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Background: Mucolipidosis type II (MLII) is an ultra-rare lysosomal storage disorder caused by defective lysosomal enzyme trafficking. Clinical hallmarks are craniofacial dysmorphia, cardiorespiratory dysfunction, hepatosplenomegaly, skeletal deformities and neurocognitive retardation. Death usually occurs in the first decade of life and no cure exists. Hematopoietic stem cell transplantation (HSCT) has been performed in few MLII patients, but comprehensive follow-up data are extremely scarce. Methods: MLII diagnosis was confirmed in a female three-month-old patient with the mutations c.2213C > A and c.2220_2221dup in the GNPTAB gene. At nine months of age, the patient received HSCT from a 9/10 human leukocyte antigen (HLA)-matched unrelated donor. Results: HSCT resulted in a sustained reduction of lysosomal storage und bone metabolism markers. At six years of age, the patient showed normal cardiac function, partial respiratory insufficiency and moderate hepatomegaly, whereas skeletal manifestations had progressed. However, the patient could walk and maintained an overall good quality of life. Neurocognitive testing revealed a developmental quotient of 36%. The patient died at 6.6 years of age following a human metapneumovirus (hMPV) pneumonia. Conclusions: The exact benefit remains unclear as current literature vastly lacks comparable data on MLII natural history patients. In order to evaluate experimental therapies, in-depth prospective studies and registries of untreated MLII patients are indispensable.

Background: Mucolipidosis II α/β (ML II) is an autosomal recessive disease associated with the abnormality of lysosomal enzyme trafficking. Case presentation: We present an unusual patient with: (a) marked skeletal anomalies with secondary hyperparathyroidism; (b) serum intact parathyroid hormone level normalized by 7 weeks but abnormally elevated serum alkaline phosphate persisted; and (c) two mutations identified in the GNPTAB gene. One mutation, c.3503_3504delTC, is the most common mutation in ML II. However, the second mutation, c.2896delA, is a rare mutation for which clinical presentation has not been described previously. [ABSTRACT FROM AUTHOR]

Objective: The present study aims to provide orientation for clinicians and radiologists to recognize the most prevalent findings leading to diagnosis in mucolipidosis from a description of the natural history of five Brazilian cases.Materials and Methods: We conducted an observational and retrospective study of five patients with clinical and radiological diagnosis of mucolipidosis. Clinical evaluation consisted of information obtained from records and including physical, neurologic, and dysmorphic evaluations. Radiologic studies consisted of complete skeletal radiographs of all patients. Enzyme assessment was performed for confirmation of the diagnosis.Results: The five patients were referred for genetic evaluation due to disproportionate short stature with short trunk accompanied by waddling gait. Age at referral varied from 11 months to 28 years. The most prevalent findings were joint restriction (4/5 patients), neuropsychomotor developmental delay (3/5), coarse facies (2/5), hypertrophic cardiomyopathy (2/5), and mental retardation (1/4 patients). The most common radiological findings were anterior beaking of the vertebral bodies (5/5), shallow acetabular fossae (5/5), epiphyseal dysplasia (5/5), platyspondyly (4/5), pelvic dysplasia (4/5), decreased bone mineralization (4/5), scoliosis (3/5), wide and oar-shaped ribs (3/5), generalized epiphyseal ossification delay (3/5), and hypoplasia of basilar portions of ilea (3/5). Enzyme assessment showed α-iduronidase, α-mannosidase, β-glucuronidase, hexosaminidase A, and total hexosaminidase increased in plasma and normal glycosaminoglycans concentration. One patient was clinically classified as ML II and four patients as ML III.Conclusions: The follow-up of five patients showed the typical clinical and radiological findings allowing the diagnosis, thus improving clinical management and providing adequate genetic counseling. Clinicians and radiologists can take advantage of the information from this work, enhancing their differential diagnosis ability. [ABSTRACT FROM AUTHOR]

