Association between polymorphisms of the VKORC1 and CYP2C9 genes and warfarin maintenance dose in Peruvian patients.

AIMS: The aim of this study was to investigate the association between VKORC1 and CYP2C9 genes polymorphisms and the maintenance dose of warfarin in Peruvian patients. METHODS: An observational study was conducted on outpatients from the Hospital Grau ESSALUD in Lima, Peru. The participants were selected using nonprobabilistic convenience sampling. Inclusion criteria required patients to have been on anticoagulation therapy for >3 months, maintain stable doses of warfarin (consistent dose for at least 3 outpatient visits), and maintain an international normalized ratio within the therapeutic range of 2.5-3.5. DNA samples were obtained from peripheral blood for gene analysis. RESULTS: Seventy patients (mean age of 69.6 ± 13.4 years, 45.7% female) were included in the study. The average weekly warfarin dose was 31.6 ± 15.2 mg. The genotypic frequencies of VKORC1 were as follows: 7.1% (95% confidence interval, 2.4-15.9) for AA; 44.3% (32.4-56.7) for GA; and 48.6% (36.4-60.8) for GG. No deviation from the Hardy-Weinberg equilibrium was observed in the variants studied (P = .56). The mean weekly warfarin doses for AA, GA and GG genotypes were 16.5 ± 2.9, 26.5 ± 9.5 and 37.9 ± 17.1 mg, respectively (P < .001). The genotypic frequencies of CYP2C9 were as follows: 82.8% (72.0-90.8) for CC (*1/*1); 4.3% (1.0-12.0) for CT (*1/*2); and 12.9% (6.1-23.0) for TT (*2/*2). We did not find a significant association between the CYP2C9 gene polymorphism and the dose of warfarin. CONCLUSIONS: The AA genotype of the VKORC1 gene was associated with a lower maintenance dose of warfarin in Peruvian patients.

Whole exome sequencing in a sample of Peruvian patients diagnosed with epidermolysis bullosa.

BACKGROUND: Epidermolysis bullosa (EB) is a complex and heterogeneous dermatological disease. Four main types of EB have been described, each of them with distinct characteristics: EB simplex (EBS), dystrophic EB (DEB), junctional EB (JEB) and Kindler EB (KEB). Each main type varies in its manifestations, severity, and genetic abnormality. METHODS: We sought mutations in 19 genes known to cause EB and 10 genes associated with other dermatologic diseases in 35 Peruvian pediatric patients of a rich Amerindian genetic background. Whole exome sequencing and bioinformatics analysis was performed. RESULTS: Thirty-four of 35 families revealed an EB mutation. Dystrophic EB was the most frequently diagnosed type, with 19 (56%) patients, followed by EBS (35%), JEB (6%), and KEB (3%). We found 37 mutations in seven genes; 27 (73%) were missense mutations; 22 (59%) were novel mutations. Five cases changed their initial diagnosis of EBS. Four were reclassified as DEB and one as JEB. Inspection into other non-EB genes revealed a variant, c.7130C>A, in the gene FLGR2, which was present in 31 of the 34 patients (91%). CONCLUSION: We were able to confirm and identify pathological mutations in 34 of 35 patients.

Novel mutation in ENG gene causing Hereditary Hemorrhagic Telangiectasia in a Peruvian family.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare disorder of vascular development. Common manifestations include epistaxis, telangiectasias and arteriovenous malformations (AVMs) in multiple organs. Most patients have deletions or missense mutations in the ENG or ACVRL1 gene respectively, significantly affecting endothelium homeostasis. We analyzed the ENG gene in five members of a Peruvian family affected by HHT. One novel mutation was found in exon four of the ENG gene c.408delA, at aminoacid residue 136. This mutation changes the subsequent reading frame producing an early stop at residue 162, preserving only one fourth of the normal protein of 658 aa. This mutation was found in the four affected members of family.

Mutational profile of KIT and PDGFRA genes in gastrointestinal stromal tumors in Peruvian samples.

