Frequency and nature of germline Rb-1 gene mutations in a series of patients with sporadic unilateral retinoblastoma.
Constitutional Rb-1 gene mutations were studied in a series of 17 families with isolated unilateral retinoblastoma patients. Peripheral blood lymphocytes were analysed by karyotyping, Southern blot hybridisation, and 'exon by exon' sequencing. Mutations were detected in 4 (24%) of the investigated probands. All mutations were identified by sequencing. No alteration was detected by Southern blotting or karyotyping. In one of our cases with a R358 stop codon mutation, retinoblastoma was unilateral at the time of diagnosis, but a tumour of the second eye was diagnosed after 35 months of follow-up. After exclusion of this case, the frequency of constitutional mutations in our series was 19% (3 of 16 cases). Alterations in our cases without involvement of the second eye included G-->A substitution in the promoter region 198 bp upstream of the initiating methionine codon; G-->C transversion in the splice donor site at position +1 leading to exon 6 skipping and a 137 bp in-frame deletion, starting 3 bp from the 5' end of exon 15 to 27 bp from the 3' end of exon 16. All alterations were germline de novo abnormalities.
Zajaczek
S
S
Department of Genetics and Pathology, Pomeranian Medical University, Szczecin, Poland.
Jakubowska
A
A
Górski
B
B
Kurzawski
G
G
Krzystolik
Z
Z
Lubiński
J
J
D015139:Blotting, Southern; D016161:Genes, Retinoblastoma / Q000235:genetics*; D018095:Germ-Line Mutation / Q000235:genetics*; D006801:Humans; D007621:Karyotyping; D019572:Retinal Neoplasms / Q000235:genetics*; D012175:Retinoblastoma / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods