@article {782, title = {CNVs cause autosomal recessive genetic diseases with or without involvement of SNV/indels.}, journal = {Genet Med}, volume = {22}, year = {2020}, month = {2020 10}, pages = {1633-1641}, abstract = {

PURPOSE: Improved resolution of molecular diagnostic technologies enabled detection of smaller sized exonic level copy-number variants (CNVs). The contribution of CNVs to autosomal recessive (AR) conditions may be better recognized using a large clinical cohort.

METHODS: We retrospectively investigated the CNVs{\textquoteright} contribution to AR conditions in cases subjected to chromosomal microarray analysis (CMA, N = ~70,000) and/or clinical exome sequencing (ES, N = ~12,000) at Baylor Genetics; most had pediatric onset neurodevelopmental disorders.

RESULTS: CNVs contributed to biallelic variations in 87 cases, including 81 singletons and three affected sibling pairs. Seventy cases had CNVs affecting both alleles, and 17 had a CNV and a single-nucleotide variant (SNV)/indel in trans. In total, 94.3\% of AR-CNVs affected one gene; among these 41.4\% were single-exon and 35.0\% were multiexon partial-gene events. Sixty-nine percent of homozygous AR-CNVs were embedded in homozygous genomic intervals. Five cases had large deletions unmasking an SNV/indel on the intact allele for a recessive condition, resulting in multiple molecular diagnoses.

CONCLUSIONS: AR-CNVs are often smaller in size, transmitted through generations, and underrecognized due to limitations in clinical CNV detection methods. Our findings from a large clinical cohort emphasized integrated CNV and SNV/indel analyses for precise clinical and molecular diagnosis especially in the context of genomic disorders.

}, keywords = {Child, DNA Copy Number Variations, Exons, Humans, INDEL Mutation, Retrospective Studies, Whole Exome Sequencing}, issn = {1530-0366}, doi = {10.1038/s41436-020-0864-8}, author = {Yuan, Bo and Wang, Lei and Liu, Pengfei and Shaw, Chad and Dai, Hongzheng and Cooper, Lance and Zhu, Wenmiao and Anderson, Stephanie A and Meng, Linyan and Wang, Xia and Wang, Yue and Xia, Fan and Xiao, Rui and Braxton, Alicia and Peacock, Sandra and Schmitt, Eric and Ward, Patricia A and Vetrini, Francesco and He, Weimin and Chiang, Theodore and Muzny, Donna and Gibbs, Richard A and Beaudet, Arthur L and Breman, Amy M and Smith, Janice and Cheung, Sau Wai and Bacino, Carlos A and Eng, Christine M and Yang, Yaping and Lupski, James R and Bi, Weimin} } @article {720, title = {Xq22 deletions and correlation with distinct neurological disease traits in females: Further evidence for a contiguous gene syndrome.}, journal = {Hum Mutat}, volume = {41}, year = {2020}, month = {2020 01}, pages = {150-168}, abstract = {

Xq22 deletions that encompass PLP1 (Xq22-PLP1-DEL) are notable for variable expressivity of neurological disease traits in females ranging from a mild late-onset form of spastic paraplegia type 2 (MIM$\#$ 312920), sometimes associated with skewed X-inactivation, to an early-onset neurological disease trait (EONDT) of severe developmental delay, intellectual disability, and behavioral abnormalities. Size and gene content of Xq22-PLP1-DEL vary and were proposed as potential molecular etiologies underlying variable expressivity in carrier females where two smallest regions of overlap (SROs) were suggested to influence disease. We ascertained a cohort of eight unrelated patients harboring Xq22-PLP1-DEL and performed high-density array comparative genomic hybridization~and breakpoint-junction sequencing. Molecular characterization of Xq22-PLP1-DEL from 17 cases (eight herein and nine published) revealed an overrepresentation of breakpoints that reside within repeats (11/17, ~65\%) and the clustering of ~47\% of proximal breakpoints in a genomic instability hotspot with characteristic non-B DNA density. These findings implicate a potential role for genomic architecture in stimulating the formation of Xq22-PLP1-DEL. The correlation of Xq22-PLP1-DEL gene content with neurological disease trait in female cases enabled refinement of the associated SROs to a single genomic interval containing six genes. Our data support the hypothesis that genes contiguous to PLP1 contribute to EONDT.

