@article {30, title = {Copy-Number Variation Contributes to the Mutational Load of Bardet-Biedl Syndrome.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Aug 04}, pages = {318-36}, abstract = {

Bardet-Biedl syndrome (BBS) is a defining ciliopathy, notable for extensive allelic and genetic heterogeneity, almost all of which has been identified through sequencing. Recent data have suggested that copy-number variants (CNVs) also contribute to BBS. We used a custom oligonucleotide array comparative genomic hybridization (aCGH) covering 20 genes that encode intraflagellar transport (IFT) components and 74 ciliopathy loci to screen 92 unrelated individuals with BBS, irrespective of their known mutational burden. We identified 17 individuals with exon-disruptive CNVs (18.5\%), including 13 different deletions in eight BBS genes (BBS1, BBS2, ARL6/BBS3, BBS4, BBS5, BBS7, BBS9, and NPHP1) and a deletion and a duplication in other ciliopathy-associated genes (ALMS1 and NPHP4, respectively). By contrast, we found a single heterozygous exon-disruptive event in a BBS-associated gene (BBS9) in 229 control subjects. Superimposing these data with resequencing revealed CNVs to (1) be sufficient to cause disease, (2) Mendelize heterozygous deleterious alleles, and (3) contribute oligogenic alleles by combining point mutations and exonic CNVs in multiple genes. Finally, we report a deletion and a splice site mutation in IFT74, inherited under a recessive paradigm, defining a candidate BBS locus. Our data suggest that CNVs contribute pathogenic alleles to a substantial fraction of BBS-affected individuals and highlight how either deletions or point mutations in discrete splice isoforms can induce hypomorphic mutations in genes otherwise intolerant to deleterious variation. Our data also suggest that CNV analyses and resequencing studies unbiased for previous mutational burden is necessary to delineate the complexity of disease architecture.

}, keywords = {Adolescent, Adult, Alleles, Animals, Bardet-Biedl Syndrome, Child, Child, Preschool, Chromosome Breakpoints, Cytoskeletal Proteins, DNA Copy Number Variations, Exons, Female, Gastrulation, Genes, Recessive, Humans, Infant, Male, Mutation, Pedigree, Young Adult, Zebrafish, Zebrafish Proteins}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2015.04.023}, author = {Lindstrand, Anna and Frangakis, Stephan and Carvalho, Claudia M B and Richardson, Ellen B and McFadden, Kelsey A and Willer, Jason R and Pehlivan, Davut and Liu, Pengfei and Pediaditakis, Igor L and Sabo, Aniko and Lewis, Richard Alan and Banin, Eyal and Lupski, James R and Davis, Erica E and Katsanis, Nicholas} } @article {345, title = {The role of combined SNV and CNV burden in patients with distal symmetric polyneuropathy.}, journal = {Genet Med}, volume = {18}, year = {2016}, month = {2016 05}, pages = {443-51}, abstract = {

PURPOSE: Charcot-Marie-Tooth (CMT) disease is a heterogeneous group of genetic disorders of the peripheral nervous system. Copy-number variants (CNVs) contribute significantly to CMT, as duplication of PMP22 underlies the majority of CMT1 cases. We hypothesized that CNVs and/or single-nucleotide variants (SNVs) might exist in patients with CMT with an unknown molecular genetic etiology.

METHODS: Two hundred patients with CMT, negative for both SNV mutations in several CMT genes and for CNVs involving PMP22, were screened for CNVs by high-resolution oligonucleotide array comparative genomic hybridization. Whole-exome sequencing was conducted on individuals with rare, potentially pathogenic CNVs.

RESULTS: Putatively causative CNVs were identified in five subjects (~2.5\%); four of the five map to known neuropathy genes. Breakpoint sequencing revealed Alu-Alu-mediated junctions as a predominant contributor. Exome sequencing identified MFN2 SNVs in two of the individuals.

CONCLUSION: Neuropathy-associated CNV outside of the PMP22 locus is rare in CMT. Nevertheless, there is potential clinical utility in testing for CNVs and exome sequencing in CMT cases negative for the CMT1A duplication. These findings suggest that complex phenotypes including neuropathy can potentially be caused by a combination of SNVs and CNVs affecting more than one disease-associated locus and contributing to a mutational burden.Genet Med 18 5, 443-451.

}, keywords = {Adult, Age of Onset, Charcot-Marie-Tooth Disease, Child, Preschool, Comparative Genomic Hybridization, DNA Copy Number Variations, Exome, Female, Genetic Predisposition to Disease, GTP Phosphohydrolases, High-Throughput Nucleotide Sequencing, Humans, Male, Mitochondrial Proteins, Motor Neurons, Myelin P0 Protein, Myelin Proteins, Neural Conduction, Polymorphism, Single Nucleotide, Polyneuropathies}, issn = {1530-0366}, doi = {10.1038/gim.2015.124}, author = {Pehlivan, Davut and Beck, Christine R and Okamoto, Yuji and Harel, Tamar and Akdemir, Zeynep H C and Jhangiani, Shalini N and Withers, Marjorie A and Goksungur, Meryem Tuba and Carvalho, Claudia M B and Czesnik, Dirk and Gonzaga-Jauregui, Claudia and Wiszniewski, Wojciech and Muzny, Donna M and Gibbs, Richard A and Rautenstrauss, Bernd and Sereda, Michael W 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 {296, title = {ARMC4 mutations cause primary ciliary dyskinesia with randomization of left/right body asymmetry.}, journal = {Am J Hum Genet}, volume = {93}, year = {2013}, month = {2013 Aug 08}, pages = {357-67}, abstract = {

The motive forces for ciliary movement are generated by large multiprotein complexes referred to as outer dynein arms (ODAs), which are preassembled in the cytoplasm prior to transport to the ciliary axonemal compartment. In humans, defects in structural components, docking complexes, or cytoplasmic assembly factors can cause primary ciliary dyskinesia (PCD), a disorder characterized by chronic airway disease and defects in laterality. By using combined high resolution copy-number variant and mutation analysis, we identified ARMC4 mutations in twelve PCD individuals whose cells showed reduced numbers of ODAs and severely impaired ciliary beating. Transient suppression in zebrafish and analysis of an ENU mouse mutant confirmed in both model organisms that ARMC4 is critical for left-right patterning. We demonstrate that ARMC4 is an axonemal protein that is necessary for proper targeting and anchoring of ODAs.

}, keywords = {Amino Acid Sequence, Animals, Armadillo Domain Proteins, Axoneme, Body Patterning, Cilia, DNA Copy Number Variations, DNA Mutational Analysis, Dyneins, Gene Expression Regulation, Humans, Kartagener Syndrome, Mice, Microtubule-Associated Proteins, Molecular Sequence Data, Mutation, Respiratory System, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2013.06.009}, author = {Hjeij, Rim and Lindstrand, Anna and Francis, Richard and Zariwala, Maimoona A and Liu, Xiaoqin and Li, You and Damerla, Rama and Dougherty, Gerard W and Abouhamed, Marouan and Olbrich, Heike and Loges, Niki T and Pennekamp, Petra and Davis, Erica E and Carvalho, Claudia M B and Pehlivan, Davut and Werner, Claudius and Raidt, Johanna and K{\"o}hler, Gabriele and H{\"a}ffner, Karsten and Reyes-Mugica, Miguel and Lupski, James R and Leigh, Margaret W and Rosenfeld, Margaret and Morgan, Lucy C and Knowles, Michael R and Lo, Cecilia W and Katsanis, Nicholas and Omran, Heymut} } @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} }