RESUMO
Mutations of the adenomatous polyposis coli (APC) gene predispose individuals to familial adenomatous polyposis (FAP), characterized by multiple tumours in the large intestine. Most mouse models heterozygous for truncating mutant Apc alleles mimic FAP, however, the intestinal tumours occur mainly in the small intestine. To model large intestinal tumours, we generated a new conditional Apc-mutant allele, Apc(15lox), with exon 15 flanked by loxP sites. Similar survival of Apc(1638N/15lox) and Apc(1638N/+) mice indicated that the normal function of Apc was not impaired by the loxP sites. Deletion of exon 15, encoding nearly all functional Apc domains and containing the polyadenylation signal, resulted in a mutant allele expressing low levels of a 74 kDa truncated Apc protein. Germ line Cre-mediated deletion of exon 15 resulted in Apc(Delta15/+) mice, showing a severe Apc(Min/+)-like phenotype characterized by multiple tumours in the small intestine and early lethality. In contrast, conditional Cre-mediated deletion of exon 15 specifically directed to the epithelia of distal small and large intestine of FabplCre;Apc(15lox/+) mice led to longer survival and to tumours that developed predominantly in the large intestine, mimicking human FAP-associated colorectal cancer and sporadic colorectal cancer. We conclude that the FabplCre;Apc(15lox/+) mouse should be an attractive model for studies on prevention and treatment of colorectal cancer.
Assuntos
Neoplasias Colorretais/genética , Modelos Animais de Doenças , Genes APC , Mutação , Animais , Fator de Transcrição CDX2 , Proteínas de Homeodomínio/genética , Humanos , Integrases/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Transcrição/genéticaRESUMO
PURPOSE: At present, clinically useful markers predicting response of primary breast carcinomas to either doxorubicin-cyclophosphamide (AC) or doxorubicin-docetaxel (AD) are lacking. We investigated whether gene expression profiles of the primary tumor could be used to predict treatment response to either of those chemotherapy regimens. PATIENTS AND METHODS: Within a single-institution, randomized, phase II trial, patients with locally advanced breast cancer received six courses of either AC (n = 24) or AD (n = 24) neoadjuvant chemotherapy. Gene expression profiles were generated from core-needle biopsies obtained before treatment and correlated with the response of the primary tumor to the chemotherapy administered. Additionally, pretreatment gene expression profiles were compared with those in tumors remaining after chemotherapy. RESULTS: Ten (20%) of 48 patients showed a (near) pathologic complete remission of the primary tumor after treatment. No gene expression pattern correlating with response could be identified for all patients or for the AC or AD groups separately. The comparison of the pretreatment biopsy and the tumor excised after chemotherapy revealed differences in gene expression in tumors that showed a partial remission but not in tumors that did not respond to chemotherapy. CONCLUSION: No gene expression profile predicting the response of primary breast carcinomas to AC- or AD-based neoadjuvant chemotherapy could be detected in this interim analysis. More subtle differences in gene expression are likely to be present but can only be reliably identified by studying a larger group of patients. Response of a breast tumor to neoadjuvant chemotherapy results in alterations in gene expression.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Regulação Neoplásica da Expressão Gênica , Invasividade Neoplásica/patologia , RNA Neoplásico/genética , Adulto , Idoso , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Ciclofosfamida/uso terapêutico , Docetaxel , Doxorrubicina/uso terapêutico , Feminino , Perfilação da Expressão Gênica , Marcadores Genéticos/genética , Humanos , Pessoa de Meia-Idade , Família Multigênica , Terapia Neoadjuvante , Estadiamento de Neoplasias , Prognóstico , Medição de Risco , Sensibilidade e Especificidade , Análise de Sobrevida , Taxoides/uso terapêutico , Resultado do TratamentoRESUMO
BACKGROUND/AIMS: In addition to genome-wide association studies (GWAS), height-associated genes may be uncovered by studying individuals with extreme short or tall stature. METHODS: Genome-wide analysis for copy number variants (CNVs), using single nucleotide polymorphism (SNP) arrays, was performed in 49 index cases born small for gestational age with persistent short stature. Segregation analysis was performed, and genes in CNVs were compared with information from GWAS, gene expression in rodents' growth plates, and published information. RESULTS: CNVs were detected in 13 cases. In 5 children a known cause of short stature was found: UPD7, UPD14, a duplication of the SHOX enhancer region, an IGF1R deletion, and a 22q11.21 deletion. In the remaining 8 cases, potential pathogenic CNVs were detected, either de novo (n = 1), segregating (n = 2), or not segregating with short stature (n = 5). Bioinformatic analysis of the de novo and segregating CNVs suggested that HOXD4, AGPS, PDE11A, OSBPL6, PRKRA and PLEKHA3, and possibly DGKB and TNFRSF11B are potential candidate genes. A SERPINA7 or NRK defect may be associated with an X-linked form of short stature. CONCLUSION: SNP arrays detected 5 known causes of short stature with prenatal onset and suggested several potential candidate genes.
