DNA Methylomes Reveal Biological Networks Involved in Human Eye Development, Functions and Associated Disorders.

This work provides a comprehensive CpG methylation landscape of the different layers of the human eye that unveils the gene networks associated with their biological functions and how these are disrupted in common visual disorders. Herein, we firstly determined the role of CpG methylation in the regulation of ocular tissue-specification and described hypermethylation of retinal transcription factors (i.e., PAX6, RAX, SIX6) in a tissue-dependent manner. Second, we have characterized the DNA methylome of visual disorders linked to internal and external environmental factors. Main conclusions allow certifying that crucial pathways related to Wnt-MAPK signaling pathways or neuroinflammation are epigenetically controlled in the fibrotic disorders involved in retinal detachment, but results also reinforced the contribution of neurovascularization (ETS1, HES5, PRDM16) in diabetic retinopathy. Finally, we had studied the methylome in the most frequent intraocular tumors in adults and children (uveal melanoma and retinoblastoma, respectively). We observed that hypermethylation of tumor suppressor genes is a frequent event in ocular tumors, but also unmethylation is associated with tumorogenesis. Interestingly, unmethylation of the proto-oncogen RAB31 was a predictor of metastasis risk in uveal melanoma. Loss of methylation of the oncogenic mir-17-92 cluster was detected in primary tissues but also in blood from patients.

Retinoblastoma and Neuroblastoma Predisposition and Surveillance.

Retinoblastoma (RB) is the most common intraocular malignancy in childhood. Approximately 40% of retinoblastomas are hereditary and due to germline mutations in the RB1 gene. Children with hereditary RB are also at risk for developing a midline intracranial tumor, most commonly pineoblastoma. We recommend intensive ocular screening for patients with germline RB1 mutations for retinoblastoma as well as neuroimaging for pineoblastoma surveillance. There is an approximately 20% risk of developing second primary cancers among individuals with hereditary RB, higher among those who received radiotherapy for their primary RB tumors. However, there is not yet a clear consensus on what, if any, screening protocol would be most appropriate and effective. Neuroblastoma (NB), an embryonal tumor of the sympathetic nervous system, accounts for 15% of pediatric cancer deaths. Prior studies suggest that about 2% of patients with NB have an underlying genetic predisposition that may have contributed to the development of NB. Germline mutations in ALK and PHOX2B account for most familial NB cases. However, other cancer predisposition syndromes, such as Li-Fraumeni syndrome, RASopathies, and others, may be associated with an increased risk for NB. No established protocols for NB surveillance currently exist. Here, we describe consensus recommendations on hereditary RB and NB from the AACR Childhood Cancer Predisposition Workshop. Clin Cancer Res; 23(13); e98-e106. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Multiple Endocrine Neoplasia and Hyperparathyroid-Jaw Tumor Syndromes: Clinical Features, Genetics, and Surveillance Recommendations in Childhood.

Children and adolescents who present with neuroendocrine tumors are at extremely high likelihood of having an underlying germline predisposition for the multiple endocrine neoplasia (MEN) syndromes, including MEN1, MEN2A and MEN2B, MEN4, and hyperparathyroid-jaw tumor (HPT-JT) syndromes. Each of these autosomal dominant syndromes results from a specific germline mutation in unique genes: MEN1 is due to pathogenic MEN1 variants (11q13), MEN2A and MEN2B are due to pathogenic RET variants (10q11.21), MEN4 is due to pathogenic CDKN1B variants (12p13.1), and the HPT-JT syndrome is due to pathogenic CDC73 variants (1q25). Although each of these genetic syndromes share the presence of neuroendocrine tumors, each syndrome has a slightly different tumor spectrum with specific surveillance recommendations based upon tumor penetrance, including the age and location for which specific tumor types most commonly present. Although the recommended surveillance strategies for each syndrome contain similar approaches, important differences do exist among them. Therefore, it is important for caregivers of children and adolescents with these syndromes to become familiar with the unique diagnostic criteria for each syndrome, and also to be aware of the specific tumor screening and prophylactic surgery recommendations for each syndrome. Clin Cancer Res; 23(13); e123-e32. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Preclinical platform of retinoblastoma xenografts recapitulating human disease and molecular markers of dissemination.

