochondrial DNA organization similar to that observed for individuals with severe ATAD3A deficiency. We hypothesize that the fusion protein acts through a dominant-negative mechanism to cause this fatal mitochondrial disorder. Our data delineate a molecular diagnosis for this disorder, extend the clinical spectrum associated with structural variation at the ATAD3 locus, and identify a third mutational mechanism for ATAD3 gene cluster variants. These results further affirm structural variant mutagenesis mechanisms in sporadic disease traits, emphasize the importance of copy number analysis in molecular genomic diagnosis, and highlight some of the challenges of detecting and interpreting clinically relevant rare gene rearrangements from next-generation sequencing data.

}, keywords = {Amino Acid Sequence, ATPases Associated with Diverse Cellular Activities, Brain Diseases, Cardiomyopathies, Cholesterol, Corneal Opacity, DNA Copy Number Variations, Female, Gene Duplication, Gene Rearrangement, Homologous Recombination, Humans, Infant, Infant, Newborn, Male, Membrane Proteins, Mitochondria, Mitochondrial Diseases, Mitochondrial Proteins, Muscle Hypotonia, Mutation, Protein Conformation, Seizures, Sequence Homology}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2020.01.007}, author = {Gunning, Adam C and Strucinska, Klaudia and Mu{\~n}oz Oreja, Mikel and Parrish, Andrew and Caswell, Richard and Stals, Karen L and Durigon, Romina and Durlacher-Betzer, Karina and Cunningham, Mitchell H and Grochowski, Christopher M and Baptista, Julia and Tysoe, Carolyn and Baple, Emma and Lahiri, Nayana and Homfray, Tessa and Scurr, Ingrid and Armstrong, Catherine and Dean, John and Fernandez Pelayo, Uxoa and Jones, Aleck W E and Taylor, Robert W and Misra, Vinod K and Yoon, Wan Hee and Wright, Caroline F and Lupski, James R and Spinazzola, Antonella and Harel, Tamar and Holt, Ian J and Ellard, Sian} } @article {366, title = {Efficient CNV breakpoint analysis reveals unexpected structural complexity and correlation of dosage-sensitive genes with clinical severity in genomic disorders.}, journal = {Hum Mol Genet}, volume = {26}, year = {2017}, month = {2017 05 15}, pages = {1927-1941}, abstract = {

Genomic disorders are the clinical conditions manifested by submicroscopic genomic rearrangements including copy number variants (CNVs). The CNVs can be identified by array-based comparative genomic hybridization (aCGH), the most commonly used technology for molecular diagnostics of genomic disorders. However, clinical aCGH only informs CNVs in the probe-interrogated regions. Neither orientational information nor the resulting genomic rearrangement structure is provided, which is a key to uncovering mutational and pathogenic mechanisms underlying genomic disorders. Long-range polymerase chain reaction (PCR) is a traditional approach to obtain CNV breakpoint junction, but this method is inefficient when challenged by structural complexity such as often found at the PLP1 locus in association with Pelizaeus-Merzbacher disease (PMD). Here we introduced {\textquoteright}capture and single-molecule real-time sequencing{\textquoteright} (cap-SMRT-seq) and newly developed {\textquoteright}asymmetry linker-mediated nested PCR walking{\textquoteright} (ALN-walking) for CNV breakpoint sequencing in 49 subjects with PMD-associated CNVs. Remarkably, 29 (94\%) of the 31 CNV breakpoint junctions unobtainable by conventional long-range PCR were resolved by cap-SMRT-seq and ALN-walking. Notably, unexpected CNV complexities, including inter-chromosomal rearrangements that cannot be resolved by aCGH, were revealed by efficient breakpoint sequencing. These sequence-based structures of PMD-associated CNVs further support the role of DNA replicative mechanisms in CNV mutagenesis, and facilitate genotype-phenotype correlation studies. Intriguingly, the lengths of gained segments by CNVs are strongly correlated with clinical severity in PMD, potentially reflecting the functional contribution of other dosage-sensitive genes besides PLP1. Our study provides new efficient experimental approaches (especially ALN-walking) for CNV breakpoint sequencing and highlights their importance in uncovering CNV mutagenesis and pathogenesis in genomic disorders.

