RESUMO
Precise breakpoint mapping of balanced chromosomal rearrangements is crucial to identify disease etiology. Ten female patients with X-autosome balanced translocations associated with phenotypic alterations were evaluated, by mapping and sequencing their breakpoints. The rearrangements' impact on the expression of disrupted genes, and inferred mechanisms of formation in each case were assessed. For four patients that presented one of the chromosomal breaks in heterochromatic and highly repetitive segments, we combined cytogenomic methods and short-read sequencing to characterize, at nucleotide resolution, breakpoints that occurred in reference genome gaps. Most of rearrangements were possibly formed by non-homologous end joining and have breakpoints at repeat elements. Seven genes were found to be disrupted in six patients. Six of the affected genes showed altered expression, and the functional impairment of three of them were considered pathogenic. One gene disruption was considered potentially pathogenic, and three had uncertain clinical significance. Four patients presented no gene disruptions, suggesting other pathogenic mechanisms. Four genes were considered potentially affected by position effect and the expression abrogation of one of them was confirmed. This study emphasizes the importance of breakpoint-junction characterization at nucleotide resolution in balanced rearrangements to reveal genetic mechanisms associated with the patients' phenotypes, mechanisms of formation that originated the rearrangements, and genomic nature of disrupted DNA sequences.
Assuntos
Pontos de Quebra do Cromossomo , Mapeamento Cromossômico , Cromossomos Humanos X/genética , Nucleotídeos/genética , Translocação Genética , Sequência de Bases , Feminino , Regulação da Expressão Gênica , Rearranjo Gênico/genética , Humanos , Fenótipo , Reprodutibilidade dos TestesRESUMO
ere, we report that a paragraph from the "Discussion" section of Cioffi et al. (2011; p. 1070, 4th paragraph of column 1) was transcribed (with only minor edits) from an introductory paragraph previously published in Chromosome Research by O'Meally et al.
RESUMO
We report five individuals with loss-of-function of the X-linked AMMECR1: a girl with a balanced X-autosome translocation and inactivation of the normal X-chromosome; two boys with maternally inherited and de novo nonsense variants; and two half-brothers with maternally inherited microdeletion variants. They present with short stature, cardiac and skeletal abnormalities, and hearing loss. Variants of unknown significance in AMMECR1 in four male patients from two families with partially overlapping phenotypes were previously reported. AMMECR1 is coexpressed with genes implicated in cell cycle regulation, five of which were previously associated with growth and bone alterations. Our knockdown of the zebrafish orthologous gene resulted in phenotypes reminiscent of patients' features. The increased transcript and encoded protein levels of AMMECR1L, an AMMECR1 paralog, in the t(X;9) patient's cells indicate a possible partial compensatory mechanism. AMMECR1 and AMMECR1L proteins dimerize and localize to the nucleus as suggested by their nucleic acid-binding RAGNYA folds. Our results suggest that AMMECR1 is potentially involved in cell cycle control and linked to a new syndrome with growth, bone, heart, and kidney alterations with or without elliptocytosis.
Assuntos
Osso e Ossos/fisiologia , Coração/fisiologia , Proteínas/genética , Animais , Western Blotting , Osso e Ossos/metabolismo , Ciclo Celular/genética , Ciclo Celular/fisiologia , Linhagem Celular , Exoma/genética , Feminino , Células HeLa , Humanos , Masculino , Sequenciamento Completo do Genoma , Peixe-ZebraRESUMO
BACKGROUND: Brazilian gas station workers are chronically exposed to benzene, toluene, xylene (BTX) during their working time. Describe below two cases of latin female gas station workers with benzene poisoning symptoms and miscarriage history. CASE PRESENTATION: In both cases were identified complex chromosomal rearrangements (CCR) with fluorescence in situ hybridization, applied to whole chromosome paints by chromosomes 1, 2 and 4. The lower natural killer cell (NK) cells have also been observed in cases correspondents, especially the rare type of NK (NKbright) in their peripheral blood cells. CONCLUSIONS: It is known that acquired chromosomal aberrations are positively correlated with cancer and reproductive risk. In concordance, lower NK cytotoxicity increases the risk for cancer, as well. Thus, this is the first study providing hints on a possible causative relation of lower NK cytotoxicity and increase rates of chromosomal rearrangements including CCRs.
