Introducción: el término secuenciación de nueva generación (NGS) hace referencia a las tecnologías diseñadas para analizar gran cantidad de ADN de forma masiva y paralela. Abordamos en esta revisión los conceptos básicos de estas tecnologías, las consideraciones de su uso clínico actual y perspectivas a futuro. Desarrollo: las pruebas basadas en NGS han revolucionado el estudio de los genomas pues permiten la lectura de millones de secuencias de ADN de forma masiva y paralela en un menor lapso de tiempo y a menor costo por base. Estas pruebas incluyen la secuenciación de panel de genes, la secuenciación completa del exoma y la secuenciación completa del genoma. El análisis de sus resultados es complejo y requiere de un proceso bioinformático y clínico exhaustivo para su adecuada interpretación. Las limitaciones de las pruebas NGS incluyen aspectos técnicos como la cobertura, profundidad y longitud de las secuencias, las cuales se pueden solventar implementando buenas prácticas de laboratorio. Conclusiones: las pruebas basadas en la secuenciación por NGS son herramientas diagnósticas que deben partir de una aproximación clínica adecuada para su uso razonado, correcta interpretación y toma de decisiones acertadas. Es de gran trascendencia que los médicos tengan la información básica para poder solicitar e interpretar estas pruebas dada su relevancia clínica actual.

Estimación de las frecuencias de las mucopolisacaridosis y análisis de agrupamiento espacial en los departamentos de Cundinamarca y Boyacá

Mucopolysaccharidoses are a group of infrequent disorders caused by the lysosomal deposit of glycosaminoglycans. Its incidence is quite variable among the countries where it has been documented. In Brazil, disorder frequencies have been reported, but in Colombia information on them is scarce. The frequency and spatial aggregations of the mucopolysaccharidoses were estimated by a retrospective study in two central Colombian provinces. The records of patients and live newborns between 1998-2007 were reviewed from several reference institutions for genetic diseases. From these records, the frequencies for each mucopolysaccharidosis were estimated. The spatial aggregation of the cases was analyzed using the SaTScan software. The combined frequency for all the mucopolysaccharidoses was 1.98 cases per 100,000 live newborns. MPS IV had the highest frequency with 0.68 cases per 100,000 live newborns and MPS III showed a lower frequency of 0.17/100,000. Three spatial aggregation areas were indicated for MPS I, MPS III and MPS IV. The combined frequency for all the mucopolysaccharidoses has been reported, with type IV the most frequent and the type VII in second place. The data herein constitute a record subset and, in spite of the difficulties inherent to the data retrieval in Colombia, they are a valid estimate of the frequencies of these diseases in central Colombia.

Down syndrome is the most frequent aneuploidy in live births, with an overall frequency of 1/600-700 births. The overexpression of cystathionine β-synthase is thought to participate in the presentation of some phenotypes observed in Down syndrome. OBJECTIVE: The aim of this study was to compare the expression levels of cystathionine β-synthase and histopathological observations from placentas of infants with Down syndrome and healthy newborns. MATERIALS AND METHODS: Six placentas of fetuses/infants with Down syndrome and sixteen placentas of healthy fetuses were studied. Cystathionine β-synthase mRNA and protein expression were performed by real-time PCR and immunohistochemistry, respectively. RESULTS: We observed an increase in cystathionine β-synthase mRNA expression ( p = 0.0465) and protein levels ( p = 0.009) in placentas of fetus/infants with Down syndrome compared with controls. Significantly more circinate edges ( p = 0.0007) and trophoblast inclusions ( p = 0.0037) were observed in the group with Down syndrome compared with control group. CONCLUSION: The results demonstrate overexpression of cystathionine β-synthase mRNA and protein in placentas of fetuses/infants with trisomy 21. Further histological abnormalities were found in placentas of patients with Down syndrome, suggesting an alteration in the development of placenta.

INTRODUCTION: Preeclampsia has a global frequency of 2–8% and a frequency of 10% in developing countries. In Colombia, preeclampsia causes 42% of maternal mortality. Alterations in placental homeostasis have been proposed to be involved in its pathophysiology. The aim of this study was to compare mRNA and protein levels of tissue factor (F3) and thrombomodulin (THBD) and the histopathological findings of placentas. MATERIALS AND METHODS: We studied 16 placentas from patients with preeclampsia and 19 term placentas with uncomplicated pregnancy. An expert pathologist, who was masked to the group assignment, conducted an evaluation to determine specific histological changes. Assessments of mRNA and protein levels of F3 and THBD were performed using real-time PCR and ELISA, respectively. RESULTS: Cases and controls differed in the frequency of decidual arteriopathy ( p = 0.027), acute infarction ( p = 0.001) and hyperplasia of the syncytiotrophoblast ( p = 0.0017). Cases had increased levels of F3 mRNA ( p = 0.0124) and protein ( p < 0.0001) and THBD mRNA ( p < 0.0001) and protein ( p < 0.0001). CONCLUSION: In placenta of patients with preeclampsia, we detected abnormal expression of F3 and THBD with increased protein and mRNA levels. The role of these molecules in the pathogenesis of this disease and in alterations of hemostatic and histopathological aspects of placentas need further studying.

Maroteaux-Lamy syndrome, or mucopolysaccharidosis (MPS) type VI, is an autosomal recessive lysosomal storage disease caused by a deficient activity of the enzyme arylsulfatase B (ARSB), required to degrade dermatan sulfate. The onset and progression of the disease vary, producing a spectrum of clinical presentation. So far, 133 mutations have been reported. The aim of this study is to determine the mutations in the ARSB gene that are responsible for this disease in Colombian patients. Fourteen patients with clinical manifestations and biochemical diagnosis of MPS VI were studied, including two siblings. The 8 exons of the gene were directly sequenced from patients' DNA, and 14 mutations were found. 57% of these mutations had not been previously reported (p.H111P, p.C121R, p.G446S, p.*534W, p.S334I, p.H147P, c.900T > G, and c.1531_1553del) and 43% had been previously reported (p.G144R, p.W322*, p.G302R, p.C447F, p.L128del, and c.1143-1G > C). Of the previously reported mutations, 80% have been associated with severe phenotypes and 20% with intermediate-severe phenotypes. Bioinformatic predictions indicate that the new mutations reported in this paper are also highly deleterious. Most of the Colombian patients in this study had private mutations.