}, keywords = {Child, Child, Preschool, Chromosome Breakpoints, Chromosome Deletion, Chromosome Mapping, Chromosomes, Human, X, Comparative Genomic Hybridization, Female, Genetic Association Studies, Genetic Predisposition to Disease, Humans, Male, Nervous System Diseases, Pedigree, Phenotype, Quantitative Trait, Heritable, Repetitive Sequences, Nucleic Acid, Sex Factors, Syndrome, X Chromosome Inactivation}, issn = {1098-1004}, doi = {10.1002/humu.23902}, author = {Hijazi, Hadia and Coelho, Fernanda S and Gonzaga-Jauregui, Claudia and Bernardini, Laura and Mar, Soe S and Manning, Melanie A and Hanson-Kahn, Andrea and Naidu, Sakkubai and Srivastava, Siddharth and Lee, Jennifer A and Jones, Julie R and Friez, Michael J and Alberico, Thomas and Torres, Barbara and Fang, Ping and Cheung, Sau Wai and Song, Xiaofei and Davis-Williams, Angelique and Jornlin, Carly and Wight, Patricia A and Patyal, Pankaj and Taube, Jennifer and Poretti, Andrea and Inoue, Ken and Zhang, Feng and Pehlivan, Davut and Carvalho, Claudia M B and Hobson, Grace M and Lupski, James R} } @article {515, title = {Clinical exome sequencing reveals locus heterogeneity and phenotypic variability of cohesinopathies.}, journal = {Genet Med}, volume = {21}, year = {2019}, month = {2019 03}, pages = {663-675}, abstract = {

PURPOSE: Defects in the cohesin pathway are associated with cohesinopathies, notably Cornelia de Lange syndrome (CdLS). We aimed to delineate pathogenic variants~in known and candidate cohesinopathy genes from a clinical exome perspective.

METHODS: We retrospectively studied patients referred for clinical exome sequencing (CES, N = 10,698). Patients with causative variants in novel or recently described cohesinopathy genes were enrolled for phenotypic characterization.

RESULTS: Pathogenic or likely pathogenic single-nucleotide and insertion/deletion variants (SNVs/indels) were identified in established disease genes including NIPBL (N = 5), SMC1A (N = 14), SMC3 (N = 4), RAD21 (N = 2), and HDAC8 (N = 8). The phenotypes in this genetically defined cohort skew towards the mild end of CdLS spectrum as compared with phenotype-driven cohorts. Candidate or recently reported cohesinopathy genes were supported by de novo SNVs/indels in STAG1 (N = 3), STAG2 (N = 5), PDS5A (N = 1), and WAPL (N = 1), and one inherited SNV in PDS5A. We also identified copy-number deletions affecting STAG1 (two de novo, one of unknown inheritance) and STAG2 (one of unknown inheritance). Patients with STAG1 and STAG2 variants presented with overlapping features yet without characteristic facial features of CdLS.

CONCLUSION: CES effectively identified disease-causing alleles at the mild end of the cohensinopathy spectrum and enabled characterization of candidate disease genes.

}, keywords = {Adolescent, Alleles, Antigens, Nuclear, Biological Variation, Population, Carrier Proteins, Cell Cycle Proteins, Child, Child, Preschool, Chromosomal Proteins, Non-Histone, Cohort Studies, De Lange Syndrome, Exome, Female, Gene Frequency, Genetic Heterogeneity, Humans, INDEL Mutation, Male, Mutation, Nuclear Proteins, Phenotype, Polymorphism, Single Nucleotide, Proto-Oncogene Proteins, Retrospective Studies, Whole Exome Sequencing}, issn = {1530-0366}, doi = {10.1038/s41436-018-0085-6}, author = {Yuan, Bo and Neira, Juanita and Pehlivan, Davut and Santiago-Sim, Teresa and Song, Xiaofei and Rosenfeld, Jill and Posey, Jennifer E and Patel, Vipulkumar and Jin, Weihong and Adam, Margaret P and Baple, Emma L and Dean, John and Fong, Chin-To and Hickey, Scott E and Hudgins, Louanne and Leon, Eyby and Madan-Khetarpal, Suneeta and Rawlins, Lettie and Rustad, Cecilie F and Stray-Pedersen, Asbj{\o}rg and Tveten, Kristian and Wenger, Olivia and Diaz, Jullianne and Jenkins, Laura and Martin, Laura and McGuire, Marianne and Pietryga, Marguerite and Ramsdell, Linda and Slattery, Leah and Abid, Farida and Bertuch, Alison A and Grange, Dorothy and Immken, LaDonna and Schaaf, Christian P and Van Esch, Hilde and Bi, Weimin and Cheung, Sau Wai and Breman, Amy M and Smith, Janice L and Shaw, Chad and Crosby, Andrew H and Eng, Christine and Yang, Yaping and Lupski, James R and Xiao, Rui and Liu, Pengfei} } @article {650, title = {Interchromosomal template-switching as a novel molecular mechanism for imprinting perturbations associated with Temple syndrome.}, journal = {Genome Med}, volume = {11}, year = {2019}, month = {2019 04 23}, pages = {25}, abstract = {

