@article {584, title = {Megabase Length Hypermutation Accompanies Human Structural Variation at 17p11.2.}, journal = {Cell}, volume = {176}, year = {2019}, month = {2019 03 07}, pages = {1310-1324.e10}, abstract = {

DNA rearrangements resulting in human genome structural variants (SVs) are caused by diverse mutational mechanisms. We used long- and short-read sequencing technologies to investigate end products of de novo chromosome 17p11.2 rearrangements and query the molecular mechanisms underlying both recurrent and non-recurrent events. Evidence for an increased rate of clustered single-nucleotide variant (SNV) mutation in cis with non-recurrent rearrangements was found. Indel and SNV formation are associated with both copy-number gains and losses of 17p11.2, occur up to \~{}1 Mb away from the breakpoint junctions, and favor C > G transversion substitutions; results suggest that single-stranded DNA is formed during the genesis of the SV and provide compelling support for a microhomology-mediated break-induced replication (MMBIR) mechanism for SV formation. Our data show an additional mutational burden of MMBIR consisting of hypermutation confined to the locus and manifesting as SNVs and indels predominantly within genes.

}, issn = {1097-4172}, doi = {10.1016/j.cell.2019.01.045}, author = {Beck, Christine R and Carvalho, Claudia M B and Akdemir, Zeynep C and Sedlazeck, Fritz J and Song, Xiaofei and Meng, Qingchang and Hu, Jianhong and Doddapaneni, Harsha and Chong, Zechen and Chen, Edward S and Thornton, Philip C and Liu, Pengfei and Yuan, Bo and Withers, Marjorie and Jhangiani, Shalini N and Kalra, Divya and Walker, Kimberly and English, Adam C and Han, Yi and Chen, Ken and Muzny, Donna M and Ira, Grzegorz and Shaw, Chad A and Gibbs, Richard A and Hastings, P J and Lupski, James R} } @article {462, title = {Marker chromosome genomic structure and temporal origin implicate a chromoanasynthesis event in a family with pleiotropic psychiatric phenotypes.}, journal = {Hum Mutat}, volume = {39}, year = {2018}, month = {2018 07}, pages = {939-946}, abstract = {

Small supernumerary marker chromosomes (sSMC) are chromosomal fragments difficult to characterize genomically. Here, we detail a proband with schizoaffective disorder and a mother with bipolar disorder with psychotic features who present with a marker chromosome that segregates with disease. We explored the architecture of this marker and investigated its temporal origin. Array comparative genomic hybridization (aCGH) analysis revealed three duplications and three triplications that spanned the short arm of chromosome 9, suggestive of a chromoanasynthesis-like event. Segregation of marker genotypes, phased using sSMC mosaicism in the mother, provided evidence that it was generated during a germline-level event in the proband{\textquoteright}s maternal grandmother. Whole-genome sequencing (WGS) was performed to resolve the structure and junctions of the chromosomal fragments, revealing further complexities. While structural variations have been previously associated with neuropsychiatric disorders and marker chromosomes, here we detail the precise architecture, human life-cycle genesis, and propose a DNA replicative/repair mechanism underlying formation.

}, issn = {1098-1004}, doi = {10.1002/humu.23537}, author = {Grochowski, Christopher M and Gu, Shen and Yuan, Bo and Tcw, Julia and Brennand, Kristen J and Sebat, Jonathan and Malhotra, Dheeraj and McCarthy, Shane and Rudolph, Uwe and Lindstrand, Anna and Chong, Zechen and Levy, Deborah L and Lupski, James R 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 {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} }