Familial retinoblastoma in developing countries

Global retinoblastoma studies: A review

In the current era of global health awareness for retinoblastoma (RB), the challenge that lies ahead of us is providing optimal care for children affected with RB in underdeveloped nations. The understanding of similarities and disparities between various nations across the world aids in achieving comparable outcomes. With dissolving geographic barriers and evolving collaboration, global collaborative studies on RB are becoming increasingly common. They provide real-world, robust evidence on several aspects of RB. This review discusses insights gained from global RB studies regarding the demographics, certain aspects of etiopathogenesis and epidemiology, international travel burden, disparities in clinical presentations based on national income levels, management protocols, pathology, treatment outcomes, and the effect of COVID-19 on RB care across the world. These insights are likely to impact individual practice as well as inform policy reforms.

Retinoblastoma in Taiwan: survival and clinical characteristics

PURPOSE

To figure out the impact of national health insurance program and treatment modalities on the clinical outcomes of patients with retinoblastoma.

STUDY DESIGN

Retrospective cohort study.

METHODS

Enrolled patients were classified into three groups according to the time period in which their initial diagnosis was performed: patients diagnosed before 1995 (group 1), patients diagnosed in the time period 1995-2010 (group 2), patients diagnosed after 2010 (group 3). Comparison was made of clinical features including presenting signs, tumor spreading, and treatment modes. Survival and globe salvage rates were analyzed within each group.

RESULTS

There were 157 patients (202 eyes) enrolled from 1978 to 2015. The overall mortality rate was 24.2%. The overall 5-year survival rate was 63.4%, 73.8%, 89.1% in the three time periods respectively (P = 0.007). The 5-year survival improved continuously in both unilateral and bilateral disease (P = 0.057; P = 0.015). Patients without extraocular spreading or diagnosed before 2 years of age had a better 5- year survival of 97.4% and 81.1% respectively. The globe salvage rate improved from 8.2%, 14.5%, to 35.1% (P < 0.001). The globe salvage rate was 46.9% in patients who received ophthalmic artery chemosurgery (OAC) and 6.4% in patients not received OAC.

CONCLUSIONS

Improvement of survival and globe salvage rate was observed over time periods. National health insurance program has made medical care easily accessible to the public, leading to earlier diagnosis and treatment. Different treatment modes could achieve a better clinical outcome; among the new treatment modalities, OAC played an important role.

At What Age Could Screening for Familial Retinoblastoma Be Discontinued? A Systematic Review

The aim of this systematic review is to assess the latest age at diagnosis for detection of familial retinoblastoma in order to evaluate at what age screening of at-risk children could be discontinued. Extended screening beyond this age would result in unnecessary patient burden and costs. However, discontinuing screening prematurely would have the adverse effect of missing tumors. We performed a literature search (PubMed, Embase, CINAHL and the Cochrane Library) up until February of 2021 and systematically included studies where patients had a family history of retinoblastoma, a known age at diagnosis, and who were ophthalmologically screened for retinoblastoma from birth. A total of 176 familial retinoblastoma patients from 17 studies were included in this review. Based on 48 months of age being the latest age of diagnosis, ophthalmological screening for familial retinoblastoma could safely be discontinued at age four years.

Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries

BACKGROUND

The travel distance from home to a treatment centre, which may impact the stage at diagnosis, has not been investigated for retinoblastoma, the most common childhood eye cancer. We aimed to investigate the travel burden and its impact on clinical presentation in a large sample of patients with retinoblastoma from Africa and Europe.

METHODS

A cross-sectional analysis including 518 treatment-naïve patients with retinoblastoma residing in 40 European countries and 1024 treatment-naïve patients with retinoblastoma residing in 43 African countries.

RESULTS

Capture rate was 42.2% of expected patients from Africa and 108.8% from Europe. African patients were older (95% CI -12.4 to -5.4, p<0.001), had fewer cases of familial retinoblastoma (95% CI 2.0 to 5.3, p<0.001) and presented with more advanced disease (95% CI 6.0 to 9.8, p<0.001); 43.4% and 15.4% of Africans had extraocular retinoblastoma and distant metastasis at the time of diagnosis, respectively, compared to 2.9% and 1.0% of the Europeans. To reach a retinoblastoma centre, European patients travelled 421.8 km compared to Africans who travelled 185.7 km (p<0.001). On regression analysis, lower-national income level, African residence and older age (p<0.001), but not travel distance (p=0.19), were risk factors for advanced disease.

