RESUMO
The purpose of this study was to analyze and molecularly describe the largest group of patients with ABCA4-associated retinal degeneration in Latin America. Pathogenic variants in ABCA4, a member of the ATP Binding Cassette (ABC) transporters superfamily, is one of the most common causes of inherited visual deficiency in humans. Retinal phenotypes associated with genetic defects in ABCA4 are collectively known as ABCA4-associated retinal degenerations (ABCA4R), a group of recessively inherited disorders associated with a high allelic heterogeneity. While large groups of Caucasian and Asiatic individuals suffering from ABCA4R have been well characterized, molecular information from certain ethnic groups is limited or unavailable, precluding a more realistic knowledge of ABCA4-related mutational profile worldwide. In this study, we describe the molecular findings of a large group of 211 ABCA4R index cases from Mexico. Genotyping was performed using either next generation sequencing (NGS) of a retinal dystrophy genes panel or exome. ABCA4 targeted mutation testing was applied to a subgroup of subjects in whom founder mutations were suspected. A total of 128 different ABCA4 pathogenic variants were identified, including 22 previously unpublished variants. The most common type of genetic variation was single nucleotide substitutions which occurred in 92.7% (408/440 alleles). According to the predicted protein effect, the most frequent variant type was missense, occurring in 83.5% of disease-causing alleles (368/440). Mutations such as p.Ala1773Val are fully demonstrated as a founder effect in native inhabitants of certain regions of Mexico. This study also gives us certain indications of other founder effects that need to be further studied in the near future. This is the largest molecularly characterized ABCA4R Latin American cohort, and our results supports the value of conducting genetic screening in underrepresented populations for a better knowledge of the mutational profile leading to monogenic diseases.
Assuntos
Transportadores de Cassetes de Ligação de ATP , Genótipo , Degeneração Retiniana , Humanos , Transportadores de Cassetes de Ligação de ATP/genética , México , Masculino , Feminino , Degeneração Retiniana/genética , Criança , Mutação , Adulto , Adolescente , Pessoa de Meia-Idade , Sequenciamento de Nucleotídeos em Larga Escala , Alelos , Fenótipo , Pré-Escolar , Adulto Jovem , LinhagemRESUMO
Hereditary breast and ovarian cancer (HBOC) syndrome is a genetic condition that increases the risk of breast cancer by 80% and that of ovarian cancer by 40%. The most common pathogenic variants (PVs) causing HBOC occur in the BRCA1 gene, with more than 3850 reported mutations in the gene sequence. The prevalence of specific PVs in BRCA1 has increased across populations due to the effect of founder mutations. Therefore, when a founder mutation is identified, it becomes key to improving cancer risk characterization and effective screening protocols. The only founder mutation described in the Mexican population is the deletion of exons 9 to 12 of BRCA1 (BRCA1Δ9-12), and its description focuses on the gene sequence, but no transcription profiles have been generated for individuals who carry this gene. In this study, we describe the transcription profiles of cancer patients and healthy individuals who were heterozygous for PV BRCA1Δ9-12 by analyzing the differential expression of both alleles compared with the homozygous BRCA1 control group using RT-qPCR, and we describe the isoforms produced by the BRCA1 wild-type and BRCA1Δ9-12 alleles using nanopore long-sequencing. Using the Kruskal-Wallis test, our results showed a similar transcript expression of the wild-type allele between the healthy heterozygous group and the homozygous BRCA1 control group. An association between the recurrence and increased expression of both alleles in HBOC patients was also observed. An analysis of the sequences indicated four wild-type isoforms with diagnostic potential for discerning individuals who carry the PV BRCA1Δ9-12 and identifying which of them has developed cancer.