INTRODUCTION: Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms usually caused by somatic mutations in the genes KIT (c-kit) or PDGFRA. Mutation characterization has become an important exam for GIST patients because it is useful in predicting the response to the inhibitors of receptor tyrosine kinase (RTK). OBJECTIVES: The aim of this study was to determine the frequency of KIT and PDGFRA mutations in 25 GIST samples collected over two years at two national reference hospitals in Peru. There were 21 samples collected from the Instituto Nacional de Enfermedades Neoplásicas (INEN, national cancer center) and 4 samples collected from Hospital A. Loayza. METHODS AND MATERIALS: In this retrospective study, we performed polymerase chain reaction (PCR) amplification and deoxyribonucleic acid (DNA) sequencing of KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 12 and 18) genes in 20 FFPE (formalin-fixed, paraffin-embedded) and 5 frozen GIST samples. RESULTS: We report 21 mutations, including deletions, duplications, and missense, no mutations in 2 samples, and 2 samples with no useful DNA for further analysis. Eighty-six percent of these mutations were located in exon 11 of KIT, and 14 % were located in exon 18 of PDGFRA. CONCLUSIONS: Our study identified mutations in 21 out of 25 GIST samples from 2 referential national hospitals in Peru, and the mutation proportion follows a global tendency observed from previous studies (i.e., the majority of samples presented KIT mutations followed by a minor percentage of PDGFRA mutations). This study presents the first mutation data of the KIT and PDGFRA genes from Peruvian individuals with GIST.

Promoter hypermethylation of RARB and GSTP1 genes in plasma cell-free DNA as breast cancer biomarkers in Peruvian women.

BACKGROUND: Promoter hypermethylation is one of the enabling mechanisms of hallmarks of cancer. Tumor suppressor genes like RARB and GSTP1 have been reported as hypermethylated in breast cancer tumors compared with normal tissues in several populations. This case-control study aimed to determine the association between the promoter methylation ratio (PMR) of RARB and GSTP1 genes (separately and as a group) with breast cancer and its clinical-pathological variables in Peruvian patients, using a liquid biopsy approach. METHODS: A total of 58 breast cancer patients and 58 healthy controls, matched by age, participated in the study. We exacted cell-free DNA (cfDNA) from blood plasma and converted it by bisulfite salts. Methylight PCR was performed to obtain the PMR value of the studied genes. We determined the association between PMR and breast cancer, in addition to other clinicopathological variables. The sensitivity and specificity of the PMR of these genes were obtained. RESULTS: A significant association was not found between breast cancer and the RARB PMR (OR = 1.90; 95% CI [0.62-6.18]; p = 0.210) or the GSTP1 PMR (OR = 6.57; 95% CI [0.75-307.66]; p = 0.114). The combination of the RARB + GSTP1 PMR was associated with breast cancer (OR = 2.81; 95% CI [1.02-8.22]; p = 0.026), controls under 50 years old (p = 0.048), patients older than 50 (p = 0.007), and postmenopausal (p = 0.034). The PMR of both genes showed a specificity of 86.21% and a sensitivity of 31.03%. CONCLUSION: Promoter hypermethylation of RARB + GSTP1 genes is associated with breast cancer, older age, and postmenopausal Peruvian patients. The methylated promoter of the RARB + GSTP1 genes needs further validation to be used as a biomarker for liquid biopsy and as a recommendation criterion for additional tests in asymptomatic women younger than 50 years.

Novel and known MYOC exon 3 mutations in an admixed Peruvian primary open-angle glaucoma population.