BACKGROUND: Intrachromosomal triplications (TRP) can contribute to disease etiology via gene dosage effects, gene disruption, position effects, or fusion gene formation. Recently, post-zygotic de novo triplications adjacent to copy-number neutral genomic intervals with runs of homozygosity (ROH) have been shown to result in uniparental isodisomy (UPD). The genomic structure of these complex genomic rearrangements (CGRs) shows a consistent pattern of an inverted triplication flanked by duplications (DUP-TRP/INV-DUP) formed by an iterative DNA replisome template-switching mechanism during replicative repair of a single-ended, double-stranded DNA (seDNA), the ROH results from an interhomolog or nonsister chromatid template switch. It has been postulated that these CGRs may lead to genetic abnormalities in carriers due to dosage-sensitive genes mapping within the copy-number variant regions, homozygosity for alleles at a locus causing an autosomal recessive (AR) disease trait within the ROH region, or imprinting-associated diseases.

METHODS: Here, we report a family wherein the affected subject carries a de novo 2.2-Mb TRP followed by 42.2 Mb of ROH and manifests clinical features overlapping with those observed in association with chromosome 14 maternal UPD~(UPD(14)mat). UPD(14)mat can cause clinical phenotypic features enabling a diagnosis of Temple syndrome. This CGR was then molecularly characterized by high-density custom aCGH, genome-wide single-nucleotide polymorphism (SNP) and methylation arrays, exome sequencing (ES), and the Oxford Nanopore long-read sequencing technology.

RESULTS: We confirmed the postulated DUP-TRP/INV-DUP structure by multiple orthogonal genomic technologies in the proband. The methylation status of known differentially methylated regions (DMRs) on chromosome 14 revealed that the subject shows the typical methylation pattern of UPD(14)mat. Consistent with these molecular findings, the clinical features overlap with those observed in Temple syndrome, including speech delay.

CONCLUSIONS: These data provide experimental evidence that, in humans, triplication can lead to segmental UPD and imprinting disease. Importantly, genotype/phenotype analyses further reveal how a post-zygotically generated complex structural variant, resulting from a replication-based mutational mechanism, contributes to expanding the clinical phenotype of known genetic syndromes. Mechanistically, such events can distort transmission genetics resulting in homozygosity at a locus for which only one parent is a carrier as well as cause imprinting diseases.

}, issn = {1756-994X}, doi = {10.1186/s13073-019-0633-y}, author = {Carvalho, Claudia M B and Coban-Akdemir, Zeynep and Hijazi, Hadia and Yuan, Bo and Pendleton, Matthew and Harrington, Eoghan and Beaulaurier, John and Juul, Sissel and Turner, Daniel J and Kanchi, Rupa S and Jhangiani, Shalini N and Muzny, Donna M and Gibbs, Richard A and Stankiewicz, Pawel and Belmont, John W and Shaw, Chad A and Cheung, Sau Wai and Hanchard, Neil A and Sutton, V Reid and Bader, Patricia I and Lupski, James R} } @article {369, title = {Haploinsufficiency of the E3 ubiquitin-protein ligase gene TRIP12 causes intellectual disability with or without autism spectrum disorders, speech delay, and dysmorphic features.}, journal = {Hum Genet}, volume = {136}, year = {2017}, month = {2017 04}, pages = {377-386}, abstract = {

