title: Screening of RB1 gene mutations in Chinese patients with retinoblastoma and preliminary exploration of genotype-phenotype correlations.
abstract: OBJECTIVE
  Retinoblastoma (RB) sets the paradigm for hereditary cancer syndromes, for which medical care can change depending on the results of genetic testing. In this study, we screened constitutional mutations in the RB1 gene via a method combining DNA sequencing and multiplex ligation-dependent probe amplification (MLPA), and performed a preliminary exploration of genotype-phenotype correlations.
  
  
  METHODS
  The peripheral blood of 85 retinoblastoma probands, including 39 bilateral and 46 unilateral, was collected, and genomic DNA was extracted. DNA sequencing was conducted first. MLPA analysis was applied for patients with bilateral RB with negative sequencing results and unilateral probands whose age at diagnosis was less than 1 year old.
  
  
  RESULTS
  Thirty-four distinct mutations were identified in 40 (47.1%) of the 85 probands (36 bilateral and four unilateral), of which 20% (8/40) was identified by MLPA. The total detection rate in bilateral cases was 92.3% (36/39). Of the total mutations identified, 77.5% (31/40) probands with a mean age of 10.7 months at diagnosis had null mutations, and 22.5% (9/40) with a mean age of 13.5 months at diagnosis had in-frame mutations. Of the 31 probands with null mutations, bilateral RB accounted for 96.8% (30/31). Of the nine probands with in-frame mutations, 66.7% had bilateral RB. There were seven new mutations of RB1 identified in this report, including six null mutations and one missense mutation. Clinical staging of the tumor did not show obvious differences between patients with null mutations and in-frame mutations.
  
  
  CONCLUSIONS
  Our results confirm that the type of mutation is related to age of onset and the laterality, but not staging of the retinoblastoma tumor. MLPA is a reliable method for detecting gross deletion or duplication of the RB1 gene. The combination of sequencing and MLPA improves the clinical diagnosis of RB.
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Fudan University, Shanghai, China.
authors.forename: Ming-yan
authors.initials: MY
authors.lastname: He
authors.affiliation: Institute of Biomedical Sciences and MOE Key Laboratory of Contemporary Anthropology, Fudan University, Shanghai, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: An
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Fudan University, Shanghai, China.
authors.forename: Yi-jin
authors.initials: YJ
authors.lastname: Gao
authors.affiliation: Department of Hematology and Oncology, Children's Hospital of Fudan University, Shanghai, China.
authors.forename: Xiao-wen
authors.initials: XW
authors.lastname: Qian
authors.affiliation: Institute of Biomedical Sciences and MOE Key Laboratory of Contemporary Anthropology, Fudan University, Shanghai, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Ophthalmology, Eye & ENT Hospital of Fudan University, Shanghai, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Qian
mesh_terms: D044466:Asian People / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D002681:China; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D005260:Female; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006801:Humans; D007223:Infant; D008297:Male; D009154:Mutation / Q000235:genetics*; D012175:Retinoblastoma / Q000235:genetics*; D016160:Retinoblastoma Protein / Q000235:genetics*
chemical_list: D016160:Retinoblastoma Protein