Assuntos
Alelos , Proteína BRCA1 , Síndrome Hereditária de Câncer de Mama e Ovário , Humanos , Proteína BRCA1/genética , Feminino , Síndrome Hereditária de Câncer de Mama e Ovário/genética , Pessoa de Meia-Idade , Predisposição Genética para Doença , Adulto , Efeito Fundador , Éxons/genética , Neoplasias da Mama/genética , Heterozigoto , Mutação , México , Neoplasias Ovarianas/genética , Relevância ClínicaRESUMO
Mutations in the FKRP gene result in phenotypes with severe forms of congenital muscular dystrophies (CMD) and limb-girdle muscular dystrophies. We present a Mexican patient with a pathogenic homozygous mutation in the FKRP gene (c.1387A > G, p.Asn463Asp) and CMD with radiological brain anomalies as disseminated hyperintensity lesions and discrete generalized cortical atrophy. These findings have not been reported to the best of our knowledge in other patients with the same mutation. The mutation c.1387A > G, p.Asn463Asp in the FKRP gene has been described to have a founder effect in central Mexico, since all the patients described to date are of Hispanic origin. Therefore, we emphasize studying mutations in the FKRP gene in Hispanic pediatric patients with clinical suspicion of CMD. Clinical and molecular diagnosis of specific CMD subtypes is needed to help clarify the prognosis, management, and genetic counseling to the patient and families.
RESUMO
Primary Ciliary Dyskinesia (PCD) is a rare genetic disease characterized by motile cilia dysfunction with a prevalence of 1 in 16,309 individuals in Hispanic populations. In Puerto Rico, the prevalence of PCD is unknown. Diagnosis of PCD in Puerto Rico is challenging due to the lack of diagnostic technology. Algorithms for PCD diagnosis include clinical history, genetic testing, ciliary biopsy, and nasal Nitric Oxide (nNO) levels. For the first time, this study successfully implemented and measured the nNO levels in subjects with the RSPH4A (c.921+3_921+6del (intronic)) as a diagnostic tool to complement the current algorithm for PCD diagnosis on the island. The nNO level differentiated homozygous subjects with PCD due to the RSPH4A (c.921+3_921+6del (intronic)) founder mutation compared to healthy gender-age matched controls and subjects with VUS or negative genetic testing for PCD. The acquisition of state-of-the-art diagnostic tools such as nNO positively impacted and expanded our current PCD diagnostic capabilities in Puerto Rico for our founder genetic mutation. The addition of nNO technology promotes earlier disease screening and recognition for patients with PCD on the island. The access to nNO helped us to properly characterize the PCD diagnosis for patients with the RSPH4A (c.921+3_921+6del (intronic)). As a result, our findings will allow us to be part of the national PCD foundation registry and represent Puerto Rican Hispanics in future PCD multicentric clinical trials.
Assuntos
Transtornos da Motilidade Ciliar , Óxido Nítrico , Humanos , Óxido Nítrico/análise , Porto Rico , Nariz/química , Mutação , Transtornos da Motilidade Ciliar/diagnósticoRESUMO
Background: Ovarian cancer (OC) is gynecologic cancer with the highest mortality rate. It is estimated that 13-17% of ovarian cancers are due to heritable mutations in BRCA1 and BRCA2. The BRCA1 (BRCA1-Del ex9-12) Mexican founder mutation is responsible for 28-35% of the cases with ovarian cancer. The aim was to describe the PFS of OC patients treated with olaparib, emphasizing patients carrying the Mexican founder mutation (BRCA1-Del ex9-12). Methods: In this observational study, of 107 patients with BRCAm, 35 patients were treated with olaparib from November 2016 to May 2021 at the Ovarian Cancer Program (COE) of Mexico; patient information was extracted from electronic medical records. Results: Of 311 patients, 107 (34.4%) were with BRCAm; 71.9% (77/107) were with BRCA1, of which 27.3% (21/77) were with BRCA1-Del ex9-12, and 28.1% (30/107) were with BRCA2 mutations. Only 35 patients received olaparib treatment, and the median follow-up was 12.87 months. The PFS of BRCA1-Del ex9-12 was NR (non-reach); however, 73% of the patients received the treatment at 36 vs. 11.59 months (95% CI; 10.43-12.75) in patients with other BRCAm (p = 0.008). Almost 50% of patients required dose reduction due to toxicity; the most frequent adverse events were hematological in 76.5% and gastrointestinal in 4%. Conclusion: Mexican OC BRCA1-Del ex9-12 patients treated with olaparib had a significant increase in PFS regardless of the line of treatment compared to other mutations in BRCA.
