title: Screening of RB1 alterations in Brazilian patients with retinoblastoma and relatives with retinoma: phenotypic and genotypic associations.
abstract: OBJECTIVE
  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). Kaplan-Meier and log-rank test were used for estimating 60-month survival rates.
  
  
  RESULTS
  One hundred two nucleotide substitutions were detected, 92 substitutions in 59 patients with retinoblastoma and 10 substitutions in 4 individuals with retinoma. Eight substitutions were novel. The majority of substitutions were intronic (86.2%). More than one substitution was present in 37.3% of patients. Twenty-one duplications and 11 deletions were found in 12 patients; some of which with both types of alterations. Duplications/deletions were found in four patients lacking constitutional alterations when analyzed by sequencing, and in eight patients carrying one or more polymorphic intronic substitutions. The global 60-month survival rate in patients was 91.8% (Confidence Interval95% = 85.0 - 99.1). Significant, lower survival rates were found in extraocular presentation (81.0%) versus intraocular tumors (P = 0.014), first enucleation after 1 month following diagnosis (80.9%) versus earlier first enucleation (P = 0.020), and relapse (100.0%) versus absence of relapse (P = 0.0005).
  
  
  CONCLUSIONS
  Fifteen substitutions (4 intronic and 11 exonic) were identified as probably or likely pathogenic. Four of these 11 exonic substitutions were novel. Survival rates, however, were not affected by presence of these probably or likely pathogenic alterations, most of which not found in patients with retinoblastoma from other Latin American countries. These differences might be related to the different ethnic composition of the Latin American cohorts. Portuguese Abstract.
authors.affiliation: Genetics Division, Instituto Nacional de Câncer, Rio de Janeiro, Brazil.
authors.forename: Raquel H
authors.initials: RH
authors.lastname: Barbosa
authors.forename: Fernanda C C
authors.initials: FC
authors.lastname: Aguiar
authors.forename: Morgana F L
authors.initials: MF
authors.lastname: Silva
authors.forename: Regis A
authors.initials: RA
authors.lastname: Costa
authors.forename: Fernando R
authors.initials: FR
authors.lastname: Vargas
authors.forename: Evandro
authors.initials: E
authors.lastname: Lucena
authors.forename: Mírian
authors.initials: M
authors.lastname: Carvalho de Souza
authors.forename: Liz Maria
authors.initials: LM
authors.lastname: de Almeida
authors.forename: Camila
authors.initials: C
authors.lastname: Bittar
authors.forename: Patrícia
authors.initials: P
authors.lastname: Ashton Prolla
authors.forename: Cibele R
authors.initials: CR
authors.lastname: Bonvicino
authors.forename: Héctor N
authors.initials: HN
authors.lastname: Seuánez
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005091:Exons / Q000235:genetics; D005260:Female; D016161:Genes, Retinoblastoma / Q000235:genetics*; D056726:Genetic Association Studies; D006801:Humans; D007438:Introns / Q000235:genetics; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction; D020125:Mutation, Missense; D010375:Pedigree; D016133:Polymerase Chain Reaction; D019572:Retinal Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D012175:Retinoblastoma / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D016160:Retinoblastoma Protein / Q000235:genetics*; D017422:Sequence Analysis, DNA; D015996:Survival Rate; D055815:Young Adult
chemical_list: D016160:Retinoblastoma Protein
keywords: gene RB1; molecular screening; retinoblastoma