CONCLUSIONS

Fewer than half the expected number of patients with retinoblastoma presented to African referral centres in 2017, suggesting poor awareness or other barriers to access. Despite the relatively shorter distance travelled by African patients, they presented with later-stage disease. Health education about retinoblastoma is needed for carers and health workers in Africa in order to increase capture rate and promote early referral.

ROUTINE FUNDUS SCREENING OF FAMILIES OF CHILDREN WITH RETINOBLASTOMA: A Prospective Study of 131 Consecutive Families

PURPOSE

To discuss the importance of routine ophthalmic examination of parents and siblings of retinoblastoma (RB) patients.

METHODS

Prospective nonrandomized observational/interventional case series of consecutive families of 131 RB patients.

RESULTS

Routine ophthalmic examination of families (parents and siblings) of 131 consecutive newly diagnosed RB patients, including 262 parents and 23 siblings, revealed spontaneously regressed RB in at least 1 parent of 10 (8%) patients and active RB in at least 1 sibling of 3 (2%) patients. Of the 10 parents with spontaneously regressed RB, the lesions were unilateral (n = 7) or bilateral (n = 3). The regression patterns (n = 13) were comparable with postirradiation regression patterns Type 1 (n = 3), Type 2 (n = 2), Type 3 (n = 2), and Type 4 (n = 3), and spontaneous phthisis bulbi (n = 3). Fundus screening of siblings revealed active RB in at least 1 sibling of 3 (2%) patients. Of these 3 siblings, 2 had unilateral and 1 had bilateral disease. The mean age at detection of RB was 15 months (median, 6 months; range, 2-36 months). The disease was unilateral in 2 and bilateral in 1 patient. Based on International Classification of Intraocular Retinoblastoma, the tumors (n = 4) were classified as Group A (n = 2) and Group B (n = 2).

CONCLUSION

Routine fundus screening of siblings allows for early detection of RB in otherwise asymptomatic children. Detection of spontaneously regressed RB in parents may act as a surrogate marker for germline RB1 mutation and is helpful in genetic counseling.

Programmed screening for retinoblastoma enhances early diagnosis and improves management outcome for high-risk children

PURPOSE

To study the impact of a Retinoblastoma (Rb) screening program in the absence of genetic testing on the management and outcome of high-risk children.

METHODS

This is a retrospective, clinical case series of 76 children from families involved in a Rb screening program as they had higher than normal risk as calculated by the conventional ways without genetic testing. Data included calculated risk, method of diagnosis, demographics, tumor features, treatment modalities, and management outcome.

RESULTS

Out of the 76 children screened, 46 children were diagnosed with Rb (12 by screening and 34 had signs of Rb), the other 30 were free of disease. Patients diagnosed by screening were younger (mean; 2.4 months vs 15.8 months for the group with signs of Rb), had significantly earlier tumor stage at diagnosis (p = .0001), higher eye salvage rate (p = .0001), less need for systemic chemotherapy (p = .022), and better visual outcome (p = .0017) than the other group. None of the eyes were group D or E, enucleated or irradiated. Six (50%) patients were cured without chemotherapy, and the visual acuity was 0.5 or better in 55% of eyes. Of interest, 71% of tumors were diagnosed by the age of 6 months, 90% by the age of 1 year, and no new tumor appeared after the age of 2 years.

CONCLUSION

Even in the absence of genetic testing, screening for children with high risk for Rb is effective in enhancing early diagnosis, improving visual outcome, and increasing eye salvage rate with limited exposure to treatment burden.

Time to diagnosis of retinoblastoma in Latin America: A systematic review

Retinoblastoma (RB) is the most common intraocular tumor of childhood. In low income countries, Time to diagnosis (TTD: interval between first symptom and diagnosis) has been associated with extraocular disease, metastasis and mortality. However, the relationship between TTD and prognosis is complex and not simply a linear correlation, particularly if TTD is <6 months. This systematic review aims to identify studies reporting TTD of retinoblastoma in Latin America, highlighting factors affecting TTD, alongside proposals and initiatives to obtain shorter intervals. The review also aims to discuss the methodology linked to cancer pathways studies. The study respected PRISMA recommendations, was registered on Prospero, an international database for systematic review registries under number CRD42017076777. MEDLINE/PUBMED, LILACS and SCIELO databases were searched. Studies from Latin America and the Caribbean, published between 1997 and 2017, reporting TTD and age at diagnosis of patients with retinoblastoma were selected. Nine studies were selected, concerning 1560 patients from Argentina, Brazil, Chile, Honduras, Mexico and Peru. The median TTD ranged from 3 to 5 months and the median age at diagnosis ranged from 16.5 to 22.2 months. A prolonged TTD was observed and was associated to damaging results on retinoblastoma outcomes, particularly increasing extraocular disease, and mortality rates. Methodological heterogeneity was observed and reiterates the importance of standardization of TTD studies, allowing more reliable comparisons and greater knowledge about retinoblastoma pathways before diagnosis. Reports on successful initiatives against delayed diagnosis were scarce, emphasizing a need for further studies.