PURPOSE: The aim of this study was to characterize a representative sample of the Peruvian population suffering open-angle glaucoma (OAG) with respect to the myocilin gene (MYOC) mutations, glaucoma phenotype, and ancestry for future glaucoma risk assessment. METHODS: DNA samples from 414 unrelated Peruvian subjects, including 205 open-angle glaucoma cases (10 juvenile glaucoma [JOAG], 19 normal-tension glaucoma [NTG], and 176 POAG) and 209 randomly sampled controls, were screened for nucleotide changes in MYOC exon 3 by conformational sensitive gel electrophoresis (CSGE) and mutation screening. RESULTS: We identified a probable causative novel MYOC missense mutation, Gly326Ser, in one POAG case and found a consistent genotype-phenotype correlation in eight of his relatives. We also found the known causative MYOC mutation Trp286Arg in one JOAG case and one POAG case. A known causative single base MYOC deletion, T1357, was found in one POAG case. Two previously reported silent polymorphisms, Thr325Thr and Tyr347Tyr, were found in both the case and the control populations. A novel missense variant, Met476Arg, was identified in two unrelated controls. CONCLUSIONS: The screening of exon 3 of MYOC in a representative sample of 205 independent POAG patients from Peru and 209 matched controls identified novel and previously reported mutations (both pathogenic and nonpathogenic) from other global regions. These results reflect the complex admixture of Amerindian and Old World ancestry in urban populations of Latin America, in general, and in Peru, in particular. It will be important to gather information about the ancestral origin of MYOC and other POAG gene mutations to develop screening panels and risk assessment for POAG in Peru.

[Molecular and genetic features of gastrointestinal stromal tumors (GIST)]. / Características genético-moleculares de los tumores estromales gastrointestinales (GIST).

Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms typically arising in the stomach, small intestine, colon, and other sites in the abdominal cavity and its identification has improved dramatically mainly due to better criteria in its detection. Most GISTs tumors harbor activating mutations in the tyrosine kinase receptor c-KIT or platelet derived growth factor receptor-alpha (PDGFRA). Those mutations are restricted to a few regions corresponding to important functional domains of c-KIT or PDGFRA. Upto 70% of cases are due to mutations in exon 11 of c-KIT corresponding to its juxtamembrane region of the receptor. The location and type of mutation will differentially determine the development of the disease, its prognosis and the response to inhibitors of tyrosine kinases as Imanatib. For this reason, genotyping c-KIT and PDGFRA is important for GIST diagnosis and assessment of sensitivity to tyrosine kinase inhibitors.

MLPA followed by target-NGS to detect mutations in the dystrophin gene of Peruvian patients suspected of DMD/DMB.

BACKGROUND: We report the molecular analysis of the DMD gene in a group of Peruvian patients with Duchenne/Becker dystrophinopathy. This is the first study to thoroughly characterize mutations in this population. METHODS: We used the combination of multiplex ligation-dependent probe amplification (MLPA) and sequencing analysis of the DMD gene. We recruited Peruvian patients in 2 years from reference national hospitals. We performed DNA tests in 152 patients, checking first exon deletion/duplication by MLPA, and subsequently, if negative, samples were sequenced to detect point mutations. RESULTS: The average age for diagnosis was 9.8 years, suggesting a delay for timely diagnosis and care. We found causal DMD mutations in 125 patients: 72 (57.6%) exon deletions/duplications (41.6% deletions, 16.0% duplications), and 53 (42.4%) point mutations (27.2% nonsense, 9.6% small indels, and 5.6% splice site). CONCLUSION: Due to our genetic background, we expected a higher number of novel and recurrent causal mutations in our sample. Results showed 16% of novel mutations, similar to other well-studied populations.

[Detection of mutations causing Duchenne and Becker muscular dystrophies: multiplex polymerase chain reaction vs. Multiplex ligation dependent probe amplification]. / Detección de mutaciones causantes de distrofia muscular de Duchenne/Becker: reacción en cadena de la polimerasa Multiplex vs. Amplificación múltiple dependiente de ligación por sondas.

Duchenne and Becker muscular dystrophies are rare diseases that receive limited attention in our field. The objective of this study was to implement the Multiplex Ligation-dependent Probe Amplification technique (MLPA) and to demonstrate that it has advantages over the Multiplex Polymerase Chain Reaction (Multiplex PCR) technique. Samples from 40 individuals with a presumptive diagnosis of Duchenne and Becker muscular dystrophies were analyzed: first by Multiplex PCR and then by MLPA. Fifteen individuals with causal deletions were detected with Multiplex PCR, while the MLPA technique was able to diagnose 21 individuals, four duplications, and 17 deletions. In conclusion, the MLPA technique can detect mutations of the exon deletion and duplication type, yielding a larger number of molecular diagnoses due to alterations in the DMD gene.