Assuntos
Variações do Número de Cópias de DNA , Recém-Nascido Pequeno para a Idade Gestacional , Polimorfismo de Nucleotídeo Único , Animais , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , CamundongosRESUMO
BACKGROUND/AIMS: Because the criteria for genetic screening of short children are unknown, we performed genetic analysis of 199 short children born small for gestational age (SGA) or with normal birth size (idiopathic short stature, ISS). METHODS: After selection with a modified scoring system for SHOX and a novel score for IGF1 and IGF1R defects, direct sequencing and multiplex ligation-dependent probe amplification (MLPA) was performed for SHOX and IGF1R in selected patients, and confirmed by SNP array analysis. RESULTS: In 6 children, gene variants were identified in SHOX, its adjacent pseudoautosomal region (PAR) and IGF1R: a SHOX mutation, terminal 15q deletion, a SHOX and IGF1R defect, a deletion of the Xp22.3 PAR region, and two patients with duplications in the Xp22.3 PAR region. In a seventh patient, steroid sulfatase deficiency was detected because a probe for STS was used as control; this syndrome has not been associated with short stature before. CONCLUSION: A selection process using clinical scores for SHOX, IGF1 and IGF1R defects followed by genetic testing with MLPA and direct sequencing led to the detection of a SHOX or IGF1R genetic variant in 6% of short children.
Assuntos
Retardo do Crescimento Fetal/genética , Transtornos do Crescimento/genética , Proteínas de Homeodomínio/genética , Fator de Crescimento Insulin-Like I/genética , Mutação , Receptor IGF Tipo 1/genética , Estudos de Coortes , Feminino , Retardo do Crescimento Fetal/metabolismo , Duplicação Gênica , Estudos de Associação Genética , Alemanha , Transtornos do Crescimento/metabolismo , Proteínas de Homeodomínio/metabolismo , Humanos , Ictiose Ligada ao Cromossomo X/genética , Ictiose Ligada ao Cromossomo X/metabolismo , Recém-Nascido , Recém-Nascido Pequeno para a Idade Gestacional , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Polimorfismo de Nucleotídeo Único , Pseudogenes , Receptor IGF Tipo 1/metabolismo , Deleção de Sequência , Proteína de Homoeobox de Baixa EstaturaRESUMO
Congenital central hypothyroidism occurs either in isolation or in conjunction with other pituitary hormone deficits. Using exome and candidate gene sequencing, we identified 8 distinct mutations and 2 deletions in IGSF1 in males from 11 unrelated families with central hypothyroidism, testicular enlargement and variably low prolactin concentrations. IGSF1 is a membrane glycoprotein that is highly expressed in the anterior pituitary gland, and the identified mutations impair its trafficking to the cell surface in heterologous cells. Igsf1-deficient male mice show diminished pituitary and serum thyroid-stimulating hormone (TSH) concentrations, reduced pituitary thyrotropin-releasing hormone (TRH) receptor expression, decreased triiodothyronine concentrations and increased body mass. Collectively, our observations delineate a new X-linked disorder in which loss-of-function mutations in IGSF1 cause central hypothyroidism, likely secondary to an associated impairment in pituitary TRH signaling.
