@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 {446, title = {WNT Signaling Perturbations Underlie the Genetic Heterogeneity of Robinow Syndrome.}, journal = {Am J Hum Genet}, volume = {102}, year = {2018}, month = {2018 01 04}, pages = {27-43}, abstract = {

Locus heterogeneity characterizes a variety of skeletal dysplasias often due to interacting or overlapping signaling pathways. Robinow syndrome is a skeletal disorder historically refractory to molecular diagnosis, potentially stemming from substantial genetic heterogeneity. All current known pathogenic variants reside in genes within the noncanonical Wnt signaling pathway including ROR2, WNT5A, and more recently, DVL1 and DVL3. However, \~{}70\% of autosomal-dominant Robinow syndrome cases remain molecularly unsolved. To investigate this missing heritability, we recruited 21 families with at least one family member clinically diagnosed with Robinow or Robinow-like phenotypes and performed genetic and genomic studies. In total, four families with variants in FZD2 were identified as well as three individuals from two families with biallelic variants in NXN that co-segregate with the phenotype. Importantly, both FZD2 and NXN are relevant protein partners in the WNT5A interactome, supporting their role in skeletal development. In addition to confirming that clustered -1 frameshifting variants in DVL1 and DVL3 are the main contributors to dominant Robinow syndrome, we also found likely pathogenic variants in candidate genes GPC4 and RAC3, both linked to the Wnt signaling pathway. These data support an initial hypothesis that Robinow syndrome results from perturbation of the Wnt/PCP pathway, suggest specific relevant domains of the proteins involved, and reveal key contributors in this signaling cascade during human embryonic development. Contrary to the view that non-allelic genetic heterogeneity hampers gene discovery, this study demonstrates the utility of rare disease genomic studies to parse gene function in human developmental pathways.

}, keywords = {Adolescent, Adult, Base Sequence, Child, Child, Preschool, Chromosome Segregation, Craniofacial Abnormalities, Diagnosis, Differential, Dwarfism, Female, Genes, Dominant, Genetic Association Studies, Genetic Heterogeneity, Humans, Limb Deformities, Congenital, Male, Middle Aged, Mutation, Missense, Phenotype, Urogenital Abnormalities, Wnt Signaling Pathway}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.10.002}, author = {White, Janson J and Mazzeu, Juliana F and Coban-Akdemir, Zeynep and Bayram, Yavuz and Bahrambeigi, Vahid and Hoischen, Alexander and van Bon, Bregje W M and Gezdirici, Alper and Gulec, Elif Yilmaz and Ramond, Francis and Touraine, Renaud and Thevenon, Julien and Shinawi, Marwan and Beaver, Erin and Heeley, Jennifer and Hoover-Fong, Julie and Durmaz, Ceren D and Karabulut, Halil Gurhan and Marzioglu-Ozdemir, Ebru and Cayir, Atilla and Duz, Mehmet B and Seven, Mehmet and Price, Susan and Ferreira, Barbara Merfort and Vianna-Morgante, Angela M and Ellard, Sian and Parrish, Andrew and Stals, Karen and Flores-Daboub, Josue and Jhangiani, Shalini N and Gibbs, Richard A and Brunner, Han G and Sutton, V Reid and Lupski, James R and Carvalho, Claudia M B} } @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 {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 {245, title = {Structural variation and missense mutation in SBDS associated with Shwachman-Diamond syndrome.}, journal = {BMC Med Genet}, volume = {15}, year = {2014}, month = {2014 Jun 04}, pages = {64}, abstract = {

BACKGROUND: Shwachman-Diamond syndrome (SDS) is an autosomal recessive ribosomopathy caused mainly by compound heterozygous mutations in SBDS. Structural variation (SV) involving the SBDS locus has been rarely reported in association with the disease. We aimed to determine whether an SV contributed to the pathogenesis of a case lacking biallelic SBDS point mutations.

CASE PRESENTATION: Whole exome sequencing was performed in a patient with SDS lacking biallelic SBDS point mutations. Array comparative genomic hybridization and Southern blotting were used to seek SVs across the SBDS locus. Locus-specific polymerase chain reaction (PCR) encompassing flanking intronic sequence was also performed to investigate mutation within the locus. RNA expression and Western blotting were performed to analyze allele and protein expression. We found the child harbored a single missense mutation in SBDS (c.98A > C; p.K33T), inherited from the mother, and an SV in the SBDS locus, inherited from the father. The missense allele and SV segregated in accordance with Mendelian expectations for autosomal recessive SDS. Complementary DNA and western blotting analysis and locus specific PCR support the contention that the SV perturbed SBDS protein expression in the father and child.

CONCLUSION: Our findings implicate genomic rearrangements in the pathogenesis of some cases of SDS and support patients lacking biallelic SBDS point mutations be tested for SV within the SBDS locus.

}, keywords = {Abdomen, Alleles, Bone Marrow Diseases, Cell Line, Transformed, Child, Preschool, Comparative Genomic Hybridization, DNA Mutational Analysis, Exocrine Pancreatic Insufficiency, Female, Gene Order, Humans, Lipomatosis, Mutagenesis, Insertional, Mutation, Mutation, Missense, Pedigree, Proteins, Radiography, Abdominal, Ultrasonography}, issn = {1471-2350}, doi = {10.1186/1471-2350-15-64}, author = {Carvalho, Claudia M B and Zuccherato, Luciana W and Williams, Christopher L and Neill, Nicholas J and Murdock, David R and Bainbridge, Matthew and Jhangiani, Shalini N and Muzny, Donna M and Gibbs, Richard A and Ip, Wan and Guillerman, Robert Paul and Lupski, James R and Bertuch, Alison A} }