Translational research in retinoblastoma - a pediatric tumor that originates during the development of the retina - would be improved by the creation of new patient-derived models. Using tumor samples from enucleated eyes we established a new battery of preclinical models that grow in vitro in serum-free medium and in vivo in immunodeficient mice. To examine whether the new xenografts recapitulate human disease and disseminate from the retina to the central nervous system, we evaluated their histology and the presence of molecular markers of dissemination that are used in the clinical setting to detect extraocular metastases. We evaluated GD2 synthase and CRX as such markers and generated a Taqman real-time quantitative PCR method to measure CRX mRNA for rapid, sensitive and specific quantification of local and metastatic tumor burden. This approach was able to detect 1 human retinoblastoma cell in 100.000 mouse brain cells. Our research adds novel preclinical tools for the discovery of new retinoblastoma treatments for clinical translation.

Use of intra-arterial chemotherapy for retinoblastoma: results of a survey.

AIM: To obtain baseline knowledge about the current use of intra-arterial chemotherapy (SSOAIC) in centers worldwide. METHODS: A survey including questions about the use of SSOAIC was emailed to retinoblastoma experts. RESULTS: Seventy-nine (response rate 69.9%) doctors from 63 centers in 35 countries responded. Thirty-one centers from 19 countries use SSOAIC. Twelve performed more than 50 procedures. Melphalan is the most commonly used drug but 15 centers use more than one drug. First line therapy for advanced unilateral disease is the most common use of SSOAIC (74.2%). Centers with larger experience (>50 applications) were less likely using melphalan alone (P=0.06) and significantly more likely using SSOAIC in more situations such as second line in preference to radiotherapy P=0.05. Nineteen (61.2%) stated that SSOAIC improved their results and 21 (77.8%) reported less toxicity compared to other treatments. Three centers reported that SSOAIC did not improve their results. There were regional variations in the use of SSOAIC which is used more frequently as secondary treatment in Europe compared to the USA and Japan. Ten centers identified cost is the major limiting factor for SSOAIC. CONCLUSION: SSOAIC is used in an increasing number of centers worldwide with regional variations. Centers with more experience in SSOAIC use it in more situations including other drugs than melphalan. The majority of the centers using this technique reported improved results and few complications.

Intra-arterial chemotherapy for retinoblastoma. Challenges of a prospective study.

PURPOSE: To report the efficacy and complications of intra-ophthalmic artery melphalan (IAM) for treatment of patients with advanced intra-ocular retinoblastoma. METHODS: Patients with newly diagnosed, unilateral, group D retinoblastoma were included in a phase II protocol. Children with relapsed-refractory disease after systemic chemoreduction were later treated under the same guidelines.Melphalan (3­5 mg/procedure) was injected through a 1.2 F microcatheter placed into the ophthalmic artery every 21 days. RESULTS: Eleven patients (12 eyes, eight as primary treatment) received 33 IAM procedures. The phase II protocol closed prematurely because of low accrual. The IAM technique was overall safe and could be performed successfully in 31 of 33(94%) attempts. After the second administration of IAM, very good partial response was achieved in all treated eyes. With a median follow-up time of 29.5 months (range 6­57), ocular salvage was achieved in 7 of 12 (58%) eyes. No systemic adverse events were observed. Two patients developed diffuse arteriolar sclerosis, hyperpigmentation of the retinal pigment epithelium and partial retinal atrophy after the second IAM. Both eyes were preserved with no tumour activity, good motility and perception of light, 56 and 30 months after the last IAM treatment. Multinucleated macrophages with intracytoplasmic foreign material were found in the choroid and the retina in 2 of 5 enucleated eyes. CONCLUSION: Our study reports the activity and reproducibility of IAM in advanced retinoblastoma but also underlines the challenges of performing prospective studies on this treatment modality. Toxicity was limited to only ocular vascular events.

