@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 {79, title = {DVL3 Alleles Resulting in a -1 Frameshift of the Last Exon Mediate Autosomal-Dominant Robinow Syndrome.}, journal = {Am J Hum Genet}, volume = {98}, year = {2016}, month = {2016 Mar 03}, pages = {553-561}, abstract = {

Robinow syndrome is a rare congenital disorder characterized by mesomelic limb shortening, genital hypoplasia, and distinctive facial features. Recent reports have identified, in individuals with dominant Robinow syndrome, a specific type of variant characterized by being uniformly located in the penultimate exon of DVL1 and resulting in a -1 frameshift allele with a premature termination codon that escapes nonsense-mediated decay. Here, we studied a cohort of individuals who had been clinically diagnosed with Robinow syndrome but who had not received a molecular diagnosis from variant studies of DVL1, WNT5A, and ROR2. Because of the uniform location of frameshift variants in DVL1-mediated Robinow syndrome and the functional redundancy of DVL1, DVL2, and DVL3, we elected to pursue direct Sanger sequencing of the penultimate exon of DVL1 and its paralogs DVL2 and DVL3 to search for potential disease-associated variants. Remarkably, targeted sequencing identified five unrelated individuals harboring heterozygous, de novo frameshift variants in DVL3, including two splice acceptor mutations and three 1 bp deletions. Similar to the variants observed in DVL1-mediated Robinow syndrome, all variants in DVL3 result in a -1 frameshift, indicating that these highly specific alterations might be a common cause of dominant Robinow syndrome. Here, we review the current knowledge of these peculiar variant alleles in DVL1- and DVL3-mediated Robinow syndrome and further elucidate the phenotypic features present in subjects with DVL1 and DVL3 frameshift mutations.

}, keywords = {Adaptor Proteins, Signal Transducing, Alleles, Base Sequence, Codon, Nonsense, Craniofacial Abnormalities, Dishevelled Proteins, Dwarfism, Exons, Female, Frameshift Mutation, Genetic Variation, Humans, Limb Deformities, Congenital, Male, Molecular Sequence Data, Phosphoproteins, Proto-Oncogene Proteins, Receptor Tyrosine Kinase-like Orphan Receptors, Sequence Analysis, DNA, Sequence Deletion, Urogenital Abnormalities, Wnt Proteins, Wnt-5a Protein}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.01.005}, author = {White, Janson J and Mazzeu, Juliana F and Hoischen, Alexander and Bayram, Yavuz and Withers, Marjorie and Gezdirici, Alper and Kimonis, Virginia and Steehouwer, Marloes and Jhangiani, Shalini N and Muzny, Donna M and Gibbs, Richard A and van Bon, Bregje W M and Sutton, V Reid and Lupski, James R and Brunner, Han G and Carvalho, Claudia M B} } @article {119, title = {Mechanisms for the Generation of Two Quadruplications Associated with Split-Hand Malformation.}, journal = {Hum Mutat}, volume = {37}, year = {2016}, month = {2016 Feb}, pages = {160-4}, abstract = {

Germline copy-number variants (CNVs) involving quadruplications are rare and the mechanisms generating them are largely unknown. Previously, we reported a 20-week gestation fetus with split-hand malformation; clinical microarray detected two maternally inherited triplications separated by a copy-number neutral region at 17p13.3, involving BHLHA9 and part of YWHAE. Here, we describe an 18-month-old male sibling of the previously described fetus with split-hand malformation. Custom high-density microarray and digital droplet PCR revealed the copy-number gains were actually quadruplications in the mother, the fetus, and her later born son. This quadruplication-normal-quadruplication pattern was shown to be expanded from the triplication-normal-triplication CNV at the same loci in the maternal grandmother. We mapped two breakpoint junctions and demonstrated that both are mediated by Alu repetitive elements and identical in these four individuals. We propose a three-step process combining Alu-mediated replicative-repair-based mechanism(s) and intergenerational, intrachromosomal nonallelic homologous recombination to generate the quadruplications in this family.