RESUMO
Primary ciliary dyskinesia (PCD) has been linked to more than 50 genes that cause a spectrum of clinical symptoms, including newborn respiratory distress, sinopulmonary infections, and laterality abnormalities. Although the RSPH4A (c.921+3_6delAAGT) pathogenic variant has been related to Hispanic groups with Puerto Rican ancestry, it is uncertain how frequently other PCD-implicated genes are present on the island. A retrospective chart review of n = 127 genetic reports from Puerto Rican subjects who underwent genetic screening for PCD variants was conducted from 2018 to 2022. Of 127 subjects, 29.1% subjects presented PCD pathogenic variants, and 13.4% were homozygous for the RSPH4A (c.921+3_6delAAGT) founder mutation. The most common pathogenic variants were in RSPH4A and ZMYND10 genes. A description of the frequency and geographic distribution of implicated PCD pathogenic variants in Puerto Rico is presented. Our findings reconfirm that the presence of PCD in Puerto Rico is predominantly due to a founder pathogenic variant in the RSPH4A (c.921+3_6delAAGT) splice site. Understanding the frequency of PCD genetic variants in Puerto Rico is essential to map a future genotype-phenotype PCD spectrum in Puerto Rican Hispanics with a heterogeneous ancestry.
RESUMO
BACKGROUND: In a previous work, we identified nine founder mutations present in close to 80% of BRCA1 and BRCA2 mutation carriers, and distributed across the country. The presence of founder mutations constitutes a valuable opportunity to develop new strategies for genetic screening. Genetic tests are primarily performed by NGS sequencing, which requires sophisticated and expensive equipment, and it takes 2-3 weeks for the results to be informed to the patient. In addition, genetic tests are not covered by insurance companies in Latin American countries. In this work, we present the standardization and technical validation of a real-time PCR based methodology for allelic discrimination in order to identify the nine Chilean founder mutations in BRCA1 and BRCA2 genes. METHODS AND RESULTS: We designed nine pairs of probes and nine pairs of primers to amplify synchronically nine regions of the BRCA1/BRCA2 genes by real-time PCR, in order to identify the nine founder mutations through allelic discrimination analyses. Technical validation was performed using 90 positive and 90 negative samples for each mutation. The methodology was tested in a second group of 60 patients. Our method correctly classified carriers and non-carriers of one of the nine Chilean founder mutations with a 100% specificity and 100% sensitivity, compared with Sanger sequencing performance. CONCLUSIONS: We develop an inexpensive, simple, and fast mutation detection method that could be implemented locally in Hospitals from the Private to Public health system. This methodology may be useful for the screening of BRCA1 and BRCA2 mutations in other populations.
