Identification of three new mutations in the RB1 gene in patients with sporadic retinoblastoma in Colombia / Identificación de tres nuevas mutaciones en el gen RB1 en pacientes con retinoblastoma esporádico en Colombia

Introduction. Retinoblastoma is a childhood cancer of the retina originated by altered or null retinoblastoma protein (pRb) expression. Genetic alterations in both RB1 alleles in the retinal cells are required for the development of retinoblastoma. In the sporadic form, non-hereditary RB1 gene mutations take place in a single retinoblast cell, and are therefore only present in tumor DNA (somatic mutations). Sporadic retinoblastoma is primarily unilateral, lacks family history and has no risk of transmission to descendants. Genetic tests for detection of RB1 mutation has improved the identification of carriers and facilitated accurate genetic counseling. Objective. To identify mutations in the RB1 gene in Colombian patients with sporadic retinoblastoma by PCR-SSCP followed by sequence. Materials and methods. Four patients with sporadic retinoblastoma were analyzed by PCR-SSCP, followed by DNA sequencing to identify variations in the RB1 gene. Results. We identified five variations in RB1 gene: three new mutations (one germline and two somatic mutations), one new polymorphism and one already reported somatic mutation. Four mutations were found in three patients with unilateral retinoblastoma and one mutation was found in a patient with bilateral retinoblastoma. One of these was a germline mutation in a sporadic unilateral retinoblastoma that was not present in the parents or three siblings analyzed. Conclusions. Our results emphasize the importance of identifying mutations for genetic counseling and clinical management of sporadic retinoblastoma patients. Description of a new RB1 gene variant is interesting since there have been a small number of polymorphisms reported for this gene.

Introducción. El retinoblastoma es un cáncer pediátrico de la retina originado por la expresión alterada o ausente de la proteína del retinoblastoma (pRb). Se requiere la alteración genética de ambos alelos RB1 en las células de la retina para el desarrollo del retinoblastoma. En la forma esporádica, las mutaciones no hereditarias del gen RB1 ocurren en un solo retinoblasto y están presentes sólo en el ADN del tumor (mutaciones somáticas). El retinoblastoma esporádico es generalmente unilateral, no tiene historia familiar y no tiene riesgo de transmisión a la descendencia. Las pruebas genéticas para la detección de mutaciones en RB1 han mejorado la identificación de portadores y han facilitado la precisión de la asesoría genética. Objetivo. Detectar mutaciones en el gen RB1 en pacientes colombianos con retinoblastoma esporádico mediante PCR-SSCP seguido de secuenciación. Materiales y métodos. Se analizaron cuatro pacientes con retinoblastoma esporádico para la detección de variaciones en el gen RB1 mediante PCR-SSCP, seguida de secuenciación. Resultados. Se identificaron cinco variaciones del gen RB1 : tres mutaciones nuevas (una de línea germinal y dos somáticas), un polimorfismo nuevo y una mutación somática ya reportada. Las cuatro mutaciones se encontraron en tres pacientes con retinoblastoma unilateral y uno con bilateral. La mutación germinal se detectó en un paciente con compromiso unilateral y no se encontró en los padres ni en los tres hermanos analizados. Conclusión. Estos resultados enfatizan la importancia, para asesoría genética y manejo clínico, de identificar mutaciones del gen RB1 en pacientes con retinoblastoma esporádico. La descripción de una nueva variante en RB1 es interesante, dado el muy bajo número de polimorfismos reportados para este gen.

Serum and aqueous lactate dehydrogenase ratio in the diagnosis of retinoblastoma

Leakage of lactate dehydrogenase hormone from malignant tumors cells has been described. To measure the serum and aqueous lactate dehydrogenase ratio as diagnostic indicator for retinoblastoma. Prospective analytical study, carried out at Khyber Teaching Hospital Peshawar between 1[st] July 1999 and 31[st] December, 2003. Hundred newly diagnosed patients with retinoblastoma were registered for treatment. The aqueous lactate dehydrogenase was determined in fourteen randomly selected retinoblastoma patients, classified as advanced stage VB group [Rees-Ellsworth classification]. Samples from aqueous of these patients were analyzed for lactate dehydrogenase level using automatic scanner [Selectra XL, vital scientific Netherlands]. The Aquous lactate dehydrogenase was determined in 14 patients, who had a mean age of 36 months [range 2 months - 7.5 years]. There was equal number of unilateral and bilateral cases. Mean serum lactate dehydrogenase level was 730 i.u/litre and aqueous lactate dehydrogenase was 27,042 i.u/litre. Serum: aqueous lactate dehydrogenase ratio was 27:1 against normal ratio of 1 to 1. Aqueous lactate dehydrogenase levels were proved to be sensitive biochemical test for supporting the diagnosis of retinoblastoma

Serum levels of soluble Fas [S-FAS] and soluble intercellular adhesion molecule-1 [S-ICAM-1] in childhood solid tumors: correlation with clinical features and outcome

The levels of s-Fas and s-ICAM-1 conjointly in sera of patients with malignant diseases were evaluated in sera of sixty-two children with solid tumor on admission. They included thirty-four children with non- Hodgkin's lymphoma [NHL], three with Hodgkin's lymphoma [HL], eight with neuroblastoma, four with retinoblastoma, five with osteosarcoma, three with Ewing's sarcoma and five with Wilm's tumor. For comparative purposes, serum samples were obtained from ten healthy children who were comparable in age and sex with the patients. The study revealed significant increase of s-Fas as well as sICAM-1 in children with solid malignant tumors as a whole and irrespective of the pathological type compared with controls. The sensitivities were 100% and 93.5%, respectively. The levels of either s-Fas or sICAM-1 reflected organomegaly and outcome in children with solid tumor as a whole. Moreover, they reflected tumor spread, grade and burden in cases with NHL. Significant positive correlation existed between s-Fas and sICAM-1