Enzyme replacement therapy in mucopolysaccharidosis type I

Mucopolysaccharidosis (MPS) type I is a lysosomal storage disorder caused by deficiency of the enzyme alpha-L-iduronidase (IDUA), which presents with a wide spectrum of phenotypes. Recently, enzyme replacement therapy (ERT) became available for patients with MPS I and has been demonstrated to be safe and effective in patients with the milder Hurler-Scheie and Scheie phenotypes. Treatment for 26 weeks with recombinant human IDUA (laronidase) has been shown to significantly increase the percentage of predicted normal forced vital capacity and the distance walked in the 6-minute walk test. There was also a clear reduction in the volume of the liver and the levels of urinary glycosaminoglycan excretion. The drug was generally well tolerated. There were no drug-related severe adverse events, and although the majority of patients developed IgG antibodies, these declined by the end of the study. Conclusion: ERT seems to be a very promising new therapeutic regimen for patients with MPS I, especially for those with the less severe variants. However, as laronidase does not cross the blood-brain barrier it will probably not influence the central nervous manifestations in the most severely affected patients with the Hurler phenotype, although it may improve general lung and heart function, making bone marrow transplantation easier to tolerate.     

Enzyme replacement therapy in mucopolysaccharidosis type I

Mucopolysaccharidosis (MPS) type I is a lysosomal storage disorder caused by deficiency of the enzyme α- l -iduronidase (IDUA), which presents with a wide spectrum of phenotypes. Recently, enzyme replacement therapy (ERT) became available for patients with MPS I and has been demonstrated to be safe and effective in patients with the milder Hurler–Scheie and Scheie phenotypes. Treatment for 26 weeks with recombinant human IDUA (laronidase) has been shown to significantly increase the percentage of predicted normal forced vital capacity and the distance walked in the 6-minute walk test. There was also a clear reduction in the volume of the liver and the levels of urinary glycosaminoglycan excretion. The drug was generally well tolerated. There were no drug-related severe adverse events, and although the majority of patients developed IgG antibodies, these declined by the end of the study.
Conclusion: ERT seems to be a very promising new therapeutic regimen for patients with MPS I, especially for those with the less severe variants. However, as laronidase does not cross the blood–brain barrier it will probably not influence the central nervous manifestations in the most severely affected patients with the Hurler phenotype, although it may improve general lung and heart function, making bone marrow transplantation easier to tolerate.     

Incidence and prevalence of mucopolysaccharidosis type 1 in the Irish republic

Mucopolysaccharidosis type 1 (MPS1) is an autosomal recessive disorder with severe, moderate and mild phenotypes: Hurler, Hurler-Scheie and Scheie syndromes. We estimated incidence (2001-2006) and prevalence (2002 census) of MPS1 in the Irish Republic (ROI) using population data, database and chart review of all live MPS1 patients attending two specialised centres. Patient genotypes, ethnicity, province of origin, age at diagnosis and presenting features were recorded. Thirty-one patients (14 females, 17 males) were alive, 27 of whom were <15 years. Twenty-six patients had Hurler syndrome, four had Hurler-Scheie and one had Scheie syndrome. The birth incidence was 1 in 26 206 births with a carrier frequency of 1 in 81. Of note, 19/26 (73%) Hurler patients were Irish Travellers. Amongst Irish Travellers the incidence was 1 in 371 with a carrier frequency of 1 in 10. This is the highest recorded incidence worldwide. Given the morbidity and mortality associated with delayed treatment we recommend targeted newborn screening for this population.     

Mucopolysaccharidosis type I: identification of alpha-L-iduronidase mutations in Tunisian families]