Assuntos
Neoplasias da Mama , Neoplasias Ovarianas , Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/genética , Carcinoma Epitelial do Ovário/genética , Chile , Detecção Precoce de Câncer , Feminino , Efeito Fundador , Genes BRCA2 , Predisposição Genética para Doença , Humanos , Mutação/genética , Neoplasias Ovarianas/genética , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Background Some breast cancer cases are related to inherited mutations, and this is the reason why early mutation screening is emerging as an area of focus for cost-effective care. However, breast cancer-related mutations vary according to race, ethnicity, geographic origin, and healthcare access. Surveillance for familial breast cancer is not performed routinely in Colombia. Our main aim in this study was to describe a cohort of breast cancer patients, carrying founder breast cancer gene (BRCA) mutations, which were followed up for up to 10 years (2010-2019) in Neiva, Colombia. Methods We performed a retrospective description from an outpatient care center in Huila, Colombia, a region with high breast cancer rates. This study included patients with both a breast cancer diagnosis and an incident genetic mutation for breast cancer (detected during a breast cancer consultation). We captured information from patient medical records. Descriptive analyses were performed. Results A total of 105 patients met the study's inclusion criteria and were included patients with the BRCA1 mutation and three with BRCA2 mutations. They had a median age of 45 years (IQR, 36 to 51 years). Relatives with a breast cancer history were found in 74 carriers (70.5%). Most patients had a report of Breast Imaging-Reporting and Data System (BIRADS) ≥ 4. A TNM (tumor, node, metastasis) changed reclassification was observed in anatomical vs. prognostic classification. Median follow-up was of 74 months (IQR, 44 to 130), overall observed mortality was 22.9%, and specific mortality was 19.1%. Conclusion Women with breast cancer who carry a mutation related to breast cancer are usually younger than age 50 at diagnosis. Developing strategies and specific policies for this population is needed, and a prevalent BRCA1 c.3331_3334delCAAG mutation could be used as a cost-effective first approach. Among these patients, a risk-increased reclassification was observed.
RESUMO
Genetic mutations in >50 genes, including RSPH4A, can lead to primary ciliary dyskinesia (PCD). RSPH4A mutations affect radial spokes, which alter the configuration of the ciliary ultrastructure and lead to chronic oto-sinopulmonary disease. The RSPH4A [c.921+3_6delAAGT] founder mutation was described as one cause of PCD without laterality defects in Puerto Rico. The average Puerto Rican genetic composition includes 64% European, 21% African ancestral, and 15% Native-American or Taino, a native tribe in the Caribbean at the start of the European colonization, genes. Due to the relatively elevated Taino ancestry on the island, it might have contributed to the endemicity of the RSPH4A [c.921+3_6delAAGT] splice site mutation. However, the ancestry of this mutation is still not confirmed. This article describes the two pediatric PCD cases with the Puerto Rican foundermutationand reports an ancestral haplotype analysis of the RSPH4A [c.921+3_6delAAGT] splice site mutation. A median-joining haplotype network was constructed with the genome sequence data from 104 Puerto Rican subjects in the 1000 Genomes Project (1000GP). This study found that the RSPH4A [c.921+3_6delAAGT] splice site mutation was carried to Puerto Rico from Europe by conquistadors or shortly after the conquest and that it gained frequency on the island through genetic drift fueled by a subsequent population expansion.
RESUMO
PURPOSE: To investigate the frequency of a founder mutation in NLRP7, L750V, in independent cohorts of Mexican patients with recurrent hydatidiform moles (RHMs). METHODS: Mutation analysis was performed by Sanger sequencing on DNA from 44 unrelated Mexican patients with RHMs and seven molar tissues from seven additional unrelated patients. RESULTS: L750V was present in homozygous or heterozygous state in 37 (86%) patients and was transmitted on the same haplotype to patients from different states of Mexico. We also identified a second founder mutation, c.2810+2T>G in eight (18.1%) patients, and a novel premature stop-codon mutation W653*. CONCLUSION: Our data confirm the strong founder effect for L750V, which appears to be the most common mutation in NLRP7. We also report on six healthy live births to five patients with biallelic NLRP7 mutations, two from spontaneous conceptions and four from donated ovum and discuss our recommendations for DNA testing and genetic counseling.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Efeito Fundador , Mola Hidatiforme/genética , Mutação , Feminino , Haplótipos , Heterozigoto , Humanos , Nascido Vivo , México , Polimorfismo de Nucleotídeo Único , GravidezRESUMO
Primary ciliary dyskinesia (PCD) is a rare, heterogeneous ciliopathy resulting in chronic oto-sino-pulmonary disease, bronchiectasis, newborn respiratory distress, and laterality defects. PCD diagnosis can be achieved by following diagnostic algorithms that include electron microscopy, genetics, and ancillary testing. Genetic mutations in more than 45 genes, including RSPH4A, can lead to PCD. RSPH4A mutations located on chromosome six, affect radial spokes and results in central complex apparatus abnormalities. The RSPH4A [c.921 + 3_6delAAGT] founder mutation was described as one cause of PCD without laterality defects in Puerto Rico. Additionally, there are further diagnostic challenges present in the Puerto Rican population to diagnose PCD. We describe the demographics, clinical features, and RSPH4A genetic variants in 13 patients with clinical PCD affecting 11 Puerto Ricans from unrelated families.