Las distrofias musculares de Duchenne/Becker son enfermedades raras que reciben poca atención en nuestro medio. El objetivo del presente estudio fue implementar la técnica de amplificación múltiple dependiente de ligación por sondas (MLPA) y demostrar que tiene ventajas sobre la técnica de reacción en cadena de la polimerasa multiplex (PCR-multiplex). Se analizaron muestras de 40 individuos con diagnóstico presuntivo de distrofia muscular de Duchenne/Becker, primero por PCR-multiplex y luego por MLPA. Con la PCR-multiplex se detectaron 15 individuos con deleciones causales y con la técnica MLPA se logró diagnosticar a 21 individuos, cuatro duplicaciones y 17 deleciones. En conclusión, la técnica MLPA logra detectar mutaciones de tipo deleción y duplicación de exones, consiguiendo un mayor número de diagnósticos moleculares por alteraciones en el gen DMD.

Recurrent Myocilin Asn480Lys glaucoma causative mutation arises de novo in a family of Andean descent.

PURPOSE: To search for MYOC mutations in Peruvian primary open angle glaucoma (POAG) families. PATIENTS AND METHODS: Two patients from each of the 11 POAG Peruvian families were screened for sequence variants in MYOC coding exons by conformational sensitive gel electrophoresis and sequencing was performed on the samples indicating probable sequence changes. RESULTS: We detected 2 families bearing distortions of conformational sensitive gel electrophoresis indicating mutations. Sequencing of these samples revealed coding sequence changes. A native Andean descent family presented with a MYOC mutation, Asn480Lys (C-->G at nucleotide 1440). This is different from the previously reported C-->A change at nucleotide 1440 that causes Asn480Lys in 2 unrelated French and Dutch families with glaucoma of variable expressivity, and indicates a third independent event. A second family of admixed origin showed the presence of the known Arg76Lys polymorphism. CONCLUSIONS: In the study of MYOC variants in 11 POAG Peruvian families, we have found a family of ethnically admixed origin with polymorphism Arg76Lys and a family of Andean descent bearing a third event of the Asn480Lys, the MYOC mutation that has been reported in the highest number of POAG patients (>80 cases). Analysis of this family could contribute with information about disease manifestation, progression, and treatment response in the context of a distinct genetic background and also climatic, altitude, and socioeconomical conditions.

Variation in optineurin (OPTN) allele frequencies between and within populations.

PURPOSE: To evaluate the extent to which mutations in the optineurin (OPTN) glaucoma gene play a role in glaucoma in different populations. METHODS: Case-controlled study of OPTN sequence variants in individuals with or without glaucoma in populations of different ancestral origins and evaluate previous OPTN reports. We analyzed 314 subjects with African, Asian, Caucasian and Hispanic ancestries included 229 cases of primary open-angle glaucoma, 51 cases of juvenile-onset open-angle glaucoma, 33 cases of normal tension glaucoma, and 371 controls. Polymerase chain reaction-amplified OPTN coding exons were resequenced and case frequencies were compared to frequencies in controls matched for ancestry. RESULTS: The E50K sequence variant was identified in one individual from Chile with normal tension glaucoma, and the 691_692insAG variant was found in one Ashkenazi Jewish individual from Russia. The R545Q variant was found in two Asian individuals with primary open-angle glaucoma; one of Filipino ancestry and one of Korean ancestry. In addition to presenting OPTN allele frequencies for Caucasian and Asian populations that have been the subject of previous reports, we also present information for populations of Hispanic and black African ancestries. CONCLUSIONS: Our study contributes additional evidence to support the previously reported association of the OPTN E50K mutation with glaucoma. After finding an additional 691_692insAG OPTN variant, we can still only conclude that this variant is rare. Combined analysis of our data with data from more than a dozen other studies indicates no association of R545Q with glaucoma in most populations. Those same studies disagree in their conclusions regarding the role of M98K in glaucoma. Our analysis of the combined data provides statistically significant evidence of association of M98K with normal tension glaucoma in Asian populations, but not in Caucasian populations; however, the validity of this conclusion is questionable because of large differences in allele frequencies between and within populations. It is currently not possible to tell how much of the underlying cause of the allele frequency difference is attributable to demographic, technical, or ascertainment differences among the studies.

