11/76. Interstitial deletion of 13q and a 13;x chromosome translocation results in partial trisomy 13 and bilateral retinoblastoma.BACKGROUND: Abnormalities of chromosome 13 have been associated with bilateral retinoblastoma. Deletion of a retinoblastoma gene is a common primary mechanism. Other abnormalities are more rare. To our knowledge, a balanced translocation of the long arms of the X and 13 chromosomes associated with bilateral retinoblastoma has been reported five times. We report an unbalanced X;13 translocation resulting in partial trisomy 13 and an interstitial deletion of an RB locus. methods: Case report. RESULTS: A 19-month-old child presented with seizures to the emergency department. A CT scan revealed bilateral intraocular calcification, and retinoblastoma (RB) was confirmed with an ophthalmic exam. Abnormal facies and developmental delay were noted. A partial trisomy derived from the translocation of X;13 was observed in both bone marrow and peripheral blood cells. fluorescence in-situ hybridization (FISH) studies confirmed triplication of a region on the q arm of chromosome 13 spanning the RB locus. One of the normal chromosome 13 homologues had an interstitial deletion of the RB locus since no signal was observed for the RB-1 probe despite the visible presence of the 13q14 region. Additional evidence of the interstitial deletion is supported by the typical facial features and developmental delay found. Presumably, the translocated X underwent X inactivation precluding systemic features typically observed in trisomy 13. Parental karyotypes were normal. The chromosomal abnormality was a de-novo constitutional event. CONCLUSIONS: Only two RB loci were present in this patient despite triplication of 13q. The third locus was deleted. We believe that the second locus was not expressed due to X inactivation of the RB gene on the der(X)t(Xq:13q) chromosome. The emergence of bilateral retinoblastoma points towards lack of heterozygosity at the third and last remaining RB loci in tumor cells. To our knowledge, an unbalanced translocation resulting in partial trisomy 13 with retinoblastoma has not been previously reported.- - - - - - - - - - ranking = 1keywords = chromosome (Clic here for more details about this article) |
12/76. Sinonasal small cell neoplasm developing after radiation therapy for retinoblastoma: an immunohistologic, ultrastructural, and cytogenetic study.patients with retinoblastoma have an increased risk of developing second primary tumors. Only a few examples of sinonasal small cell neoplasms developing after radiation therapy for retinoblastoma have been reported. We report one such case that developed 18 years after treatment for retinoblastoma. Histologic examination revealed a small, blue, round cell tumor without rosettes or cytoplasmic glycogen. Immunohistochemically, the tumor cells were positive for neuron-specific enolase, synaptophysin, and S-100 protein, but negative for epithelial and mesenchymal markers, suggesting that this was a primitive neuroectodermal tumor. Cytogenetic studies of this tumor failed to reveal the chromosome 13 abnormality typical of retinoblastoma and the t(11:22) translocation typical of the group of peripheral neuroepitheliomas.- - - - - - - - - - ranking = 0.11111111111111keywords = chromosome (Clic here for more details about this article) |
13/76. Cytogenetic abnormalities in an ossifying fibroma from a patient with bilateral retinoblastoma.cytogenetic analysis of a cemento-ossifying fibroma from a patient with nonfamilial bilateral multicentric retinoblastoma revealed three reciprocal translocations with the karyotype 46,XY,t(1;18)(q21;q21.3),t(3;10)(p13;q22),t(6;11)(p22;p15). Routine and high-resolution cytogenetic analysis of peripheral blood leukocytes showed an apparently normal, 46,XY chromosome pattern with no deletion of chromosome 13. Molecular analysis demonstrated no gross differences in the retinoblastoma gene or the TP53 gene between constitutional and tumor dna. This is the first cytogenetic analysis of a cemento-ossifying fibroma and the first report of this tumor in a retinoblastoma patient. The data may be added to the small, but growing literature on cytogenetic aberrations in benign tumors and may lend insight into genes involved in cell proliferation and neoplastic transformation.- - - - - - - - - - ranking = 0.22222222222222keywords = chromosome (Clic here for more details about this article) |
