Mucopolysaccharidosis III
Mucopolysaccharidosis I
Mucopolysaccharidosis VI
Mucopolysaccharidosis VII
Mucopolysaccharidosis II
Mucopolysaccharidoses
Mucopolysaccharidosis IV
Iduronidase
N-Acetylgalactosamine-4-Sulfatase
Chondro-4-Sulfatase
Iduronate Sulfatase
Chondroitinsulfatases
Enzyme Replacement Therapy
Sanfilippo type B syndrome (mucopolysaccharidosis III B): allelic heterogeneity corresponds to the wide spectrum of clinical phenotypes. (1/99)
Sanfilippo B syndrome (mucopolysaccharidosis IIIB, MPS IIIB) is caused by a deficiency of alpha-N-acetylglucosaminidase, a lysosomal enzyme involved in the degradation of heparan sulphate. Accumulation of the substrate in lysosomes leads to degeneration of the central nervous system with progressive dementia often combined with hyperactivity and aggressive behaviour. Age of onset and rate of progression vary considerably, whilst diagnosis is often delayed due to the absence of the pronounced skeletal changes observed in other mucopolysaccharidoses. Cloning of the gene and cDNA encoding alpha-N-acetylglucosaminidase enabled a study of the molecular basis of this syndrome. We were able to identify 31 mutations, 25 of them novel, and two polymorphisms in the 40 patients mostly of Australasian and Dutch origin included in this study. The observed allellic heterogeneity reflects the wide spectrum of clinical phenotypes reported for MPS IIIB patients. The majority of changes are missense mutations; also four nonsense and nine frameshift mutations caused by insertions or deletions were identified. Only five mutations were found in more than one patient and the observed frequencies are well below those observed for the common mutations in MPS IIIA. R643C and R297X each account for around 20% of MPS IIIB alleles in the Dutch patient group, whilst R297X, P521L, R565W and R626X each have a frequency of about 6% in Australasian patients. R643C seems to be a Dutch MPS IIIB allele and clearly confers the attenuated phenotype. One region of the gene shows a higher concentration of mutations, probably reflecting the instability of this area which contains a direct repeat. Several arginine residues seem to be 'hot-spots' for mutations, being affected by two or three individual base pair exchanges. (+info)A mouse model for mucopolysaccharidosis type III A (Sanfilippo syndrome). (2/99)
Mucopolysaccharidosis type III A (MPS III A, Sanfilippo syndrome) is a rare, autosomal recessive, lysosomal storage disease characterized by accumulation of heparan sulfate secondary to defective function of the lysosomal enzyme heparan N- sulfatase (sulfamidase). Here we describe a spontaneous mouse mutant that replicates many of the features found in MPS III A in children. Brain sections revealed neurons with distended lysosomes filled with membranous and floccular materials with some having a classical zebra body morphology. Storage materials were also present in lysosomes of cells of many other tissues, and these often stained positively with periodic-acid Schiff reagent. Affected mice usually died at 7-10 months of age exhibiting a distended bladder and hepatosplenomegaly. Heparan sulfate isolated from urine and brain had nonreducing end glucosamine- N -sulfate residues that were digested with recombinant human sulfamidase. Enzyme assays of liver and brain extracts revealed a dramatic reduction in sulfamidase activity. Other lysosomal hydrolases that degrade heparan sulfate or other glycans and glycosaminoglycans were either normal, or were somewhat increased in specific activity. The MPS III A mouse provides an excellent model for evaluating pathogenic mechanisms of disease and for testing treatment strategies, including enzyme or cell replacement and gene therapy. (+info)Analysis of glycosaminoglycans in urine by using acridine orange fluorescence. (3/99)
The fluorescence technique described here utilizes the electrostatic interaction between the polyanionic sites of glycosaminoglycans and the cationic dye Acridine Orange to analyse urinary glycosaminoglycans from patients suffering from mucopolysaccharidoses. The basis of the titration is the decrease in the fluorescence of free Acridine Orange that occurs when it is bound to polyanions. The effect of the presence of possible interfering materials such as salt, proteins and trace materials in urine was evaluated. This fluorescence technique is technically simple. (+info)Mouse model of Sanfilippo syndrome type B produced by targeted disruption of the gene encoding alpha-N-acetylglucosaminidase. (4/99)