Mutational analysis of BRCA1 and BRCA2 genes in Peruvian families with hereditary breast and ovarian cancer.

BACKGROUND: Breast cancer is one of the most prevalent malignancies in the world. In Peru, breast cancer is the second cause of death among women. Five to ten percent of patients present a high genetic predisposition due to BRCA1 and BRCA2 germline mutations. METHODS: We performed a comprehensive analysis of BRCA1 and BRCA2 genes by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) to detect large rearrangements in patients from 18 families, which met the criteria for hereditary breast cancer. RESULTS: In this series, we found four pathogenic mutations, three previously reported (BRCA1: c.302-1G>C and c.815_824dup10; BRCA2: c.5946delT) and a duplication of adenines in exon 15 in BRCA1 gene (c.4647_4648dupAA, ClinVar SCV000256598.1). We also found two exonic and four intronic variants of unknown significance and 28 polymorphic variants. CONCLUSION: This is the first report to determine the spectrum of mutations in the BRCA1/BRCA2 genes in Peruvian families selected by clinical and genetic criteria. The alteration rate in BRCA1/BRCA2 with proven pathogenic mutation was 22.2% (4 out 18) and this finding could be influenced by the reduced sample size or clinical criteria. In addition, we found three known BRCA1/BRCA2 mutations and a BRCA1 c.4647_4648dupAA as a novel pathogenic mutation.

Genetic counseling to a DMD asymptomatic carrier: First case report in the Peruvian public healthcare system / Asesoramiento genético a una portadora asintomática de DMD: Primer caso reportado en el Sistema de Salud Pública del Perú

SUMMARY Duchenne muscular dystrophy (DMD) is a rapidly progressive dystrophinopathy with X-linked inheritance. This report describes a woman with a family history of male relatives affected by DMD, as she sought out genetic counseling about her concerns related to family planning and risks of eventually having children with the disease. We proposed her to get involved in a pilot program for carrier-status diagnosis and genetic counseling. This case illustrates the importance of a genetic counseling program for diagnosis of asymptomatic carriers in neurogenetic diseases, particularly in regions with low-resource settings. We discussed successes and misunderstandings faced throughout the process, supporting policies for present and future challenges from this and similar kinds of diagnoses.

RESUMEN La distrofia muscular de Duchenne (DMD) es una distrofinopatía rápidamente progresiva con herencia ligada al cromosoma X. Este reporte describe el caso de una mujer con historia familiar de hermano y sobrinos con DMD, que acudió a consulta para orientación e información sobre riesgos inherentes a una eventual planificación familiar. Le propusimos participar en un programa piloto de asesoramiento genético para determinar su estado de portador o no de la variante causal de DMD en la familia. Esta primera experiencia ilustra la importancia de tener un programa de asesoramiento genético para el diagnóstico de portadores asintomáticos de enfermedades neurogenéticas en regiones con bajos recursos. Se incluyen reflexiones y comentarios sobre aspectos positivos y retos presentados durante el proceso, las políticas de apoyo presente y futuro para el afronte de los complejos problemas planteados por éste y similares diagnósticos.

Detección de mutaciones causantes de distrofia muscular de Duchenne/Becker: reacción en cadena de la polimerasa Multiplex vs. Amplificación múltiple dependiente de ligación por sondas / Detection of mutations causing Duchenne and Becker muscular dystrophies: multiplex polymerase chain reaction vs. Multiplex ligation dependent probe amplification

RESUMEN Las distrofias musculares de Duchenne/Becker son enfermedades raras que reciben poca atención en nuestro medio. El objetivo del presente estudio fue implementar la técnica de amplificación múltiple dependiente de ligación por sondas (MLPA) y demostrar que tiene ventajas sobre la técnica de reacción en cadena de la polimerasa multiplex (PCR-multiplex). Se analizaron muestras de 40 individuos con diagnóstico presuntivo de distrofia muscular de Duchenne/Becker, primero por PCR-multiplex y luego por MLPA. Con la PCR-multiplex se detectaron 15 individuos con deleciones causales y con la técnica MLPA se logró diagnosticar a 21 individuos, cuatro duplicaciones y 17 deleciones. En conclusión, la técnica MLPA logra detectar mutaciones de tipo deleción y duplicación de exones, consiguiendo un mayor número de diagnósticos moleculares por alteraciones en el gen DMD.

