Berta Campos

Germline mutations in NF1 and BRCA1 in a family with neurofibromatosis type 1 and early-onset breast cancer

Neurofibromatosis type 1 (NF1) is a common dominant autosomal disorder caused by mutations in the NF1 gene. The main manifestations of NF1 are café-au-lait spots, neurofibromas, intertriginous freckling, Lisch nodules, and malignancy, including peripheral nerve sheath tumors, central nervous system gliomas, and a variety of other tumors not so clearly defined. The association between NF1 and breast cancer or other gynecologic malignancies seems uncommon and has been scarcely referred in the literature. We describe a family with two females affected by both NF1 and early-onset breast cancer, and a male with NF1. We evaluated whether the concomitance of both disorders could be attributed to a NF1 mutation and its supposed increased risk of breast cancer or to the concurrence of two NF1 and BRCA1/2 germline mutations. Mutation analyses identified a frameshift mutation in BRCA1 and a nonsense mutation in NF1. Our findings stress the importance of considering all phenotypic features in families with both NF1 and breast tumors. To offer a specific risk assessment and management of both conditions, NF1 and BRCA1/2 cancer predisposing genes should be analyzed.

Conditions for single-strand conformation polymorphism (SSCP) analysis of BRCA1 gene using an automated electrophoresis unit.

Abstract The single-strand conformation polymorphism procedure has been applied in routine testing for hereditary diseases and cancer. However, temperature, running time, gel composition, fragment length, etc. can influence its sensitivity. Mutation detection in the clinical setting depends on the development of automated technology, especially for large genes such as the breast cancer gene BRCA1. We analysed DNA samples with BRCA1 mutations in an automated system (GenePhor System; Amersham-Pharmacia Biotech, Uppsala, Sweden). The concentrations of DNA template and PCR primers, the effect of chilling after denaturation, and the temperature and time of the electrophoresis were investigated. All band-shifts were detected by electrophoresis at 5 °C for 2 h 15 min. Concentrations of DNA and samples used in the PCR did not affect the SSCP pattern, but chilling the PCR product in ice after denaturation was required. The type and position of mutation in the fragments did not influence the probability of a mobility shift, although SSCP analysis was more sensitive for fragments shorter than 350 bp. This automated SSCP method meets the requirements of fast turnaround and sensitivity and can be readily adapted to the screening of large genes such as BRCA1.

Análisis del haplotipo en portadores de la mutación 6857delAA en el gen BRCA2 en 4 familias con cáncer de mama u ovario hereditario

Fundamento y objetivo: Entre un 5 y un 10% de los canceres de mama son de caracter hereditario y se conocen en la actualidad 2 genes principalmente responsables: BRCA1 y BRCA2. Pacientes y metodo: En el estudio genetico de pacientes con antecedentes familiares de cancer de mama/ovario hereditario realizado en 2 centros, en Espana y Chile, se identifico la mutacion 6857delAA en el gen BRCA2 de 3 familias espanolas y de una chilena. Se realizo el analisis del haplotipo en los portadores mediante 5 microsatelites que rodean el gen y abarcan una region de 6 cM: cen-D13S260, D13S1698 (BRCA2), D13S171, D13S310 y D13S267-tel. Resultados: Dos familias comparten la variante alelica de los 5 microsatelites estudiados. Los marcadores D13S260 y D13S267 difieren cada uno en una familia. No se identifico el haplotipo comun en los no portadores de la mutacion y su frecuencia fue menor del 10% en los cromosomas control. Conclusiones: Los resultados apuntan a la existencia de un ancestro comun con la mutacion, originada en el area de Cataluna. Teniendo en cuenta los movimientos migratorios desde Espana a Latinoamerica, la busqueda en estos paises de mutaciones aparecidas recurrentemente en Espana puede favorecer un analisis mas racional, efectivo y de menor coste en dichos genes.

Características clinicopatológicas y evolución clínica de pacientes con cáncer de mama y mutaciones en los genes BRCA1 o BRCA2

BACKGROUND: Clinico-pathological differences between BRCA1 or BRCA2 mutation-associated breast cancer (BC) and sporadic BC are little known. PATIENT AND METHODS: We analysed the clinico-pathological characteristics and clinical follow-up of 30 patients with BC. BRCA1 and BRCA2 mutations were detected by SSCP and PTT. RESULTS: There were no differences in age, size or nodal status at the time of diagnosis. Mammography features were more heterogeneous in BRCA2 than in BRCA1 BC. All BRCA1 mutation-associated BC corresponded to infiltrating ductal carcinomas (20% medullary carcinomas) with a more aggressive pathological behavior. The frequency of local recurrences was 14% in BRCA1 and 20% in BRCA2. Contralateral BC and ovarian cancer (OC) were observed in 27% and 20% of BRCA1 cases, respectively, and 6% and 6% of BRCA2 cases. The median follow-up in BRCA1 and BRCA2 BC was 131 and 54 months, respectively. CONCLUSIONS: There were no differences in age at diagnosis and stage between BRCA1 and BRCA2 breast cancer. The mammographic pattern in BRCA2 was more heterogeneous. BRCA1 mutations were associated with more aggressive histopathologic findings and a higher risk of a second BC and OC.