Morquio Disease Type Research Articles

Cervical Disorders in Mucopolysaccharidosis IVA—Morquio disease

Morquio disease or mucopolysaccharidosis type IVA (Online Mendelian Inheritance in Man No. 253000) is a rare autosomal recessive disease classified in the group of metabolism inborn errors. The glycosaminoglycans accumulate in chondrocytes, which disturbs bone growth and leads to skeletal manifestations, such as skeletal dysplasia and a short stature. In addition, the disproportionate growth of the trachea can lead to airway insufficiency. We report the case of a 27-year-old man with dwarfism due to Morquio disease, which had resulted in quadriparesis, hyperreflexia, and dyspnea, requiring a "look up to the sky" compensatory position. Imaging studies of the neck showed tracheal tortuosity, spinal stenosis, myelopathy, and neurogenic arthropathy (Charcot joint). The patient was treated with occipital-cervical-thoracic instrumentation. However, postoperative tracheal correction was required. Considering the wide spectrum of clinical features in those with mucopolysaccharidosis type IVA, individualized multidisciplinary treatment is recommended.

Disentangling molecular and clinical stratification patterns in beta-galactosidase deficiency

IntroductionThis study aims to define the phenotypic and molecular spectrum of the two clinical forms of β-galactosidase (β-GAL) deficiency, GM1-gangliosidosis and mucopolysaccharidosis IVB (Morquio disease type B, MPSIVB).MethodsClinical and genetic...

4-epi-Isofagomine derivatives as pharmacological chaperones for the treatment of lysosomal diseases linked to β-galactosidase mutations: Improved synthesis and biological investigations.

(5aR)-5a-C-pentyl-4-epi-isofagomine 1 is a powerful inhibitor of lysosomal β-galactosidase and a remarkable chaperone for mutations associated with GM1-gangliosidosis and Morquio disease type B. We report herein an improved synthesis of this compound and analogs (5a-C-methyl, pentyl, nonyl and phenylethyl derivatives), and a crystal structure of a synthetic intermediate that confirms its configuration resulting from the addition of a Grignard reagent. These compounds were evaluated as glycosidase inhibitors and their potential as chaperones for mutant lysosomal galactosidases determined. Based on these results and on docking studies, the 5-C-pentyl derivative 1 was selected as the optimal structure for further investigations: this compound induces the maturation of mutated β-galactosidase in fibroblasts of a GM1-gangliosidosis patient and promote the decrease of keratan sulfate and oligosaccharide load in patient cells. Compound 1 is clearly capable of restoring β-galactosidase activity and of promoting maturation of the protein, which should result in significant clinical benefit. These properties strongly support the development of compound 1 for the treatment of GM1-gangliosidosis and Morquio disease type B patients harboring β-galactosidase mutations sensitive to pharmacological chaperoning.

SAAMP 2.0: An algorithm to predict genotype-phenotype correlation of lysosomal storage diseases.

Lysosomal storage diseases (LSDs) are a group of genetic disorders, resulting from deficiencies of lysosomal enzyme. Genotype-phenotype correlation is essential for timely and proper treatment allocation. Recently, by integrating prediction outcomes of 7 bioinformatics tools, we developed a SAAMP algorithm to predict the impact of individual amino-acid substitution. To optimize this approach, we evaluated the performance of these bioinformatics tools in a broad array of genes. PolyPhen and PROVEAN had the best performances, while SNP&GOs, PANTHER and I-Mutant had the worst performances. Therefore, SAAMP 2.0 was developed by excluding 3 tools with worst performance, yielding a sensitivity of 94% and a specificity of 90%. To generalize the guideline to proteins without known structures, we built the three-dimensional model of iduronate-2-sulfatase by homology modeling. Further, we investigated the phenotype severity of known disease-causing mutations of the GLB1 gene, which lead to 2 LSDs (GM1 gangliosidosis and Morquio disease type B). Based on the previous literature and structural analysis, we associated these mutations with disease subtypes and proposed a theory to explain the complicated genotype-phenotype correlation. Collectively, an updated guideline for phenotype prediction with SAAMP 2.0 was proposed, which will provide essential information for early diagnosis and proper treatment allocation, and they may be generalized to many monogenic diseases.

