RT Journal Article SR Electronic T1 Identification of RB1 germline mutations in Argentinian families with sporadic bilateral retinoblastoma. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 475 OP 479 DO 10.1136/jmg.32.6.475 VO 32 IS 6 A1 I Szijan A1 D R Lohmann A1 D L Parma A1 B Brandt A1 B Horsthemke YR 1995 UL http://jmg.bmj.com/content/32/6/475.abstract AB Hereditary predisposition to retinoblastoma is caused by germline mutations in the RB1 gene. Most of these mutations occur de novo and differ from one patient to another. DNA samples from 10 families with a child presenting sporadic bilateral retinoblastoma have been analysed for the causative mutation. Using intragenic DNA polymorphisms we detected large deletions in two patients. Heteroduplex and DNA sequence analysis of PCR products from each exon and the promoter region showed small mutations in four patients: a C to T transition in exon 18; 1 bp and 2 bp deletion in exons 20 and 19 respectively; and a 4 bp insertion in exon 7. All these mutations are likely to result in premature termination of transcription. In one of these families, an unaffected carrier was detected. This emphasises the importance of detection of the causative mutation for predictive diagnosis in families with sporadic bilateral retinoblastoma.