A survey of the clinicopathological and molecular characteristics of patients with suspected Lynch syndrome in Latin America.

BACKGROUND: Genetic counselling and testing for Lynch syndrome (LS) have recently been introduced in several Latin America countries. We aimed to characterize the clinical, molecular and mismatch repair (MMR) variants spectrum of patients with suspected LS in Latin America. METHODS: Eleven LS hereditary cancer registries and 34 published LS databases were used to identify unrelated families that fulfilled the Amsterdam II (AMSII) criteria and/or the Bethesda guidelines or suggestive of a dominant colorectal (CRC) inheritance syndrome. RESULTS: We performed a thorough investigation of 15 countries and identified 6 countries where germline genetic testing for LS is available and 3 countries where tumor testing is used in the LS diagnosis. The spectrum of pathogenic MMR variants included MLH1 up to 54%, MSH2 up to 43%, MSH6 up to 10%, PMS2 up to 3% and EPCAM up to 0.8%. The Latin America MMR spectrum is broad with a total of 220 different variants which 80% were private and 20% were recurrent. Frequent regions included exons 11 of MLH1 (15%), exon 3 and 7 of MSH2 (17 and 15%, respectively), exon 4 of MSH6 (65%), exons 11 and 13 of PMS2 (31% and 23%, respectively). Sixteen international founder variants in MLH1, MSH2 and MSH6 were identified and 41 (19%) variants have not previously been reported, thus representing novel genetic variants in the MMR genes. The AMSII criteria was the most used clinical criteria to identify pathogenic MMR carriers although microsatellite instability, immunohistochemistry and family history are still the primary methods in several countries where no genetic testing for LS is available yet. CONCLUSION: The Latin America LS pathogenic MMR variants spectrum included new variants, frequently altered genetic regions and potential founder effects, emphasizing the relevance implementing Lynch syndrome genetic testing and counseling in all of Latin America countries.

Identification and frequencies of cystic fibrosis mutations in central Argentina.

BACKGROUND: The Argentinian population is mainly of Caucasian origin, with a small contingent of indigenous descent. The aim of this study is to test the hypothesis that a panel of mutations designed for European countries is not optimal as a first-line molecular diagnosis for routine use in this country of mixed European origin. METHODS: Phenotype analyses combined with a European screening panel of 71 mutations followed by Sanger sequencing and large rearrangement study, were used to characterize the identification and distribution of CFTR mutations in the Santa Fe province of Argentina. RESULTS: Clinical review of 121 subjects suspected of CF during childhood led to selection of 83 unrelated patients. Thirty four different mutations, including two new ones, c.2554dupT and p.Leu49Pro, were detected. The total sensitivity was 91% (n = 151/166 alleles). CONCLUSIONS: Frequencies of CFTR mutations in Argentinian populations differ from those of their European ancestry. A new first line panel of 21 CFTR mutations with a sensitivity of 84% is proposed for routine use in central Argentina.

BRCA1 And BRCA2 analysis of Argentinean breast/ovarian cancer patients selected for age and family history highlights a role for novel mutations of putative south-American origin.

BACKGROUND: The spectrum of BRCA1/2 genetic variation in breast-ovarian cancer patients has been scarcely investigated outside Europe and North America, with few reports for South America, where Amerindian founder effects and recent multiracial immigration are predicted to result in high genetic diversity. We describe here the results of BRCA1/BRCA2 germline analysis in an Argentinean series of breast/ovarian cancer patients selected for young age at diagnosis or breast/ovarian cancer family history. METHODS: The study series (134 patients) included 37 cases diagnosed within 40 years of age and no family history (any ethnicity, fully-sequenced), and 97 cases with at least 2 affected relatives (any age), of which 57 were non-Ashkenazi (fully-sequenced) and 40 Ashkenazi (tested only for the founder mutations c.66_67delAG and c.5263insC in BRCA1 and c.5946delT in BRCA2). DISCUSSION: We found 24 deleterious mutations (BRCA1:16; BRCA2: 8) in 38/134 (28.3%) patients, of which 6/37 (16.2%) within the young age group, 15/57 (26.3%) within the non-Ahkenazi positive for family history; and 17/40 (42.5%) within the Ashkenazi. Seven pathogenetic mutations were novel, five in BRCA1: c.1502_1505delAATT, c.2626_2627delAA c.2686delA, c.2728 C > T, c.3758_3759delCT, two in BRCA2: c.7105insA, c.793 + 1delG. We also detected 72 variants of which 54 previously reported and 17 novel, 33 detected in an individual patient. Four missense variants of unknown clinical significance, identified in 5 patients, are predicted to affect protein function. While global and European variants contributed near 45% of the detected BRCA1/2 variation, the significant fraction of new variants (25/96, 26%) suggests the presence of a South American genetic component. This study, the first conducted in Argentinean patients, highlights a significant impact of novel BRCA1/2 mutations and genetic variants, which may be regarded as putatively South American, and confirms the important role of founder BRCA1 and BRCA2 mutations in Argentinean Ashkenazi Jews.

