RESUMEN
INTRODUCTION: The Li-Fraumeni syndrome (LFS) is an autosomal dominant hereditary disorder associated with different tumor types in childhood and young adults. Approximately 70% of LFS cases contain germline mutations in the TP53 gene. We report a case of a family suspected of LFS. MATERIALS AND METHODS: The proband and four members of the family affected were diagnosed with cancer at an early age and they all died except the proband. Exons 5-9 from TP53 gene were analysed by direct amplification and sequencing in 7 family members. RESULTS: The analysis revealed a germline nonsense mutation in exon 8 at codon 306 of the codified region of the TP53 gene, causing a change of CGA to TGA (ArgâStop) in the proband, her mother, her cousin and her maternal uncle. Proband's maternal grandmother and aunt do not have the mutation. CONCLUSIONS: The members of this family that were studied meet the criteria of classic LFS and the described mutation increases their susceptibility to develop cancer. The proband's maternal grandfather died of lung cancer in 1993, and we believe that he was the carrier of the mutation in this family.
Asunto(s)
Codón sin Sentido/genética , Exones/genética , Mutación de Línea Germinal/genética , Síndrome de Li-Fraumeni/genética , Proteína p53 Supresora de Tumor/genética , Adulto , Niño , ADN de Neoplasias/genética , Femenino , Estudios de Seguimiento , Genotipo , Heterocigoto , Humanos , Incidencia , Lactante , Síndrome de Li-Fraumeni/epidemiología , Masculino , Persona de Mediana Edad , Linaje , Reacción en Cadena de la Polimerasa , Pronóstico , Estudios Prospectivos , Tasa de SupervivenciaRESUMEN
Constitutional mutations in the RB1 gene predispose to retinoblastoma development. Hence genetic screening of retinoblastoma patients and relatives is important for genetic counseling purposes. In addition, RB1 gene mutation studies may help decipher the molecular mechanisms leading to tumors with different degrees of penetrance or expressivity. In the course of genetically screening of 107 hereditary and non-hereditary retinoblastoma patients (11 familiar bilateral, 4 familiar unilateral, 49 sporadic bilateral and 43 sporadic unilateral) and kindred from Spain, Colombia and Cuba, using direct PCR sequencing, we observed 45 distinct mutations and four RB1 deletions in 53 patients (9 familiar bilateral, 2 familiar unilateral, 31 sporadic bilateral and 11 sporadic unilateral). Most of these mutations (26/45, 57%) have not been reported before. In 32 patients, the predisposing mutations correspond to nonsense (mainly CpG transitions) and small insertions or deletions whose expected outcome is a truncated Rb protein that lacks the functional pockets and tail. Five single aminoacid replacements and seventeen mutations affecting splicing sites were also observed in retinoblastoma patients. Two of these sixteen mutations are of unclear pathogenic nature.