}, keywords = {Base Sequence, Comparative Genomic Hybridization, DNA Copy Number Variations, DNA Replication, Female, Gene Dosage, Gene Duplication, Gene Rearrangement, Genetic Association Studies, Genome, Human, Genomics, Humans, Male, Mutation, Pelizaeus-Merzbacher Disease, Sequence Analysis, DNA}, issn = {1460-2083}, doi = {10.1093/hmg/ddx102}, author = {Zhang, Ling and Wang, Jingmin and Zhang, Cheng and Li, Dongxiao and Carvalho, Claudia M B and Ji, Haoran and Xiao, Jianqiu and Wu, Ye and Zhou, Weichen and Wang, Hongyan and Jin, Li and Luo, Yang and Wu, Xiru and Lupski, James R and Zhang, Feng and Jiang, Yuwu} } @article {103, title = {Chimeric transcripts resulting from complex duplications in chromosome Xq28.}, journal = {Hum Genet}, volume = {135}, year = {2016}, month = {2016 Feb}, pages = {253-6}, abstract = {

Gene fusions have been observed in somatic alterations in cancer and in schizophrenia. However, the underlying mechanism(s) for their formation are poorly understood. We experimentally demonstrated the expression of splicing variants of in silico predicted chimeric genes F8/CSAG1 and BCAP31/TEX28 in two individuals with de novo complex genomic rearrangements of Xq28; F8/CSAG1 includes exonization of an ERVL-MaLR intronic repetitive element. We provide evidence that replicative repair may contribute to exon shuffling processes and diversify the repertoire of expressed transcripts.

}, keywords = {Antigens, Neoplasm, Base Sequence, Cell Line, Chromosomes, Human, X, Exons, Gene Duplication, Gene Expression Regulation, Gene Rearrangement, Humans, Introns, Male, Membrane Proteins, Molecular Sequence Data, Neoplasm Proteins, RNA Splicing, RNA, Messenger, Transcription, Genetic}, issn = {1432-1203}, doi = {10.1007/s00439-015-1614-x}, author = {Zuccherato, Luciana W and Alleva, Benjamin and Whiters, Marjorie A and Carvalho, Claudia M B and Lupski, James R} } @article {78, title = {Mechanisms underlying structural variant formation in genomic disorders.}, journal = {Nat Rev Genet}, volume = {17}, year = {2016}, month = {2016 Apr}, pages = {224-38}, abstract = {

With the recent burst of technological developments in genomics, and the clinical implementation of genome-wide assays, our understanding of the molecular basis of genomic disorders, specifically the contribution of structural variation to disease burden, is evolving quickly. Ongoing studies have revealed a ubiquitous role for genome architecture in the formation of structural variants at a given locus, both in DNA recombination-based processes and in replication-based processes. These reports showcase the influence of repeat sequences on genomic stability and structural variant complexity and also highlight the tremendous plasticity and dynamic nature of our genome in evolution, health and disease susceptibility.

}, keywords = {Gene Rearrangement, Genetic Diseases, Inborn, Genetic Predisposition to Disease, Genetic Variation, Genome, Human, Genomic Instability, Homologous Recombination, Humans, Models, Genetic, Mutation, Repetitive Sequences, Nucleic Acid}, issn = {1471-0064}, doi = {10.1038/nrg.2015.25}, author = {Carvalho, Claudia M B and Lupski, James R} } @article {116, title = {Novel mutations in the genes TGM1 and ALOXE3 underlying autosomal recessive congenital ichthyosis.}, journal = {Int J Dermatol}, volume = {55}, year = {2016}, month = {2016 May}, pages = {524-30}, abstract = {

BACKGROUND: Ichthyoses are clinically characterized by scaling or hyperkeratosis of the skin or both. It can be an isolated condition limited to the skin or appear secondarily with involvement of other cutaneous or systemic abnormalities.

