Molecular Genetic Analysis ofRB1gene among Sudanese children with Retinoblastoma

Abstract

BACKGROUND: Retinoblastoma (RB), the commonest early childhood intraocular tumor, is most often related to mutations in the RB1 gene with an incidence of 3% of all pediatric tumors. It has good prognosis if diagnosed early but it is life-threatening when diagnosed late. OBJECTIVE: To study the Molecular Genetic Analysis of Retinoblastoma (RB) in Sudanese families. METHODS: Thirty one (n=31) clinically and histopathologically diagnosed cases of RB attending Makkah Eye Complex (MEC) Orbit clinic (Khartoum, Sudan) were included in this Molecular Genetic RB Analysis. Fresh blood samples extracted from seven RB patients and 15 close families for DNA extraction and PCR were sent for Genetic Sequencing and In silico approach for "Exon 18 mutations" which is one of the highly mutated exons worldwide. RESULTS: The majority of patients (41.9%) were below five years old. Females were 58.1%, males were 41.9%. Leukocoria was the commonest sign at presentation (41.9%). RB Unilaterality were in (77.4%) while Bilaterality in 19.4%. Both eyes were equally affected 50% each. The age at diagnosis time ranged from 0.02 to five years. Consanguinity of parents was very high (85.7%), the 1 st degree cousins were less (28.6%) while the 2 nd degree was high (57.1%). The patients' ethnic background and geographical area were from seven different tribes; all belong to the Western Sudan. The molecular genetic study showed that exon 18 was free of mutation among the seven patients + their three relatives. The Functional Analysis and (SNPs) prediction study of exon 18 from NCBI data base showed that the various computational approaches used (SIFT, PolyPhen-2, I-mutant and Project hope) identified 16 reported mutations worldwide, three of which (rs137853292, rs375645171 and rs772068738) are major nsSNPs (non-synonymous) which might contribute to native RB1 protein malfunction and ultimately causing carcinoma. CONCLUSION: RB mainly affected children under five years and both sexes are equally affected. Unilaterality was predominant. Consanguinity plays a role in inheritance and the majority of patients were from Western Sudan. The most commonly detected deleterious mutations worldwide in exon 18 were not found in the Sudanese studies samples. Further screening for the highly reported mutations in exons 8, 10 and 14 or Next Generation Sequencing (NGS) are recommended. In silico tools are useful in studying the functional analysis of SNPs.

Genetic Component of Retinoblastoma in Bukavu, Democratic Republic of Congo

“…According to the literature, the RB observed in low incomes areas is the sporadic, non-hereditary type, with no associated family history of RB [1,2]. Isolated leukocoria and/or strabismus are generally described as the most frequent telltale signs of RB in high incomes areas [17,21]. Many authors have incriminated herbal medicine and certain traditional and religious beliefs, as factors in the poor management outcome of RB in low resources areas, which delay of the management [16,17,19,20].…”

“…Commonly described mutations are nonsense (56%), frameshift (12%), splice site changes (12%) and missense (12%). Exons 8,9,10,11,16,17,18,19,20,21,23 have been reported as frequent mutation carriers [9,10].…”

Sanger Sequencing of Exon 14 of RB1 Gene Among North Indian Children with Retinoblastoma

“…Early identification of carriers with heritable RB1 mutations and timely diagnosis can significantly enhance disease management and overall outcomes [1]. While the prognosis of retinoblastoma is generally favorable with early detection, delayed diagnosis can potentially pose life-threatening risks [8]. The RB1 gene has been a subject of study for several decades, with a substantial body of research emanating from the Western world, while a limited number of studies are accessible online from India [9,10].…”