The Sanfilippo syndrome type B is an autosomal recessive disorder caused by mutation in the gene (NAGLU) encoding alpha-N-acetylglucosaminidase, a lysosomal enzyme required for the stepwise degradation of heparan sulfate. The most serious manifestations are profound mental retardation, intractable behavior problems, and death in the second decade. To generate a model for studies of pathophysiology and of potential therapy, we disrupted exon 6 of Naglu, the homologous mouse gene. Naglu-/- mice were healthy and fertile while young and could survive for 8-12 mo. They were totally deficient in alpha-N-acetylglucosaminidase and had massive accumulation of heparan sulfate in liver and kidney as well as secondary changes in activity of several other lysosomal enzymes in liver and brain and elevation of gangliosides G(M2) and G(M3) in brain. Vacuolation was seen in many cells, including macrophages, epithelial cells, and neurons, and became more prominent with age. Although most vacuoles contained finely granular material characteristic of glycosaminoglycan accumulation, large pleiomorphic inclusions were seen in some neurons and pericytes in the brain. Abnormal hypoactive behavior was manifested by 4.5-mo-old Naglu-/- mice in an open field test; the hyperactivity that is characteristic of affected children was not observed even in younger mice. In a Pavlovian fear conditioning test, the 4.5-mo-old mutant mice showed normal response to context, indicating intact hippocampal-dependent learning, but reduced response to a conditioning tone, perhaps attributable to hearing impairment. The phenotype of the alpha-N-acetylglucosaminidase-deficient mice is sufficiently similar to that of patients with the Sanfilippo syndrome type B to make these mice a good model for study of pathophysiology and for development of therapy. (+info)Expression and characterization of wild type and mutant recombinant human sulfamidase. Implications for Sanfilippo (Mucopolysaccharidosis IIIA) syndrome. (5/99)
Mucopolysaccharidosis IIIA (MPS-IIIA) is an autosomal recessive lysosomal storage disorder caused by the deficiency of sulfamidase (NS; EC 3.10.1.1), resulting in defective degradation and storage of heparan sulfate. This paper reports the production and characterization of monoclonal and polyclonal antibodies against recombinant human sulfamidase (rhNS) to quantitate and characterize normal and mutant sulfamidase produced from the wild type NS expression vector. Glycosylation and phosphorylation studies of immunoprecipitated rhNS show that all five potential glycosylation sites are utilized, with three high mannose/hybrid oligosaccharides and two simpler chains, with at least one functional mannose 6-phosphate group. An NS quantification system was developed to determine the effect of the three most common and severe patient mutations: S66W (Italy), R74C (Poland), and R245H (The Netherlands). The quantity and specific activity of expressed mutant rhNS was significantly lower than expressed normal rhNS, with 0.3, 0.2, and 0.05% of normal rhNS produced and 15, 17, and 83% of normal specific activity for S66W, R74C, and R245H observed, respectively. The recent structural elucidation of N-acetylgalactosamine-4-sulfatase was utilized to postulate the effect on the structure-function relationship of NS. The characterization of normal and mutated rhNS has relevance for efficient diagnosis and therapeutic developments for MPS-IIIA patients. (+info)Impaired elastogenesis in Hurler disease: dermatan sulfate accumulation linked to deficiency in elastin-binding protein and elastic fiber assembly. (6/99)
Hurler disease resulting from a deficiency in alpha-L-iduronidase, which causes an accumulation of dermatan sulfate and heparan sulfate glycosaminoglycans, is characterized by connective tissue and skeletal deformations, cardiomyopathy, cardiac valve defects, and progressive coronary artery stenosis. In this report, we present evidence that accumulation of dermatan sulfate but not heparan sulfate moieties is linked to impaired elastic fiber assembly that, in turn, contributes substantially to the development of the clinical phenotype in Hurler disease. Our data suggest that dermatan sulfate-bearing moieties bind to and cause functional inactivation of the 67-kd elastin-binding protein, a molecular chaperone for tropoelastin, which normally facilitates its secretion and assembly into elastic fibers. We demonstrate that, in contrast to normal skin fibroblasts and cells from Sanfilippo disease, which accumulate heparan sulfate, Hurler fibroblasts show reduced expression of elastin-binding protein and do not assemble elastic fibers, despite an adequate synthesis of tropoelastin and sufficient production of a microfibrillar scaffold of elastic fibers. Because cultured Hurler fibroblasts proliferate more quickly than their normal counterparts and the addition of exogenous insoluble elastin reduces their proliferation, we suggest that cell contacts with insoluble elastin play an important role in controlling their proliferation. (+info)Heparan N-sulfatase gene: two novel mutations and transient expression of 15 defects. (7/99)
Sanfilippo syndrome type A or mucopolysaccharidosis IIIA (MPS IIIA) results from the deficiency of the enzyme heparan N-sulfatase (NS, EC 3.10.1.1), required for the degradation of heparan sulfate. Molecular defects of 24 Italian MPS IIIA patients were recently reported by our group. We report here two novel mutations: 1040insT and Q365X and the expression studies on 15 of the identified defects. Transient expression of COS cells by cDNA mutagenized to correspond to heparan N-sulfatase mutations Y40N, A44T, 166delG, G122R, P128L, L146P, R150Q, D179N, R182C, R206P, P227R, 1040insT, 1093insG, E369K, R377C did not yield active enzyme, demonstrating the deleterious nature of the mutations. Western blot analysis and metabolic labeling experiments revealed, for cells transfected with wild-type enzyme, a precursor 62-kDa form and a mature 56-kDa form. Western blot resulted, for 11 mutations, in the presence of both forms, indicating a normal maturation of the mutant enzyme. Western blot, metabolic labeling and immunofluorescence experiments suggested, for mutations 166delG, L146P, 1040insT and 1093insG, an increased degradation of the mutant enzymes. (+info)Mucopolysaccharidosis type IIIB: characterisation and expression of wild-type and mutant recombinant alpha-N-acetylglucosaminidase and relationship with sanfilippo phenotype in an attenuated patient. (8/99)
Mucopolysaccharidosis type IIIB (MPS-IIB) is a lysosomal storage disorder characterised by the defective degradation of heparan sulfate due to a deficiency of alpha-N-acetylglucosaminidase (NAG). The clinical severity of MPS-IIIB ranges from an attenuated to severely affected Sanfilippo phenotype. This paper describes the expression and characterisation of wild-type recombinant NAG and the molecular characterisation of a previously identified R297X/F48L compound heterozygous MPS-IIIB patient with attenuated Sanfilippo syndrome. We have previously shown R297X to be the most common mutation in a cohort of Dutch and Australian patients, occurring at a frequency of approximately 12.5%. To date F48L has only been described in the proband. To determine the contribution of each mutation to the overall clinical phenotype of the patient, both mutant alleles were engineered into the wild-type NAG cDNA and expressed in Chinese hamster ovary cells. The wild-type NAG and F48L mutant alleles were also retrovirally expressed in MPS-IIIB skin fibroblasts. Residual NAG activity and the stability and maturation of immunoprecipitated NAG were determined for wild-type NAG and mutant NAG. The combined biochemical phenotypes of the two NAG mutant alleles demonstrated a good correspondence with the observed attenuated Sanfilippo phenotype of the patient. (+info)Mucopolysaccharidosis III, also known as Sanfilippo syndrome, is a genetic disorder caused by the deficiency of specific enzymes needed to break down complex sugar molecules called glycosaminoglycans (GAGs) or mucopolysaccharides. This results in an accumulation of these substances in various tissues and organs, leading to progressive damage.
There are four main types of Mucopolysaccharidosis III (A, B, C, and D), each caused by a deficiency in one of the following enzymes: heparan N-sulfatase (type A), alpha-N-acetylglucosaminidase (type B), acetyl-CoAlpha-glucosaminide acetyltransferase (type C), or N-acetylglucosamine 6-sulfatase (type D).
