Abstract
Purpose: :
Retinoblastoma (RB) is the most common primary malignant intraocular neoplasm of childhood in all racial groups with a cumulative lifetime incidence of 1 in 15 0000 individuals. RB results from loss or inactivation of both normal alleles of the retinoblastoma gene (RB1) a suppressor tumor gene located in the long arm of chromosome 13. Approximately 60% of RB cases are unilateral and non heritable, 25% are bilateral and heritable and 15% are unilateral and heritable. Most mutations in RB1 are nonsense mutations and small insertions or deletions. As children having germinal RB1 mutations have a strong tendency to develop other malignancies, the identification of germinal mutations in patients with bilateral RB allows a precise genetic assessment and establishes the prognosis and the management. We report the mutational analysis of the RB1 in a group of Mexican patients with RB.
Methods: :
Ten (4 females and 6 males) unrelated RB probands from Mexican origin and with bilateral disease were included. Complete ophthalmologic examination and genomic DNA analysis were performed. The complete coding sequence of RB1 (27 exons) was amplified by PCR and sequenced by the dye terminator method.
Results: :
Deleterious mutations in the RB1 gene were identified in all patients. Six of these changes were novel mutations, including: E125X, E539K, S838X, PinsGlu555, and two frameshifting deletions originating premature stop codons at residues 703 and 610.
Conclusions: :
This study allows the identification of novel mutations in RB1 in Mexican patients with bilateral RB. A high prevalence of new mutations in this particular population was observed. Further molecular analysis with a more numerous group of patients will reveal the particular spectrum of RB1 defects in this ethnic group.
Keywords: retinoblastoma • gene screening • mutations