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
Congenital disorders of glycosylation (CDG) are a heterogeneous group of inborn errors of metabolism mostly causing multisystem disease. In 2013, biallelic mutations in the GMPPA gene were described in association with one such CDG known as alacrima, achalasia, and mental retardation syndrome (AAMR). To date, 18 patients have been reported, nearly all displaying the same pathognomonic triad of symptoms described in the name. This condition shares considerable phenotypic overlap with Triple-A syndrome caused by biallelic mutations in the AAAS gene; however, AAMR lacks the characteristic adrenocortical findings associated with Triple-A syndrome. We report three patients from two unrelated families with the same homozygous GMPPA mutation (c.265dup, p.L89fs). Notably, both families reported indigenous Maya-Mam heritage and originated from the town of Concepción Chiquirichapa in Quezaltenango, Guatemala. Our cases help to expand the AAMR phenotype by outlining dysmorphic features not well described in the prior cases. Additionally, we encourage all providers with patients presenting with this unique triad of symptoms to consider sequencing of the GMPPA gene. Special consideration should be given to families of Guatemalan Maya-Mam ancestry who may also have this identified founder mutation. Finally, this condition may indeed be underdiagnosed based on a review of the literature.
Assuntos
Insuficiência Adrenal/genética , Acalasia Esofágica/genética , Glicosilação , Deficiência Intelectual/genética , Nucleotidiltransferases/genética , Adolescente , Insuficiência Adrenal/epidemiologia , Insuficiência Adrenal/patologia , Criança , Consanguinidade , Acalasia Esofágica/epidemiologia , Acalasia Esofágica/patologia , Éxons/genética , Feminino , Homozigoto , Humanos , Deficiência Intelectual/epidemiologia , Deficiência Intelectual/patologia , Masculino , Mutação/genética , Proteínas do Tecido Nervoso/genética , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Linhagem , FenótipoRESUMO
INTRODUCTION: More than the twenty percent of ovarian cancers are hereditary, and most have BRCA mutations. The 30% of Mexican patients with the BRCA1 mutation have the BRCA1 gene exon 9-12del deletion founder mutation (BRCA1 ex9-12del). BRCA-mutated tumors are more sensitive to PARP inhibitors such as olaparib. OBJECTIVE: To show the clinical experience on the use of olaparib at Instituto Nacional de Cancerología in Mexico. METHOD: Ovarian cancer patients treated with olaparib from November 2016 to December 2018 were studied, and their characteristics, clinical response, progression-free survival (PFS) and toxicities were described. RESULTS: Nineteen patients were assessed, with BRCA1 mutation being found in 78.9%, out of which 21.1% were carriers of the ex9-12del founder mutation. The median of PFS was 12 months; for patients treated on second and third line it was > 15 months, and for those treated with a fourth and subsequent line it was 8.3 months. Patients with the founder mutation had better results. Toxicities were like those reported in previous studies. CONCLUSIONS: Olaparib offers greater PFS benefit as maintenance therapy after a first and second relapse. Patients with founder mutation have had sustained PFS.
