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PubMed2006

Haematopoietic cell transplantation (HCT) in combination with enzyme replacement therapy (ERT) in patients with Hurler syndrome.

Hurler syndrome (MPS 1H) is the severe form of mucopolysaccharidosis type 1 (MPS 1). Haematopoietic cell transplantation (HCT) is the treatment of choice, but carries a high incidence of graft failure and morbidity. The use of enzyme replacement therapy (ERT) might improve the clinical signs and symptoms before HCT, resulting in less transplantation-related complications. Moreover, clearance of glycosaminoglycans (GAG's) from the bone marrow might improve engraftment. Twenty-two patients with MPS 1H received one or more HCT procedures in combination with ERT. One patient with severe cardiomyopathy improved significantly after ERT. All children were in a relatively good clinical condition before HCT. Of patients 59, 82 and 86% were alive and engrafted after one, two and three HCT procedures, respectively. Two patients died after repetitive HCT. No serious ERT-infusion-related toxicity occurred. ERT with HCT was well tolerated. Neither a positive nor a negative effect on the number of patients who are alive and engrafted after receiving ERT before HCT as compared to a historic cohort was noted. However, patients in a poor clinical condition before HCT might benefit from ERT.

Child, Preschool↗
PubMed2007

Biochemical monitoring after haemopoietic stem cell transplant for Hurler syndrome (MPSIH): implications for functional outcome after transplant in metabolic disease.

Hurler Syndrome is corrected by allogeneic BMT by the action of donor enzyme on recipient tissue. In this paper, we describe monitoring of 39 patients transplanted in two centres to determine donor chimerism, enzyme level and residual substrate - expressed as dermatan sulphate to chondroitin sulphate ratio. We show that in fully engrafted recipients, the enzyme level, expressed as mumol/g total protein/h, post-transplant is 24.2 from an unrelated donor and 10.2 from a heterozygote family donor (P<0.0001). There is a tight relationship between mean post-transplant enzyme level and residual substrate - Spearman's rank correlation coefficient (Rho) was -0.76 and -0.80 at 12 and 24 months, respectively (P<0.0001). We propose that these differences affect patient outcome. As unrelated donor transplant outcomes improve and especially given the higher levels of donor cell engraftment following cord transplants, our data might influence donor selection where only heterozygote-matched family members are available.

Chimerism↗
PubMed2002

Stop codons affect 5' splice site selection by surveillance of splicing.

Pre-mRNA splicing involves recognition of a consensus sequence at the 5' splice site (SS). However, only some of the many potential sites that conform to the consensus are true ones, whereas the majority remain silent and are not normally used for splicing. We noticed that in most cases the utilization of such a latent intronic 5' SS for splicing would introduce an in-frame stop codon into the resultant mRNA. This finding suggested a link between SS selection and maintenance of an ORF within the mRNA. Here we tested this idea by analyzing the splicing of pre-mRNAs in which in-frame stop codons upstream of a latent 5' SS were mutated. We found that splicing with the latent site is indeed activated by such mutations. Our findings predict the existence of a checking mechanism, as a component of the nuclear pre-mRNA splicing machine, to ensure the maintenance of an ORF. This notion is highly important for accurate gene expression, as perturbations that would lead to splicing at these latent sites are expected to introduce in-frame stop codons into the majority of mRNAs.

Alternative Splicing↗
PubMed1976

The mucopolysaccharidoses (a review).

The mucopolysaccharidoses are a group of genetic diseases characterized by storage of incompletely degraded glycosaminoglycans. Such storage causes marked distortion of many tissues with consequent severe somatic changes and mental retardation. Storage of glycosaminoglycans results from markedly diminished activity of specific hydrolases requisite for the normal degradation of glycosaminoglycans. The specific enzymic defects have been identified in nine different diseases. In some cases evidence has been obtained indicating the existence of additional allelic diseases based on the same enzyme. The knowledge obtained from these studies has made prenatal diagnosis possible and has led to the possibility that therapy may be undertaken utilizing enzyme replacement.

Acetylglucosaminidase↗
PubMed2002

Heparin sequencing.

Heparin is a highly sulfated glycosaminoglycan widely used as an anticoagulant. Modifications in its relatively uniform structure appear to be key to its recognition and modulation of serine proteases, growth factors, chemokines, and extracellular proteins, as has been most clearly demonstrated in the antithrombin binding site. We sequenced the major oligosaccharides released from mastocytoma heparin by partial nitrous acid using a highly sensitive technique tailored for sequencing of metabolically radiolabeled heparin. It utilizes partial nitrous acid cleavage to allow simultaneous sequencing of the internal components of the oligosaccharide under investigation by specific lysosomal exoenzymes. Sequencing revealed that although the majority of the heparin disaccharides are N-, 2-O-, and 6-O-sulfated, the less sulfated disaccharides (lacking 2-O- or 6-O-sulfates) seem to be spaced out along the chain. The technique may be particularly useful for characterizing heparin from novel sources, such as the glial progenitor cells and Ascidia, as well as for sequencing protein binding sites.