Assuntos
Benzeno/intoxicação , Exposição Ocupacional/efeitos adversos , Aborto Espontâneo , Adulto , Aberrações Cromossômicas , Coloração Cromossômica , Cromossomos/ultraestrutura , Feminino , Rearranjo Gênico , Humanos , Hibridização in Situ Fluorescente , Células Matadoras Naturais/citologia , Fatores de Tempo , Tolueno/intoxicação , Xilenos/intoxicaçãoRESUMO
Several alterations involving the pericentromeric region of chromosome 9 are considered as normal population variants. These heterochromatic variants or heteromorphisms can include 9qh+, 9cen+, 9ph+, 9ph-, inv(9)(p11q13), and other patterns which can only be defined by FISH studies. However, some heteromorphisms have been found more frequently in patients with several clinical disorders. Here, we report on a patient with intellectual disability, language and neurodevelopmental delay, as well as facial dysmorphism and an unusual chromosome 9. While the banding karyotype was indicative of a simple pericentric inversion of one chromosome 9 [46,XX,inv(9)(p12q13)], array comparative genomic hybridization showed a 6-Mb duplication, including 22 genes: arr[hg19] 9p13.1p11.2(38,869,901- 44,870,714)×3 dn. Molecular cytogenetics using a panel of probes specific for the pericentromeric region of chromosome 9 showed an unusual, rearranged chromosome 9, der(9)(pterâp11.2::q21.11âq12::p11.2âp13.2::q12âp11.2::q21.11âqter), that has not been described before. The patient's phenotypic alterations are probably due to the de novo 6-Mb 9p duplication, although a review of similar cases showed some reports considering this duplication in the euchromatic region as a benign variant. Interestingly, this is the first report of a possible adverse inversion loop formation due to a known heteromorphic pericentric inversion present in the phenotypically normal father of the patient.
Assuntos
Duplicação Cromossômica , Inversão Cromossômica , Cromossomos Humanos Par 9/genética , Anormalidades Múltiplas/genética , Adolescente , Centrômero/genética , Bandeamento Cromossômico , Hibridização Genômica Comparativa , Deficiências do Desenvolvimento/genética , Feminino , Humanos , Hibridização in Situ Fluorescente , Cariótipo , Masculino , FenótipoRESUMO
Detailed molecular characterization of chromosomal rearrangements involving X-chromosome has been a key strategy in identifying X-linked intellectual disability-causing genes. We fine-mapped the breakpoints in four women with balanced X-autosome translocations and variable phenotypes, in order to investigate the corresponding genetic contribution to intellectual disability. We addressed the impact of the gene interruptions in transcription and discussed the consequences of their functional impairment in neurodevelopment. Three patients presented with cognitive impairment, reinforcing the association between the disrupted genes (TSPAN7-MRX58, KIAA2022-MRX98, and IL1RAPL1-MRX21/34) and intellectual disability. While gene expression analysis showed absence of TSPAN7 and KIAA2022 expression in the patients, the unexpected expression of IL1RAPL1 suggested a fusion transcript ZNF611-IL1RAPL1 under the control of the ZNF611 promoter, gene disrupted at the autosomal breakpoint. The X-chromosomal breakpoint definition in the fourth patient, a woman with normal intellectual abilities, revealed disruption of the ZDHHC15 gene (MRX91). The expression assays did not detect ZDHHC15 gene expression in the patient, thus questioning its involvement in intellectual disability. Revealing the disruption of an X-linked intellectual disability-related gene in patients with balanced X-autosome translocation is a useful tool for a better characterization of critical genes in neurodevelopment. © 2015 Wiley Periodicals, Inc.
Assuntos
Deficiência Intelectual Ligada ao Cromossomo X/genética , Translocação Genética , Adolescente , Adulto , Criança , Mapeamento Cromossômico , Feminino , Genes Ligados ao Cromossomo X , Humanos , Hibridização in Situ FluorescenteRESUMO
OBJECTIVE: To map the X-chromosome and autosome breakpoints in women with balanced X-autosome translocations and primary amenorrhea, searching candidate genomic loci for female infertility. DESIGN: Retrospective and case-control study. SETTING: University-based research laboratory. PATIENT(S): Three women with balanced X-autosome translocation and primary amenorrhea. INTERVENTION(S): Conventional cytogenetic methods, genomic array, array painting, fluorescence in situ hybridization, and quantitative reverse transcription-polymerase chain reaction. MAIN OUTCOME MEASURE(S): Karyotype, copy number variation, breakpoint mapping, and gene expression levels. RESULT(S): All patients presented with breakpoints in the Xq13q21 region. In two patients, the X-chromosome breakpoint disrupted coding sequences (KIAA2022 and ZDHHC15 genes). Although both gene disruptions caused absence of transcription in peripheral blood, there is no evidence that supports the involvement of these genes with ovarian function. The ZDHHC15 gene belongs to a conserved syntenic region that encompasses the FGF16 gene, which plays a role in female germ line development. The break in the FGF16 syntenic block may have disrupted the interaction between the FGF16 promoter and its cis-regulatory element. In the third patient, although both breakpoints are intergenic, a gene that plays a role in the DAX1 pathway (FHL2 gene) flanks distally the autosome breakpoint. The FHL2 gene may be subject to position effect due to the attachment of an autosome segment in Xq21 region. CONCLUSION(S): The etiology of primary amenorrhea in balanced X-autosome translocation patients may underlie more complex mechanisms than interruption of specific X-linked candidate genes, such as position effect. The fine mapping of the rearrangement breakpoints may be a tool for identifying genetic pathogenic mechanisms for primary amenorrhea.