Implementación de un método in house para el tamizaje de los Virus de la Hepatitis C e Inmunodeficiencia Humana en donantes de sangre: resultados / Implementation of an in-house method for screening for Hepatitis C and Human Immunodeficiency Virus in blood donors: results

La implementación de técnicas de amplificación de ácidos nucleicos (NAT) para la detección de Virus de Hepatitis C (VHC) y Virus de Inmunodeficiencia Humana (VIH) en el tamizaje de donantes de sangre permite acortar los períodos ventana para los ensayos utilizados en la detección de antígenos y/o anticuerpos, identificando donaciones infectivas y evitando su transfusión. Todos los usuarios de NAT deben proceder a su validación para investigar si los procedimientos involucrados cumplen y garantizan confiabilidad en la reducción del período ventana en unidades de hemocomponentes factibles de ser transfundidas. El objetivo de este trabajo fue mostrar los resultados obtenidos de la implementación de técnica NAT in house validadas frente a estándares internacionales para la detección de VHC y VIH en donantes de sangre. Los resultados fueron analizados con el software Probit analysis programs. Para un 95% de positividad, el límite de detección fue de 98,50 Ul/ml para VHC y 294, 84 Ul/ml para VIH. La especificidad fue del 100% y los procedimientos presentaron robustez. La validación de técnicas de PCR in house permite demostrar que, por sensibilidad y especificidad, son una alternativa válida y aplicable en el tamizaje de donantes de sangre.

The technical implementation of nucleic acid amplification (NAT) for detecting hepatitis C virus (HCV) and Human Immunodeficiency Virus (HIV) in blood donors screening can shorten the window periods of tests used in the detection antigen and/or antibodies, identifying and preventing infectious donations transfusion. All users of NAT should proceed to validation to investigate whether the procedures involved meet and ensure reliability in reducing the window period in units of transfused blood products to be feasible. The aim of this study was to report the results of the technical implementation of NAT in-house validated against international standards for the detection of HCV and HIV genomes in blood donors. The results were analyzed using Probit analysis software programs. For a 95% positivity, the detection limit was 98.50 IU/ml for HCV and 294. 84 IU/ml for HIV. The specificity was 100% and showed robust procedures. Validation of in-house PCR techniques can demonstrate that for sensitivity and specificity, are a valid and applicable in screening blood donors.

Un caso de grupo sanguíneo raro: fenotipo p / A rare blood group: p phenotype

Un individuo con un fenotipo eritrocitario raro carece de uno o varios antígenos presentes en la mayor parte de la población de pertenencia. Cuando presenta el anticuerpo correspondiente, se pueden producir complicaciones perinatales, transfusionales y/o transplantológicas. Se presenta el caso de una embarazada aloinmunizada derivada a nuestro servicio en la semana 12 de su tercera gesta para su evaluación y seguimiento. El diagnóstico inmunohematológico le asignó el excepcional fenotipo "p" (aproximadamente 1/200 000 individuos), asociado con una mayor tasa de abortos espontáneos y a reacciones transfusionales graves cuando se transfunden unidades incompatibles. El estudio del gen A4GALT demostró la presencia de la mutación c.752C > T en doble dosis. Esta mutación lleva a un cambio de una prolina por una leucina en el residuo 251 de la 4-α-galactosiltransferasa. Por parto inducido por sufrimiento fetal, nace a las 36 semanas una bebé con prueba de antiglobulina (Coombs) directa negativa, eluido reactivo, con ictericia que requirió luminoterapia. Una semana después el neonato fue externado sin secuelas aparentes. Posteriormente, a raíz de una cirugía inminente y la improbabilidad de encontrar sangre compatible, se elaboró un plan para cubrir las posibles demandas. Este caso pone en evidencia la necesidad de contar a nivel nacional con un laboratorio de referencia de inmunohematología y un banco de sangre de grupos raros, que permita resolver con celeridad situaciones que requieran transfundir a estos individuos.