METHODS: The present study investigated clinical and molecular characterization of three consanguineous families (A, B, C) segregating two different forms of autosomal recessive congenital ichthyosis (ARCI). Linkage in three consanguineous families (A, B, C) segregating two different forms of ARCI was searched by typing microsatellite and single nucleotide polymorphism marker analysis. Sequencing of the two genes TGM1 and ALOXE3 was performed by the dideoxy chain termination method.

RESULTS: Genome-wide linkage analysis established linkage in family A to TGM1 gene on chromosome 14q11 and in families B and C to ALOXE3 gene on chromosome 17p13. Subsequently, sequencing of these genes using samples from affected family members led to the identification of three novel mutations: a missense variant p.Trp455Arg in TGM1 (family A); a nonsense variant p.Arg140* in ALOXE3 (family B); and a complex rearrangement in ALOXE3 (family C).

CONCLUSION: The present study further extends the spectrum of mutations in the two genes involved in causing ARCI. Characterizing the clinical spectrum resulting from mutations in the TGM1 and ALOXE3 genes will improve diagnosis and may direct clinical care of the family members.

}, keywords = {Adolescent, Chromosomes, Human, Pair 14, Chromosomes, Human, Pair 17, Codon, Nonsense, Consanguinity, Female, Gene Rearrangement, Genotype, Humans, Ichthyosiform Erythroderma, Congenital, Ichthyosis, Lamellar, Lipoxygenase, Male, Mutation, Missense, Pakistan, Pedigree, Phenotype, Transglutaminases, Young Adult}, issn = {1365-4632}, doi = {10.1111/ijd.12950}, author = {Ullah, Rahim and Ansar, Muhammad and Durrani, Zaka Ullah and Lee, Kwanghyuk and Santos-Cortez, Regie Lyn P and Muhammad, Dost and Ali, Mahboob and Zia, Muhammad and Ayub, Muhammad and Khan, Suliman and Smith, Josh D and Nickerson, Deborah A and Shendure, Jay and Bamshad, Michael and Leal, Suzanne M and Ahmad, Wasim} } @article {185, title = {Absence of heterozygosity due to template switching during replicative rearrangements.}, journal = {Am J Hum Genet}, volume = {96}, year = {2015}, month = {2015 Apr 02}, pages = {555-64}, abstract = {

We investigated complex genomic rearrangements (CGRs) consisting of triplication copy-number variants (CNVs) that were accompanied by extended regions of copy-number-neutral absence of heterozygosity (AOH) in subjects with multiple congenital abnormalities. Molecular analyses provided observational evidence that in humans, post-zygotically generated CGRs can lead to regional uniparental disomy (UPD) due to template switches between homologs versus sister chromatids by using microhomology to prime DNA replication-a prediction of the replicative repair model, MMBIR. Our findings suggest that replication-based mechanisms might underlie the formation of diverse types of genomic alterations (CGRs and AOH) implicated in constitutional disorders.

}, keywords = {Base Sequence, DNA Copy Number Variations, DNA Repair, DNA Replication, Gene Rearrangement, Humans, In Situ Hybridization, Fluorescence, Loss of Heterozygosity, Models, Genetic, Molecular Sequence Data, Netherlands, Polymerase Chain Reaction, Polymorphism, Single Nucleotide, Sequence Analysis, DNA, Uniparental Disomy}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.01.021}, author = {Carvalho, Claudia M B and Pfundt, Rolph and King, Daniel A and Lindsay, Sarah J and Zuccherato, Luciana W and Macville, Merryn V E and Liu, Pengfei and Johnson, Diana and Stankiewicz, Pawel and Brown, Chester W and Shaw, Chad A and Hurles, Matthew E and Ira, Grzegorz and Hastings, P J and Brunner, Han G and Lupski, James R} } @article {170, title = {Alu-mediated diverse and complex pathogenic copy-number variants within human chromosome 17 at p13.3.}, journal = {Hum Mol Genet}, volume = {24}, year = {2015}, month = {2015 Jul 15}, pages = {4061-77}, abstract = {