Cooperativa de pediatras. Una alternativa para garantizar la atención pediátrica en áreas de difícil cobertura / A cooperative of pediatricians. A model for providing universar pediatric primary care in underserved areas

Fundamento. Dado el déficit de pediatras, existen dificultades para la cobertura pediátrica en diferentes zonas, obligando a buscar nuevas alternativas. Objetivo. Presentamos los resultados de dos años de funcionamiento de un modelo innovador de autogestión, basado en una cooperativa de profesionales ligada a un hospital docente de referencia. Métodos. En octubre de 2009 se realizó un convenio entre la Fundació Sant Hospital de la Seu d’Urgell (FSH), el Institut Català de la Salut, el Hospital Sant Joan de Déu de Barcelona y el Departament de Salut, para prestar asistencia pediátrica (primaria y hospitalaria) en la comarca del Alt Urgell. Los pediatras se constituyeron en una sociedad cooperativa catalana limitada professional, Pediatria dels Pirineus, asumiendo las decisiones asistenciales, organizativas, económicas y legales. Resultados. Se ha conseguido cubrir el 100% de la asistencia pediátrica, dotar de una excelente accesibilidad en el ambulatorio (100% de éxito para visitas pediátricas <48 horas y 0,46-0,66 días de demora para cita previa), incrementar notablemente los estándares de calidad asistencial y disminuir en un 30% las visitas pediátricas en el Servicio de Urgencias de la FSH (del 66% en horarios de obertura del ambulatorio). Se ha objetivado una disminución del 33% de las derivaciones a otros centros y del 41% de los traslados interhospitalarios. A nivel docente se han consolidado las sesiones en el territorio y mejorado la asistencia de los profesionales a los cursos formativos (media de 6,5 cursos/profesional año 2010 y 5,6 año 2011). Conclusiones. Este modelo permite una mejor cobertura pediátrica, con visión territorial, continuidad en la atención, integración en el sistema de salud y sostenibilidad(AU)

Background. The shortage of pediatricians makes universal pediatric coverage of some areas difficult to achieve; new approaches are needed. Objective. We present the results of two years of operation of an innovative model of self-management, based on a cooperative of health care professionals linked to a tertiary academic center. Method. An agreement was signed in October 2009 between the Sant Hospital Foundation of La Seu d’Urgell (SHF), the Catalan Institute of Health, the Sant Joan de Deu Hospital in Barcelona, and the Department of Health, to provide primary and hospital pediatric care in the Alt Urgell county. As part of this agreement, pediatricians were organized around the professional cooperative society Pyrenees Pediatrics, assuming the patient care, organizational, legal, and financial responsibilities. Results. Pyrenees Pediatrics provides coverage to 100% of children in the region, with excellent access to primary clinics. There has been a 100% success rate for pediatric visits in < 48 hours, and 0.46-0.66 days delay for appointments, a remarkable improvement in the quality of care standards, and a decrease from 60% to 30% in the pediatric visits to the Emergency Department at SHF during primary clinic hours. There has been a decrease of referrals to centers outside the region and hospital transfers of 33% and 41%, respectively. Finally, there has been a significant improvement in attendance to continuing medical education courses (average of 6.5 and 5.6 courses/professional in 2010 and 2011, respectively). Conclusions. This model allows for the provision of a better pediatric coverage, with a regional vision, continuity in care, integration within the health care system, and sustainability(AU)

Treatment of Ewing sarcoma family of tumors with a modified P6 protocol in children and adolescents.

BACKGROUND: Reported overall survival (OS) rates of patients with localized Ewing sarcoma family of tumors (ESFT) are >80% when treated with the MSKCC P6 protocol. However, it has been associated with a 5.8% incidence of secondary leukemias. A modified P6 (mP6) protocol with reduced exposure to chemotherapy is presented. PROCEDURE: Thirty-one newly diagnosed ESFT patients were enrolled onto this phase II, single-arm, non-randomized protocol. Courses 1, 2 and 4 consisted of cyclophosphamide 4.2 g/m², doxorubicin 75 mg/m², and vincristine 2 mg/m² (CDV). Cycles 3 and 5 consisted of ifosfamide 9 g/m² and etoposide 500 mg/m² (IE). Course 5 ifosfamide was 14 g/m² if necrosis was <90%. RESULTS: Twenty-four patients had loco-regional disease and seven had metastases. The 4-year event-free survival (EFS) rate for patients with localized tumors is 83% and overall survival (OS) is 92%. The 3-year EFS rate for patients with distant metastases is 28% and OS rate is 42%. EWS-FLI1 fusion genes were detected in 17 cases (74%) and EWS-ERG in six cases (26%). Type 1 EWS-FLI1 variant was present in 6/7 metastatic patients and 3/16 loco-regional cases (P = 0.001). None of the patients experienced tumor progression before remission. All relapses occurred within 2 years from the end of treatment and local relapses (n = 3) happened in patients who did not receive radiation therapy. No secondary malignancies have been observed, median follow-up of 4.3 years for surviving patients. CONCLUSIONS: In this pilot study, the mP6 protocol produced a complete remission rate of 83% at 4 years in non-metastatic ESFT reducing the risk of secondary malignancies.