Retinoblastoma: The importance of early diagnosis

INTRODUCTION

Retinoblastoma is the most frequent malignant intraocular tumour in childhood, and both its cure and the sequelae arising from it, mainly depend on an early diagnosis. There is currently no consensus on its diagnostic and therapeutic management.

PATIENTS AND METHODS

A descriptive, retrospective, and non-randomised study was conducted on a series of cases (39 patients -58 eyes), treated during the period 2006-2013, in the Regional Reference Centre for Tumours of the National Health Service Quality Agency.

RESULTS

The most frequent presentation sign is leukocoria (71.8%), followed by strabismus (17.9%). All cases of bilateral tumour had a germline mutation of the RB1 gene, and 20% had a family history. Stage E was observed in 55% of the patients, and 90% required chemotherapy treatment. The eye was maintained in 57% of those who had mild stages, compared to 43% who maintained it in advanced stages.

CONCLUSIONS

This analysis included 58 eyes. There are no previous studies in our community and there are few series so numerous throughout the country. Based on non-standardised treatment, the most appropriate is chosen according to the characteristics of the tumour. The multidisciplinary management, formed by ophthalmology, paediatric oncology, radiotherapy, and radiophysical oncology, is fundamental for the selection of the most appropriate treatment. Chemo-reduction, along with consolidation treatments, offers encouraging results in the control of these tumours, especially in those of less severity. Enucleation continues to be the method of choice in the most advanced staging with vitreous involvement, with the importance of early diagnosis being highlighted.

Retinoblastoma in the United States: A 40-Year Incidence and Survival Analysis

PURPOSE

To determine the incidence of retinoblastoma in the United States from 1973 to 2012 (40 years) and characterize the 5-year overall survival rate of the included patients.

METHODS

Cases of retinoblastoma were derived from the Surveillance, Epidemiology, and End Results (SEER) Program (National Cancer Institute, Rockville, MD). Incidence rates were calculated using U.S. Census Bureau data as the standard population, and trends over time were determined using the chi-square test. Hazard ratios with a 95% confidence interval (CI) were estimated for variables associated with mortality using Cox regression models. Survival rates were calculated using the Kaplan-Meier method and compared among different clinical and demographic categories.

RESULTS

A total of 879 cases of retinoblastoma were derived from the SEER databases. The annual incidence rates of retinoblastoma for a period of 40 years were 12.14 (95% CI: 11.32 to 12.96) cases per 1 million children 4 years or younger and 0.49 (95% CI: 0.36 to 0.65) cases per 1 million children between the ages of 5 and 9 years. There was no significant trend for children 4 years or younger (P = .6324) or between the ages of 5 and 9 years (P = .7695). The 5-year overall survival rates were 97.6%, 92.7%, 91.1%, and 96.4% for children diagnosed at the first, second, third, and after the third year of life, respectively (P = .0136). The 5-year overall survival rates were 92.5% for bilateral and 96.3% for unilateral cases (P = .0116). The 5-year overall survival rates were 90.8%, 92.5%, 97.6%, 97.3% for increasing time intervals (1973 to 1979, 1980 to 1989, 1990 to 1999, and 2000 to 2012, respectively; P = .0017).

CONCLUSIONS

The incidence rate of retinoblastoma in the United States has remained stable for the past 40 years. Survival rate analysis indicates a significant effect of laterality of tumor, age at diagnosis, and decade of diagnosis. [J Pediatr Ophthalmol Strabismus. 2018;55(3):182-188.].

A 20-Year Retrospective Review of Retinoblastoma at Two Tertiary Academic Hospitals in Johannesburg, South Africa

Aim

This paper presents a 20-year review of retinoblastoma in Johannesburg, South Africa, aiming to better characterize the disease in this sub-Saharan setting.