ABSTRACT Duchenne and Becker muscular dystrophies are rare diseases that receive limited attention in our field. The objective of this study was to implement the Multiplex Ligation-dependent Probe Amplification technique (MLPA) and to demonstrate that it has advantages over the Multiplex Polymerase Chain Reaction (Multiplex PCR) technique. Samples from 40 individuals with a presumptive diagnosis of Duchenne and Becker muscular dystrophies were analyzed: first by Multiplex PCR and then by MLPA. Fifteen individuals with causal deletions were detected with Multiplex PCR, while the MLPA technique was able to diagnose 21 individuals, four duplications, and 17 deletions. In conclusion, the MLPA technique can detect mutations of the exon deletion and duplication type, yielding a larger number of molecular diagnoses due to alterations in the DMD gene.

Three novel polymorphic microsatellite markers for the glaucoma locus GLC1B by datamining tetranucleotide repeats on chromosome 2p12-q12.

In order to identify new markers around the glaucoma locus GLC1B as a tool to refine its critical region at 2p11.2-2q11.2, we searched the critical region sequence obtained from the UCSC database for tetranucleotide (GATA)n and (GTCT)n repeats of at least 10 units in length. Three out of four potential microsatellite loci were found to be polymorphic, heterozygosity ranging from 64.56% to 79.59%. The identified markers are useful not only for GLC1B locus but also for the study of other disease loci at 2p11.2-2q11.2, a region with scarcity of microsatellite markers.

Identificación de una deleción causante de tumor del estroma gastrointestinal (Gist) por el análisis de los genes KIT y PDGFRA / Identification of a causative deletion of gastrointestinal stromal tumor (gist) by the analysis of the KIT and PDGFRA genes

Optimizar la detección de mutaciones en los genes KIT y PDGFRA en una muestra de tumor del estroma gastrointestinal (GIST). Material y Métodos: Se analizó una muestra de tumor GIST fijada y embebida en parafina. Mediante la técnica de reacción en cadena de la polimerasa (PCR) se amplificaron los exones 9, 11, 13 y 17 del gen KIT y los exones 12 y 18 del gen PDGFR que contienen las mutaciones causales de GIST. Se confirmó la amplificación mediante electroforesis en gel de agarosa al 2%. Los fragmentos amplificados, fueron purificados y secuenciados en un analizador genético. Se detectó una sobreposición de bases propio de una deleción por lo que se tuvo que clonar los productos del exón 11 para identificar el alelo mutado. Resultados: Se determinó la presencia de una mutación patogénica en el exón 11 del gen KIT. Dicha mutación es una deleción de 15 pares de bases que genera la pérdida de 5 aminoácidos en el receptor tirosina kinasa KIT. Se encontraron polimorfismos neutrales en los exones 11 del gen KIT y en el exón 18 del gen PDGFRA. Conclusión: El análisis molecular mediante secuenciación automática, permitió identificar una mutación en el gen KIT en una muestra de tumor GIST. Esta técnica puede ser aplicada para caracterizar las mutaciones genéticas de casos peruanos de GIST y así poder establecer un tratamiento adecuado según su perfil mutacional...