Impairment of ubiquitin-proteasome system activity involving ubiquitin ligase genes UBE3A, UBE3B, and HUWE1 and deubiquitinating enzyme genes USP7 and USP9X has been reported in patients with neurodevelopmental delays. To date, only a handful of single-nucleotide variants (SNVs) and copy-number variants (CNVs) involving TRIP12, encoding a member of the HECT domain E3 ubiquitin ligases family on chromosome 2q36.3 have been reported. Using chromosomal microarray analysis and whole-exome sequencing (WES), we have identified, respectively, five deletion CNVs and four inactivating SNVs (two frameshifts, one missense, and one splicing) in TRIP12. Seven of these variants were found to be de novo; parental studies could not be completed in two families. Quantitative PCR analyses of the splicing mutation showed a dramatically decreased level of TRIP12 mRNA in the proband compared to the family controls, indicating a loss-of-function mechanism. The shared clinical features include intellectual disability with or without autistic spectrum disorders, speech delay, and facial dysmorphism. Our findings demonstrate that E3 ubiquitin ligase TRIP12 plays an important role in nervous system development and function. The nine presented pathogenic variants further document that TRIP12 haploinsufficiency causes a childhood-onset neurodevelopmental disorder. Finally, our data enable expansion of the phenotypic spectrum of ubiquitin-proteasome dependent disorders.

}, keywords = {Adolescent, Autism Spectrum Disorder, Carrier Proteins, Child, Child, Preschool, Cohort Studies, DNA Copy Number Variations, Facies, Female, Haploinsufficiency, Humans, Infant, Intellectual Disability, Language Development Disorders, Male, Ubiquitin-Protein Ligases}, issn = {1432-1203}, doi = {10.1007/s00439-017-1763-1}, author = {Zhang, Jing and Gambin, Tomasz and Yuan, Bo and Szafranski, Przemyslaw and Rosenfeld, Jill A and Balwi, Mohammed Al and Alswaid, Abdulrahman and Al-Gazali, Lihadh and Shamsi, Aisha M Al and Komara, Makanko and Ali, Bassam R and Roeder, Elizabeth and McAuley, Laura and Roy, Daniel S and Manchester, David K and Magoulas, Pilar and King, Lauren E and Hannig, Vickie and Bonneau, Dominique and Denomm{\'e}-Pichon, Anne-Sophie and Charif, Majida and Besnard, Thomas and B{\'e}zieau, St{\'e}phane and Cogn{\'e}, Benjamin and Andrieux, Joris and Zhu, Wenmiao and He, Weimin and Vetrini, Francesco and Ward, Patricia A and Cheung, Sau Wai and Bi, Weimin and Eng, Christine M and Lupski, James R and Yang, Yaping and Patel, Ankita and Lalani, Seema R and Xia, Fan and Stankiewicz, Pawe{\l}} } @article {376, title = {Identification of novel candidate disease genes from de novo exonic copy number variants.}, journal = {Genome Med}, volume = {9}, year = {2017}, month = {2017 09 21}, pages = {83}, abstract = {

BACKGROUND: Exon-targeted microarrays can detect small (<1000~bp) intragenic copy number variants (CNVs), including those that affect only a single exon. This genome-wide high-sensitivity approach increases the molecular diagnosis for conditions with known disease-associated genes, enables better genotype-phenotype correlations, and facilitates variant allele detection allowing novel disease gene discovery.

METHODS: We retrospectively analyzed data from 63,127 patients referred for clinical chromosomal microarray analysis (CMA) at Baylor Genetics laboratories, including 46,755 individuals tested using exon-targeted arrays, from 2007 to 2017. Small CNVs harboring a single gene or two to five non-disease-associated genes were identified; the genes involved were evaluated for a potential disease association.