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease due to mutations in the gene encoding alpha-l-iduronidase (IDUA) leading to variable clinical phenotypes with progressive severe organomegaly, bone and neurological involvement in the most severe forms. The aim of our study was to propose in Tunisia a strategy of molecular and prenatal diagnosis of the MPS I. POPULATION AND METHODS: Our study was carried out on 8 MPS I patients recruited from different Tunisian regions and issued from 5 unrelated families. All the patients were offspring of consanguineous marriages. RESULTS: The clinical and biological study led to diagnose 5 Hurler patients and 3 Hurler-Scheie patients. Three IDUA mutations were identified by molecular analysis within 6 different families: a novel mutation p.F602X and 2 already described mutations p.P533R and p.R628X. DISCUSSION: MPS I is a heterogeneous disease characterized by variability of the phenotypes. The missense mutation p.P533R associated with the intermediate phenotype was the most frequent in the Tunisian but also in the Moroccan population. In Tunisia, the incidence of p.P533R mutation seems to be associated with the high frequency of consanguineous marriages. CONCLUSION: The identification of known MPS I mutations (p.P533R and p.R628X) and of the novel mutation p.F602X permits reliable genetic counselling of at-risk relatives and molecular prenatal diagnosis.     

Enzyme replacement therapy for mucopolysaccharidosis I: a randomized, double-blinded, placebo-controlled, multinational study of recombinant human alpha-L-iduronidase (laronidase)

OBJECTIVE: To confirm the efficacy and safety of recombinant human alpha-L-iduronidase (laronidase) in patients with mucopolysaccharidosis I (MPS I). STUDY DESIGN: This was a randomized, double-blinded, multinational study of 45 patients with MPS I administered 100 U/kg (0.58 mg/kg) laronidase, or placebo intravenously weekly for 26 weeks. The coprimary efficacy end points compared the median change from baseline to week 26 between groups in percentage of predicted normal forced vital capacity (FVC) and in 6-minute walk test (6MWT) distance through the use of the Wilcoxon rank sum test. RESULTS: The laronidase (n=22) and placebo (n=23) groups had similar baseline characteristics. After 26 weeks, patients receiving laronidase compared with placebo showed mean improvements of 5.6 percentage points in percent of predicted normal FVC (median, 3.0; P=.009) and 38.1 meters in 6MWT distance (median, 38.5; P=.066; P=.039, analysis of covariance). Laronidase also significantly reduced hepatomegaly and urinary glycosaminoglycans, and, in more severely affected patients, improved sleep apnea/hypopnea and shoulder flexion. Laronidase was well-tolerated. Nearly all patients receiving enzyme had development of IgG antibodies, without apparent clinical effects. CONCLUSIONS: In patients with MPS I, laronidase significantly improves respiratory function and physical capacity, reduces glycosaminoglycan storage, and has a favorable safety profile.     

Hurler syndrome. Early diagnosis and successful enzyme replacement therapy: a new therapeutic approach. Case report]

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder due to alpha-L-iduronidase deficiency. Its severe prognosis has been significantly improved by enzyme replacement therapy using recombinant human alpha-L-iduronidase (laronidase). We report the case of a boy who was diagnosed at 19 months of age with Hurler's disease, the most severe form of MPS I, and received thereafter a treatment by laronidase, resulting in clinical and biological improvement. The aim of this case report is to draw physicians' attention on the presenting signs of Hurler's disease, in order to enable an earlier diagnosis, increasing the treatment's benefits.     

Morbus Gaucher, Mukopolysaccharidose Typ I (Scheie) und Morbus Fabry

Enzyme replacement therapies with the potential to improve prognosis are available for the lysosomal storage disorders Gaucher disease, mucopolysaccharidosis type I (MPS I-S; Scheie disease) and Fabry disease. Differential diagnosis is required to exclude a number of other conditions, including some rheumatic diseases. The bone pain associated with Gaucher disease can be misdiagnosed as juvenile idiopathic arthritis (JIA), and hepatosplenomegaly and pancytopenia may suggest collagen disorders. Symptoms such as contractures of the finger joints caused by Scheie disease can also imitate JIA. Fabry disease can also be confused with systemic JIA, collagen or vascular disorders, because of the pain it causes in hands and feet, sometimes associated with fever episodes, and renal and cerebrovascular symptoms. Critical evaluation of the clinical symptoms of lysosomal storage disorders in association with laboratory and test results should allow diagnosis of these diseases at an early stage, thereby facilitating better treatment and avoiding their misdiagnosis as any of several rheumatic diseases.     