Assuntos
Hipotireoidismo Congênito/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Imunoglobulinas/genética , Proteínas de Membrana/genética , Mutação , Doenças Testiculares/genética , Adolescente , Adulto , Idoso , Animais , Sequência de Bases , Criança , Pré-Escolar , Exoma , Compostos Ferrosos , Humanos , Lactente , Masculino , Metalocenos , Camundongos , Pessoa de Meia-Idade , Hipófise/metabolismo , Hipófise/patologia , Prolactina/sangue , Receptores do Hormônio Liberador da Tireotropina/biossíntese , Análise de Sequência de DNA , Síndrome , Testículo/anatomia & histologia , Testículo/patologia , Tireotropina/sangue , Tri-Iodotironina/análise , Adulto JovemRESUMO
We report a 797 kb de novo interstitial deletion of 18q21.31 in a 6-year-old boy with speech delay, mental retardation, sleeping problems, facial dysmorphism, and feet anomalies. Examination of the region showed two genes, TXNL1 and WDR7, to be involved in the deletion. Haploinsufficiency of these genes could potentially contribute to the phenotype. Our patient has some clinical features that overlap with earlier described patients with a larger deletion of the distal part of chromosome 18q. The small deletion in region 18q21.31 may be responsible for some of the common features found in patients with larger 18q deletions.
Assuntos
Anormalidades Múltiplas/genética , Deleção Cromossômica , Cromossomos Humanos Par 18/genética , Deficiência Intelectual/patologia , Transtornos do Desenvolvimento da Linguagem/patologia , Anormalidades Múltiplas/patologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Criança , Face/anormalidades , Deformidades Congênitas do Pé/patologia , Haploinsuficiência , Humanos , Masculino , Transtornos do Sono-Vigília/patologia , Tiorredoxinas/genéticaRESUMO
Mosaicism involving a normal cell line and an unbalanced autosomal translocation are rare. In this study we present three new cases with such a mosaicism, which were detected by Single Nucleotide Polymorphism (SNP) array analysis in our routine diagnostic setting. These cases were further characterized using Fluorescence in situ Hybridisation (FISH) analysis and conventional karyotyping. The first case is a mentally retarded male who carries an unbalanced translocation in 87% of his cells. The phenotypically normal mother carries the balanced form of the translocation in all her cells. The second case is a phenotypically normal female who has an unbalanced translocation in 52% of her cells. The inheritance could not be determined. The third case is a female referred for Rubinstein-Taybi syndrome who carries an unbalanced translocation in 60% of her cells. Both parents of this case showed a normal karyotype. The mechanisms that might be responsible for these mosaic karyotypes are discussed. Furthermore, we demonstrate that high-resolution whole-genome SNP array is a powerful tool to reveal cryptic unbalanced translocations and mosaicisms, including the more rare cases.
