Molecular mechanisms of oncogenic mutations in tumors from patients with bilateral and unilateral retinoblastoma.
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Hogg A, Bia B, Onadim Z, Cowell JK
Molecular mechanisms of oncogenic mutations in tumors from patients with bilateral and unilateral retinoblastoma.
Proc Natl Acad Sci U S A. 1993 Aug 1;90(15):7351-5.
- PubMed ID
- 8346255 [ View in PubMed]
- Abstract
The RB1 gene from 12 human retinoblastoma tumors has been analyzed exon-by-exon with the single-strand conformation polymorphism technique. Mutations were found in all tumors, and one-third of the tumors had independent mutations in both alleles neither of which were found in the germ line, confirming their true sporadic nature. In the remaining two-thirds of the tumors only one mutation was found, consistent with the loss-of-heterozygosity theory of tumorigenesis. Point mutations, the majority of which were C-->T transitions, were the most common abnormality and usually resulted in the conversion of an arginine codon to a stop codon. Small deletions were the second most common abnormality and most often created a downstream stop codon as the result of a reading frameshift. Deletions and point mutations also affected splice junctions. Direct repeats were present at the breakpoint junctions in the majority of deletions, supporting a slipped-mispairing mechanism. Point mutations generally produced DNA sequences which resulted in perfect homology with endogenous sequences which lay within 14 bp.