Mucopolysaccharidoses type I and II: New neuroimaging findings in the cerebellum

BackgroundThe neuroimaging literature on mucopolysaccharidoses (MPS) is focusing mostly on supratentorial findings. Our study aims to extend the spectrum of neuroimaging findings in patients with MPS focusing on the cerebellum.MethodsTwelve patients were included (7 MPS type I and 5 MPS type II). The median age at last MRI was 9.9 years (mean age 10.1 years, range 1.8–28.8 years). All available brain MR images were retrospectively evaluated for infratentorial and supratentorial abnormalities with semiquantitative analysis and qualitative evaluation.ResultsInfratentorial findings included enlarged perivascular spaces (PVS) in the cerebellum in 7/12, mega cisterna magna in 3/12 and macrocerebellum in 2/12 patients. Enlarged cerebellar PVS developed later than those in the supratentorial brain and showed mild changes in size over time. The macrocerebellum developed progressively and seems to be caused by a thickening of the cortical cerebellar gray matter. Enlarged PVS in the brain stem were found in 10/12 patients. Supratentorial findings included enlarged PVS in all patients. Ventriculomegaly and white matter signal abnormalities were noted in 8/12, cerebral atrophy in 7/12 patients.ConclusionInvolvement of the posterior fossa structures in MPS I and II is not uncommon. Our study revealed two neuroimaging findings that have not been previously described in MPS: enlarged PVS in the cerebellum and a macrocerebellum. The pathogenesis and clinical significance of these new findings remain unclear and should be assessed in a larger cohort of patients.     

Biochemical and molecular analysis of mucopolysaccharidoses in Turkey

The mucopolysaccharidoses (MPSs) are a family of heritable disorders caused by deficiency of lysosomal enzymes needed to degrade glycosaminoglycans (GAGs). The undegraded or partially degraded GAGs are stored in lysosomes and/or excreted in urine. In our study, 118 patients seen over the past 20 years and suspected to have lysosomal storage disorders (LSDs) were subjected to clinical and biochemical analysis at Hacettepe University Children's Hospital. We analyzed urine and blood samples from 42 patients given a clinical MPS diagnosis. Using urine screening technique, we were able to show that 34 of the 42 patients had MPS condition. Further analysis of eight patients with normal urine MPS patterns revealed four patients as likely to have alpha-mannosidosis, fucosidosis, sialidosis, and aspartylglucosaminuria (one each). Four patients had normal oligosaccharide patterns. We were able to clearly identify 4 MPS I, 2 MPS II, 5 MPS IIIA, 8 MPS IIIB, 11 MPS IVA, 3 MPS VI, and 1 MPS IIIC patients. These results provided biochemical diagnosis for these 34 patients, and clearly show that Turkey has a higher incidence of MPS IVA, IIIB, and IIIA than of previously suspected MPS types. Molecular analysis of four MPS I patients revealed three polymorphisms which have been previously reported (A314, T388, and A461T). In MPS II patients, mutation analysis identified one previously detected (R172X) and one novel mutation (W109C).     

Clinical presentation and follow-up of patients with the attenuated phenotype of mucopolysaccharidosis type I

Aim: To review the heterogeneity and severity of the clinical features at the attenuated end of the mucopolysaccharidosis (MPS) type I disease spectrum. Methods: The course of disease in 29 patients with attenuated mucopolysaccharidosis I who attended the MPS clinic in Manchester, UK, was reviewed. Results: For more than half of the patients, onset of symptoms was in the first 2 y of life, and the age at diagnosis ranged from 15 mo to 40 y. Joint stiffness, corneal clouding, umbilical hernia and recurrent ear, nose and throat symptoms were the commonest features at presentation. Patients experienced significant morbidity during the course of this inherited disease. Skeletal problems predominated and cardiac valve pathology, upper airway obstruction and hearing deficits were detected in a notable number of patients. Nerve decompression for carpal tunnel syndrome, cervical cord decompression, and grommet insertion for serous otitis media were the most frequent surgical interventions.

Conclusion: Clinical presentation of attenuated (“non-Hurler”) mucopolysaccharidosis type I is heterogeneous in time of onset and types of clinical features. A better understanding of the spectrum of disease and of the related disease progression will contribute to more accurate diagnosis, and patients will benefit from early intervention.     