}, keywords = {14-3-3 Proteins, Adult, Aged, Alu Elements, Base Sequence, Basic Helix-Loop-Helix Transcription Factors, Chromosome Duplication, Chromosomes, Human, Pair 17, DNA Copy Number Variations, Female, Genetic Loci, Genome, Human, Hand Deformities, Congenital, Humans, Infant, Male, Molecular Sequence Data, Pedigree, Sequence Alignment, Sequence Analysis, DNA}, issn = {1098-1004}, doi = {10.1002/humu.22929}, author = {Gu, Shen and Posey, Jennifer E and Yuan, Bo and Carvalho, Claudia M B and Luk, H M and Erikson, Kelly and Lo, Ivan F M and Leung, Gordon K C and Pickering, Curtis R and Chung, Brian H Y and Lupski, James R} } @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 {183, title = {DVL1 frameshift mutations clustering in the penultimate exon cause autosomal-dominant Robinow syndrome.}, journal = {Am J Hum Genet}, volume = {96}, year = {2015}, month = {2015 Apr 02}, pages = {612-22}, abstract = {

Robinow syndrome is a genetically heterogeneous disorder characterized by mesomelic limb shortening, genital hypoplasia, and distinctive facial features and for which both autosomal-recessive and autosomal-dominant inheritance patterns have been described. Causative variants in the non-canonical signaling gene WNT5A underlie a subset of autosomal-dominant Robinow syndrome (DRS) cases, but most individuals with DRS remain without a molecular diagnosis. We performed whole-exome sequencing in four unrelated DRS-affected individuals without coding mutations in WNT5A and found heterozygous DVL1 exon 14 mutations in three of them. Targeted Sanger sequencing in additional subjects with DRS uncovered DVL1 exon 14 mutations in five individuals, including a pair of monozygotic twins. In total, six distinct frameshift mutations were found in eight subjects, and all were heterozygous truncating variants within the penultimate exon of DVL1. In five families in which samples from unaffected parents were available, the variants were demonstrated to represent de novo mutations. All variant alleles are predicted to result in a premature termination codon within the last exon, escape nonsense-mediated decay (NMD), and most likely generate a C-terminally truncated protein with a distinct -1 reading-frame terminus. Study of the transcripts extracted from affected subjects{\textquoteright} leukocytes confirmed expression of both wild-type and variant alleles, supporting the hypothesis that mutant mRNA escapes NMD. Genomic variants identified in our study suggest that truncation of the C-terminal domain of DVL1, a protein hypothesized to have a downstream role in the Wnt-5a non-canonical pathway, is a common cause of DRS.

}, keywords = {Adaptor Proteins, Signal Transducing, Amino Acid Sequence, Base Sequence, Craniofacial Abnormalities, Dishevelled Proteins, DNA Primers, Dwarfism, Exome, Exons, Frameshift Mutation, Gene Components, Humans, Limb Deformities, Congenital, Molecular Sequence Data, Phosphoproteins, Sequence Analysis, DNA, Urogenital Abnormalities}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.02.015}, author = {White, Janson and Mazzeu, Juliana F and Hoischen, Alexander and Jhangiani, Shalini N and Gambin, Tomasz and Alcino, Michele Calijorne and Penney, Samantha and Saraiva, Jorge M and Hove, Hanne and Skovby, Flemming and Kayserili, H{\"u}lya and Estrella, Elicia and Vulto-van Silfhout, Anneke T and Steehouwer, Marloes and Muzny, Donna M and Sutton, V Reid and Gibbs, Richard A and Lupski, James R and Brunner, Han G and van Bon, Bregje W M and Carvalho, Claudia M B} } @article {209, title = {Dosage changes of a segment at 17p13.1 lead to intellectual disability and microcephaly as a result of complex genetic interaction of multiple genes.}, journal = {Am J Hum Genet}, volume = {95}, year = {2014}, month = {2014 Nov 06}, pages = {565-78}, abstract = {

The 17p13.1 microdeletion syndrome is a recently described genomic disorder with a core clinical phenotype of intellectual disability, poor to absent speech, dysmorphic features, and a constellation of more variable clinical features, most prominently microcephaly. We identified five subjects with copy-number variants (CNVs) on 17p13.1 for whom we performed detailed clinical and molecular studies. Breakpoint mapping and retrospective analysis of published cases refined the smallest region of overlap (SRO) for microcephaly to a genomic interval containing nine genes. Dissection of this phenotype in zebrafish embryos revealed a complex genetic architecture: dosage perturbation of four genes (ASGR1, ACADVL, DVL2, and GABARAP) impeded neurodevelopment and decreased dosage of the same loci caused a reduced mitotic index in~vitro. Moreover, epistatic analyses in~vivo showed that dosage perturbations of discrete gene pairings induce microcephaly. Taken together, these studies support a model in which concomitant dosage perturbation of multiple genes within the CNV drive the microcephaly and possibly other neurodevelopmental phenotypes associated with rearrangements in the 17p13.1 SRO.