Animals↗
PubMed2003

In vivo microstructural analysis of the cornea in Scheie's syndrome.

PURPOSE: To analyze clinical and in vivo microstructural characteristics of both corneas of a 13-year-old male subject with Scheie's syndrome and compare the observations with the pathologic reports in the literature. METHODS: Standard clinical examination and real-time, slit-scanning in vivo confocal microscopy were performed and repeated after 1 year. RESULTS: In vivo confocal microscopy images at all cellular layers demonstrated brighter intercellular spaces than those of normal corneas. Cicatrization of the anterior stroma was identified, and the keratocytes of the middle and posterior stroma exhibited markedly altered morphology, often round or elliptical in shape, and with clearly demarcated, hyporeflective centers. The nerve fibers of the subbasal plexus were somewhat more irregular and difficult to distinguish, possibly due to underlying fibrosis. CONCLUSIONS: The potential of in vivo confocal microscopy to highlight microstructural alterations of the intact human cornea and evaluate such changes over time might reduce reliance on histopathologic investigations in such conditions and contribute to the ophthalmic management of the mucopolysaccharidoses in the future.

Adolescent↗
PubMed1986

Transplantation of fetal fibroblasts and correction of enzymatic deficiencies in patients with Hunter's or Hurler's disorders.

An attempt was made at correcting the specific lysosomal enzyme deficiencies in 7 children with Hunter's or Hurler's diseases by transplantation of fetal fibroblasts. In spite of pretreating the young patients with stored blood, following a procedure employed successfully to avoid rejection of kidneys from incompatible donors, the use of serum-free media for culturing the cells before being harvested and incubation of the cells with chorionic gonadotrophin, the transplantation of fetal fibroblasts was not associated with biochemical or clinical changes. None of the seven patients showed immune reactions against the transplanted cells, HLA antigens, or the missing enzymes.

Animals↗
PubMed2004

Hurler disease.

Explore the source record for details and available documents.

Child↗
PubMed2005

Safety and efficacy of enzyme replacement therapy in combination with hematopoietic stem cell transplantation in Hurler syndrome.

PURPOSE: Hurler syndrome is a debilitating genetic disease with a typical life span of 5 to 8 years. Early hematopoietic stem cell transplantation (HSCT) mitigates disease symptoms and improves survival. However, morbidity and mortality associated with HSCT can limit its success. We describe the initial experience with combined use of enzyme replacement therapy (ERT, laronidase) and HSCT in Hurler syndrome. METHODS: Thirteen transplants were performed in 12 patients. ERT was given at a standard dose of 0.58 mg/kg per week. Transplant conditioning regimen and donor graft source were determined by institutional protocol. RESULTS: The median age at initiation of ERT was 12 months (range, 8 to 18 months). The median duration of pre-HSCT ERT was 12 weeks (range, 4 to 28). All but 1 patient tested showed decrease in urinary GAG excretion during ERT. ERT infusion-related toxicity was limited to mild reactions. Development of antibodies to laronidase did not correlate with infusion reactions or responses in urinary GAG excretion. ERT was given for a median of 7 weeks (range, 3 to 20) after HSCT. After transplantation, eight patients demonstrated complete donor engraftment and four suffered graft failure. Two patients required ventilator support and three developed acute GVHD. Eleven of the 12 patients are surviving with a median follow-up of 3 months (range, 1 to 7 months). CONCLUSIONS: In children with Hurler syndrome, ERT with HSCT is feasible and well tolerated. Development of antibodies against exogenous enzyme does not appear to correlate with infusion reactions or response to ERT. A prospective study is needed to determine the effect of concomitant ERT on transplant outcomes.

Acute Disease↗
PubMed1978

Acute myelogenous leukaemia in Hurler's syndrome.

The occurrence of the Hurler syndrome and acute myelogenous leukaemia in a 2 1/2-year-old girl is described. This represents the first published report of the concurrence of these two diseases.

Bone Marrow↗
PubMed2002

Enzyme replacement therapy for the mucopolysaccharide storage disorders.

The mucopolysaccharide storage disorders are a group of lysosomal storage disorders associated with deficiencies of lysosomal enzymes required for the normal sequential degradation of glycosaminoglycans, formerly known as mucopolysaccharides. The accumulation of glycosaminoglycans in a wide variety of tissues results in a complex and progressive disease leading to death in the first or second decade in most patients. Studies of enzyme replacement in animal models of mucopolysaccharide disorders have demonstrated the potential of parenterally administered enzyme to reduce glycosaminoglycan storage and microscopic pathology. Clinical studies of enzyme replacement therapy are currently underway for mucopolysaccharidosis I, mucopolysaccharidosis VI and mucopolysaccharidosis II. The complexity and heterogeneity of the mucopolysaccharide disorders provide significant challenges for clinical study design and evaluation. Innovative clinical development strategies may be needed to lower the development cost and time for complex rare disease therapies to assure that such patients receive therapies they deserve.

Animals↗
PubMed2006

A systematic review of the clinical effectiveness and cost-effectiveness of enzyme replacement therapies for Fabry's disease and mucopolysaccharidosis type 1.