Methods

The study represents a retrospective case series of retinoblastoma patients presenting to Charlotte Maxeke Johannesburg Academic Hospital and Chris Hani Baragwanath Academic Hospital between January 1, 1992, and December 31, 2011.

Results

The total number of cases identified was 282, with 245 meeting the study inclusion criteria. Retinoblastoma comprised 6.9% of the total pediatric oncology presentations; 65.3% were unilateral, 34.3% bilateral, and 0.4% trilateral. The overall male-to-female ratio was 1.08. The mean age at presentation overall was 32.6 months (median 28.0), in the unilateral group 39.4 months (median 33.0), and in the bilateral group 19.7 months (median 17.0). The mean delay to presentation overall was 7.0 months (median 4.0). The most frequent presenting symptoms were leukocoria (37.1%) and proptosis (34.7%). The distribution of disease stages at presentation (International Retinoblastoma Staging System) was 1.6% stage 0, 24.1% stage I, 27.8% stage II, 16.3% stage III, and 25.3% stage IV. 26.5% defaulted care. The 5-year Kaplan-Meier survival estimate was 57.7% overall.

Conclusion

This study shows that delayed presentation and refusal of therapy remains a significant barrier to effective treatment in this African setting.

A tool for planning retinoblastoma services in sub-Saharan Africa

BACKGROUND

Cancer care remains inadequate in low-middle income countries (LMICs). Children with cancer have 80% chance of surviving in high-income countries compared to 20% in LMICs. Retinoblastoma (RB), an aggressive eye cancer of childhood and top childhood cancer in sub-Saharan Africa (SSA), has a low survival rate, due to a delay in diagnosis and abandonment of treatment. The purpose of this study is to provide a tool for planning human resources required to manage RB in SSA.

PROCEDURE

Online tool was developed with 19 modifiable fields and 23 estimates. Routine data were used to populate modifiable fields: population, birthrate, infant mortality rate, and total fertility rate. Values were held constant: frequency, 1:17,000; familial cases, 8%; unilateral RB, 74%; extraocular disease, 70%; and survival postextraocular treatment, 10%.

RESULTS

One thousand twenty-three RB incident and familial cases are estimated each year across Ethiopia, Ghana, Malawi, Nigeria, Tanzania, Uganda, Zambia, and Zimbabwe: 75 familial, 700 unilateral, 717 extraocular disease, and 645 palliative. Nigeria represents 431 cases and Zimbabwe 33 cases. Over the eight countries, a total of 41,558 patient visits are estimated each year consisting of unilateral enucleation, follow-up visits, intensive treatment, and familial screening, with a total of 2,802 prosthetic eyes being required each year.

CONCLUSIONS

In the absence of data, estimates are essential for planning countrywide medical services. More attention is needed around planning for services from the Ministry level including emphasis on building multidisciplinary teams for diseases such as RB, including countrywide database and integrated clinical practice guidelines among all levels of care.

Familial Retinoblastoma: Raised Awareness Improves Early Diagnosis and Outcome

Purpose. To study the impact of awareness of retinoblastoma in the affected families on the management and outcome of familial retinoblastoma patients. Methods and Materials. This is a retrospective, clinical case series of 44 patients with familial retinoblastoma. Collected data included patient's demographics, laterality, family history, age at diagnosis, presenting signs, treatment modalities, tumor stage, eye salvage rate, metastasis, and mortality. Results. Out of 200 retinoblastoma patients in our registry, 44 (22%) patients were familial, 18 were probands, and 26 were second, third, or fourth affected family members. There were 76 affected eyes: 31 eyes of probands and 45 eyes of the other affected family members. Among probands, all patients (100%) had at least one eye enucleated: 58% (18 eyes) of the affected eyes were enucleated and 32% (10 eyes) of the affected eyes were radiated. On the other hand, among the nonprobands, only 20% had one eye enucleated, and only 4 eyes (9%) received radiation. The eye salvage rate was significantly higher in the nonprobands than in the probands in this series (p = 0.00206). Patients diagnosed by screening (38%) had excellent visual outcome, and both eyes were salvaged. Conclusion. Awareness of families of the possibility of retinoblastoma and adequate screening led to a significantly higher rate of eye salvage in patients with familial retinoblastoma.