}, keywords = {Abnormalities, Multiple, Acyl-CoA Dehydrogenase, Long-Chain, Adaptor Proteins, Signal Transducing, Animals, Asialoglycoprotein Receptor, Base Sequence, Cell Line, Chromosome Breakpoints, Chromosome Deletion, Chromosomes, Human, Pair 17, Dishevelled Proteins, Flow Cytometry, Gene Dosage, Humans, Immunohistochemistry, Intellectual Disability, Microcephaly, Microtubule-Associated Proteins, Molecular Sequence Data, Phosphoproteins, Retrospective Studies, Sequence Analysis, DNA, Smith-Magenis Syndrome, Syndrome, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2014.10.006}, author = {Carvalho, Claudia M B and Vasanth, Shivakumar and Shinawi, Marwan and Russell, Chad and Ramocki, Melissa B and Brown, Chester W and Graakjaer, Jesper and Skytte, Anne-Bine and Vianna-Morgante, Angela M and Krepischi, Ana C V and Patel, Gayle S and Immken, LaDonna and Aleck, Kyrieckos and Lim, Cynthia and Cheung, Sau Wai and Rosenberg, Carla and Katsanis, Nicholas and Lupski, James R} } @article {285, title = {Exonic duplication CNV of NDRG1 associated with autosomal-recessive HMSN-Lom/CMT4D.}, journal = {Genet Med}, volume = {16}, year = {2014}, month = {2014 May}, pages = {386-394}, abstract = {

PURPOSE: Copy-number variations as a mutational mechanism contribute significantly to human disease. Approximately one-half of the patients with Charcot-Marie-Tooth (CMT) disease have a 1.4 Mb duplication copy-number variation as the cause of their neuropathy. However, non-CMT1A neuropathy patients rarely have causative copy-number variations, and to date, autosomal-recessive disease has not been associated with copy-number variation as a mutational mechanism.

METHODS: We performed Agilent 8 {\texttimes} 60 K array comparative genomic hybridization on DNA from 12 recessive Turkish families with CMT disease. Additional molecular studies were conducted to detect breakpoint junctions and to evaluate gene expression levels in a family in which we detected an intragenic duplication copy-number variation.

RESULTS: We detected an ~6.25 kb homozygous intragenic duplication in NDRG1, a gene known to be causative for recessive HMSNL/CMT4D, in three individuals from a Turkish family with CMT neuropathy. Further studies showed that this intragenic copy-number variation resulted in a homozygous duplication of exons 6-8 that caused decreased mRNA expression of NDRG1.

CONCLUSION: Exon-focused high-resolution array comparative genomic hybridization enables the detection of copy-number variation carrier states in recessive genes, particularly small copy-number variations encompassing or disrupting single genes. In families for whom a molecular diagnosis has not been elucidated by conventional clinical assays, an assessment for copy-number variations in known CMT genes might be considered.

}, keywords = {Adult, Base Sequence, Cell Cycle Proteins, Charcot-Marie-Tooth Disease, Comparative Genomic Hybridization, DNA Copy Number Variations, Female, Gene Duplication, Gene Expression, Genes, Recessive, Humans, Intracellular Signaling Peptides and Proteins, Male, Mutation, Refsum Disease, Sequence Analysis, DNA, Turkey, Young Adult}, issn = {1530-0366}, doi = {10.1038/gim.2013.155}, author = {Okamoto, Yuji and Goksungur, Meryem Tuba and Pehlivan, Davut and Beck, Christine R and Gonzaga-Jauregui, Claudia and Muzny, Donna M and Atik, Mehmed M and Carvalho, Claudia M B and Matur, Zeliha and Bayraktar, Serife and Boone, Philip M and Akyuz, Kaya and Gibbs, Richard A and Battaloglu, Esra and Parman, Yesim and Lupski, James R} } @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} }