Assuntos
Mosaicismo , Translocação Genética , Adulto , Alelos , Aberrações Cromossômicas , Feminino , Humanos , Deficiência Intelectual/genética , Cariotipagem , Masculino , Pessoa de Meia-Idade , Modelos Genéticos , Linhagem , Fenótipo , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
Apparently balanced chromosome abnormalities are occasionally associated with mental retardation (MR). These balanced rearrangements may disrupt genes. However, the phenotype may also be caused by small abnormalities present at the breakpoints or elsewhere in the genome. Conventional karyotyping is not instrumental for detecting small abnormalities because it only identifies genomic imbalances larger than 5-10 Mb. In contrast, high-resolution whole-genome arrays enable the detection of submicroscopic abnormalities in patients with apparently balanced rearrangements. Here, we report on the whole-genome analysis of 13 MR patients with previously detected balanced chromosomal abnormalities, five de novo, four inherited, and four of unknown inheritance, using Single Nucleotide Polymorphism (SNP) arrays. In all the cases, the patient had an abnormal phenotype. In one familial case and one unknown inheritance case, one of the parents had a phenotype which appeared identical to the patient's phenotype. Additional copy number variants (CNVs) were identified in eight patients. Three patients contained CNVs adjacent to one or either breakpoints. One of these patients showed four and two deletions near the breakpoints of a de novo pericentric inversion. In five patients we identified CNVs on chromosomes unrelated to the previously observed genomic imbalance. These data demonstrate that high-resolution array screening and conventional karyotyping is necessary to tie complex karyotypes to phenotypes of MR patients.
Assuntos
Anormalidades Múltiplas/genética , Aberrações Cromossômicas , Variações do Número de Cópias de DNA , Deficiência Intelectual/genética , Cariotipagem , Adolescente , Adulto , Estudos de Casos e Controles , Pré-Escolar , Inversão Cromossômica , Feminino , Rearranjo Gênico , Humanos , Hibridização in Situ Fluorescente , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Polimorfismo de Nucleotídeo Único , Translocação GenéticaRESUMO
High-density single-nucleotide polymorphism (SNP) genotyping technology enables extensive genotyping as well as the detection of increasingly smaller chromosomal aberrations. In this study, we assess molecular karyotyping as first-round analysis of patients with mental retardation and/or multiple congenital abnormalities (MR/MCA). We used different commercially available SNP array platforms, the Affymetrix GeneChip 262K NspI, the Genechip 238K StyI, the Illumina HumanHap 300 and HumanCNV 370 BeadChip, to detect copy number variants (CNVs) in 318 patients with unexplained MR/MCA. We found abnormalities in 22.6% of the patients, including six CNVs that overlap known microdeletion/duplication syndromes, eight CNVs that overlap recently described syndromes, 63 potentially pathogenic CNVs (in 52 patients), four large segments of homozygosity and two mosaic trisomies for an entire chromosome. This study shows that high-density SNP array analysis reveals a much higher diagnostic yield as that of conventional karyotyping. SNP arrays have the potential to detect CNVs, mosaics, uniparental disomies and loss of heterozygosity in one experiment. We, therefore, propose a novel diagnostic approach to all MR/MCA patients by first analyzing every patient with an SNP array instead of conventional karyotyping.
Assuntos
Anormalidades Múltiplas/diagnóstico , Aberrações Cromossômicas , Deficiência Intelectual/diagnóstico , Cariotipagem/métodos , Análise de Sequência com Séries de Oligonucleotídeos , Pré-Escolar , Dosagem de Genes , Humanos , Masculino , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Human carcinoma in situ of the breast already demonstrates genomic changes found in invasive lesions. However, no specific genetic alterations have previously been identified that are associated with progression from the in situ to the invasive stage. By comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH) analysis of an invasive breast carcinoma with a large associated in situ component, high-level amplification of C-MYC was found in the invasive component only. To determine the frequency of this correlation in a panel of 188 invasive breast carcinomas, 18 additional cases with C-MYC amplification were identified. Nine of these cases had a detectable adjacent in situ component. FISH analysis demonstrated increased (>5) C-MYC signals per nucleus in seven invasive components and increased (>4) C-MYC/centromere 8 signal ratios in five of these. None of the associated in situ components demonstrated these increases. The minimal amplified region was defined at 8q24.13-8qter. C-MYC amplification was correlated with overexpression of C-MYC and two of its target genes, TERT and FBL. Thus, C-MYC amplification is the first identified genetic alteration that is associated with progression from the in situ to the invasive stage of breast carcinoma.