(5aR)-5a-C-Pentyl-4-epi-isofagomine: A powerful inhibitor of lysosomal β-galactosidase and a remarkable chaperone for mutations associated with GM1-gangliosidosis and Morquio disease type B

This report is about the identification, synthesis and initial biological characterization of derivatives of 4-epi-isofagomine as pharmacological chaperones (PC) for human lysosomal β-galactosidase. The two epimers of 4-epi-isofagomine carrying a pentyl group at C-5a, namely (5aR)- and (5aS)-5a-C-pentyl-4-epi-isofagomine, were prepared by an innovative procedure involving in the key step the addition of nitrohexane to a keto-pentopyranoside. Both epimers were evaluated as inhibitors of the human β-galactosidase: the (5aR)-stereoisomer (compound 1) was found to be a very potent inhibitor of the enzyme (IC50 = 8 nM, 30× more potent than 4-epi-isofagomine at pH 7.3) with a high selectivity for this glycosidase whereas the (5aS) epimer was a much weaker inhibitor. In addition, compound 1 showed a remarkable activity as a PC. It significantly enhanced the residual activity of mutant β-galactosidase in 15 patient cell lines out of 23, with enhancement factors greater than 3.5 in 10 cell lines and activity restoration up to 91% of normal. Altogether, these results indicated that (5aR)-5a-C-pentyl-4-epi-isofagomine constitutes a promising PC-based drug candidate for the treatment of GM1-gangliosidosis and Morquio disease type B.

4th Rare Disease South Eastern Europe (See) Meeting Skopje, Macedonia (November 14th, 2015).

The 4th meeting on rare diseases in South Eastern Europe (SEE) was held in Skopje, at the Macedonian Academy of Sciences and Arts (MASA) on the 14(th) of November 2015. The focuses were metabolic, rare brain diseases as well as the rare dysmorphic syndrome. The authors of the report are particularly keen on stating that one of the main goals of the meeting, namely to help the treatment of patients with rare disease has begun to bear fruits. The talk on an iminosugar-based pharmacological chaperone compound as a drug candidate for the treatment of GM1-gangliosidosis and mucopolysaccharidosis IVB (Morquio disease type B) was enlightening. To date, there is no treatment available to be offered to patients, but chaperones lead mutated proteins to adopt a native-like conformation and to successfully traffic to their normal cellular destination. DORPHAN is developing an iminosugar-based pharmacological chaperone compound for the treatment of GM1-gangliosidosis and mucopolysaccharidosis IVB. A talk on recent developments in the laboratory diagnosis of mucopolysaccharidoses (MPS) was particularly interesting, covering the laboratory diagnosis of the MPS diseases by a strategy of clinical examination, biochemical analysis of urine samples, enzyme tests and genetic characterization of underlying mutations. New techniques were developed, including analysis of urinary glycosaminoglycans with tandem mass spectrometry, miniaturized enzyme tests or novel synthetic substrates for enzyme assays using mass spectrometry detection of products using dried blood spots. Feasibility and cost-effectiveness of these methods in newborn screening programs have been demonstrated. Neuromuscular RDs, and especially familial amyloid polyneuropathy (FAP) were a topic of the Bulgarian colleagues. Diagnosis, screening and the role of microglia were also topics of particular interest. In summary, this year RD meeting was exciting and productive on a wide range of diseases and on a novel insights on diagnosis and treatment. New methods are expanding our capabilities for a fast and precise diagnosis. Novel knowledge offers better distinction on whom to treat with which medications (e.g. steroid dependent nephrotic syndrome). Novel diseases or variants are published (segmental overgrowth). The authors of the report are particularly keen on stating that one of the main goals of the meeting, namely to help the treatment of patients with rare disease has begun to bear fruits. Namely, the Health Fund of Macedonia for the first time treats the patients with Gaucher's disease. We are hopeful that the number of patients treated for Gaucher's disease and the number of treated patients with other treatable RDs diseases will continue to grow.

Towards the development of a less immunogenic protein for enzyme replacement therapy of Morquio disease type A

Towards the development of a less immunogenic protein for enzyme replacement therapy of Morquio disease type A

Forme atténuée du syndrome de Morquio : une cause méconnue de retard statural (à propos de trois cas)

Morquio disease is a rare genetic disorder characterized by the accumulation of keratan sulfate in tissues. We distinguish two forms according to the deficient enzyme: type A, with a poor prognosis, and type B. Its management is essentially symptomatic. Enzyme replacement therapy and gene therapy are still being evaluated. We report observations of three patients with Morquio disease type A in its moderate form. This article reports the latest facts in both Morquio disease diagnosis and treatment, emphasizing the minor forms usually presented by short stature that should bring out this disorder.