Axenfeld-Rieger ocular anomaly and retinoblastoma caused by constitutional chromosome 13q deletion.

Axenfeld-Rieger (AR) ocular anomaly might be due to deletions of different chromosomes. No association between AR, mental retardation, and retinoblastoma has been described. We report a 2-month-old female with general development delay and dysmorphic features. AR anomaly was detected, and a retinoblastoma (RB) was diagnosed in a very early stage. De novo 13q deletion was identified. Systemic chemotherapy, focal cryotherapy, transpupillary thermotherapy, brachytherapy, and intra-arterial chemotherapy were needed to control the RB. This is the first report of an association of AR, 13q deletion, and retinoblastoma, to be disclosed in patients born with such ocular and dysmorphic features.

Treatment of relapsed/refractory pediatric sarcomas with gemcitabine and docetaxel.

AIM OF THE STUDY: In this report we describe experience with gemcitabine-docetaxel in pediatric patients with relapsed or refractory sarcomas. PATIENTS AND METHODS: Ten relapsed/refractory pediatric sarcoma patients including 6 Ewing sarcoma, 2 synovial sarcoma, 1 osteosarcoma, and 1 undifferentiated sarcoma, were treated prospectively, in an outpatient setting, with gemcitabine 1000 mg/m over 90 minutes on day 1 and 8, and docetaxel 100 mg/m over 2 to 4 hours on day 8 of a 21-day cycle, as an investigational rescue therapy. RESULTS: The patients (ages 4 to 18) received a total of 70 cycles of therapy (median 6 cycles; range: 4 to 10 y). All symptomatic patients responded clinically to the new regimen. By Response Evaluation Criteria in Solid Tumors criteria, 4 (40%) patients had a complete response (CR), 1 (10%) had a partial response (PR), 3 (30%) had stable disease (SD), and 2 (20%) had a progressive disease (PD), which provides an objective response rate (CR+PR) of 50%. Median duration of response (CR+PR+SD) was 10 months (range: 6 to 32+ mo). Five out of the 10 patients (50%) are alive, with a median follow-up of 48 months from diagnosis. Mild toxicities (no grades 3 to 4) were encountered and managed in the ambulatory setting. CONCLUSIONS: The gemcitabine-docetaxel regimen demonstrated antitumor activity against advanced pediatric (mainly Ewing) sarcomas, allowing for good quality of life. Evaluation in a large, formal phase 2 trials for Ewing patients is ongoing.

Treatment of disseminated paraganglioma with gemcitabine and docetaxel.

A male with metastatic paraganglioma received different chemotherapy regimens and 14 arterial embolizations with no or short-lasting clinical benefit. He was started on gemcitabine and docetaxel and, after two cycles, remission of all clinical signs occurred over 2 months. A complete biochemical response was achieved and angiographic signs of portal hypertension disappeared. He received 18 cycles of therapy and no limiting side effects were observed. More than 2 years after gemcitabine and docetaxel treatment, the patient remains symptom free. Gemcitabine and docetaxel could be a potential therapeutic strategy for this patient.

Prognostic impact of the detection of microcirculating tumor cells by a real-time RT-PCR assay of tyrosine hydroxylase in patients with advanced neuroblastoma.

Molecular detection of microcirculating or microdisseminated disease (MDD) with a sensitive methodology could contribute to a better treatment for children with neuroblastoma. To detect circulating neuroblastoma cells, we developed a quantitative assay for the analysis of tyrosine hydroxylase (TH) gene expression. We analyzed 155 samples of peripheral blood (PB) from 25 patients with neuroblastoma in advanced stages (8 stage III and 17 stage IV). TH mRNA was analyzed by RT-PCR assay using TaqMan technology. PB samples (n=25) from donors were used for normalizing TH, and values <7 were considered negative. With a median follow-up of 40 months (range 15-73 months), 9 patients relapsed and 8 patients died of progressive disease. TH expression was detected in the PB of 16 patients (64%) at diagnosis. During treatment, 10 patients had positive samples and 9 patients were still positive for circulating tumor cells at the end of treatment. Actuarial 3-year event-free survival of patients with PB positive for TH mRNA after induction therapy (40%) (p=0.018) and at the completion of treatment (33%) (p=0.003) were significantly worse than the survival of TH-negative patients (86 and 87%, respectively). In multivariate analysis, MYCN status and TH expression in PB at the end of treatment remained significant prognostic factors. Our results show that patients with advanced neuroblastoma who have PB positive for TH at the end of treatment seem to have a worse prognosis compared with patients with undetectable TH. These results suggest the usefulness of MDD monitoring in neuroblastoma.