RESULTS: In this clinical population, among rare CNVs involving any single gene reported in 7200 patients (11\%), we identified 145 de novo autosomal CNVs (117 losses and 28 intragenic gains), 257 X-linked deletion CNVs in males, and 1049 inherited autosomal CNVs (878 losses and 171 intragenic gains); 111 known disease genes were potentially disrupted by de novo autosomal or X-linked (in males) single-gene CNVs. Ninety-one genes, either recently proposed as candidate disease genes or not yet associated with diseases, were disrupted by 147 single-gene CNVs, including 37 de novo deletions and ten de novo intragenic duplications on autosomes and 100 X-linked CNVs in males. Clinical features in individuals with de novo or X-linked CNVs encompassing at most five genes (224~bp to 1.6~Mb in size) were compared to those in individuals with larger-sized deletions (up to 5~Mb in size) in the internal CMA database or loss-of-function single nucleotide variants (SNVs) detected by clinical or research whole-exome sequencing (WES). This enabled the identification of recently published genes (BPTF, NONO, PSMD12, TANGO2, and TRIP12), novel candidate disease genes (ARGLU1 and STK3), and further confirmation of disease association for two recently proposed disease genes (MEIS2 and PTCHD1). Notably, exon-targeted CMA detected several pathogenic single-exon CNVs missed by clinical WES analyses.

CONCLUSIONS: Together, these data document the efficacy of exon-targeted CMA for detection of genic and exonic CNVs, complementing and extending WES in clinical diagnostics, and the potential for discovery of novel disease genes by genome-wide assay.

}, keywords = {Cohort Studies, DNA Copy Number Variations, Exons, Genetic Diseases, Inborn, Genome, Human, Homeodomain Proteins, Humans, Intracellular Signaling Peptides and Proteins, Membrane Proteins, Neurodevelopmental Disorders, Protein-Serine-Threonine Kinases, Retrospective Studies, Transcription Factors, Whole Genome Sequencing}, issn = {1756-994X}, doi = {10.1186/s13073-017-0472-7}, author = {Gambin, Tomasz and Yuan, Bo and Bi, Weimin and Liu, Pengfei and Rosenfeld, Jill A and Coban-Akdemir, Zeynep and Pursley, Amber N and Nagamani, Sandesh C S and Marom, Ronit and Golla, Sailaja and Dengle, Lauren and Petrie, Heather G and Matalon, Reuben and Emrick, Lisa and Proud, Monica B and Treadwell-Deering, Diane and Chao, Hsiao-Tuan and Koillinen, Hannele and Brown, Chester and Urraca, Nora and Mostafavi, Roya and Bernes, Saunder and Roeder, Elizabeth R and Nugent, Kimberly M and Bader, Patricia I and Bellus, Gary and Cummings, Michael and Northrup, Hope and Ashfaq, Myla and Westman, Rachel and Wildin, Robert and Beck, Anita E and Immken, LaDonna and Elton, Lindsay and Varghese, Shaun and Buchanan, Edward and Faivre, Laurence and Lefebvre, Mathilde and Schaaf, Christian P and Walkiewicz, Magdalena and Yang, Yaping and Kang, Sung-Hae L and Lalani, Seema R and Bacino, Carlos A and Beaudet, Arthur L and Breman, Amy M and Smith, Janice L and Cheung, Sau Wai and Lupski, James R and Patel, Ankita and Shaw, Chad A and Stankiewicz, Pawe{\l}} } @article {348, title = {An Organismal CNV Mutator Phenotype Restricted to Early Human Development.}, journal = {Cell}, volume = {168}, year = {2017}, month = {2017 02 23}, pages = {830-842.e7}, abstract = {

De novo copy number variants (dnCNVs) arising at~multiple loci in a personal genome have usually been considered to reflect cancer somatic genomic instabilities. We describe a multiple dnCNV (MdnCNV) phenomenon in which individuals with genomic disorders carry five to ten constitutional dnCNVs. These CNVs originate from independent formation incidences, are predominantly tandem duplications or complex gains, exhibit breakpoint junction features reminiscent of replicative repair, and show increased de novo point mutations flanking the rearrangement junctions. The active CNV mutation shower appears to be restricted to a transient perizygotic period. We~propose that a defect in the CNV formation process is responsible for the "CNV-mutator state," and this state is dampened after early embryogenesis. The constitutional MdnCNV phenomenon resembles chromosomal instability in various cancers. Investigations of this phenomenon may provide unique access to understanding genomic disorders, structural variant mutagenesis, human evolution, and cancer biology.