INTRODUCCIÓN: Más del 20 % de los cánceres de ovario puede ser hereditario y la mayoría tiene mutaciones BRCA. El 33 % de las pacientes mexicanas con mutación BRCA1 tiene la mutación fundadora deleción del exón 9-12del del gen BRCA1 (BRCA1 ex9-12del). Los tumores BRCA mutados son más sensibles a inhibidores PARP como olaparib. OBJETIVO: Mostrar la experiencia clínica del uso de olaparib en el Instituto Nacional de Cancerología de México. MÉTODO: Se estudiaron las pacientes con cáncer de ovario tratadas con olaparib de noviembre de 2016 a diciembre de 2018 y se describieron sus características, respuesta clínica, supervivencia libre de progresión y toxicidades. RESULTADOS: Se evaluaron 19 pacientes, 78.9 % presentó mutación BRCA1, del cual 21.1 % era portador de la mutación fundadora ex9-12del. La mediana de supervivencia libre de progresión global fue de 12 meses, para las pacientes tratadas tratadas con olaparib de mantenimiento posterior a segunda y tercera línea fue de > 15 meses y para las de cuarta línea o más fue de 8.3 meses. Las pacientes con mutación fundadora presentaron mejores respuestas. Las toxicidades fueron similares a las de estudios con el uso de olaparib. CONCLUSIONES: Olaparib ofrece mayor beneficio en supervivencia libre de progresión como tratamiento de mantenimiento después de la primera y segunda recaída. Las pacientes con mutación fundadora han tenido respuesta sostenida.
Assuntos
Proteína BRCA1/genética , Neoplasias Ovarianas/tratamento farmacológico , Ftalazinas/administração & dosagem , Piperazinas/administração & dosagem , Inibidores de Poli(ADP-Ribose) Polimerases/administração & dosagem , Adulto , Idoso , Feminino , Humanos , México , Pessoa de Meia-Idade , Mutação , Recidiva Local de Neoplasia , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Ftalazinas/efeitos adversos , Piperazinas/efeitos adversos , Inibidores de Poli(ADP-Ribose) Polimerases/efeitos adversos , Intervalo Livre de ProgressãoRESUMO
PURPOSE: Each year, 17,000 new breast cancer cases are diagnosed in Argentina, and 5400 women die of breast cancer. The contribution of cancer-related mutations to the incidence of breast cancer in Argentina has not yet been explored. METHODS: We sequenced the entire coding regions of BRCA1, BRCA2, PALB2 and RAD51C in 112 unselected Argentinian breast cancer patients. RESULTS: A pathogenic genetic variant was found in 12 of 112 (10.7%) patients; two in BRCA1 (1.8%), five in BRCA2 (4.5%), four in PALB2 (3.6%) and one in RAD51C (0.9%). Three of four (75%) PALB2 mutation carriers carried the same variant (c.1653T > A). CONCLUSIONS: A founder mutation in PALB2 accounts for up to 4% of breast cancer patients in Argentina. BRCA1, BRCA2, PALB2 and RAD51C should be included in the genetic testing panel of breast cancer patients in Argentina.
Assuntos
Neoplasias da Mama/genética , Proteínas de Grupos de Complementação da Anemia de Fanconi/genética , Predisposição Genética para Doença/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Argentina/epidemiologia , Proteína BRCA1/genética , Proteína BRCA2/genética , Biomarcadores Tumorais/genética , Neoplasias da Mama/sangue , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/patologia , Proteínas de Ligação a DNA/genética , Proteína do Grupo de Complementação N da Anemia de Fanconi/genética , Feminino , Estudos de Associação Genética , Mutação em Linhagem Germinativa , Humanos , Pessoa de Meia-Idade , LinhagemRESUMO
Identifying founder mutations in BRCA1 and BRCA2 in specific populations constitute a valuable opportunity for genetic screening. Several studies from different populations have reported recurrent and/or founder mutations representing a relevant proportion of BRCA mutation carriers. In Latin America, only few founder mutations have been described. We screened 453 Chilean patients with hereditary breast cancer for mutations in BRCA1 and BRCA2. For recurrent mutations, we genotyped 11 microsatellite markers in BRCA1 and BRCA2 in order to determine a founder effect through haplotype analysis. We found a total of 25 mutations (6 novel) in 71 index patients among which, nine are present exclusively in Chilean patients. Our analysis revealed the presence of nine founder mutations, 4 in BRCA1 and 5 in BRCA2, shared by 2 to 10 unrelated families and spread in different regions of Chile. Our panel contains the highest amount of founder mutations until today and represents the highest percentage (78%) of BRCA1 and BRCA2 mutation carriers. We suggest that the dramatic reduction of Amerindian population due to smallpox and wars with Spanish conquerors, a scarce population increase during 300 years, and the geographic position of Chile constituted a favorable scenario to establish founder genetic markers in our population.