Expression of multidrug resistance-1 and multidrug resistance-associated protein genes in pediatric rhabdomyosarcoma.

Overexpression of multidrug resistance-1 (MDR-1), and multidrug resistance-associated protein (MRP) genes has been linked with resistance to chemotherapy in vitro and in vivo. Their role in chemotherapy resistance in pediatric rhabdomyosarcoma is unclear. The study was undertaken to analyze the expression of MDR-1 and MRP genes in the embryonal and the alveolar subtypes of rhabdomyosarcoma and to elucidate its clinical relevance. Twenty-three rhabdomyosarcoma samples were analyzed for the expression of MDR-1 and MRP genes using a semi-quantitative competitive RT-PCR assay. MRP gene expression was associated with a reduction in survival (p=0.02). The overall survival of patients with tumors positive or negative for MRP expression were 50% (95% confidence interval, 30-70%) and 93% (95% confidence interval, 76-100%) respectively. In contrast, the expression of MDR-1 gene was not predictive of survival. These findings suggest that MRP expression could be a prognostic factor in patients with rhabdomyosarcoma.

La població immigrant infantil a Manlleu: un nou repte sociosanitàri / La población inmigrante infantil de Manlleu. Un nuevo reto sociosanitario / The pediatric immigrant population in Manlleu: a new challenge for the health care system

Fonament. La immigració és un fet que està transformant les nostres consultes. En l’àmbit de l’atenció primària les dades publicades sobre població immigrant infantil són escasses. Objectiu. Conèixer les dades sobre l’increment dels nens immigrants al Centre d’Assistència Primària (CAP) Manlleu durant els últims cinc anys i analitzar les principals característiques sociosanitàries. Mètode. Estudi: descriptiu retrospectiu. Període: 01/01/97-31/12/01. Població d’estudi: nens immigrants i fills d’immigrants nascuts en aquest període atesos al CAP Manlleu. Variables: dades de filiació; edat dels pares, país de procedència, treball, consanguinitat, nombre de fills, necessitat d’intèrpret; alletament, immunitzacions, seguiment del Programa del Nen Sa (PNS), guarderia. Anàlisi estadística amb paquet SPSS 10.0. Resultats. Dels 1.055 nens nascuts en aquest període, 281 (26.6%) són immigrants o fills d’immigrants; d’aquests, el 92% procedeixen del Marroc. Distribució per anys: 97-20%; 98-25.1%; 99-26.4%; 00-29.6%; 01-31.7%. El 57% van fer alletament matern exclusiu 3 mesos. El 91% estan correctament vacunats. El seguiment del PNS és del 75.8%. La majoria del pares (80%) treballen i no treballen el 81.8% de les mares. En el 38.6% dels matrimonis la diferència d’edat és major de deu anys, la consanguinitat és alta (17.8%) i el 40% són famílies nombroses. El 42% de les mares necessita intèrpret. Conclusions. 1. Augment progressiu dels nens immigrants, principalment marroquins, arribant al 31.7% dels nadons al 2001. 2. Elevada cobertura vacunal. 3. Acceptable compliment del PNS. 4. Dificultat de comunicació amb les mares. 5. Necessitat de recursos per donar resposta a aquesta realitat (AU)