Alu repetitive elements are known to be major contributors to genome instability by generating Alu-mediated copy-number variants (CNVs). Most of the reported Alu-mediated CNVs are simple deletions and duplications, and the mechanism underlying Alu-Alu-mediated rearrangement has been attributed to non-allelic homologous recombination (NAHR). Chromosome 17 at the p13.3 genomic region lacks extensive low-copy repeat architecture; however, it is highly enriched for Alu repetitive elements, with a fraction of 30\% of total sequence annotated in the human reference genome, compared with the 10\% genome-wide and 18\% on chromosome 17. We conducted mechanistic studies of the 17p13.3 CNVs by performing high-density oligonucleotide array comparative genomic hybridization, specifically interrogating the 17p13.3 region with \~{}150 bp per probe density; CNV breakpoint junctions were mapped to nucleotide resolution by polymerase chain reaction and Sanger sequencing. Studied rearrangements include 5 interstitial deletions, 14 tandem duplications, 7 terminal deletions and 13 complex genomic rearrangements (CGRs). Within the 17p13.3 region, Alu-Alu-mediated rearrangements were identified in 80\% of the interstitial deletions, 46\% of the tandem duplications and 50\% of the CGRs, indicating that this mechanism was a major contributor for formation of breakpoint junctions. Our studies suggest that Alu repetitive elements facilitate formation of non-recurrent CNVs, CGRs and other structural aberrations of chromosome 17 at p13.3. The common observation of Alu-mediated rearrangement in CGRs and breakpoint junction sequences analysis further demonstrates that this type of mechanism is unlikely attributed to NAHR, but rather may be due to a recombination-coupled DNA replicative repair process.

}, keywords = {Alleles, Alu Elements, Base Sequence, Chromosomes, Human, Pair 17, Comparative Genomic Hybridization, DNA Copy Number Variations, Female, Gene Duplication, Gene Rearrangement, Genome, Human, Genomic Instability, Genomics, Homologous Recombination, Humans, Male, Molecular Sequence Data, Segmental Duplications, Genomic, Sequence Deletion}, issn = {1460-2083}, doi = {10.1093/hmg/ddv146}, author = {Gu, Shen and Yuan, Bo and Campbell, Ian M and Beck, Christine R and Carvalho, Claudia M B and Nagamani, Sandesh C S and Erez, Ayelet and Patel, Ankita and Bacino, Carlos A and Shaw, Chad A and Stankiewicz, Pawe{\l} and Cheung, Sau Wai and Bi, Weimin and Lupski, James R} } @article {107, title = {Comparative Genomic Analyses of the Human NPHP1 Locus Reveal Complex Genomic Architecture and Its Regional Evolution in Primates.}, journal = {PLoS Genet}, volume = {11}, year = {2015}, month = {2015 Dec}, pages = {e1005686}, abstract = {

Many loci in the human genome harbor complex genomic structures that can result in susceptibility to genomic rearrangements leading to various genomic disorders. Nephronophthisis 1 (NPHP1, MIM$\#$ 256100) is an autosomal recessive disorder that can be caused by defects of NPHP1; the gene maps within the human 2q13 region where low copy repeats (LCRs) are abundant. Loss of function of NPHP1 is responsible for approximately 85\% of the NPHP1 cases-about 80\% of such individuals carry a large recurrent homozygous NPHP1 deletion that occurs via nonallelic homologous recombination (NAHR) between two flanking directly oriented ~45 kb LCRs. Published data revealed a non-pathogenic inversion polymorphism involving the NPHP1 gene flanked by two inverted ~358 kb LCRs. Using optical mapping and array-comparative genomic hybridization, we identified three potential novel structural variant (SV) haplotypes at the NPHP1 locus that may protect a haploid genome from the NPHP1 deletion. Inter-species comparative genomic analyses among primate genomes revealed massive genomic changes during evolution. The aggregated data suggest that dynamic genomic rearrangements occurred historically within the NPHP1 locus and generated SV haplotypes observed in the human population today, which may confer differential susceptibility to genomic instability and the NPHP1 deletion within a personal genome. Our study documents diverse SV haplotypes at a complex LCR-laden human genomic region. Comparative analyses provide a model for how this complex region arose during primate evolution, and studies among humans suggest that intra-species polymorphism may potentially modulate an individual{\textquoteright}s susceptibility to acquiring disease-associated alleles.