RESUMO
Lynch syndrome is the most frequent syndrome in hereditary colorectal cancer, a family-specific deleterious mutations in genes encoding DNA reparation proteins: MLH1 (mutL homolog 1), MSH2, MSH6 (mutS homolog 2 y 6, respectively), PMS2 (PMS1 homolog 2, mismatch repair system component) y MUTYH (mutY DNA glycosylase). The c.2252_2253delAA, p.Lys751Serfs*3 mutation in MLH1 gene segregates with a haplotype reported in the northern region of Italy and whose origin was attributed to a founder effect. This mutation co-segregates with typical characteristics of Lynch syndrome, including early age at onset and multiple primary tumors in the same individual, a high frequency of pancreatic cancer, high microsatellite instability and lack of PMS2 expression. This report describes a mutation in an Argentinian patient with endometrioid adenocarcinoma of uterus. Her first-degree relatives had a history of colon cancer diagnosed before 50 years, fulfilling the Amsterdam Criteria I and Lynch syndrome II. The high pathogenicity associated to this mutation makes necessary the study of all members from families with hereditary cancer, allowing pre-symptomatic genetic diagnosis, early assessment and the instauration of preventive treatments.
Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/genética , Efeito Fundador , Endonuclease PMS2 de Reparo de Erro de Pareamento/genética , Proteína 1 Homóloga a MutL/genética , Mutação/genética , Reparo do DNA/genética , Feminino , Humanos , Síndrome de Lynch II/genética , Pessoa de Meia-Idade , LinhagemRESUMO
El síndrome de Lynch es la más frecuente de las neoplasias colorrectales hereditarias. Se origina por mutaciones germinales deletéreas familia-específicas en los genes que codifican proteínas de reparación del ADN: MLH1 (homólogo humano de mutL), MSH2 y MSH6 (homólogo humano de mutS 2 y 6, respectivamente), PMS2 (homólogo humano de PMS1 2) y MUTYH (homólogo humano de la ADN-glycosilasa mutY). La mutación c.2252_2253delAA, p.Lys751Serfs*3 en el exón 19 del gen MLH1 segrega con un haplotipo descripto en la región norte de Italia y cuyo origen fue atribuido a un efecto fundador. Esta mutación co-segrega con características típicas del síndrome de Lynch, incluyendo afectación temprana y múltiples tumores primarios en el mismo individuo, una alta frecuencia de cáncer pancreático, elevada inestabilidad microsatelital y falta de expresión de PMS2. En el presente trabajo se comunica dicha mutación en una paciente argentina con adenocarcinoma endometroide de útero en cuya historia familiar existen antecedentes de cáncer de colon diagnosticado antes de los 50 años en familiares de primer grado, reuniendo los criterios de Ámsterdam I y síndrome de Lynch II. Los polimorfismos presentes en la paciente coinciden con el haplotipo descripto en una región del norte de Italia. El alto grado de patogenicidad asociada a esta mutación hace imprescindible el estudio de todos los integrantes de las familias con cáncer hereditario permitiendo el diagnóstico genético pre-sintomático, la instauración de tratamientos o conductas preventivas y su seguimiento.
