1/76. Sporadic bilateral retinoblastoma and 13q- chromosomal deletion.Unilateral retinoblastoma (Rb) is usually a sporadic occurrence while bilateral (multifocal) cases are often familial. Sporadic bilateral Rb associated with a long-arm deletion of a D-group chromosome has been reported in 8 children. We have studied a 6-year-old female with bilateral sporadic retinoblastoma, treated during infancy by enucleation and radiotherapy. chromosome banding studies on peripheral lymphocytes revealed an interstitial deletion from the long arm of a chromosome 13: del(13) (q12q14). Three additional patients reported in the literature had interstitial 13q- deletions, involving slightly different though overlapping regions. The only chromosomal region consistently missing in all of these 4 cases appears to be part of the lightly staining band 13q14. We, therefore, propose this site as the precise location of a gene (or genes) involved in retinal development. Our patient lacked features of the classic 13q- or 13-ring syndrome, which involves deletion of a more distal portion of the 13 long arm. When compared to reported patients with Rb and 13q-, it became apparent that there may be a separate recognizable syndrome consisting of moderate growth and developmental delay, characteristic facies and external ears, and bilateral sporadic Rb, which is associated with an interstitial 13q- deletion.- - - - - - - - - - ranking = 1keywords = chromosome (Clic here for more details about this article) |
2/76. Establishment and characterization of a second primary osteosarcoma cell line (OSrb/N-M) from a patient cured of bilateral retinoblastoma.A cell line, designated OSrb/N-M, was established from the second primary osteosarcoma that developed in a 17-year-old Japanese female patient who had suffered from bilateral retinoblastoma at infancy. The OSrb/N-M cells grew as an adherent monolayer and retained some osteogenic biochemical phenotypes. In cytogenetic analyses, this cell line revealed many structural and numerical abnormalities, however, the bands q14 of both chromosomes 13 appeared to be normal, whereas the constitutional cells displayed normal female karyotypes. Immunoblot studies using monoclonal antibodies specific to RB protein demonstrated that the tumor cells did not express RB protein, suggesting that the OSrb/N-M cells might suffer from a loss-of-function mutation at this gene locus. Thus, this cell line is useful to study the molecular mechanism for the tumorigenesis of osteosarcoma with regard to an association with retinoblastoma.- - - - - - - - - - ranking = 0.5keywords = chromosome (Clic here for more details about this article) |
3/76. retinoblastoma with an unusual presentation in a child with polydactyly. Clinical associations and genetic implications.retinoblastoma is the most common intraocular malignancy of childhood. It may rarely present with white spots on the iris and pseudohypopyon. We report a case of an 11-month old child with polydactyly with this presentation of retinoblastoma. There was no positive family history of the disease. Investigations included anterior segment examination under anaesthesia, fundoscopy with scleral indentation, A- and B-scan ultrasound and MRI examination of the head. This was a Reese Ellsworth group 5 retinoblastoma with an indication for enucleation. pathology reports of the enucleated globe showed choroidal and ciliary body invasion. Therefore, subsequent chemotherapy treatment was undertaken. The retinoblastoma gene is located in the long arm of chromosome 13. Almost all familial and bilateral cases carry the abnormal gene. In unilateral isolated retinoblastomas--as in our case--most patients do not have a germinal mutation, however, only dna analysis can safely exclude that. We also discuss possible factors having a link to both polydactyly and retinoblastoma.- - - - - - - - - - ranking = 0.5keywords = chromosome (Clic here for more details about this article) |
4/76. Boy with bilateral retinoblastoma due to an unusual ring chromosome 13 with activation of a latent centromere.We present a patient with bilateral retinoblastoma and developmental delay who has an abnormal male karyotype containing 47 chromosomes, including an acentric derivative chromosome 13. We postulate that the derivative 13 occurred after a break at 13q14, with the proximal portion of the chromosome forming a ring and the distal portion undergoing duplication. Thus, this patient is trisomic for 13q14-->qter. The derivative chromosome with duplicated distal portion (13q14-->qter) lacked the 13 centromere and was negative for chromosome 13 alpha-satellite dna by low stringency FISH. Nevertheless, this chromosome is stably transmitted in lymphocytes and fibroblasts. A single primary constriction was observed at band 13q21, consistent with activation of a latent centromere (neocentromere) at this band. The neocentromere on der(13) was positive for multiple centromeric proteins, suggesting that it acts as the functional centromere. By FISH, the Rb gene was present on the normal 13, the proximally derived ring chromosome, but not on the derivative chromosome. Although there was no evidence for disruption of the Rb gene, this chromosome rearrangement most likely results in abnormal expression of the Rb gene product. copyright Wiley-Liss. Inc.- - - - - - - - - - ranking = 6.5keywords = chromosome (Clic here for more details about this article) |
5/76. Dup(12)(q13-q22) and 13q14 deletion in a case of B-cell chronic lymphocytic leukemia.Cases with partial trisomy 12 have rarely been found in B-cell chronic lymphocytic leukemia (CLL). We report our clinical, cytogenetic and fluorescence in situ hybridization (FISH) findings in a CLL patient with a duplication of part of the long arm of chromosome 12 between bands q13-q22. This patient was the only case with this duplication among the 112 cases (0.9%) of CLL cytogenetically analyzed in our laboratory. FISH studies using unique-sequence specific probes for the RB-1 (retinoblastoma) gene and the D13S319 locus at the 13q14 band showed a monoallelic loss for the D13S319 locus (20% of cells) with a diploid RB-1 gene. Our case showed an atypical morphology (35% prolymphocytes), a high proliferation rate and progression of the disease, indicating that the duplication of this region may be equivalent to complete trisomy 12 in CLL patients.- - - - - - - - - - ranking = 0.5keywords = chromosome (Clic here for more details about this article) |