}, keywords = {Chromosome Aberrations, Chromosome Breakpoints, Chromosome Duplication, DNA Copy Number Variations, DNA Replication, Embryonic Development, Female, Gametogenesis, Genetic Diseases, Inborn, Genomic Instability, Humans, Male, Mutation}, issn = {1097-4172}, doi = {10.1016/j.cell.2017.01.037}, author = {Liu, Pengfei and Yuan, Bo and Carvalho, Claudia M B and Wuster, Arthur and Walter, Klaudia and Zhang, Ling and Gambin, Tomasz and Chong, Zechen and Campbell, Ian M and Coban Akdemir, Zeynep and Gelowani, Violet and Writzl, Karin and Bacino, Carlos A and Lindsay, Sarah J and Withers, Marjorie and Gonzaga-Jauregui, Claudia and Wiszniewska, Joanna and Scull, Jennifer and Stankiewicz, Pawe{\l} and Jhangiani, Shalini N and Muzny, Donna M and Zhang, Feng and Chen, Ken and Gibbs, Richard A and Rautenstrauss, Bernd and Cheung, Sau Wai and Smith, Janice and Breman, Amy and Shaw, Chad A and Patel, Ankita and Hurles, Matthew E 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 {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 {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 {281, title = {The genetic basis of DOORS syndrome: an exome-sequencing study.}, journal = {Lancet Neurol}, volume = {13}, year = {2014}, month = {2014 Jan}, pages = {44-58}, abstract = {

BACKGROUND: Deafness, onychodystrophy, osteodystrophy, mental retardation, and seizures (DOORS) syndrome is a rare autosomal recessive disorder of unknown cause. We aimed to identify the genetic basis of this syndrome by sequencing most coding exons in affected individuals.

METHODS: Through a search of available case studies and communication with collaborators, we identified families that included at least one individual with at least three of the five main features of the DOORS syndrome: deafness, onychodystrophy, osteodystrophy, intellectual disability, and seizures. Participants were recruited from 26 centres in 17 countries. Families described in this study were enrolled between Dec 1, 2010, and March 1, 2013. Collaborating physicians enrolling participants obtained clinical information and DNA samples from the affected child and both parents if possible. We did whole-exome sequencing in affected individuals as they were enrolled, until we identified a candidate gene, and Sanger sequencing to confirm mutations. We did expression studies in human fibroblasts from one individual by real-time PCR and western blot analysis, and in mouse tissues by immunohistochemistry and real-time PCR.

FINDINGS: 26 families were included in the study. We did exome sequencing in the first 17 enrolled families; we screened for TBC1D24 by Sanger sequencing in subsequent families. We identified TBC1D24 mutations in 11 individuals from nine families (by exome sequencing in seven families, and Sanger sequencing in two families). 18 families had individuals with all five main features of DOORS syndrome, and TBC1D24 mutations were identified in half of these families. The seizure types in individuals with TBC1D24 mutations included generalised tonic-clonic, complex partial, focal clonic, and infantile spasms. Of the 18 individuals with DOORS syndrome from 17 families without TBC1D24 mutations, eight did not have seizures and three did not have deafness. In expression studies, some mutations abrogated TBC1D24 mRNA stability. We also detected Tbc1d24 expression in mouse phalangeal chondrocytes and calvaria, which suggests a role of TBC1D24 in skeletogenesis.

INTERPRETATION: Our findings suggest that mutations in TBC1D24 seem to be an important cause of DOORS syndrome and can cause diverse phenotypes. Thus, individuals with DOORS syndrome without deafness and seizures but with the other features should still be screened for TBC1D24 mutations. More information is needed to understand the cellular roles of TBC1D24 and identify the genes responsible for DOORS phenotypes in individuals who do not have a mutation in TBC1D24.

FUNDING: US National Institutes of Health, the CIHR (Canada), the NIHR (UK), the Wellcome Trust, the Henry Smith Charity, and Action Medical Research.