Mucopolysaccharidosis I and intracranial tumor in a patient with high-pressure hydrocephalus

In a 19-month-old patient with mucopolysaccharidosis I (Pfaundler-Hurler, MPS I/H) high-pressure hydrocephalus required the implantation of a ventriculoperitoneal shunt. Despite a reduction in both ventricular volume and intracranial pressure, clinical symptoms suggesting compression of the brain stem persisted. Brain MRI revealed a tumor within the posterior cranial fossa. Cytologic examination of the cerebrospinal fluid was suggestive of a poorly differentiated ependymoma. Highpressure hydrocephalus is a common complication in MPS I/H. As changes in mucopolysaccharide metabolism may be associated with an increased risk of developing neoplasms, the possibility of an intracranial tumor should be considered in patients with MPS I/H and high-pressure hydrocephalus.     

Enzyme replacement therapy: efficacy and limitations

Enzyme replacement therapy (ERT) is available for mucopolysaccharidosis (MPS) I, MPS II, MPS VI, and MPS IVA. The efficacy of ERT has been evaluated in clinical trials and in many post-marketing studies with a long-term follow-up for MPS I, MPS II, and MPS VI. While ERT is effective in reducing urinary glycosaminoglycans (GAGs) and liver and spleen volume, cartilaginous organs such as the trachea and bronchi, bones and eyes are poorly impacted by ERT probably due to limited penetration in the specific tissue. ERT in the present formulations also does not cross the blood–brain barrier, with the consequence that the central nervous system is not cured by ERT. This is particularly important for severe forms of MPS I and MPS II characterized by cognitive decline. For severe MPS I patients (Hurler), early haematopoietic stem cell transplantation is the gold standard, while still controversial is the role of stem cell transplantation in MPS II. The use of ERT in patients with severe cognitive decline is the subject of debate; the current position of the scientific community is that ERT must be started in all patients who do not have a more effective treatment. Neonatal screening is widely suggested for treatable MPS, and many pilot studies are ongoing. The rationale is that early, possibly pre-symptomatic treatment can improve prognosis. All patients develop anti-ERT antibodies but only a few have drug-related adverse reactions. It has not yet been definitely clarified if high-titre antibodies may, at least in some cases, reduce the efficacy of ERT.     

Early diagnosis and management of cardiac manifestations in mucopolysaccharidoses: a practical guide for paediatric and adult cardiologists

Mucopolysaccharidoses (MPS) are a group of hereditary disorders caused by lysosomal storage of glycosaminoglycans (GAGs) and characterized by a wide variability of phenotypes from severe fetal-neonatal forms to attenuated diseases diagnosed in adult individuals. The clinical picture generally worsens with age due to progressive storage involving mucosal tissue, upper airways and lungs, bones and joints, central and peripheral nervous system, heart, liver, eye, and ear. Cardiac storage of GAGs involves valves, heart muscle, and vessels (particularly the coronary arteries), and can be specific in relation to different MPS types and enzyme defects. MPS I, II, and VI are those with the most severe cardiac involvement. The cardiologist is a key figure in MPS, and their role is expanding from cardiac-specific management to early diagnosis when the mild disease phenotypes have not yet been recognized by other specialists. Familial and personal history, electrocardiography, imaging, and laboratory findings represent important steps in the clinical investigation of these patients. New treatments have led to an increased need for cardiologists to be on the lookout for MPS patients since they can significantly improve the lives of people with MPS if they suspect the diagnosis and refer them for enzyme replacement therapy or bone marrow transplantation.     