A rare blood group is usually defined as the absence of a high prevalence antigen or the absence of several antigens within a single blood group system. These individuals may develop clinically significant red cell antibodies to the high incidence red cell antigens they lack. A 33-year-old alloimmunized woman was referred to our center at the 12th week of her third pregnancy for evaluation and follow up. The laboratory work-up grouped her as belonging to "p" phenotype, associated with difficulties to find compatible blood for transfusion and a high incidence of recurrent miscarriage. At 36 weeks, a baby girl was born by induced labor due to fetal suffering. With a negative direct antiglobulin test but a positive elution test, she was in the neonatology ward for one week receiving luminotherapy. Homozygosity for a missense mutation at position 752 (c.752C > T) in the A4GALT gene was found to be responsible for the p phenotype. This mutation changes a proline to a leucine at codon 251 of the 4-α-galactosyltransferase. Recently, due to an imminent chirurgical intervention and the impossibility to have compatible blood available for transfusion, an autologous donation plan was designed to satisfy probable demand. This case showed the need for blood bank facilities capable to respond satisfactorily to these situations in Argentina. This would facilitate the storage of cryopreserved blood from individuals with rare blood groups for homologous use or to develop rare blood donors programs.

[A rare blood group: p phenotype]. / Un caso de grupo sanguíneo raro: fenotipo p.

A rare blood group is usually defined as the absence of a high prevalence antigen or the absence of several antigens within a single blood group system. These individuals may develop clinically significant red cell antibodies to the high incidence red cell antigens they lack. A 33-year-old alloimmunized woman was referred to our center at the 12th week of her third pregnancy for evaluation and follow up. The laboratory work-up grouped her as belonging to "p" phenotype, associated with difficulties to find compatible blood for transfusion and a high incidence of recurrent miscarriage. At 36 weeks, a baby girl was born by induced labor due to fetal suffering. With a negative direct antiglobulin test but a positive elution test, she was in the neonatology ward for one week receiving luminotherapy. Homozygosity for a missense mutation at position 752 (c.752C > T) in the A4GALT gene was found to be responsible for the p phenotype. This mutation changes a proline to a leucine at codon 251 of the 4-?-galactosyltransferase. Recently, due to an imminent chirurgical intervention and the impossibility to have compatible blood available for transfusion, an autologous donation plan was designed to satisfy probable demand. This case showed the need for blood bank facilities capable to respond satisfactorily to these situations in Argentina. This would facilitate the storage of cryopreserved blood from individuals with rare blood groups for homologous use or to develop rare blood donors programs.

Microsatellite instability analysis in hereditary non-polyposis colon cancer using the Bethesda consensus panel of microsatellite markers in the absence of proband normal tissue.