6/76. A 13-year-old boy with cognitive impairment, retinoblastoma, and Wilson disease.A developmentally delayed child manifested retinoblastoma at age 4 years and Wilson disease at age 11, a previously unreported association. Cytogenetic and molecular analysis showed an interstitial deletion in the long arm of the paternally derived homologue of chromosome 13 (13q14.2-13q22.2), which encompasses the retinoblastoma and Wilson disease loci. The authors postulate that the co-occurrence of retinoblastoma and Wilson disease was the consequence of an acquired somatic mutation at the retinoblastoma locus and an inherited mutation at the Wilson disease locus of the maternally derived chromosome 13, superimposed on the hemizygosity associated with the paternally derived deletion.- - - - - - - - - - ranking = 1keywords = chromosome (Clic here for more details about this article) |
7/76. Trilateral retinoblastoma variant indicative of the relevance of the retinoblastoma tumor-suppressor pathway to medulloblastomas in humans.Results of recent studies have led investigators to suggest that the retinoblastoma tumor-suppressor (rb) gene plays an underappreciated role in the genesis of brain tumors. Such tumors cause significant rates of mortality in children suffering from hereditary retinoblastoma. It has been assumed that the pineal gland, which is ontogenetically related to the retina, accounts for the intracranial origin of these trilateral neoplasms. To address this issue, the authors describe an unusual trilateral retinoblastoma variant. The authors provide a detailed clinicopathological correlation by describing the case of a child with bilateral retinoblastoma who died of a medulloblastoma. The intraocular and intracranial neoplasms were characterized by performing detailed imaging, histopathological, and postmortem studies. karyotype analysis and fluorescence in situ hybridization were used to define the chromosomal defect carried by the patient and members of her family. An insertion of the q12.3q21.3 segment of chromosome 13 into chromosome 18 at band q23 was identified in members of the patient's family. This translocation was unbalanced in the proband. The intraocular and cerebellar neoplasms were found to be separate primary neoplasms. Furthermore, the pineal gland was normal and the cerebellar neoplasm arose within the vermis as a medulloblastoma. Finally, the two neoplasms had different and characteristically identifiable cytolological and immunohistochemical profiles. The findings of the present study, taken together with those of recent molecular and transgenic studies, support the emerging concept that rb inactivation is not restricted to central nervous system regions of photoreceptor lineage and that inactivation of this tumor suppressor pathway may be relevant to the determination of etiological factors leading to medulloblastoma in humans.- - - - - - - - - - ranking = 1keywords = chromosome (Clic here for more details about this article) |
8/76. genome instability in secondary solid tumors developing after radiotherapy of bilateral retinoblastoma.genome alterations of seven secondary tumors (five osteosarcomas, one malignant peripheral sheath nerve tumor, one leiomyosarcoma) occurring in the field of irradiation of patients treated for bilateral retinoblastoma have been studied. These patients were predisposed to develop radiation-induced tumors because of the presence of a germ line mutation in the retinoblastoma gene (RB1). Tumor cells were characterized by a high chromosome instability whereas microsatellites and minisatellites were found to be stable. In all tumors, the normal RB1 allele was lost with the corresponding chromosome 13, whereas the germ line mutated allele was retained. The two alleles of TP53 were inactivated, one by deletion of the short arm of chromosome 17, the other by mutation. As compared with non-radiation-induced tumors, the observed panel of TP53 mutations was uncommon with sites not recurrently found otherwise and a high rate of deletions (3/7). In these predisposed patients, the loss of the single normal allele of RB1 is rather due to the radiation-induced chromosome instability than a direct effect of ionizing radiation.- - - - - - - - - - ranking = 2keywords = chromosome (Clic here for more details about this article) |
9/76. retinoblastoma in a patient with an X;13 translocation and facial abnormalities consistent with 13q-syndrome.PURPOSE: To report a patient with an X;13 translocation and facial features of 13q-syndrome who developed retinoblastoma. DESIGN: Observational case report. methods: A 9-month-old girl known to have an X;13 chromosomal translocation with a break point at 13q12.1 and dysmorphic facial features characteristic of 13q-syndrome presented with leukocoria in her right eye. RESULTS: By clinical examination, retinoblastoma was diagnosed in the right eye. CONCLUSION: Chromosomal abnormalities on the long arm of chromosome 13 predispose to retinoblastoma formation and characteristic facial features.- - - - - - - - - - ranking = 0.5keywords = chromosome (Clic here for more details about this article) |
10/76. New findings in the chromosome 13 long-arm deletion syndrome and retinoblastoma.New clinical and pathologic findings in patients with deletion of the long arm of chromosome 13 (13q-) include optic nerve hypoplasia and retinal dysplasia. fibroblasts derived from patients with a 13q- syndrome with and without retinoblastoma, as well as from familial and sporadic retinoblastoma, are a useful model for the study of genetic susceptibility to the development of spontaneous and radiation-induced cancers. fibroblasts from patients with hereditary retinoblastoma appear more radiosensitive than fibroblasts from patients with sporadic retinoblastoma or normal control patients.- - - - - - - - - - ranking = 2.5keywords = chromosome (Clic here for more details about this article) |
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