The symptoms of Mucopolysaccharidosis III typically become apparent between the ages of 2 and 6, and may include developmental delays, hyperactivity, behavioral problems, sleep disturbances, coarse facial features, hirsutism, hepatosplenomegaly (enlarged liver and spleen), and joint stiffness. Over time, individuals with Mucopolysaccharidosis III may experience a decline in cognitive abilities, loss of previously acquired skills, and mobility issues.
Currently, there is no cure for Mucopolysaccharidosis III, and treatment is focused on managing the symptoms and improving quality of life. Enzyme replacement therapy, gene therapy, and stem cell transplantation are some of the experimental treatments being investigated for this condition.
Mucopolysaccharidosis I (MPS I) is a rare genetic disorder caused by the deficiency of an enzyme called alpha-L-iduronidase. This enzyme is responsible for breaking down complex sugars called glycosaminoglycans (GAGs), also known as mucopolysaccharides, in the body.
When the enzyme is deficient, GAGs accumulate in various tissues and organs, leading to a range of symptoms that can affect different parts of the body, including the skeletal system, heart, respiratory system, eyes, and central nervous system. There are three subtypes of MPS I: Hurler syndrome (the most severe form), Hurler-Scheie syndrome (an intermediate form), and Scheie syndrome (the least severe form).
The symptoms and severity of MPS I can vary widely depending on the specific subtype, with Hurler syndrome typically causing more significant health problems and a shorter life expectancy than the other two forms. Treatment options for MPS I include enzyme replacement therapy, bone marrow transplantation, and various supportive therapies to manage symptoms and improve quality of life.
Mucopolysaccharidosis VI (MPS VI), also known as Maroteaux-Lamy syndrome, is a rare genetic disorder caused by the deficiency of an enzyme called N-acetylgalactosamine 4-sulfatase. This enzyme is responsible for breaking down complex sugars called glycosaminoglycans (GAGs) or mucopolysaccharides, which are found in various tissues and organs throughout the body.
When the enzyme is deficient, GAGs accumulate within the lysosomes of cells, leading to cellular dysfunction and tissue damage. This accumulation results in a range of symptoms that can affect multiple organ systems, including the skeletal system, cardiovascular system, respiratory system, and central nervous system.
The signs and symptoms of MPS VI can vary widely among affected individuals, but common features include: coarse facial features, short stature, stiff joints, restricted mobility, recurrent respiratory infections, hearing loss, heart valve abnormalities, and clouding of the cornea. The severity of the disease can range from mild to severe, and life expectancy is generally reduced in individuals with more severe forms of the disorder.
MPS VI is inherited as an autosomal recessive trait, which means that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition.
Mucopolysaccharidosis (MPS) VII, also known as Sly syndrome, is a rare genetic disorder caused by the deficiency of the enzyme beta-glucuronidase. This enzyme is responsible for breaking down complex sugars called glycosaminoglycans (GAGs), or mucopolysaccharides, in the body. When this enzyme is not present in sufficient amounts, GAGs accumulate in various tissues and organs, leading to progressive damage.
The symptoms of MPS VII can vary widely, but often include coarse facial features, short stature, skeletal abnormalities, hearing loss, heart problems, and intellectual disability. Some individuals with MPS VII may also have cloudy corneas, enlarged liver and spleen, and difficulty breathing due to airway obstruction. The severity of the condition can range from mild to severe, and life expectancy is often reduced in those with more severe symptoms.
MPS VII is inherited in an autosomal recessive manner, which means that an individual must inherit two copies of the mutated gene (one from each parent) in order to develop the condition. Treatment for MPS VII typically involves enzyme replacement therapy, which can help to slow down the progression of the disease and improve some symptoms. However, there is currently no cure for this condition.
Mucopolysaccharidosis II (MPS II), also known as Hunter syndrome, is a rare X-linked recessive genetic disorder caused by the deficiency of an enzyme called iduronate sulfatase. This enzyme is responsible for breaking down complex sugars called glycosaminoglycans (GAGs) or mucopolysaccharides in the body.