}, keywords = {Adolescent, Carrier Proteins, Child, Child, Preschool, Craniofacial Abnormalities, Exome, Female, Hand Deformities, Congenital, Hearing Loss, Sensorineural, Humans, Infant, Intellectual Disability, Internationality, Male, Nails, Malformed, Phenotype, Sequence Analysis, DNA, Young Adult}, issn = {1474-4465}, doi = {10.1016/S1474-4422(13)70265-5}, author = {Campeau, Philippe M and Kasperaviciute, Dalia and Lu, James T and Burrage, Lindsay C and Kim, Choel and Hori, Mutsuki and Powell, Berkley R and Stewart, Fiona and F{\'e}lix, T{\^e}mis Maria and van den Ende, Jenneke and Wisniewska, Marzena and Kayserili, H{\"u}lya and Rump, Patrick and Nampoothiri, Sheela and Aftimos, Salim and Mey, Antje and Nair, Lal D V and Begleiter, Michael L and De Bie, Isabelle and Meenakshi, Girish and Murray, Mitzi L and Repetto, Gabriela M and Golabi, Mahin and Blair, Edward and Male, Alison and Giuliano, Fabienne and Kariminejad, Ariana and Newman, William G and Bhaskar, Sanjeev S and Dickerson, Jonathan E and Kerr, Bronwyn and Banka, Siddharth and Giltay, Jacques C and Wieczorek, Dagmar and Tostevin, Anna and Wiszniewska, Joanna and Cheung, Sau Wai and Hennekam, Raoul C and Gibbs, Richard A and Lee, Brendan H and Sisodiya, Sanjay M} } @article {229, title = {Parental somatic mosaicism is underrecognized and influences recurrence risk of genomic disorders.}, journal = {Am J Hum Genet}, volume = {95}, year = {2014}, month = {2014 Aug 07}, pages = {173-82}, abstract = {

New human mutations are thought to originate in germ cells, thus making a recurrence of the same mutation in a sibling exceedingly rare. However, increasing sensitivity of genomic technologies has anecdotally revealed mosaicism for mutations in somatic tissues of apparently healthy parents. Such somatically mosaic parents might also have germline mosaicism that can potentially cause unexpected intergenerational recurrences. Here, we show that somatic mosaicism for transmitted mutations among parents of children with simplex genetic disease is more common than currently appreciated. Using the sensitivity of individual-specific breakpoint PCR, we prospectively screened 100 families with children affected by genomic disorders due to rare deletion copy-number variants (CNVs) determined to be de novo by clinical analysis of parental DNA. Surprisingly, we identified four cases of low-level somatic mosaicism for the transmitted CNV in DNA isolated from parental blood. Integrated probabilistic modeling of gametogenesis developed in response to our observations predicts that mutations in parental blood increase recurrence risk substantially more than parental mutations confined to the germline. Moreover, despite the fact that maternally transmitted mutations are the minority of alleles, our model suggests that sexual dimorphisms in gametogenesis result in a greater proportion of somatically mosaic transmitting mothers who are thus at increased risk of recurrence. Therefore, somatic mosaicism together with sexual differences in gametogenesis might explain a considerable fraction of unexpected recurrences of X-linked recessive disease. Overall, our results underscore an important role for somatic mosaicism and mitotic replicative mutational mechanisms in transmission genetics.

}, keywords = {Cell Division, DNA Copy Number Variations, Female, Gametogenesis, Genetic Diseases, Inborn, Genomics, Germ Cells, Germ-Line Mutation, Humans, Male, Models, Genetic, Mosaicism, Mutation, Pedigree, Prospective Studies, Recurrence, Risk, Sex Characteristics, Smith-Magenis Syndrome}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2014.07.003}, author = {Campbell, Ian M and Yuan, Bo and Robberecht, Caroline and Pfundt, Rolph and Szafranski, Przemyslaw and McEntagart, Meriel E and Nagamani, Sandesh C S and Erez, Ayelet and Bartnik, Magdalena and Wi{\'s}niowiecka-Kowalnik, Barbara and Plunkett, Katie S and Pursley, Amber N and Kang, Sung-Hae L and Bi, Weimin and Lalani, Seema R and Bacino, Carlos A and Vast, Mala and Marks, Karen and Patton, Michael and Olofsson, Peter and Patel, Ankita and Veltman, Joris A and Cheung, Sau Wai and Shaw, Chad A and Vissers, Lisenka E L M and Vermeesch, Joris R and Lupski, James R and Stankiewicz, Pawe{\l}} } @article {301, title = {Deletions of recessive disease genes: CNV contribution to carrier states and disease-causing alleles.}, journal = {Genome Res}, volume = {23}, year = {2013}, month = {2013 Sep}, pages = {1383-94}, abstract = {