Neonatal Retinoblastoma

From 7% to 10% of all retinoblastomas and from 44% to 71% of familial retinoblastomas in developed countries are diagnosed in the neonatal period, usually through pre- or post-natal screening prompted by a positive family history and sometimes serendipitously during screening for retinopathy of prematurity or other reasons. In developing countries, neonatal diagnosis of retinoblastoma has been less common. Neonatal retinoblastoma generally develops from a germline mutation of RB1, the retinoblastoma gene, even when the family history is negative and is thus usually hereditary. At least one-half of infants with neonatal retinoblastoma have unilateral tumors when the diagnosis is made, typically the International Intraocular Retinoblastoma Classification (Murphree) Group B or higher, but most germline mutation carriers will progress to bilateral involvement, typically Group A in the fellow eye. Neonatal leukokoria usually leads to the diagnosis in children without a family history of retinoblastoma, and a Group C tumor or higher is typical in the more advanced involved eye. Almost all infants with neonatal retinoblastoma have at least one eye with a tumor in proximity to the foveola, but the macula of the fellow eye is frequently spared. Consequently, loss of reading vision from both eyes is exceptional. A primary ectopic intracranial neuroblastic tumor known as trilateral retinoblastoma is no more common after neonatal than other retinoblastoma. For many reasons, neonatal retinoblastoma may be a challenge to eradicate, and the early age at diagnosis and relatively small tumors do not guarantee the preservation of both eyes of every involved child. Oncology nurses can be instrumental in contributing to better outcomes by ensuring that hereditary retinoblastoma survivors receive genetic counseling, by referring families of survivors to early screening programs when they are planning for a baby, and by providing psychological and practical support for parents when neonatal retinoblastoma has been diagnosed.

Retinoblastoma

Retinoblastoma is a rare cancer of the infant retina that is diagnosed in approximately 8,000 children each year worldwide. It forms when both retinoblastoma gene (RB1) alleles are mutated in a susceptible retinal cell, probably a cone photoreceptor precursor. Loss of the tumour-suppressive functions of the retinoblastoma protein (pRB) leads to uncontrolled cell division and recurrent genomic changes during tumour progression. Although pRB is expressed in almost all tissues, cone precursors have biochemical and molecular features that may sensitize them to RB1 loss and enable tumorigenesis. Patient survival is >95% in high-income countries but <30% globally. However, outcomes are improving owing to increased disease awareness for earlier diagnosis, application of new guidelines and sharing of expertise. Intra-arterial and intravitreal chemotherapy have emerged as promising methods to salvage eyes that with conventional treatment might have been lost. Ongoing international collaborations will replace the multiple different classifications of eye involvement with standardized definitions to consistently assess the eligibility, efficacy and safety of treatment options. Life-long follow-up is warranted, as survivors of heritable retinoblastoma are at risk for developing second cancers. Defining the molecular consequences of RB1 loss in diverse tissues may open new avenues for treatment and prevention of retinoblastoma, as well as second cancers, in patients with germline RB1 mutations.

Cancer genetics education in a low- to middle-income country: evaluation of an interactive workshop for clinicians in Kenya

Background

Clinical genetic testing is becoming an integral part of medical care for inherited disorders. While genetic testing and counseling are readily available in high-income countries, in low- and middle-income countries like Kenya genetic testing is limited and genetic counseling is virtually non-existent. Genetic testing is likely to become widespread in Kenya within the next decade, yet there has not been a concomitant increase in genetic counseling resources. To address this gap, we designed an interactive workshop for clinicians in Kenya focused on the genetics of the childhood eye cancer retinoblastoma. The objectives were to increase retinoblastoma genetics knowledge, build genetic counseling skills and increase confidence in those skills.

Methods

The workshop was conducted at the 2013 Kenyan National Retinoblastoma Strategy meeting. It included a retinoblastoma genetics presentation, small group discussion of case studies and genetic counseling role-play. Knowledge was assessed by standardized test, and genetic counseling skills and confidence by questionnaire.

Results

Knowledge increased significantly post-workshop, driven by increased knowledge of retinoblastoma causative genetics. One-year post-workshop, participant knowledge had returned to baseline, indicating that knowledge retention requires more frequent reinforcement. Participants reported feeling more confident discussing genetics with patients, and had integrated more genetic counseling into patient interactions.

Conclusion

A comprehensive retinoblastoma genetics workshop can increase the knowledge and skills necessary for effective retinoblastoma genetic counseling.