52例黏多糖病酶学分型及临床特点分析

目的：探讨黏多糖病（MPS）疾病谱及其临床特点。方法：对2009年1月至2011年12月75例高度疑似MPS患儿同时进行尿黏多糖（GAG）定量和电泳分析以及7种MPS酶学分析。采用荧光分析法分别检测白细胞α-L-艾杜糖酶、艾杜糖-2-硫酸酯酶、α-N-乙酰氨基葡糖苷酶、半乳糖胺-6-硫酸酯酶、β-半乳糖苷酶、芳基硫酸酯酶B及β-葡萄糖醛酸酶活性。结果：根据临床、放射学及酶学检查确诊MPS 52例,年龄4.0±2.2岁,其中I型5例（10%）,Ⅱ型20例（38%）,ⅣA型20例（38%）,Ⅵ型6例（12%）,Ⅶ型1例（2%）,未发现ⅢB、ⅣB型患儿。除2例ⅣA型患儿外,其余50例MPS 患儿尿GAG/Gr比值均较同龄儿增高。尿GAG定量增高者均确诊为MPS。绝大多数患儿于生后1~2岁起病,常伴有疝、心脏瓣膜病。Ⅰ、Ⅱ、Ⅵ 型患儿表现面容丑陋、皮肤粗糙、矮小、关节僵硬及活动受限,ⅣA型主要表现为矮小、骨骼畸形及关节松弛。结论：MPS Ⅱ型和ⅣA型是MPS最常见类型,其次是Ⅵ型及Ⅰ型。MPS患儿以特殊外貌为临床特点,包括面容丑陋、皮肤粗糙、矮小、骨骼畸形等。尿GAG定量测定可作为一种简便、快速、可靠的MPS筛查方法在临床上推广应用。     

Mucopolysaccharidosis type I in Morocco: clinical features and genetic profile]

BACKGROUND: Mucopolysaccharidoses (MPS) are inherited metabolic disorders due to lysosomal enzyme deficiencies, leading to glycosaminoglycan accumulation in lysosomes of different tissues. The aim of this study was to characterize MPS types, particularly MPS I, which are difficult to differentiate by clinical features. PATIENTS AND METHODS: Over a period of three years (June 1996-May 1999), 16 Moroccan patients (3-20 years old) with MPS were investigated. Twelve of them came from the Souss region. In subjects with suspected clinical MPS I or II, the diagnosis was confirmed by biochemical investigations, which included the quantification of total glycosaminoglycans (GAGs) released in urine, their identification, and the assay of alpha-L-iduronidase activity in leucocytes. A molecular analysis was performed in parallel, to provide the genetic proof of the diagnosis. RESULTS: These 16 patients belonged to 12 families, nine of which were consanguineous (75%). Twelve patients had Hurler syndrome and three had Hurler/Scheie's syndrome; no case of Scheie's syndrome was observed. Short stature, coarse face, organomegaly, hernia, cardiac disease, mental delay and dysostosis were observed in variable degrees. We report three cases without corneal clouding. Increased total urinary GAGs, identified as dermatan sulfate and heparan sulfate by thin-layer chromatography and total deficiency of alpha-L-iduronidase activity, were noted in studied subjects. At the molecular level the P533R mutation was detected in 24 among 26 alleles studied. CONCLUSION: It is now possible to perform the screening of MPS I and II in Morocco by analysis of clinical, radiologic observations and biological investigation. The predominance of P533R mutation could permit the screening of healthy heterozygotes and genetic counselling for families of Moroccan descent.     

多巴反应性肌张力障碍临床分析及GCH Ⅰ基因突变的研究

目的探讨多巴反应性肌张力障碍(DRD)临床及GTP环化水解酶Ⅰ(GCH Ⅰ)基因突变特点.方法对14例DRD患儿的临床资料进行总结分析,并对其中6例进行了GCH Ⅰ基因全长外显子的突变检测.结果14例患儿平均发病年龄为(10±3)岁,女性起病较男性早,发病年龄(9±4)岁,男性发病年龄(12±1)岁.常见的首发症状为步态异常、下肢僵硬和震颤.伴晨轻暮重者9例(64%).小剂量多巴制剂治疗3个月后痊愈13例(93%),显效1例(7%),长期随访未发现多巴制剂的不良反应.对6例患儿进行GCH Ⅰ基因突变检测,在3例患儿中发现了2种GCH Ⅰ基因突变.其中一家系2例患儿存在第6号外显子的Lys224Arg杂合错义突变,临床表型较轻,与国外研究报道一致.在1例散发病例中发现了国际上未曾报道过的位于第3号外显子的Gln161Pro突变,临床表型较重.结论DRD临床表现复杂多样,晨轻暮重是其特点之一.多巴制剂对其有快速、显著和持续的疗效.GCH Ⅰ基因突变类型与临床表型之间有一定关联,对GCH Ⅰ基因突变的检测有助于不典型病例的早期诊断.     