OBJECTIVES: To determine the clinical effectiveness and cost-effectiveness of the administration of intravenous enzyme replacement therapy (ERT) to symptomatic patients for the prevention of long-term damage and symptoms in Fabry's disease and in mucopolysaccharidosis type 1 (MPS1). DATA SOURCES: Electronic databases from inception up to mid-2004. Contact with clinical experts. REVIEW METHODS: Relevant studies were identified and assessed using recommended quality criteria. RESULTS: The results suggested beneficial effects of ERT for Fabry's disease on measures of pain, cardiovascular function and some end-points reflecting neurosensory function. Renal function appeared to be stabilised by ERT. At present there are no utility-related health-related quality of life data on which to assess the relative health gain of ERT in MPS1. In order to be able to demonstrate the full extent of health gain from treatment, it was necessary to review the natural history of untreated patients in each disease in order to try to estimate the health loss prevented. The published information for Fabry's disease tallied with descriptions of a multi-system, life-threatening disorder particularly involving kidney, heart and brain with individual patients exhibiting many manifestations. The fragmentary information reviewed in 16 studies relevant to the natural history of MPS1 did not generate a coherent picture of disease progression and could provide little added value to published narrative reviews. For Fabry's disease, the mean cost per patient (50 kg) treated is around pounds sterling 85,000 per annum in England and Wales. The cost per patient varies considerably by dose. No published evidence reporting an economic evaluation of ERT for Fabry's disease was identified by this review. A dynamic decision model was constructed based on a birth cohort of male patients who are followed up until death. Owing to lack of information reported in the literature, many assumptions had to be applied. The key assumptions were that ERT returns patients to full health and a normal life expectancy. As far as possible, all assumptions favoured rather than detracted from the value of ERT. ERT was assumed to restore patients to full health in the base case. The estimated incremental cost-effectiveness ratio (ICER) in the base case was pounds sterling 252,000 per QALY (agalsidase beta). Univariate sensitivity analysis around the key assumptions produced ICERs ranging from pounds sterling 602,000 to pounds sterling 241,000. The base case unit cost of ERT was taken as pounds sterling 65.1/mg based on the cost of agalsidase beta. The unit cost would have had to be reduced to pounds sterling 9 to obtain an ICER of pounds sterling 30,000 per QALY. For MPS1, the mean cost per child patient (20 kg) treated is approximately pounds sterling 95,000 and an adult (70 kg) around pounds sterling 335,000 per annum in England and Wales. The cost per patient varies considerably by dose. There is no published evidence reporting an economic evaluation of ERT for MPS1 and no study was identified that reported the quality of life of MPS1 patients within a utility format. Furthermore, no or minimal information of the severity and rate of change of clinical manifestations of disease or the impact of ERT on these factors was identified. Information on the effect of ERT on mortality is also lacking owing to the relatively short time that the treatment has been available. Given this lack of data, it was not possible to develop a cost-effectiveness model of ERT treatment for MPS1 as the model would consist almost completely of assumptions based on no published evidence, leading to an incremental cost per QALY result that would be meaningless. CONCLUSIONS: Although ERT for treating the 'average' patient with Fabry's disease exceeds the normal upper threshold for cost-effectiveness seen in NHS policy decisions by over sixfold, and the value for MPS1 is likely to be of a similar order of magnitude, clinicians and the manufacturers argue that, as the disease is classified as an orphan disease under European Union legislation, it has special status, and the NHS has no option but to provide ERT. More information is required before the generalisability of the findings can be determined. Although data from the UK have been used wherever possible, this was very thin indeed. Nonetheless, even large errors in assumptions made will not reduce the ICER to anywhere near the upper level of treatments usually considered cost-effective. In order to overcome limited evidence on the natural history of the disease and the clinical effectiveness of the intervention, the establishment of disease-specific data registries is suggested to facilitate the process of technology assessment and improving patient care. These registries should attempt to include all affected patients in the UK, and collect longitudinal patient level data on clinically relevant problems, interventions received and quality of life in a utility format.

Adult↗
PubMed1999

Sequence analysis of heparan sulphate and heparin oligosaccharides.

The biological activity of heparan sulphate (HS) and heparin largely depends on internal oligosaccharide sequences that provide specific binding sites for an extensive range of proteins. Identification of such structures is crucial for the complete understanding of glycosaminoglycan (GAG)-protein interactions. We describe here a simple method of sequence analysis relying on the specific tagging of the sugar reducing end by 3H radiolabelling, the combination of chemical scission and specific enzymic digestion to generate intermediate fragments, and the analysis of the generated products by strong-anion-exchange HPLC. We present full sequence data on microgram quantities of four unknown oligosaccharides (three HS-derived hexasaccharides and one heparin-derived octasaccharide) which illustrate the utility and relative simplicity of the technique. The results clearly show that it is also possible to read sequences of inhomogeneous preparations. Application of this technique to biologically active oligosaccharides should accelerate progress in the understanding of HS and heparin structure-function relationships and provide new insights into the primary structure of these polysaccharides.

Animals↗