Research, diagnosis and education in inborn errors of metabolism in Colombia: 20 years' experience from a reference center.

The use of specialized centers has been the main alternative for an appropriate diagnosis, management and follow up of patients affected by inborn errors of metabolism (IEM). These centers facilitate the training of different professionals, as well as the research at basic, translational and clinical levels. Nevertheless, few reports have described the experience of these centers and their local and/or global impact in the study of IEM. In this paper, we describe the experience of a Colombian reference center for the research, diagnosis, training and education on IEM. During the last 20 years, important advances have been achieved in the clinical knowledge of these disorders, as well as in the local availability of several diagnosis tests. Organic acidurias have been the most frequently detected diseases, followed by aminoacidopathies and peroxisomal disorders. Research efforts have been focused in the production of recombinant proteins in microorganisms towards the development of new enzyme replacement therapies, the design of gene therapy vectors and the use of bioinformatics tools for the understanding of IEM. In addition, this center has participated in the education and training of a large number professionals at different levels, which has contributed to increase the knowledge and divulgation of these disorders along the country. Noteworthy, in close collaboration with patient advocacy groups, we have participated in the discussion and construction of initiatives for the inclusion of diagnosis tests and treatments in the health system.

Understanding the Metabolic Consequences of Human Arylsulfatase A Deficiency through a Computational Systems Biology Study.

The nervous system is responsible for the communication between the organism and its environment. This task is possible by the presence of the myelin sheath, which is a double membrane formed by about 75% lipids and 25% proteins. The sulfatide represents one of the main lipids of the myelin band; its degradation is catabolized by the enzyme Arylsulfatase A (ARSA), to generated galactosylceramide. Mutations affecting ARSA function lead to the neurodegenerative disease Metachromatic Leukodystrophy. This disease is characterized by accumulation of sulfatide within the band of myelin affecting its functionality. The biochemical consequences of ARSA deficiency are not well understood yet. In this paper, we used an in-silico systems-biology approach to model the biochemical consequences of ARSA deficiency within a general human metabolic network (Recon2) and a glia cellular model. We expected that ARSA deficiency mainly affected the glycosphingolipid pathways. However, the results suggest that mitochondrial metabolism and amino acid transport were the main reactions affected within both cellular models. In the glia cell model, it was highlighted the high number of affected reactions of neurotransmitters metabolism, while only a reduced effect was observed in reactions involved in glycosphingolipids metabolism. We hypothesize that ARSA deficiency might lead to metabolic consequences that not only compromise the myelin band or the glycosphingolipids metabolism but also the overall metabolic function of the nervous system. Furthermore, these results offer the bases for the design of in-vitro and in-vivo experiments that allow generating new knowledge of MLD pathophysiology and other neurodegenerative diseases.

Effect of elongation factor 1alpha promoter and SUMF1 over in vitro expression of N-acetylgalactosamine-6-sulfate sulfatase.

Morquio A is an autosomal recessive disease caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS), leading to the lysosomal accumulation of keratan-sulfate and chondroitin-6-sulfate. We evaluated in HEK293 cells the effect of the cytomegalovirus immediate early enhancer/promoter (CMV) or the elongation factor 1alpha (EF1alpha) promoters, and the coexpression with the sulfatase modifying factor 1 (SUMF1) on GALNS activity. Four days postransfection GALNS activity in transfected cells with CMV-pIRES-GALNS reached a plateau, whereas in cells transfected with EF1alpha-pIRES-GALNS continued to increase until day 8. Co-transfection with pCXN-SUMF1 showed an increment up to 2.6-fold in GALNS activity. Finally, computational analysis of transcription factor binding-sites and CpG islands showed that EF1alpha promoter has long CpG islands and high-density binding-sites for Sp1 compared to CMV. These results show the advantage of the SUMF1 coexpression on GALNS activity and indicate a considerable effect on the expression stability using EF1alpha promoter compared to CMV.