When this enzyme is missing or not functioning properly, GAGs accumulate in various tissues and organs, leading to progressive cellular damage and organ dysfunction. The symptoms of MPS II can vary widely but often include developmental delays, coarse facial features, hearing loss, airway obstruction, heart problems, enlarged liver and spleen, and joint stiffness.
The severity of the disease can range from mild to severe, with some individuals experiencing only moderate symptoms while others may have significant intellectual disability and life-threatening complications. Treatment options for MPS II include enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT), but there is currently no cure for the disease.
Mucopolysaccharidoses (MPS) are a group of inherited metabolic disorders caused by the deficiency of specific enzymes needed to break down complex sugars called glycosaminoglycans (GAGs or mucopolysaccharides). As a result, these GAGs accumulate in various tissues and organs, leading to progressive cellular damage and multi-organ dysfunction. There are several types of MPS, including Hurler syndrome, Hunter syndrome, Sanfilippo syndrome, Morquio syndrome, Maroteaux-Lamy syndrome, and Sly syndrome, each resulting from a deficiency in one of the eleven different enzymes involved in GAGs metabolism. The clinical presentation, severity, and prognosis vary among the types but commonly include features such as developmental delay, coarse facial features, skeletal abnormalities, hearing loss, heart problems, and reduced life expectancy.
Mucopolysaccharidosis IV (MPS IV), also known as Morquio Syndrome, is a rare genetic disorder that belongs to the family of diseases called mucopolysaccharidoses. It is characterized by the accumulation of glycosaminoglycans (GAGs or mucopolysaccharides) in various tissues and organs due to deficiencies in specific enzymes needed to break down these complex carbohydrates.
There are two types of MPS IV: Type A and Type B, which are caused by deficiencies in different enzymes (GALNS and B3GALNT1, respectively). Both types result in similar symptoms but may vary in severity. The accumulation of GAGs primarily affects the bones, cartilage, eyes, ears, heart, and respiratory system.
Common features of MPS IV include:
* Dwarfism with short trunk and long limbs
* Progressive skeletal abnormalities such as kyphosis (hunchback), scoliosis (curvature of the spine), pectus carinatum (protruding breastbone), and joint laxity or stiffness
* Coarse facial features
* Corneal clouding
* Hearing loss
* Heart valve abnormalities
* Respiratory issues
* Hypermobile and dislocated joints
* Carpal tunnel syndrome
* Spinal cord compression
Treatment for MPS IV primarily focuses on managing symptoms, improving quality of life, and preventing complications. Enzyme replacement therapy (ERT) is available for Type B but not for Type A. Other treatments may include physical therapy, surgery, and medications to address specific symptoms.
Iduronidase is a type of enzyme that helps break down complex sugars called glycosaminoglycans (GAGs) in the body. Specifically, iduronidase is responsible for breaking down a type of GAG called dermatan sulfate and heparan sulfate.
Deficiency or absence of this enzyme can lead to a genetic disorder known as Mucopolysaccharidosis Type I (MPS I), which is characterized by the accumulation of GAGs in various tissues and organs, leading to progressive damage and impairment. There are two forms of MPS I: Hurler syndrome, which is the severe form, and Scheie syndrome, which is the milder form.
Iduronidase replacement therapy is available for the treatment of MPS I, in which the missing enzyme is delivered directly to the patient's body through intravenous infusion. This helps break down the accumulated GAGs and prevent further damage to the tissues and organs.
N-Acetylgalactosamine-4-Sulfatase is an enzyme that is responsible for breaking down complex carbohydrates in the body. Its specific function is to remove a sulfate group from a particular type of sugar molecule called N-acetylgalactosamine-4-sulfate, which is found on certain proteoglycans (large, complex sugars attached to proteins) in the body.
This enzyme plays an important role in the normal functioning of cells and tissues, particularly in the development and maintenance of bones, cartilage, and other connective tissues. Deficiencies in this enzyme can lead to a rare genetic disorder called Morquio A syndrome (also known as MPS IVA), which is characterized by skeletal abnormalities, short stature, and other health problems.
