• Available evidence on the diagnosis and treatment of MPS and oligosaccharidosis is limited. Furthermore, the studies included in this review were very heterogeneous, thus rendering comparison difficult and preventing definitive and categorical conclusions from being drawn on the various aspects evaluated. No information was obtained on the possible existence of population screening programmes that include these disorders.
• Laboratory diagnoses most frequently used were: determination of urinary excretion of glycosaminoglycans; and blood or plasma assay of enzymatic activity of deficient enzyme. Diagnostic techniques were very varied, with tandem mass spectrometry registering sensitivities and specificities of close on 100% in some forms of MPS.
• Insofar as treatment was concerned, the different types of transplantation used (bone marrow, cord-blood and peripheral-blood stem cells) yielded results of varying effectiveness.
• The recent appearance of enzyme replacement therapy (alphaiduronidase, idursulfase and N-acetylgalactosamine 4-sulfatase) is serving to change the panorama of these diseases. Promising results have been obtained in terms of safely stabilising many clinical signs and symptoms, and it is argued that treatment in the early stages –namely, before skeletal or cardiac changes have taken place- could lead to better outcomes being obtained. Yet more data are needed to establish whether treatment with enzyme replacement therapy reduces transplantation-related morbidity and mortality.
• In conclusion, the lack of quality studies which thoroughly analyse the different aspects of neonatal mucopolysaccharidosis and oligosaccharidosis screening means that their inclusion in neonatal screening programmes of congenital errors of metabolism cannot be recommended. Selective performance of diagnostic tests for MPS and oligosaccharidosis would however appear wise among patients judged to be at risk, specifically, those who present with metabolic disorders or scant weight gain at birth or in the first weeks of life. To enable active and regular follow-up in such cases, it is considered advisable for a case registry to be established, which, for health-care, teaching and research purposes, would then pool all information on incidence, trends, survival and other aspects linked to neonatal screening of these diseases.
• Lastly, epidemiological studies should be conducted so as to enable us to ascertain the distribution and frequency of these diseases, the validity of diagnoses based on enzymatic determination with tandem mass spectrometry, and the cost-effectiveness of the new therapies available. It would be extremely useful if advantage could be taken of the experience of existing screening teams and routine collection of specimens on paper strips to design and undertake parallel studies, which would be aimed at carrying out long-term assessment of results, and enabling a definitive conclusion to be arrived at regarding the use of these techniques and implementation of this type of screening in the context of a neonatal programme.