}, keywords = {Adaptor Proteins, Signal Transducing, Alleles, Animals, Comparative Genomic Hybridization, Evolution, Molecular, Gene Dosage, Gene Rearrangement, Genome, Human, Genomic Structural Variation, Haplotypes, Humans, Kidney Diseases, Cystic, Membrane Proteins, Primates}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1005686}, author = {Yuan, Bo and Liu, Pengfei and Gupta, Aditya and Beck, Christine R and Tejomurtula, Anusha and Campbell, Ian M and Gambin, Tomasz and Simmons, Alexandra D and Withers, Marjorie A and Harris, R Alan and Rogers, Jeffrey and Schwartz, David C and Lupski, James R} } @article {120, title = {Nonrecurrent 17p11.2p12 Rearrangement Events that Result in Two Concomitant Genomic Disorders: The PMP22-RAI1 Contiguous Gene Duplication Syndrome.}, journal = {Am J Hum Genet}, volume = {97}, year = {2015}, month = {2015 Nov 05}, pages = {691-707}, abstract = {

The genomic duplication associated with Potocki-Lupski syndrome (PTLS) maps in close proximity to the duplication associated with Charcot-Marie-Tooth disease type 1A (CMT1A). PTLS is characterized by hypotonia, failure to thrive, reduced body weight, intellectual disability, and autistic features. CMT1A is a common autosomal dominant distal symmetric peripheral polyneuropathy. The key dosage-sensitive genes RAI1 and PMP22 are respectively associated with PTLS and CMT1A. Recurrent duplications accounting for the majority of subjects with these conditions are mediated by nonallelic homologous recombination between distinct low-copy repeat (LCR) substrates. The LCRs flanking a contiguous genomic interval encompassing both RAI1 and PMP22 do not share extensive homology; thus, duplications encompassing both loci are rare and potentially generated by a different mutational mechanism. We characterized genomic rearrangements that simultaneously duplicate PMP22 and RAI1, including nine potential complex genomic rearrangements, in 23 subjects by high-resolution array comparative genomic hybridization and breakpoint junction sequencing. Insertions and microhomologies were found at the breakpoint junctions, suggesting potential replicative mechanisms for rearrangement formation. At the breakpoint junctions of these nonrecurrent rearrangements, enrichment of repetitive DNA sequences was observed, indicating that they might predispose to genomic instability and rearrangement. Clinical evaluation revealed blended PTLS and CMT1A phenotypes with a potential earlier onset of neuropathy. Moreover, additional clinical findings might be observed due to the extra duplicated material included in the rearrangements. Our genomic analysis suggests replicative mechanisms as a predominant mechanism underlying PMP22-RAI1 contiguous gene duplications and provides further evidence supporting the role of complex genomic architecture in genomic instability.

}, keywords = {Abnormalities, Multiple, Charcot-Marie-Tooth Disease, Child, Child, Preschool, Chromosome Disorders, Chromosome Duplication, Chromosomes, Human, Pair 17, Comparative Genomic Hybridization, Female, Follow-Up Studies, Gene Duplication, Gene Rearrangement, Genome, Human, Genomics, Humans, Infant, Male, Models, Genetic, Myelin Proteins, Phenotype, Prognosis, Recombination, Genetic, Transcription Factors}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.10.003}, author = {Yuan, Bo and Harel, Tamar and Gu, Shen and Liu, Pengfei and Burglen, Lydie and Chantot-Bastaraud, Sandra and Gelowani, Violet and Beck, Christine R and Carvalho, Claudia M B and Cheung, Sau Wai and Coe, Andrew and Malan, Val{\'e}rie and Munnich, Arnold and Magoulas, Pilar L and Potocki, Lorraine and Lupski, James R} } @article {176, title = {PacBio-LITS: a large-insert targeted sequencing method for characterization of human disease-associated chromosomal structural variations.}, journal = {BMC Genomics}, volume = {16}, year = {2015}, month = {2015 Mar 19}, pages = {214}, abstract = {