14/76. retinoblastoma associated with chromosomal 13q14 deletion mosaicism.PURPOSE: To assess the risk of retinoblastoma developing in children with microscopic chromosomal with mosaic deletions involving 13q14. DESIGN: Case report and systematic literature review. PARTICIPANTS: Data on 29 patients with a mosaic and 107 patients with a nonmosaic somatic deletion of chromosome 13q14 were compared. MAIN OUTCOME MEASURES: Age at diagnosis, frequency, and laterality of retinoblastoma. CASE REPORT: A dysmorphic baby, who carried a chromosomal deletion involving 13q14 in 34% of peripheral blood lymphocytes, had neuroradiologic evidence of retinoblastoma at the age of 2 weeks. She developed trilateral retinoblastoma, a pineal neuroblastic tumor, at the age of 10 months. The diagnosis of her tumor was delayed because of misjudgment of risk of retinoblastoma developing. RESULTS: meta-analysis revealed no difference between children with mosaic and nonmosaic chromosomal deletion of 13q14 regarding the age at diagnosis, laterality of tumor, and presence of family history for retinoblastoma. A lower percentage of somatic cells with mosaic deletion did not predict a higher age at diagnosis or unilateral tumors. No statistically significant difference was noted regarding the presence of mental retardation, dysmorphic features, and anomalies of internal organs between mosaic and nonmosaic deletions. Only 7% (95% confidence interval, 1-23) of 29 patients who had a mosaic chromosomal deletion including 13q14 were not reported to develop retinoblastoma. CONCLUSIONS: Whenever a 13q14 deletion is diagnosed, immediate ophthalmologic evaluation is recommended to ensure prompt diagnosis of retinoblastoma. Mosaic and nonmosaic chromosomal deletions of 13q14 do not differ regarding the risk and type of retinoblastoma developing.- - - - - - - - - - ranking = 0.11111111111111keywords = chromosome (Clic here for more details about this article) |
15/76. Molecular-genetic analysis of two cases with retinoblastoma: benefits for disease management.Effective counselling and management of retinoblastoma families using genetic information is presently practised in many parts of the world. We studied histopathological, chromosomal and molecular-genetic data of two retinoblastoma patients from india. The two patients, one with bilateral and the other with unilateral retinoblastoma, underwent complete ophthalmic examination, cytogenetic study, retinoblastoma gene (RB1) mutational analysis and RB1 promoter region methylation screening. In the bilateral retinoblastoma patient deletion of chromosome region 13q14 in peripheral blood lymphocytes and a hemizygous novel 8-bp deletion in exon 4 of RB1 in tumour sample were observed. In the unilaterally affected patient CGA to TGA transition protein truncation mutations were observed in exons 8 and 14 of RB1.- - - - - - - - - - ranking = 0.11111111111111keywords = chromosome (Clic here for more details about this article) |
16/76. retinoblastoma, pinealoma, and mild overgrowth in a boy with a deletion of RB1 and neighbor genes on chromosome 13q14.We report on a 10-year-old boy with a normal karyotype and a chromosome 13q14 deletion of the retinoblastoma gene (RB1) by fluorescence in situ hybridization (FISH). He showed subtle signs of overgrowth, including macrocephaly, hepatomegaly, and inguinal hernia. The boy also had cryptorchism and mild developmental delay. In his first months of life, variant Wiedemann-Beckwith syndrome was tentatively suspected and he was included in a careful tumor prevention program. At the age of 11 months, bifocal retinoblastoma of the left eye was diagnosed. pinealoma was suspected at the age of 19 months and was removed by neurosurgery at the age of 29 months. At 4 years and 4 months, the deletion of the RB1 gene was suspected on clinical grounds and was diagnosed by FISH and molecular studies. At that time, he was a near-normal healthy playful kindergarten child, height 107 cm (-0.3 SD), OFC 52.5 cm ( 0.8 SD), developmental age 3-3.5 years. The combination of retinoblastoma, pinealoma, and deletion of the RB1 gene diagnosed by FISH has not been reported previously. The deletion spans at least 370-420 kb in size and is predicted to include proximal and distal neighbor genes. This report may assist in establishing the clinical signs of the contiguous gene syndrome at the RB1 locus on 13q14.- - - - - - - - - - ranking = 0.55555555555556keywords = chromosome (Clic here for more details about this article) |