The mucopolysaccharidoses: A study of 48 cases

Based on precise diagnostic criteria, 48 cases of mucopolysaccharidoses (MPS) were recognized among 4604 cases referred over 7 years to a specialized Genetics Clinic, giving an incidence of 1.04% of all referred cases and 13.8% of all cases with inborn errors of metabolism (IEM). The subtypes seen most frequently were MPS IVA, MPS VI and MPS II. Most cases presented between 2–5 years of age with onset of symptoms since infancy. An unusually low frequency of skin lesions in patients with MPS II, 9/48 cases with hearing defects, six cases with cardiac disease and one child with paraparesis were some of the clinical manifestations noted. Radiological, biochemical and enzymatic studies are detailed. Clinical problems related to diagnosis of MPS are discussed.     

儿童晚期肝母细胞瘤伴肺转移综合诊疗分析:附12例报告

目的总结晚期儿童肝母细胞瘤伴肺转移的诊疗经验。方法收集2006年4月—2012年1月收治的12例经病理确诊及分期明确的晚期肝母细胞瘤伴有肺部转移患儿的临床资料,其中男7例、女5例。分析经化疗、介入治疗、手术治疗及自体外周血干细胞移植治疗的临床疗效及随访结果。结果至2012年2月,12例患儿完全缓解3例,部分缓解4例,死亡4例,进展1例,缓解率达到58.3%(7/12),其中10例患儿随访时间超过12个月(12～66月),95%平均生存可信区间是35.3～66.8月,5年生存率估计值为30.41%。结论肺是肝母细胞瘤最常见的转移部位,起病隐匿,预后较差,应注意早期、综合、规律治疗以提高生存率。     

Neurobehavioral phenotypes of neuronopathic mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of lysosomal multisystemic, chronic, and progressive diseases characterized by the storage of glycosaminoglycans (GAGs) that may affect the central nervous system. Neuronopathic MPS such as MPS IH, MPS II, MPS IIIA–D, and MPS VII are characterized by neurocognitive regression. In severe MPS I (MPS IH, or Hurler syndrome) initial developmental trajectory is usually unremarkable but cognitive development shows a plateau by 2 to 4 years of age and then progressively regresses with aging. Patients with neuronopathic MPS II have a plateau of cognitive and adaptive development on average by 4 to 4.5 years of age, although there is significant variability, followed by progressive neurocognitive decline. In patients with classic MPS III, developmental trajectory reaches a plateau around 3 years of age, followed by regression. Sleep disturbances and behavioral problems occur early in MPS II and III with features of externalizing disorders. Acquired autism-like behavior is often observed in children with MPS III after 4–6 years of age. Impaired social and communication abilities do occur, but MPS III children do not have restricted and repetitive interests such as in autism spectrum disorder. MPS type VII is an ultra-rare neuronopathic MPS with a wide clinical spectrum from very severe with early mortality to milder phenotypes with longer survival into adolescence and adulthood. Most patients with MPS VII have intellectual disability and severely delayed speech development, usually associated with hearing impairment. Cognitive regression in neuronopathic MPS runs parallel to a significant decrease in brain tissue volume. Assessment of the developmental profile is challenging because of low cognitive abilities, physical impairment, and behavioral disturbances. Early diagnosis is crucial as different promising treatment approaches have been extensively studied in animal MPS models and are currently being applied in clinical trials.     

I Cell Disease (Mucolipidosis II Alpha/Beta): From Screening to Molecular Diagnosis

Mucopolysaccharidosis (MPS) and Mucolipidosis (ML) share common phenotypes (coarse facial features, organomegaly, dysostosis multiplex) despite having different molecular basis. Thus, they pose great diagnostic challenge to treating clinicians. Differentiating between the two conditions requires a battery of tests from screening to molecular diagnosis. Besides discussing differential diagnosis of MPS like features with negative urinary Glycosaminoglycans (GAG), the authors also discuss the utility of p-nitrocatechol sulphate based chemical test as an important screening tool, besides establishing molecular basis in index case.