BACKGROUND: Generation of long (>5 Kb) DNA sequencing reads provides an approach for interrogation of complex regions in the human genome. Currently, large-insert whole genome sequencing (WGS) technologies from Pacific Biosciences (PacBio) enable analysis of chromosomal structural variations (SVs), but the cost to achieve the required sequence coverage across the entire human genome is high.

RESULTS: We developed a method (termed PacBio-LITS) that combines oligonucleotide-based DNA target-capture enrichment technologies with PacBio large-insert library preparation to facilitate SV studies at specific chromosomal regions. PacBio-LITS provides deep sequence coverage at the specified sites at substantially reduced cost compared with PacBio WGS. The efficacy of PacBio-LITS is illustrated by delineating the breakpoint junctions of low copy repeat (LCR)-associated complex structural rearrangements on chr17p11.2 in patients diagnosed with Potocki-Lupski syndrome (PTLS; MIM$\#$610883). We successfully identified previously determined breakpoint junctions in three PTLS cases, and also were able to discover novel junctions in repetitive sequences, including LCR-mediated breakpoints. The new information has enabled us to propose mechanisms for formation of these structural variants.

CONCLUSIONS: The new method leverages the cost efficiency of targeted capture-sequencing as well as the mappability and scaffolding capabilities of long sequencing reads generated by the PacBio platform. It is therefore suitable for studying complex SVs, especially those involving LCRs, inversions, and the generation of chimeric Alu elements at the breakpoints. Other genomic research applications, such as haplotype phasing and small insertion and deletion validation could also benefit from this technology.

}, keywords = {Chromosome Aberrations, Gene Library, Gene Rearrangement, Genetic Association Studies, Genomics, High-Throughput Nucleotide Sequencing, Humans, Workflow}, issn = {1471-2164}, doi = {10.1186/s12864-015-1370-2}, author = {Wang, Min and Beck, Christine R and English, Adam C and Meng, Qingchang and Buhay, Christian and Han, Yi and Doddapaneni, Harsha V and Yu, Fuli and Boerwinkle, Eric and Lupski, James R and Muzny, Donna M and Gibbs, Richard A} } @article {288, title = {Replicative mechanisms for CNV formation are error prone.}, journal = {Nat Genet}, volume = {45}, year = {2013}, month = {2013 Nov}, pages = {1319-26}, abstract = {

We investigated 67 breakpoint junctions of gene copy number gains in 31 unrelated subjects. We observed a strikingly high frequency of small deletions and insertions (29\%) apparently originating from polymerase slippage events, in addition to frameshifts and point mutations in homonucleotide runs (13\%), at or flanking the breakpoint junctions of complex copy number variants. These single-nucleotide variants were generated concomitantly with the de novo complex genomic rearrangement (CGR) event. Our findings implicate low-fidelity, error-prone DNA polymerase activity in synthesis associated with DNA repair mechanisms as the cause of local increase in point mutation burden associated with human CGR.

}, keywords = {Base Sequence, DNA Breaks, DNA Copy Number Variations, DNA Repair, DNA Replication, Frameshift Mutation, Gene Rearrangement, Genetic Variation, Genotype, Humans, Sequence Analysis, DNA, Sequence Deletion}, issn = {1546-1718}, doi = {10.1038/ng.2768}, author = {Carvalho, Claudia M B and Pehlivan, Davut and Ramocki, Melissa B and Fang, Ping and Alleva, Benjamin and Franco, Luis M and Belmont, John W and Hastings, P J and Lupski, James R} }