Chondro-4-sulfatase is an enzyme that belongs to the family of hydrolases, specifically those acting on ester bonds in sulfuric acid esters. It is responsible for catalyzing the hydrolysis of the 4-sulfate ester group from N-acetylgalactosamine 4-sulfate residues found in chondroitin 4-sulfate, a type of glycosaminoglycan (GAG) that is abundant in connective tissues such as cartilage.
Chondroitin 4-sulfate plays important roles in the structure and function of the extracellular matrix, including regulating cell adhesion, migration, and differentiation. The action of chondro-4-sulfatase helps to control the balance between sulfated and non-sulfated GAG chains, which is critical for maintaining normal tissue homeostasis.
Defects in chondro-4-sulfatase activity can lead to a rare genetic disorder called chondrodysplasia punctata type 1B (CDPX1B), also known as multiple sulfatase deficiency (MSD). This condition is characterized by skeletal abnormalities, developmental delay, and other neurological symptoms.
Iduronate sulfatase is an enzyme that plays a crucial role in the breakdown and recycling of complex sugars called glycosaminoglycans (GAGs). These GAGs are important components of various tissues, including connective tissues, bones, and cartilage.
Iduronate sulfatase is specifically responsible for breaking down a type of GAG known as dermatan sulfate and heparan sulfate by removing sulfate groups from specific sugar molecules in these GAGs. This enzyme is located in the lysosomes, which are membrane-bound organelles within cells that break down and recycle various materials.
Deficiency of iduronate sulfatase leads to a genetic disorder called Mucopolysaccharidosis Type II (MPS II), also known as Hunter syndrome. In this condition, the lack of functional iduronate sulfatase enzyme results in an accumulation of dermatan sulfate and heparan sulfate in various tissues and organs, leading to progressive damage and a range of symptoms, including developmental delays, coarse facial features, hearing loss, heart problems, and joint stiffness.
Chondroitin sulfatases are a group of enzymes that break down chondroitin sulfate, which is a type of glycosaminoglycan (GAG) found in connective tissues such as cartilage, bone, and skin. Glycosaminoglycans are long, complex chains of sugars that help provide structure, hydration, and elasticity to these tissues.
Chondroitin sulfate is composed of alternating units of glucuronic acid and N-acetylgalactosamine, with various sulfate groups attached at different positions along the chain. Chondroitin sulfatases cleave specific bonds within this structure to help regulate the turnover and remodeling of GAGs in tissues.
There are several types of chondroitin sulfatases (designated as chondroitin sulfatase A, B, C, D, etc.), each with distinct substrate specificities and cellular localizations. Defects in these enzymes can lead to various genetic disorders, such as skeletal dysplasias and neurodegenerative diseases, due to the accumulation of unprocessed or partially degraded chondroitin sulfate in tissues.
Enzyme Replacement Therapy (ERT) is a medical treatment approach in which functional copies of a missing or deficient enzyme are introduced into the body to compensate for the lack of enzymatic activity caused by a genetic disorder. This therapy is primarily used to manage lysosomal storage diseases, such as Gaucher disease, Fabry disease, Pompe disease, and Mucopolysaccharidoses (MPS), among others.
In ERT, the required enzyme is produced recombinantly in a laboratory using biotechnological methods. The purified enzyme is then administered to the patient intravenously at regular intervals. Once inside the body, the exogenous enzyme is taken up by cells, particularly those affected by the disorder, and helps restore normal cellular functions by participating in essential metabolic pathways.
ERT aims to alleviate disease symptoms, slow down disease progression, improve quality of life, and increase survival rates for patients with lysosomal storage disorders. However, it does not cure the underlying genetic defect responsible for the enzyme deficiency.
Glucuronidase is an enzyme that catalyzes the hydrolysis of glucuronic acid from various substrates, including molecules that have been conjugated with glucuronic acid as part of the detoxification process in the body. This enzyme plays a role in the breakdown and elimination of certain drugs, toxins, and endogenous compounds, such as bilirubin. It is found in various tissues and organisms, including humans, bacteria, and insects. In clinical contexts, glucuronidase activity may be measured to assess liver function or to identify the presence of certain bacterial infections.