An Autophagic Vacuolar Myopathy-Like Disorder Presenting as Nonimmune Hydrops in a Female Fetus

A 37-year-old woman presented for routine obstetrical care at 15 weeks' gestational age and the fetus was found to have hydrops fetalis. Following elective termination of the pregnancy at 18 weeks' gestational age, pathologic examination of the female conceptus revealed findings suggestive of a lysosomal storage disease within the liver and cardiac muscle. Enzyme assays for beta-galactosidase, neuraminidase, alpha-l-iduronidase, beta-glucuronidase, beta-glucosidase, Morquio disease type A enzyme, beta-fucosidase, alpha-mannosidase, and beta-mannosidase were all normal, ruling out many of the common storage diseases. Electron microscopy identified vacuoles within hepatocytes, Kupffer cells, and cardiac myocytes resembling the autophagic vacuoles characteristic of a group of diseases known as the autophagic vacuolar myopathies (AVMs). Because these diseases are exceptionally rare in females, and because such autophagic vacuoles have never before been described in liver, we propose a novel entity of "AVM-like lysosomal storage disease" presenting as nonimmune hydrops in a female fetus.

Variable clinical presentation in lysosomal storage disorders.

Extensive clinical heterogeneity is seen in lysosomal storage disorders, regarding the age of onset and severity of symptoms, the organs involved, and effects on the central nervous system. A broad phenotypic spectrum is seen, for example, in mucopolysaccharidosis type I (Hurler/Scheie disease), Gaucher disease, the several forms of GM2-gangliosidosis and the different manifestations of beta-galactosidase deficiency (GM1-gangliosidosis and Morquio disease type B). Variable clinical expression of the same enzyme defect is not well understood. The presence of different mutations is only part of the explanation, as intrafamilial variability is observed in many cases. Other mechanisms, for example the effect of specific activators, may also have an influence on phenotype.

Lysosomal multienzyme complex: Biochemistry, genetics, and molecular pathophysiology

Lysosomal enzymes sialidase (alpha-neuraminidase), beta-galactosidase, and N-acetylaminogalacto-6-sulfate sulfatase are involved in the catabolism of glycolipids, glycoproteins, and oligosaccharides. Their functional activity in the cell depends on their association in a multienzyme complex with lysosomal carboxypeptidase, cathepsin A. We review the data suggesting that the integrity of the complex plays a crucial role at different stages of biogenesis of lysosomal enzymes, including intracellular sorting and proteolytic processing of their precursors. The complex plays a protective role for all components, extending their half-life in the lysosome from several hours to several days; and for sialidase, the association with cathepsin A is also necessary for the expression of enzymatic activity. The disintegration of the complex due to genetic mutations in its components results in their functional deficiency and causes severe metabolic disorders: sialidosis (mutations in sialidase), GM1-gangliosidosis and Morquio disease type B (mutations in beta-galactosidase), galactosialidosis (mutations in cathepsin A), and Morquio disease type A (mutations in N-acetylaminogalacto-6-sulfate sulfatase). The genetic, biochemical, and direct structural studies described here clarify the molecular pathogenic mechanisms of these disorders and suggest new diagnostic tools.

Elastic-Fiber Pathologies: Primary Defects in Assembly—and Secondary Disorders in Transport and Delivery

Accession numbers and the URL for data in this article are as follows:Online Mendelian Inheritance in Man (OMIM), www.ncbi.nlm.nih.gov/Omim (for congenital contractural arachnodactyly [MIM 121050], adCL [MIM 123700], MFS [MIM 154700]), SVAS [MIM 185500], Williams-Beuren syndrome [MIM 194050], Costello syndrome [MIM 218040], GM1-gangliosidosis [MIM 230500, MIM 230600, and MIM 230650], MPSI [MIM 252800], and MPS IVB [MIM 253010])

First-trimester diagnosis of Morquio disease type A

Since the introduction in 1990 of a novel fluorogenic substrate for galactose-6-sulphate sulphatase we have used this substrate for prospective prenatal diagnosis in 10 pregnancies at risk for Morquio disease type A. Chorionic villi were analysed in five cases. The results indicated an affected fetus in one pregnancy which represents the first case of first-trimester diagnosis of this disorder; heterozygosity was demonstrated in two cases. Following amniocentesis, two affected fetuses and one heterozygote were diagnosed. The results of the present prospective prenatal analyses confirm our previous retrospective studies and demonstrate the reliability and convenience of the 4-methylumbelliferyl substrate.

First‐trimester diagnosis of Morquio disease type A

First‐trimester diagnosis of Morquio disease type A

Radiological findings in mild forms of Morquio's disease (MPS 1V A)

Clinical and radiological features of seven patients with Morquio's disease Type A (MPS 1V A) are presented. The diagnosis was established by two-dimensional electrophoresis of the urinary glycosaminoglycans and enzyme assay. The clinical manifestations were mild or moderate in all patients and the radiological changes were milder than those described in classical Morquio's disease.