SIOP-PODC recommendations for graduated-intensity treatment of retinoblastoma in developing countries

Retinoblastoma remains incurable in many regions of the world. The major obstacles to cure are delayed diagnosis, poor treatment compliance, and lack of evidence-based recommendations for clinical management. Although enucleation is curative for intraocular disease, in developing countries retinoblastoma is often diagnosed after the disease has disseminated beyond the eye. A SIOP-PODC committee generated guidelines for the clinical management of retinoblastoma in developing countries and developed a classification system based on the resources available in those settings. Recommendations are provided for staging and treatment of unilateral and bilateral retinoblastoma and counseling of families for whom compliance is an issue.

Familial retinoblastoma: fundus screening schedule impact and guideline proposal. A retrospective study

AIMS

To assess if systematic fundus screening according to an 'intensive' schedule alters ocular outcome and to propose fundus screening schedule guidelines for children related to a retinoblastoma patient.

METHODS

For children with a positive family history of retinoblastoma, we perform fundus exams shortly after birth under general anaesthesia and then at regular intervals according to schedules based on the risk. Familial retinoblastoma cases seen at our institution from January 1995 to December 2004 were retrospectively classified as 'screened' or 'non-screened' (NS) and, among the 'screened' patients, as 'intensively screened' (IS) if screening matched our recommendations or 'non-intensively screened' (S). Groups were compared by Fisher exact test for categorical variables and Kruskal-Wallis test for continuous variables.

RESULTS

Among the 547 retinoblastoma patients managed at our institution during this period, 59 were familial cases. In all, 20 were in the NS group, 23 in the S group, and 16 in the IS group. The number of children enucleated was, respectively, 13, 2, and 0 (P<10(-4)); external beam radiation (EBRT) was required for, respectively, 6, 0, and 2 children (P<0.009). Chemotherapy burden and visual acuity were not significantly different between groups.

CONCLUSION

An 'intensive' fundus screening schedule decreased the need for enucleation and EBRT. Therefore, despite the heavy burden of the screening schedule, we recommend physicians and health-care professionals to better inform and refer children with a family history of retinoblastoma for genetic counselling and proper fundus screening in specialized centres.

Strategies to manage retinoblastoma in developing countries

Survival of retinoblastoma is >90% in developed countries but there are significant differences with developing countries in stage at presentation, available treatment options, family compliance, and survival. In low-income countries (LICs), children present with advanced disease, and the reasons are socioeconomic and cultural. In middle-income countries (MICs), survival rates are better (>70%), but there is a high prevalence of microscopically disseminated extraocular disease. Programs for eye preservation have been developed, but toxicity-related mortality is higher. Although effective treatment of microscopically extraocular disease improved the outcome, worldwide survival will be increased only by earlier diagnosis and better treatment adherence.

Epidemiology and Rb1 gene of retinoblastoma

Retinoblastoma (Rb) is the most common eye cancer in children and it can be inherited. Rb is quite rare and originators from the neural retina with a significant genetic component in etiology, which occurs in approximately 1 in every 20 0000 births. In children with the heritable genetic form of Rb, there is a mutation on chromosome 13, called the retinoblastoma 1 (Rb1) gene. Early diagnosis and intervention is critical to the successful treatment of the Rb. The Rb1 gene is the first cloned tumor suppressor gene. As a negative regulator of the cell cycle, Rb1 gene could maintain a balance between cell growth and development through binding to transcription factors and regulating the expression of genes involved in cell proliferation and differentiation. Thus, it is involved in cell cycle, cell senescence, growth arrest, apoptosis and differentiation. We summarized the recent advances on the epidemiology and Rb1 gene of Rb in this review.

A c.1363C>T (p.R455X) nonsense mutation of RB1 gene in a southern Chinese retinoblastoma pedigree

Retinoblastoma (RB) is the most common malignant intraocular tumor in children. Fifty percent of RB patients are carriers of a predisposing germline mutation with high penetrance. RB1 has been identified as the only pathological gene. We present the rapid detection of an RB1 gene mutation in a Han pedigree of two RB patients from southern China. Total RNA was extracted from whole blood for reverse transcriptase-polymerase chain reaction (PCR) to analyze RB1 transcripts, and genomic DNA for PCR and direct sequencing to test RB1 exons. Allele-specific PCR was used to verify the mutation. The results showed that the bilaterally affected son and the unilaterally affected father were both heterozygous for the nonsense mutation c.1363C>T (p.R455X) in exon 14 of RB1. Our studies suggest the molecular basis of RB in this Chinese family and provide further evidence that codon 455 is one of the recurrent spots for mutations in RB1.