RESUMO
BACKGROUND: The BRCA1 c.3331_3334delCAAG founder mutation has been reported in hereditary breast and ovarian cancer families from multiple Hispanic groups. We aimed to evaluate BRCA1 c.3331_3334delCAAG haplotype diversity in cases of European, African, and Latin American ancestry. METHODS: BC mutation carrier cases from Colombia (n = 32), Spain (n = 13), Portugal (n = 2), Chile (n = 10), Africa (n = 1), and Brazil (n = 2) were genotyped with the genome-wide single nucleotide polymorphism (SNP) arrays to evaluate haplotype diversity around BRCA1 c.3331_3334delCAAG. Additional Portuguese (n = 13) and Brazilian (n = 18) BC mutation carriers were genotyped for 15 informative SNPs surrounding BRCA1. Data were phased using SHAPEIT2, and identical by descent regions were determined using BEAGLE and GERMLINE. DMLE+ was used to date the mutation in Colombia and Iberia. RESULTS: The haplotype reconstruction revealed a shared 264.4-kb region among carriers from all six countries. The estimated mutation age was ~ 100 generations in Iberia and that it was introduced to South America early during the European colonization period. CONCLUSIONS: Our results suggest that this mutation originated in Iberia and later introduced to Colombia and South America at the time of Spanish colonization during the early 1500s. We also found that the Colombian mutation carriers had higher European ancestry, at the BRCA1 gene harboring chromosome 17, than controls, which further supported the European origin of the mutation. Understanding founder mutations in diverse populations has implications in implementing cost-effective, ancestry-informed screening.
Assuntos
Proteína BRCA1/genética , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/genética , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Haplótipos , Polimorfismo de Nucleotídeo Único , África/epidemiologia , Brasil/epidemiologia , Chile/epidemiologia , Cromossomos Humanos Par 17/genética , Colômbia/epidemiologia , Feminino , Efeito Fundador , Estudo de Associação Genômica Ampla/métodos , Humanos , Portugal/epidemiologia , Espanha/epidemiologiaRESUMO
BACKGROUND: The presence of somatic mutations in the KRAS gene has been identified as a reliable strong negative predictor for the response to targeting the epidermal growth factor receptor (EGFR), in patients with metastatic colorectal cancer and the use of anti-EGFR monoclonal antibodies such as Cetuximab and Panitumumab is now restricted to patients with no detectable KRAS mutations. Between 30 and 40 % of colorectal cancers contain a mutated KRAS oncogene. The aim of this study was to evaluate concordance between three methods to analyze KRAS mutational status in regard to clinical testing. METHODS: We analyzed KRAS mutations in codons 12 and 13 of exon 2 in one hundred formalin-fixed paraffin-embedded (FFPE) colorectal cancer samples by three different methods: Direct Sequencing and two commercial kits on allele-specific oligonucleotide hybridization (KRAS StripAssay, Vienna Lab.) and Amplification Refractory Mutation System/Scorpions (ARMS/S; TheraScreen KRAS Mutation kit DxS) based on q-PCR. RESULTS: We have found similar frequencies of KRAS mutations by TheraScreen and Strip-Assay (44 and 48 %), with a κ value of 0.90, indicating almost perfect agreement between methods. The frequency by direct sequencing was much lower (26 %) and the κ values were 0.67 (compared to TheraScreen) and 0.57 (compared to Strip-Assay) indicating low sensitivity. CONCLUSIONS: On analyzing KRAS mutation in FFPE tumor samples, direct sequencing sensitivity is too low to be used in a clinical setting. Choosing between ARMS/S; TheraScreen KRAS Mutation kit DxS and KRAS StripAssay, Vienna Lab, will depend on laboratory facilities and expertise.
Assuntos
Neoplasias Colorretais/genética , Proteínas Proto-Oncogênicas/genética , Proteínas ras/genética , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Códon , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Receptores ErbB/genética , Humanos , Mutação , Proteínas Proto-Oncogênicas p21(ras) , Análise de Sequência de ProteínaRESUMO
OBJECTIVE: To analyse the level of adherence to prophylactic surgery of breast and/or ovarian cancer in female carriers of the BRCA1 or BRCA2 mutation in a referential genetic counselling unit in Spain. METHODS: Between January 1998 and November 2006, a total of 684 families with several cases of breast and/or ovarian cancer were selected by the Genetic Counselling Unit at the Hospital Clínico Universitario San Carlos. Some of them opted for prophylactic surgery after genetic counselling and genetic testing. RESULTS: The pathogenic mutation was found in 57 families out of a total of 449 families who fulfilled the hereditary breast/ovarian cancer criteria. Out of a total of 238 individuals who were carriers of the mutation, 136 (57%) were offered risk-reducing prophylactic surgery. Prophylactic surgery was chosen by 58 (43%) women out of a total of 136 who were offered this possibility; the histological findings observed 7% malignant lesions in the breast and, in the ovarian-fallopian complex, 2 cases (8%) of a borderline tumour and one case (4%) of papillary adenocarcinoma. CONCLUSION: This is the first study published on the role of prophylactic surgery in BRCA mutation carriers in the Spanish population. The incidence of occult carcinoma in these cases is lower than in other series.