Multiplex screening for RB1 germline mutations in 106 patients with hereditary retinoblastoma
- Universitaetsklinikum Essen (Germany); and others
The identification of germline mutations in the retinoblastoma susceptibility gene (RB1) is important for genetic counseling in hereditary retinoblastoma. Due to the complex genomic organization of this gene and the heterogeneity of mutations, efficient screening procedures are important for rapid mutation detection. We have developed methods based on simultaneous analysis of multiple regions of this gene in an ABI automated DNA fragment analyzer to examine 106 patients with hereditary retinoblastoma in which no alteration was identified by Southern blot hybridization. Primers for the amplification of all 27 exons of the RB1 gene as well as the promoter and poly(A) signal sequences were labelled with distinct fluorescent dyes (FAM, HEX, TAMRA) to enable simultaneous electrophoretic analysis of PCR products with similar mobility. PCR fragments distinguishable by size or color were co-amplified by multiplex PCR and analyzed for length by GENESCAN analysis. Using this approach, small deletions ranging from 1 bp to 22 bp were identified in 24 patients (23%). Short sequence repeats or polypyrimidine runs were present in the vicinity of most of these deletions. In 4 patients (4%), insertions from 1 bp to 4 bp were found. The majority of length mutations resulted in a truncated gene product due to frameshift and premature termination. No mutation was identified in exons 25 to 27 possibly indicating that the encoded protein domains have minor functional importance. In order to screen for base substitutions that are not detectable by fragment length analysis, we adapted heteroduplex analysis for the use in the DNA fragment analyzer. During the optimization of this method we detected 10 single base substitutions most of which generated stop codons. Intriguingly, two identical missense mutations were identified in two unrelated families with a low-penetrance phenotype.
- OSTI ID:
- 133289
- Report Number(s):
- CONF-941009--
- Journal Information:
- American Journal of Human Genetics, Journal Name: American Journal of Human Genetics Journal Issue: Suppl.3 Vol. 55; ISSN AJHGAG; ISSN 0002-9297
- Country of Publication:
- United States
- Language:
- English
Similar Records
Detection of mutations of the RB1 gene in retinoblastoma patients by using exon-by-exon PCR-SSCP analysis
Exon 24-25 deletion of RB1 in a four-generation low-penetrance retinoblastoma family