Objective: To optimize the detection of mutations in the genes KIT and PDGFRA in a sample of gastrointestinal stromal tumor (GIST). Material and Methods: We analyzed a GIST tumor sample fixed and embedded in paraffin. Using the technique of the polymerase chain reaction (PCR) we amplified exons 9, 11, 13 and 17 of the KIT gene and exons 12 and 18 PDGFR gene which contain tha causal mutations of GIST. PCR amplification was confirmed by gel electrophoresis on 2% agarose. The amplified fragments were purified and cloned for subsequent sequencing. An overlap of baeses, characteristic of a deletion was detected, so we had to clone the exon 11 products to identify mutated allele. Results: We determined the presence of a pathogenic mutation in exon 11 of KIT gene. The mutation is a deletion of 15 base pairs and generates a loss of 5 amino acids in the KIT receptor tyrosine kinase. Neutral polymorphisms were also found in exon 11 of KIT gene and exon 18 of PDGFRA gene. Conclusion: Molecular analysis by automatic sequencing identified a mutation in the KIT gene in a tumor sample GIST. This technique can be applied to characterize genetic mutations Peruvian cases of GIST and thus establish adequate treatment by mutational profile...

Estudio genotóxico de una bebida experimental de quinua, kiwicha y kañiwa / Genotoxic study of an experimental drink of quinoa, kiwicha and kañiwa

La evaluación genotóxica de un producto es un paso importante para determinar su viabilidad para consumo humano. Se ha elaborado una bebida experimental a base de pseudocereales de alto valor nutricional como son quinua (Chenopodium quinoa Willd.), kiwicha (Amaranthus caudatus L.) y kañiwa (Chenopodium pallidicaule Aellen), preparada para inducir un posible efecto hipolipemiante en un grupo de personas. El objetivo de este estudio fue evaluar el potencial genotóxico de esta bebida experimental mediante dos pruebas in vitro validadas por agencias internacionales. En la prueba de Ames se utilizaron las cepas TA98 y TA10 de Salmonella typhimurium, con y sin fracción microsomal (S9). Se evaluaron 4 dosis de bebida y además un posible efecto antimutagénico (mismas 4 dosis más mutágeno). Para la prueba de micronúcleos se usó cultivos de linfocitos con células binucleadas, en presencia de cinco dosis de la bebida. Ambas pruebas indican que la bebida estudiada en sus distintas dosis, no presenta efecto genotóxico. Sin embargo, en la evaluación del posible efecto protector de la bebida, se evidenciaría que por el contrario, se potencia el efecto mutagénico de los mutágenos empleados para cada cepa. Por lo tanto, es importante que esta bebida experimental sea sometida a pruebas adicionales in vitro e in vivo para evaluar el potencial genotóxico antes de su consumo.

Características genético-moleculares de los tumores estromales gastrointestinales (GIST) / Molecular and genetic features of gastrointestinal stromal tumors (GIST)

Los tumores estromales gastrointestinales (GIST) son neoplasias mesenquimales que típicamente surgen a nivel del estómago, intestino delgado, colon, y otros sitios en la cavidad abdominal y su identificación se ha incrementado por mejoras en los criterios de detección. La mayor parte de los tumores GIST son causados por mutaciones activadoras en los genes de receptores transmembranares tirosina quinasa c-KIT y receptor alpha del factor de crecimiento derivado de plaquetas (PDGFRA). Las mutaciones causales de GIST se restringen solo a ciertas regiones del gen que corresponden a importantes zonas funcionales de c-KIT o PDGFRA. Se reporta que hasta 70% de casos de GIST se debe a mutaciones en el exón 11 del gen c-Kit que corresponde a la región yuxtamembrana del receptor. La región y el tipo de mutación determinan diferencialmente cómo se desarrolla la neoplasia, el pronóstico y su respuesta a inhibidores de las tirosina quinasas como el Imanatib. Por tal motivo, el genotipado de KIT y PDGFRA es importante para el diagnóstico y establecimiento de la sensibilidad a los inhibidores tirosina quinasa.

Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms typically arising in the stomach, small intestine, colon, and other sites in the abdominal cavity and its identification has improved dramatically mainly due to better criteria in its detection. Most GISTs tumors harbor activating mutations in the tyrosine kinase receptor c-KIT or platelet derived growth factor receptor-alpha (PDGFRA). Those mutations are restricted to a few regions corresponding to important functional domains of c-KIT or PDGFRA. Upto 70% of cases are due to mutations in exon 11 of c-KIT corresponding to its juxtamembrane region of the receptor. The location and type of mutation will differentially determine the development of the disease, its prognosis and the response to inhibitors of tyrosine kinases as Imanatib. For this reason, genotyping c-KIT and PDGFRA is important for GIST diagnosis and assessment of sensitivity to tyrosine kinase inhibitors.