BACKGROUND: Hereditary non-polyposis colon cancer (HNPCC) is an autosomal dominant syndrome predisposing to the early development of various cancers including those of colon, rectum, endometrium, ovarium, small bowel, stomach and urinary tract. HNPCC is caused by germline mutations in the DNA mismatch repair genes, mostly hMSH2 or hMLH1. In this study, we report the analysis for genetic counseling of three first-degree relatives (the mother and two sisters) of a male who died of colorectal adenocarcinoma at the age of 23. The family fulfilled strict Amsterdam-I criteria (AC-I) with the presence of extracolonic tumors in the extended pedigree. We overcame the difficulty of having a proband post-mortem non-tumor tissue sample for MSI testing by studying the alleles carried by his progenitors. METHODS: Tumor MSI testing is described as initial screening in both primary and metastasis tumor tissue blocks, using the reference panel of 5 microsatellite markers standardized by the National Cancer Institute (NCI) for the screening of HNPCC (BAT-25, BAT-26, D2S123, D5S346 and D17S250). Subsequent mutation analysis of the hMLH1 and hMSH2 genes was performed. RESULTS: Three of five microsatellite markers (BAT-25, BAT-26 and D5S346) presented different alleles in the proband's tumor as compared to those inherited from his parents. The tumor was classified as high frequency microsatellite instability (MSI-H). We identified in the HNPCC family a novel germline missense (c.1864C>A) mutation in exon 12 of hMSH2 gene, leading to a proline 622 to threonine (p.Pro622Thr) amino acid substitution. CONCLUSION: This approach allowed us to establish the tumor MSI status using the NCI recommended panel in the absence of proband's non-tumor tissue and before sequencing the obligate carrier. According to the Human Gene Mutation Database (HGMD) and the International Society for Gastrointestinal Hereditary Tumors (InSiGHT) Database this is the first report of this mutation.

Enfermedad hemolítica fetoneonatal por anticuerpo anti-Diª / Haemolytic anemia in neonatal period produced by anti-Diª antibody

El sistema Diego está compuesto por dos pares independientes de antígenos: Diª/Dib, Wrª/Wrb, ubicados en una proteína de la membrana eritrocitaria, la banda 3. Este sistema tiene mucho valor en antropología porque informa del origen mongoloide de los japoneses, chinos e indios americanos. El 36 por ciento de las poblaciones indígenas de América Central y del Sur y un 3-15 por ciento de orientales presentan el antígenos Diª. pero en América y Europa casi todas las personas son Di(a-,b+). el objetivo de este trabajo es informar el caso de una mujer con 3 hijos, uno de los cuales desarrolló enfermedad hemolítica fetoneonatal (EHFN) debida a anticuerpos anti-Diª. El estudio de anticuerpos irregulares en el suero de la mujer usando panel celular comercial fue negativo; pero la prueba antiglobulínica indirecta enfrentando los globulos rojos del marido con el suero de la esposa fue fuertemente positiva. El anticuerpo se identificó como anti-Diª. De los tres hijos, el primero fue normal, pero el segundo presentó ictericia y prueba antiglobulínica directa positiva, por lo que fue necesario realizar una exanguinotransfusión, transfusiones de hematíes y luminoterapia. La ictericia fue causada por el anti-Diª materno inducido por el primer embarazo. El tercer neonato fue antígeno Diª negativo.

Enfermedad hemolítica fetoneonatal por anticuerpo anti-Di¬ / Haemolytic anemia in neonatal period produced by anti-Di¬ antibody

El sistema Diego está compuesto por dos pares independientes de antígenos: Di¬/Dib, Wr¬/Wrb, ubicados en una proteína de la membrana eritrocitaria, la banda 3. Este sistema tiene mucho valor en antropología porque informa del origen mongoloide de los japoneses, chinos e indios americanos. El 36 por ciento de las poblaciones indígenas de América Central y del Sur y un 3-15 por ciento de orientales presentan el antígenos Di¬. pero en América y Europa casi todas las personas son Di(a-,b+). el objetivo de este trabajo es informar el caso de una mujer con 3 hijos, uno de los cuales desarrolló enfermedad hemolítica fetoneonatal (EHFN) debida a anticuerpos anti-Di¬. El estudio de anticuerpos irregulares en el suero de la mujer usando panel celular comercial fue negativo; pero la prueba antiglobulínica indirecta enfrentando los globulos rojos del marido con el suero de la esposa fue fuertemente positiva. El anticuerpo se identificó como anti-Di¬. De los tres hijos, el primero fue normal, pero el segundo presentó ictericia y prueba antiglobulínica directa positiva, por lo que fue necesario realizar una exanguinotransfusión, transfusiones de hematíes y luminoterapia. La ictericia fue causada por el anti-Di¬ materno inducido por el primer embarazo. El tercer neonato fue antígeno Di¬ negativo. (AU)