Designing and implementation of a T-ARMS-PCR assay to genotype genetic variants associated with retinoblastoma in a cohort of Sri Lankan population

Abstract

Retinoblastoma (RB) is the most common intraocular malignancy, characterized by high mortality if not detected early and treated promptly. The rare childhood malignancy retinoblastoma serves one of the most important models in modern cancer genetics. Since the study of its familial and sporadic occurrence has led to the identification of the first tumor suppressor gene RB1. Mutations screening is important for risk assessment in future siblings and offspring of RB patients.The aim of this study was to design and implement a novel genetic assay to identify genetic variants associated with retinoblastoma in a cohort of Sri Lankan patients.Materials and methods: A prospective descriptive study was carried out with 59 patients referred to the Eye Unit of the Lady Ridgeway Hospital. Genomic DNA of 59 patients were genotyped using primers designed for Tetra-primer amplification refractory mutation system PCR (T-ARMS-PCR).Results: The median age at diagnosis was 2 years and 7 months. Female to male ratio was 3:2. Out of which, 63% had unilateral retinoblastoma and 36% had bilateral retinoblastoma. Family history of RB was seen in 6.78% patients. Most cases were advanced group D at presentation. As the final result, all patients tested homozygous for the ancestral allele for both rs587776789 and rs121913305 variants of the RB1 gene.Discussion and conclusion: The discovery of germ-line mutations in unilateral patients is valuable since they can be segregated based on their mutational status and this would impact the genetic counselling given to them as they age. In conclusion, this assay can be introduced as a sensitive, specific and simple diagnostic technique for screening related genetic variants for retinoblastoma in the Sri Lankan population.