Screening of RB1 alterations in Brazilian patients with retinoblastoma and relatives with retinoma: phenotypic and genotypic associations.

Purpose: To identify constitutional alterations of the retinoblastoma 1 gene (RB1) in two cohorts of Brazilian patients with retinoblastoma and to analyze genotype-phenotype associations.

Methods: Molecular screening was carried out by direct sequencing of the 27 RB1 exons and flanking regions in blood DNA of 71 patients with retinoblastoma and 4 relatives with retinoma, and with multiplex ligation-dependent probe amplification (MLPA) in 21 patients. The presumed impact of nucleotide substitutions on the structure of the retinoblastoma protein (pRB) was predicted by Polymorphism Phenotyping-2 (PolyPhen-2).