Assuntos
Amenorreia/genética , Cromossomos Humanos X , Translocação Genética , Amenorreia/diagnóstico , Amenorreia/fisiopatologia , Pontos de Quebra do Cromossomo , Coloração Cromossômica , Hibridização Genômica Comparativa , Proteínas de Ligação a DNA/genética , Feminino , Fertilidade/genética , Fatores de Crescimento de Fibroblastos/genética , Regulação da Expressão Gênica , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Hibridização in Situ Fluorescente , Proteínas com Homeodomínio LIM/genética , Proteínas Musculares/genética , Proteínas do Tecido Nervoso/genética , Fenótipo , Estudos Retrospectivos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Risco , Fatores de Transcrição/genéticaRESUMO
Results from the analysis of copy number variations (CNVs) in human pluripotent cell-derived neuroprogenitor cell lines (hiPSC and hESC-derived NPC) are presented. Two different types of CNVs were detected: a) CNVs inherited from the original source of pluripotent cells (hESC and hiPSC) and b) CNVs detected either in the original source of pluripotent cells or in the derived NPC cell lines but not in both at the same time. Our data suggest that submicroscopic chromosomal changes happened during culture and manipulation of cells and those differentiation procedures could result in gains and losses of genomic regions in pluripotent cell-derived neuroprogenitors. Overall, the results indicate that even chromosomally stable stem cell lines would need to be analyzed in detail by high resolution methodologies before their clinical use.
Assuntos
Variações do Número de Cópias de DNA , Células-Tronco Pluripotentes Induzidas/citologia , Neurônios/citologia , Diferenciação Celular , Linhagem Celular , Hibridização Genômica Comparativa , Dosagem de Genes , Instabilidade Genômica , Humanos , Cariotipagem , Modelos Genéticos , Esquizofrenia/genéticaRESUMO
The wolf fish Hoplias malabaricus includes well differentiated sex systems (XY and X(1)X(2)Y in karyomorphs B and D, respectively), a nascent XY pair (karyomorph C) and not recognized sex chromosomes (karyomorph A). We performed the evolutionary analysis of these sex chromosomes, using two X chromosome-specific probes derived by microdissection from the XY and X(1)X(2)Y sex systems. A putative-sex pair in karyomorph A was identified, from which the differentiated XY system was evolved, as well as the clearly evolutionary relationship between the nascent XY system and the origin of the multiple X(1)X(2)Y chromosomes. The lack of recognizable signals on the sex chromosomes after the reciprocal cross-FISH experiments highlighted that they evolved independently from non-homologous autosomal pairs. It is noteworthy that these distinct pathways occur inside the same nominal species, thus exposing the high plasticity of sex chromosome evolution in lower vertebrates. Possible mechanisms underlying this sex determination liability are also discussed.
Assuntos
Caraciformes/genética , Coloração Cromossômica , Filogenia , Cromossomos Sexuais/genética , Animais , Evolução Molecular , Feminino , Masculino , MicrodissecçãoRESUMO
BACKGROUND: The Erythrinidae fish family is characterized by a large variation with respect to diploid chromosome numbers and sex-determining systems among its species, including two multiple X1X2Y sex systems in Hoplias malabaricus and Erythrinus erythrinus. At first, the occurrence of a same sex chromosome system within a family suggests that the sex chromosomes are correlated and originated from ancestral XY chromosomes that were either homomorphic or at an early stage of differentiation. To identify the origin and evolution of these X1X2Y sex chromosomes, we performed reciprocal cross-species FISH experiments with two sex-chromosome-specific probes designed from microdissected X1 and Y chromosomes of H. malabaricus and E. erythrinus, respectively. RESULTS: Our results yield valuable information regarding the origin and evolution of these sex chromosome systems. Our data indicate that these sex chromosomes evolved independently in these two closed related Erythrinidae species. Different autosomes were first converted into a poorly differentiated XY sex pair in each species, and additional chromosomal rearrangements produced both X1X2Y sex systems that are currently present. CONCLUSIONS: Our data provide new insights into the origin and evolution of sex chromosomes, which increases our knowledge about fish sex chromosome evolution.