Over 1200 recessive disease genes have been described in humans. The prevalence, allelic architecture, and per-genome load of pathogenic alleles in these genes remain to be fully elucidated, as does the contribution of DNA copy-number variants (CNVs) to carrier status and recessive disease. We mined CNV data from 21,470 individuals obtained by array-comparative genomic hybridization in a clinical diagnostic setting to identify deletions encompassing or disrupting recessive disease genes. We identified 3212 heterozygous potential carrier deletions affecting 419 unique recessive disease genes. Deletion frequency of these genes ranged from one occurrence to 1.5\%. When compared with recessive disease genes never deleted in our cohort, the 419 recessive disease genes affected by at least one carrier deletion were longer and located farther from known dominant disease genes, suggesting that the formation and/or prevalence of carrier CNVs may be affected by both local and adjacent genomic features and by selection. Some subjects had multiple carrier CNVs (307 subjects) and/or carrier deletions encompassing more than one recessive disease gene (206 deletions). Heterozygous deletions spanning multiple recessive disease genes may confer carrier status for multiple single-gene disorders, for complex syndromes resulting from the combination of two or more recessive conditions, or may potentially cause clinical phenotypes due to a multiply heterozygous state. In addition to carrier mutations, we identified homozygous and hemizygous deletions potentially causative for recessive disease. We provide further evidence that CNVs contribute to the allelic architecture of both carrier and recessive disease-causing mutations. Thus, a complete recessive carrier screening method or diagnostic test should detect CNV alleles.

}, keywords = {Alleles, Comparative Genomic Hybridization, Databases, Genetic, DNA Copy Number Variations, Gene Deletion, Gene Frequency, Genes, Dominant, Genes, Recessive, Genetic Diseases, Inborn, Homozygote, Humans}, issn = {1549-5469}, doi = {10.1101/gr.156075.113}, author = {Boone, Philip M and Campbell, Ian M and Baggett, Brett C and Soens, Zachry T and Rao, Mitchell M and Hixson, Patricia M and Patel, Ankita and Bi, Weimin and Cheung, Sau Wai and Lalani, Seema R and Beaudet, Arthur L and Stankiewicz, Pawel and Shaw, Chad A and Lupski, James R} } @article {323, title = {Incidental copy-number variants identified by routine genome testing in a clinical population.}, journal = {Genet Med}, volume = {15}, year = {2013}, month = {2013 Jan}, pages = {45-54}, abstract = {

PURPOSE: Mutational load of susceptibility variants has not been studied on a genomic scale in a clinical population, nor has the potential to identify these mutations as incidental findings during clinical testing been systematically ascertained.

METHODS: Array comparative genomic hybridization, a method for genome-wide detection of DNA copy-number variants, was performed clinically on DNA from 9,005 individuals. Copy-number variants encompassing or disrupting single genes were identified and analyzed for their potential to confer predisposition to dominant, adult-onset disease. Multigene copy-number variants affecting dominant, adult-onset cancer syndrome genes were also assessed.

RESULTS: In our cohort, 83 single-gene copy-number variants affected 40 unique genes associated with dominant, adult-onset disorders and unrelated to the patients{\textquoteright} referring diagnoses (i.e., incidental) were found. Fourteen of these copy-number variants are likely disease-predisposing, 25 are likely benign, and 44 are of unknown clinical consequence. When incidental copy-number variants spanning up to 20 genes were considered, 27 copy-number variants affected 17 unique genes associated with dominant, adult-onset cancer predisposition.

CONCLUSION: Copy-number variants potentially conferring susceptibility to adult-onset disease can be identified as incidental findings during routine genome-wide testing. Some of these mutations may be medically actionable, enabling disease surveillance or prevention; however, most incidentally observed single-gene copy-number variants are currently of unclear significance to the patient.

}, keywords = {Age of Onset, Base Sequence, Chromosome Mapping, Comparative Genomic Hybridization, DNA Copy Number Variations, Female, Gene Order, Genetic Predisposition to Disease, Humans, Inheritance Patterns, Male, Reproducibility of Results}, issn = {1530-0366}, doi = {10.1038/gim.2012.95}, author = {Boone, Philip M and Soens, Zachry T and Campbell, Ian M and Stankiewicz, Pawel and Cheung, Sau Wai and Patel, Ankita and Beaudet, Arthur L and Plon, Sharon E and Shaw, Chad A and McGuire, Amy L and Lupski, James R} }