Diagnóstico molecular de enfermedades genéticas: del diagnóstico genético al diagnóstico genómico con la secuenciación masiva / Molecular diagnosis of genetic diseases: from genetic to genomic diagnosis using next generation sequencing

En la actualidad se conocen 8.000 enfermedades genéticas monogénicas. La mayoría de ellas son heterogéneas, por lo que el diagnóstico molecular por técnicas convencionales de secuenciación suele ser largo y costoso debido al gran número de genes implicados. El tiempo estimado para el diagnóstico molecular se encuentra entre 1 y 10 años, y este retraso impide que los pacientes reciban medidas terapéuticas y de rehabilitación específicas, que sus familiares entren en programas preventivos y que reciban asesoramiento genético. La secuenciación masiva está cambiando el modelo de diagnóstico molecular de los afectos, sin embargo, los médicos y profesionales de la salud se enfrentan al dilema de la selección del método más eficiente, con el menor coste sanitario y con la mayor precisión de sus resultados. El objetivo de este trabajo es revisar la tecnología de secuenciación masiva y definir las ventajas y los problemas en su utilización.

Currently 8000 monogenic genetic diseases are known. Most of them are heterogeneous, so their molecular diagnosis by conventional sequencing techniques is labour intensive and time consuming due to the large number of genes involved. The estimated time is between 1 and 10 years for molecular diagnosis and this delay prevents patients from receiving therapy and rehabilitation measures, and their families from entering prevention programs and being given genetic counselling. Next generation sequencing (NGS) is changing the model of molecular diagnosis of patients; however, doctors and health professionals are faced with the dilemma of choosing the most efficient method, with lower health care costs and the most accurate results. The aim of this paper is to review the NGS technology and define the advantages and problems in the use of this technology.

Studies on chemical structure of polysaccharide Ⅰ obtained from Paecilomyces tenuipes / 中草药

Object To study the isolation and purification of a polysaccharide, obtained from Paecilomyces tenuipes Samson, its molecular weight, sugar composition, and mode of linkage Methods Crude polysaccharide was extracted by water at ambient temperature and purified on Sephadex G 100 column Its monosaccharide composition was determined by ionic ion exchange column after complete hydrolysis with acid Their mode of linkage was determined by methylation and glycosidic linkage established by IR and NMR spectra Results HPLC spectrum showed that the polysaccharide was of homogeneous composition, which was also proved latter by GC MS and NMR Conclusion Polysaccharide obtained from P tenuipes Samson is ? (1→6) linked and composed of only D glucose The molecular weight was 2 05?10 4

Studies on structural features of two neutral heteropolysaccharides from Cuscuta chinensis / 中草药

Object Polysaccharide constituents in the seed of Cuscuta chinensis Lam were investigated Methods Individual constituent was isolated and purified by DEAE cellulose and gel filtration chromatography, and its structural features were further studied by physicochemical constants, and spectral analysis Results Two polysaccharides, named H6 and H8, were obtained from alkalescent or boiling water extract fractions, respectively The molecular mass of H6 was 3 14?10 5 and that of H8 was more than 1 0?10 6 Both structures were found to be complex neutral heteropolysaccharides composed of Ara, Rha, Gal and Xyl Conclusion These polysaccharides were obtained from this plant for the first time

Glycoprotein I_(1-2-1) from Irpex lacteus / 中草药

Objective To study the chemical structure of a pure glycoprotein I_(1-2-1) from Irpex lacteus.Methods Based on chemical and spectral analysis,the structural characterization of I_(1-2-1) was investigated.Results I_(1-2-1) was composed of Ara,Xyl,Man,Gal,and Glu with its mean molecular weight of(40 000.) Methylation analysis showed that the main chain of I_(1-2-1)was all 1→2,1→6 linked Manp.Conclusion I_(1-2-1) is a complicated glycoprotein obtained for the first time from I.lacteus.

Intra- and inter-generic homology in polysaccharide structure of Rhizobium and Alcaligenes.

A study was conducted on the structure of extracellular, water-soluble polysaccharides from 5 different strains of Rhizobium viz. R. trifolii J60 and R. meliloti strains J7017, 202, 204 and 207. All these polysaccharides were found to contain glucose and galactose in the approximate molar ratio of 7:1. Methylation analysis revealed these polysaccharides to contain (1 → 3), (1 → 6), (1 → 4), (1 → 4, 1 → 6)-linked D-glucose residues, (1 → 3)-linked D-galactose and nonreducing terminal D-glucose attached to pyruvate. These polysaccharides were also found to be acylated by both acetyl and succinyl residue. This structure was found to be similar to that of succinoglycan, a succinic acid-containing water-soluble, extra-cellular polysaccharide elaborated by Alcaligenes faecalis var. myxogenes 10C3. This similarity in structure of polysaccharides from two different species of Rhizobium and also the polysaccharide produced by Alcaligenes has been discussed.