Implementación de la Prueba del Multiplex PCR para el Gen DMD en Pacientes con sospecha de Distrofia Muscular de Duchenne/Becker y la identificación de una deleción de los exones 48-51 / Establishment of the multiplex PCR test for the DMD gene in patients with suspicion of Duchenne/Becker muscular dystrophy and the identification of a deletion of exons 48-51

OBJETIVO: Estandarizar la prueba del Multiplex PCR para identificar las deleciones más frecuentes que incluye nueve exones: 45, 48, 19, 17, 51, 8, 12, 44 y 4 del gen DMD cuyas mutaciones producen las distrofias musculares de Duchenne y de Becker. MATERIAL Y MÉTODO: La prueba fue realizada con 9 individuos, usando DNA obtenido de sangre periférica. De ellos, incluyendo 2 hermanos, tenían diagnóstico clínico de distrofia muscular compatible con DMD. Nueve pares de primers de los exones mencionados se usaron simultáneamente en una amplificación PCR y analizados por geles de agarosa y acrilamida. Uno de los pacientes (DMD-1) tenía diagnóstico molecular de deleción del exón 45 (control positivo) y 5 controles sanos (controles negativos). RESULTADOS: Los controles normales mostraron segmentos normales del tamaño esperado de los 9 exones luego de la amplificación PCR. El paciente DMD-1, evidenció la deleción del exón 45 (control positivo). Uno de los pacientes (DMD-3) presentó una nueva deleción que incluyó los exones 48 a 51, el resultado fue replicado en su hermano (también afectado con DMD). CONCLUSIONES: Se optimizó la prueba de Multiplex-PCR del gen DMD. Esto nos permite contar con una prueba para discernir gran número de pacientes con distrofia y determinar si tienen DMD/DMB. Uno de los pacientes mostró una mutación consistente en la deleción de los exones 48 a 51 que fué corroborada en su hermano afectado con distrofia.

OBJETIVE: To establish the Multiplex PCR test to identify the most frequent mutations caused by deletions that include DMD gene exons 45, 48, 19, 17, 51, 8, 12, 44 and 4 causing Duchenne and Becker dystrophies (DMD/BMD). MATERIALS AND METHOD: The test was performed in DNA obtained from peripheral blood of 9 individuals, four of them (including 2 brothers) patients clinically diagnosed with muscular dystrophies compatible DMD. Nine pair of primers corresponding to the above mentioned exons were used simultaneously for PCR amplification and analyzed in agarose and polyacrilamide gel electrophoresis. One of the patients (DMD-1) used as positive control, had a previous molecular diagnosis with a deletion of exon 45. RESULTS: Normal controls showed the expected size for the 9 segments amplified by PCR. The study of the sample of patient DMD- 1 with previous molecular diagnosis corroborated the lack of the band corresponding to exon 45. One of the patients (DMD-3) evidenced a new deletion spanning exons 48 to 51, that mutation was also replicated in his dystrophic brother. CONCLUSIONS: We have established the Multiplex-PCR test for the DMD gene. This will enable us to have a system for the serial screening of patients suspected of Duchenne or Becker muscular dystrophy. One of the patients showed a deletion comprising exons 48 to 51, mutation corroborated in his afflicted dystrophic brother.

Three novel polymorphic microsatellite markers for the glaucoma locus GLC1B by datamining tetranucleotide repeats on chromosome 2p12-q12

In order to identify new markers around the glaucoma locus GLC1B as a tool to refine its critical region at 2p11.2-2q11.2, we searched the critical region sequence obtained from the UCSC database for tetranucleotide (GATA)n and (GTCT)n repeats of at least 10 units in length. Three out of four potential microsatellite loci were found to be polymorphic, heterozygosity ranging from 64.56 percent to 79.59 percent. The identified markers are useful not only for GLC1B locus but also for the study of other disease loci at 2p11.2-2q11.2, a region with scarcity of microsatellite markers.