Lynch syndrome is the most frequent syndrome in hereditary colorectal cancer, a family-specific deleterious mutations in genes encoding DNA reparation proteins: MLH1 (mutL homolog 1), MSH2, MSH6 (mutS homolog 2 y 6, respectively), PMS2 (PMS1 homolog 2, mismatch repair system component) y MUTYH (mutY DNA glycosylase).The c.2252_2253delAA, p.Lys751Serfs*3 mutation in MLH1 gene segregates with a haplotype reported in the northern region of Italy and whose origin was attributed to a founder effect. This mutation co-segregates with typical characteristics of Lynch syndrome, including early age at onset and multiple primary tumors in the same individual, a high frequency of pancreatic cancer, high microsatellite instability and lack of PMS2 expression. This report describes a mutation in an Argentinian patient with endometrioid adenocarcinoma of uterus. Her first-degree relatives had a history of colon cancer diagnosed before 50 years, fulfilling the Amsterdam Criteria I and Lynch syndrome II. The high pathogenicity associated to this mutation makes necessary the study of all members from families with hereditary cancer, allowing pre-symptomatic genetic diagnosis, early assessment and the instauration of preventive treatments.
Assuntos
Humanos , Feminino , Pessoa de Meia-Idade , Neoplasias Colorretais Hereditárias sem Polipose/genética , Efeito Fundador , Endonuclease PMS2 de Reparo de Erro de Pareamento/genética , Proteína 1 Homóloga a MutL/genética , Mutação/genética , Linhagem , Reparo do DNA/genética , Síndrome de Lynch II/genéticaRESUMO
In Brazil, several recurring mutations in BRCA1 and BRCA2 and a TP53 mutation (R337H) have been reported in high risk breast cancer cases. We hypothesized that these recurring mutations may also be detected in the general population and ovarian cancer cases in the state of Minas Gerais. To test this notion, participants were recruited from the outpatient and the Gynecological clinic in the UFMG Medical Center in Belo Horizonte, Minas Gerais, Brazil. BRCA1 (c.68_69delAG, c.5266dupC, c.181T>G, c.4034delA, c.5123C>A), BRCA2 (c.5946delT, c.8537_8538delAG, 4936_4939delGAAA), the c.156_157insAlu* BRCA2 and the c.1010G>A *TP53 mutation were genotyped using validated techniques. Overall, 513 cancer free participants (273 men) (mean age 47.7 ± 15.1 years) and 103 ovarian cancer cases (mean age at diagnosis 58.7 ± 9.6 years) were studied. None of the participants were found to carry any of the genotyped mutations. We conclude that the recurring mutations in BRCA1, BRCA2 and TP53 cannot be detected in the general population or consecutive ovarian cancer cases in this geographical region in Brazil.
Assuntos
Genes BRCA1 , Genes BRCA2 , Genes p53 , Mutação em Linhagem Germinativa , Neoplasias Ovarianas/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil/epidemiologia , Estudos de Casos e Controles , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/epidemiologia , Recidiva Local de Neoplasia/genética , Neoplasias Ovarianas/epidemiologia , Adulto JovemRESUMO
Laron syndrome, an autosomal recessive condition of extreme short stature, is caused by the absence or dysfunction of the growth hormone receptor. A recurrent mutation in the GHR gene, p.E180, did not alter the encoded amino acid, but activated a cryptic splice acceptor resulting in a receptor protein with an 8-amino acid deletion in the extracellular domain. This mutation has been observed among Sephardic Jews and among individuals in Ecuador, Brazil and Chile, most notably in a large genetic isolate in Loja, Ecuador. A common origin has been postulated based on a shared genetic background of markers flanking this mutation, suggesting that the Lojanos (and others) may have Sephardic (Converso) Jewish ancestry. Analysis of the population structure of Lojanos based on genome-wide analysis demonstrated European, Sephardic Jewish and Native American ancestry in this group. X-autosomal comparison and monoallelic Y chromosomal and mitochondrial genetic analysis demonstrated gender-biased admixture between Native American women and European and Sephardic Jewish men. These findings are compatible with the co-occurrence of the Inquisition and the colonization of the Americas, including Converso Jews escaping the Inquisition in the Iberian Peninsula. Although not found among Lojanos, Converso Jews also brought founder mutations to contemporary Hispanic and Latino populations in the BRCA1 (c.68_69delAG) and BLM (c.2207_2212delATCTGAinsTAGATTC) genes.