Assuntos
Biomarcadores Tumorais/genética , Perfilação da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Mutação/genética , Sarcoma Mieloide/genética , Análise de Sequência de DNA/métodos , Adulto , Idoso , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , PrognósticoRESUMO
We report on 2 similarly affected cousins with a compound imbalance resulting from a familial t(5;9)(q34;p23) and entailing both an â¼17-Mb 5q terminal duplication and an â¼12-Mb 9p terminal deletion as determined by G-banding, subtelomere FISH, and aCGH. The proband's karyotype was 46,XX,der(9)t(5;9)(q34;p23)mat.ish der(9)t(5;9)(q34;p23)(9pter-,5qter+).arr 5q34q35(163,328,000-180,629,000)×3, 9p24p23(194,000-12,664,000)×1. Her cousin had the same unbalanced karyotype inherited from his father. The clinical phenotype mainly consists of a distinct craniofacial dysmorphism featuring microcephaly, flat facies, down slanting palpebral fissures, small flat nose, long philtrum, and small mouth with thin upper lip. Additional remarkable findings were craniosynostosis of several sutures, craniolacunia and preaxial polydactyly in the proband and hypothyroidism in both subjects. The observed clinical constellation generally fits the phenotypic spectrum of the 5q distal duplication syndrome (known also as Hunter-McAlpine syndrome), except for the thyroid insufficiency which can likely be ascribed to the concurrent 9p deletion, as at least 4 other 9pter monosomic patients without chromosome 5 involvement had this hormonal disorder. The present observation further confirms the etiology of the HMS phenotype from gain of the 5q35âqter region, expands the clinical pictures of partial trisomy 5q and monosomy 9p, and provides a comprehensive list of 160 patients with 5q distal duplication.
Assuntos
Cromossomos Humanos Par 5/genética , Hipotireoidismo/genética , Adulto , Deleção Cromossômica , Cromossomos Humanos Par 9/genética , Craniossinostoses/genética , Síndrome de Cri-du-Chat/genética , Feminino , Transtornos do Crescimento/genética , Humanos , Hibridização in Situ Fluorescente , Lactente , Deficiência Intelectual/genética , Cariotipagem , Masculino , Trissomia/genéticaRESUMO
Effects of d(CAG)(n).d(CTG)(n) repeats on expression of a reporter gene in human cell culture were studied using transient transfection, RNase protection and coupled transcription/translation assays. Cloning these repeats into the reporter 3'-UTR did not affect gene functioning. In contrast, placing the repeats in the reporter 5'-UTR led to strong inhibition of expression. This inhibition depended on the repeat orientation, being prominent only when the (CTG)(n) tracts were in the sense strand for transcription. Further, the strength of inhibition increased exponentially with an increase in repeat length. Our data indicate that expanded (CTG)(n) repeats prevent efficient translation of the reporter mRNA both in vitro and in vivo. We suggest that formation of stable hairpins by (CUG)(n) runs of increasing length in the 5'-UTR of a mRNA progressively inhibits the scanning step of translation initiation. This points to a novel mechanism of regulating gene expression by expandable d(CTG)(n) repeats.
Assuntos
Regiões 5' não Traduzidas/genética , Regulação para Baixo , Genes Reporter/genética , Biossíntese de Proteínas/genética , Expansão das Repetições de Trinucleotídeos/genética , Regiões 5' não Traduzidas/biossíntese , Regiões 5' não Traduzidas/química , Regiões 5' não Traduzidas/metabolismo , Sequência de Bases , Códon/genética , Humanos , Ensaios de Proteção de Nucleases , Conformação de Ácido Nucleico , Iniciação Traducional da Cadeia Peptídica/genética , Plasmídeos/genética , Transcrição Gênica/genética , Transfecção , Células Tumorais CultivadasRESUMO
(CGG)n.(CCG)n and (CTG)n.(CAG)n repeats of varying length were cloned into a bacterial plasmid, and the progression of the replication fork through these repeats was followed using electrophoretic analysis of replication intermediates. We observed stalling of the replication fork within repeated DNAs and found that this effect depends on repeat length, repeat orientation relative to the replication origin and the status of protein synthesis in a cell. Interruptions within repeated DNAs, similar to those observed in human genes, abolished the replication blockage. Our results suggest that the formation of unusual DNA structures by trinucleotide repeats in the lagging-strand template may account for the observed replication blockage and have relevance to repeat expansion in humans.