Fundamento. La inmigración es un hecho que está transformando nuestras consultas. En el ámbito de la atención primaria los datos publicados sobre población inmigrante infantil son escasos. Objetivo. Conocer los datos sobre el aumento de los niños inmigrantes en el Centro de Asistencia Primaria (CAP) de Manlleu durante los últimos cinco años y analizar sus principales características socio sanitarias. Método. Estudio: descriptivo retrospectivo. Periodo: 01/01/97-31/12/01. Población de estudio: niños inmigrantes e hijos de inmigrantes nacidos durante este periodo atendidos en el CAP Manlleu. Variables: datos de filiación; edad de los padres, país de procedencia, trabajo, consanguinidad, número de hijos, necesidad de intérprete; lactancia, inmunizaciones, seguimiento del Programa del Niño Sano (PNS), guardería. Análisis estadístico con paquete SPSS 10.0. Resultados. De los 1.055 niños nacidos en este periodo, 281 (26.6%) son inmigrantes o hijos de inmigrantes; de éstos, el 92% proceden de Marruecos. Distribución por años: 97-20%; 98-25.1%; 99-26.4%; 00-29.6%; 01-31.7%;. El 57% siguió lactancia materna exclusiva 3 meses. El 91% están bien vacunados. El seguimiento del PNS es del 75.8%. La mayoría de los padres trabajan (80%) y no trabajan el 81.8% de las madres. En el 38.6% de los matrimonios la diferencia de edad es mayor de diez años, la consanguinidad es alta (17.8%) y un 40% son familias numerosas. El 42% de las madres necesita intérprete. Conclusiones. 1. Aumento progresivo de los niños inmigrantes, principalmente marroquíes, alcanzando el 31.7% de los recién nacidos en el 2001. 2. Elevada cobertura vacunal. 3. Aceptable cumplimiento del PNS. 4. Dificultad de comunicación con las madres. 5. Necesidad de recursos para dar respuesta a esta realidad (AU)

Background. Immigration is impacting the activities of our primary care centers, but data regarding the pediatric immigrant population in our area is scarce. Objective. To analyze the increase in the number of immigrant children seen in the primary care center of Manlleu during the last 5 years, and to describe the social characteristics and the health condition of this group of patients. Method. We performed a retrospective and descriptive study of all children born to immigrant parents seen in our primary care center from January 1, 1999 until December 31, 2001. The variables studies included child demographics, parental age, country of origin, occupation of the parents, consanguinity, number of children, need for an interpreter, breast-feeding, immunizations, compliance with the Care of the Healthy Child program, and use of day-care. Statistical analysis was performed using the SPSS 10.0 software. Results. Of the 1,055 children born during this period in the area of Manlleu, 281 (26.6%) were immigrants (26.6%), and 92% of them were of Moroccan origin. The distribution by years was as follows: 1997, 20%; 1998, 25.1%, 1999, 26.4%; 2000, 29.6%; 2001, 31.7%. Fifty-seven percent of the infants followed exclusive breast-feeding for 3 months. Ninety-one percent were immunized correctly. The compliance with the Care of the Healthy Child program was 75.8%. The majority of the fathers (80%) had a regular job, whereas 81.8% of the mothers did not work outside of the home. In 38.6% of the families, the age difference between both parents was greater than 10 years. Consanguinity was present in 17.8% of the families and 40% of the families had three or more children. An interpreter was needed to communicate with 42% of the mothers. Conclusions. 1) We have documented a progressive increase in the number of children born to immigrant parents, mainly of Moroccan origin; 2) The majority of children have been well immunized; 3) Compliance with the Care of the Healthy Child program is good; 4) There is a language barrier with the mothers; 5) There is a need for an improvement of resources to better serve this population (AU)

New splicing variants for human Tyrosine Hydroxylase gene with possible implications for the detection of minimal residual disease in patients with neuroblastoma.

Expression of Tyrosine Hydroxylase (TH) is frequently seen in neuroblastomas, the most common extracranial tumor in children, and TH mRNA detection is used for the analysis of microcirculating or micrometastatic disease in this neoplasia. TH is known to have at least seven isoforms produced by alternative splicing of the N-terminal region (exons 1-4), although no other splicing variants have been described downstream. TH expression was analyzed in six samples of neuroblastoma by RT-PCR using highly restrictive conditions and primers between exons 5 and 12, a region of the gene previously considered to be constant. In the analyzed samples we found two novel TH mRNAs, one lacking exon 8, and another lacking exons 8+9. These new splicing variants are described in a region of TH previously reported to be conserved, and that has been used for the design of reverse transcriptase-polymerase chain-reaction assays for the detection of minimal residual disease [Eur. J. Cancer, 27 (1991) 762]. The splicing pattern characteristic of every tumor could allow the monitoring of the minimal residual disease in a tumor-specific manner.