17/76. retinoblastoma, microphthalmia and the chromosome 13q deletion syndrome.A 10-month-old boy, known to have the 13q deletion syndrome, presented with leukocoria in a microphthalmic right eye. He was found to have bilateral retinoblastoma requiring enucleation of the right eye and laser, cryotherapy and external beam radiation to the left eye. This case demonstrates that retinoblastoma may be present in a microphthalmic eye and that more than one imaging modality should be used in the evaluation of suspected retinoblastoma, as calcification may be absent on the computed tomography scan but present on B-mode ultrasound. Children with a known 13q deletion require immediate and serial ophthalmological examinations.- - - - - - - - - - ranking = 0.44444444444444keywords = chromosome (Clic here for more details about this article) |
18/76. bone marrow transplantation for therapy-related acute myeloid leukemia in congenital retinoblastoma associated with 13q deletion syndrome.Children with constitutional deletion of the long arm of chromosome 13 are at risk for retinoblastoma (RB) due to loss of the RB tumor suppressor gene. The prognosis is poor since the tumors are often bilateral, aggressive, and recurrent and the patients often harbor other congenital abnormalities. One further complication is that of therapy-related malignancies later in life. We report a case of allogeneic stem cell transplantation for therapy-related acute myeloid leukemia in an 8-year-old girl after multimodality treatment for refractory bilateral relapsing RB, with excellent outcome in both the ophthalmic and marrow disease.- - - - - - - - - - ranking = 0.11111111111111keywords = chromosome (Clic here for more details about this article) |
19/76. Cytogenetic and molecular investigation of a balanced Xq13q translocation in a patient with retinoblastoma.We report on a 4-year-old girl with retinoblastoma and de novo balanced translocation [46,X,t (X;13) (q23;q13)]. Unilateral retinoblastoma was discovered at age 9 months along with developmental delay and several manifestations of turner syndrome. Chromosome studies showed an X/13 translocation and an X inactivation pattern showing the translocated x chromosome active in all 50 cells examined. Standard Southern blot analysis and pulsed field gel electrophoresis using a 3.8 kb EcoR1 fragment of the cDNA probe to the 3' end of the RB1 locus demonstrated a normal genomic pattern. The results of the cytogenetic and molecular analysis suggests that the RB1 locus has not been disrupted by the chromosome rearrangement. This case is the fifth report of an X/13 translocation associated with a retinoblastoma.- - - - - - - - - - ranking = 0.22222222222222keywords = chromosome (Clic here for more details about this article) |
20/76. Molecular studies of loss of heterozygosity in Chinese sporadic retinoblastoma patients.BACKGROUND: retinoblastoma, an embryonic neoplasm of retinal origin, is the most common and severe intra-ocular tumor affecting infants and young children. methods: loss of heterozygosity (LOH) on chromosome 13 was investigated in 16 Chinese sporadic RB patients, using 14 microsatellite markers spanning the complete chromosome 13, to determine whether those alterations different from the alteration of RB1 gene on 13q14 may play a role in the development of RB. Loss of RB1 allele is commonly encountered in sporadic RB. Microdissected RB tissues and their matched blood DNAs were analyzed for PCR-based LOH by using fluorescence-based dna sequencing technology. RESULTS: Of 16 RB cases, 13 showed LOH on chromosome 13. The frequency of LOH on 13q14 was about 75% (12/16), consistent with other reports. Investigation of parental origin of lost RB1 alleles showed that, in all these cases, the paternal alleles were preferentially lost. Aside from the RB1 locus, other regions with the frequency of LOH above 30% in these tumors were D13S265, D13S158, D13S170, D13S218, D13S285 and D13S159. In particular, the D13S265 locus at 13q31-32 showed the highest rate of allele loss (64%, 9/14 informative cases), suggesting the presence of 1 or several genes whose loss of function may contribute to the development of RB. Comparison of the genotypic characteristics of 3 sites of frequent LOH (D13S153, D13S263 and D13S265) with the clinicopathological phenotype, respectively, showed that LOH of each locus was preferentially associated with a significantly younger age at diagnosis of RB. CONCLUSIONS: LOH analysis at some specific loci on chromosome 13 may be of a value in RB patients as diagnostic markers.- - - - - - - - - - ranking = 0.44444444444444keywords = chromosome (Clic here for more details about this article) |
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