Dental findings in mucopolysaccharidosis type IV A (Morquio's disease type A)

Dental examinations on nine patients with mucopolysaccharidosis type IV A (MPS IV A, Morquio's disease type A) were carried out. Detailed medical, radiologic, and biochemical studies of each case were also performed independently. Dental changes were present in all cases, although the severity varied. The severity of the dental changes did not correlate with the clinical or biochemical findings in all cases. These dental changes are seen only in MPS IV A (N-acetylgalactosamine-6-sulphate sulphatase deficiency) and are not found in MPS IV B (β-galactosidase deficiency) or the recently delineated MPS IV C (enzyme defect unknown). The dental changes can aid in the diagnosis of patients affected by MPS IV A and are especially useful in mild atypical cases.

A fluorimetric enzyme assay for the diagnosis of Morquio disease type A (MPS IV A)

4-Methylumbelliferyl-β-D-galactopyranoside-6-sulphate was synthesized and used for the determination of galactose-6-sulphate sulphatase activity. Fibroblasts and leucocytes from 12 different Morquio A patients, showed 0.0–2.7% of mean normal galactose-6-sulphate sulphatase activity. Heterozygotes showed intermediate activities. The enzymatic liberation of the fluorochrome from 4-methylumbelliferyl-β-D-galactopyranoside-6-sulphate requires the sequential action of galactose-6-sulphate sulphatase and β-galactosidase. Normal β-galactosidase activity caused nearly complete hydrolysis of non-fluorescing 4-methylumbelliferyl-galactoside, formed during incubation. In cell extracts with a β-galactosidase deficiency however, a second incubation in the presence of excess β-galactosidase is needed to avoid underestimation of galactose-6-sulphate sulphatase activity.

Prenatal diagnosis of morquio disease type a using a simple fluorometric enzyme assay

A new fluorogenic substrate, 4 methylumbelliferyl beta-D-6-sulphogalactoside, was used for the assay of galactose-6-sulphate sulphatase activity in chorionic villi, cultured villus cells, and amniocytes. The fluorometric assay is much more convenient than the conventional assay using radiolabelled, sulphated oligosaccharides. Both types of substrate were used in the prenatal diagnosis of three pregnancies at risk for Morquio type A disease using amniocytes. These enzyme tests, as well as electrophoresis of glycosaminoglycans in the amniotic fluid, indicated affected fetuses in two pregnancies and a non-affected fetus in one.

Clinical findings in 12 patients with MPS IV A (Morquio's disease)

Clinical heterogeneity in MPS IV A (Mucopolysaccharidosis IV A, Morquio Disease Type A)has become more clearly identified in recent years. The clinical findings in 12 cases of MPS IV A are described. Clinical presentation was variable, and some cases were only mildly affected. All showed deficiency of N-acetylgalactosamine-6-sulphate sulphatase in fibroblasts, but the patient with the mildest clinical presentation showed a high residual enzyme activity. The urinary glycosaminoglycans (GAGs) were examined on all patients by a two-dimensional electrophoresis technique which proved to be highly reliable and efficient. In particular, no false negative results were obtained, a problem often encountered with routine screening methods. These cases support the division of MPS IV A into three subgroups: the severe "classical" type, an intermediate type and a mild type, all caused by N-acetylgalactosamine-6-sulphate sulphatase deficiency. Residual enzyme activity may be an important prognostic indicator.

Incorporation and degradation of G M1 ganglioside and asialoG m1 ganglioside in cultured fibroblasts from normal individuals and patients with β-galactosidase deficiency

The uptake and degradation of G M1 ganglioside (G M1) and asialoG M1 ganglioside (G A1) were studied in cultured fibroblasts from normal individuals and patients with β-galactosidase deficiency, using the lipid-loading test. The glycolipids were incorporated from the media into the fibroblasts and the terminal galactose was hydrolyzed in normal cells. The hydrolysis rates of G A1 were 80–86% of normal on the 3rd day after loading, while G M1 was hydrolyzed slowly; 35–54% on the 14th day. In infantile G M1 gangliosidosis and I-cell disease, little G M1 and G A1 was hydrolyzed on any day of culture, while fibroblasts from patients with adult G M1 gangliosidosis, Morquio disease type B and galactosialidosis hydrolyzed the lipids at nearly normal rates. The intracellular accumulation of the glycolipids, on the basis of protein content, was abnormally high in the case of infantile G M1 gangliosidosis and I-cell disease, but normal in the other disorders examined. These observations indicate that the in situ metabolism of G M1 and G A1 is probably normal in fibroblasts from patients with adult G M1 gangliosidosis, Morquio disease type B and galactosialidosis, although in vitro β-galactosidase activities in these disorders are very low. The results are compatible with findings that G M1 and G A1 do not accumulate in the somatic organs of patients with adult G M1 gangliosidosis and galactosialidosis. In I-cell disease, however, the results of the loading test did not agree with the finding that there is little accumulation of glycolipids in postmortem tissues.