Mucolipidosis type II (ML-II, I-cell disease) is a fatal inherited lysosomal storage disease caused by a deficiency of the enzyme N-acetylglucosamine-1-phosphotransferase. A characteristic skeletal phenotype is one of the many clinical manifestations of ML-II. Since the mechanisms underlying these skeletal defects in ML-II are not completely understood, we hypothesized that a defect in osteogenic differentiation of ML-II bone marrow mesenchymal stem cells (BM-MSCs) might be responsible for this skeletal phenotype. Here, we assessed and characterized the cellular phenotype of BM-MSCs from a ML-II patient before (BBMT) and after BM transplantation (ABMT), and we compared the results with BM-MSCs from a carrier and a healthy donor. Morphologically, we did not observe differences in ML-II BBMT and ABMT or carrier MSCs in terms of size or granularity. Osteogenic differentiation was not markedly affected by disease or carrier status. Adipogenic differentiation was increased in BBMT ML-II MSCs, but chondrogenic differentiation was decreased in both BBMT and ABMT ML-II MSCs. Immunophenotypically no significant differences were observed between the samples. Interestingly, the proliferative capacity of BBMT and ABMT ML-II MSCs was increased in comparison to MSCs from age-matched healthy donors. These data suggest that MSCs are not likely to cause the skeletal phenotype observed in ML-II, but they may contribute to the pathogenesis of ML-II as a result of lysosomal storage-induced pathology. [ABSTRACT FROM AUTHOR]

My initial research experience involved studying how bacteria synthesize nucleotide sugars, the donors for the formation of cell wall polysaccharides. During this time, I became aware that mammalian cells also have a surface coat of sugars and was intrigued as to whether these sugars might be arranged in specific sequences that function as information molecules in biologic processes. Thus began a long journey that has taken me from glycan structural analysis and determination of plant lectin-binding preferences to the biosynthesis of Asn-linked oligosaccharides and the mannose 6-phosphate (Man-6-P) lysosomal enzyme targeting pathway. The Man-6-P system represents an early example of a glycan serving as an information molecule in a fundamental cellular function. The remarkable advances in the field of glycobiology since I entered have uncovered scores of additional examples of oligosaccharide-lectin interactions mediating critical biologic processes. It has been a rewarding experience to participate in the efforts that have established a central role for glycans in biology. [ABSTRACT FROM AUTHOR]

Background: Although mucolipidosis type II has similar metabolic abnormalities to those found in all the mucopolysaccharidoses and mucolipidoses, there are distinctive diagnostic radiographic changes of mucolipidosis II in the perinatal/newborn/infant period.Objective: To describe the early characteristic radiographic changes of mucolipidosis II and to document when these changes manifest and resolve.Materials and Methods: We retrospectively reviewed radiographs and clinical records of 19 cases of mucolipidosis II from the International Skeletal Dysplasia Registry (1971-present; fetal age to 2½ years). A radiologist with special expertise in skeletal dysplasias evaluated the radiographs.Results: The most common abnormalities were increased vertebral body height (80%, nonspecific), talocalcaneal stippling (86%), periosteal cloaking (74%) and vertebral body rounding (50%). Unreported findings included sacrococcygeal sclerosis (54%) and vertebral body sclerosis (13%). Rickets and hyperparathyroidism-like (pseudohyperparathyroidism) changes (rarely reported) were found in 33% of cases. These changes invariably started in the newborn period and resolved by 1 year of age. The conversion from these early infantile radiographic features to dysostosis multiplex changes occurred in 41% of cases, and within the first year after birth.Conclusion: Several findings strongly suggest the diagnosis of mucolipidosis II, including cloaking in combination with one or more of the following radiographic criteria: talocalcaneal stippling, sacrococcygeal or generalized vertebral body sclerosis, vertebral body rounding, or rickets/hyperparathyroidism-like changes in the perinatal/newborn/infancy period. These findings are not found in the other two forms of mucolipidosis nor in any of the mucopolysaccharidoses. [ABSTRACT FROM AUTHOR]

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I-cell disease (mucolipidosis II) is a rare metabolic disorder resulting from the deficiency of a specific lysosomal enzyme, N-acetylglucosamine-1-phosphotransferease. Developmental delay and growth failure are common presentations of I-cell disease. Psychomotor deterioration is rapid and progressive. Some physical signs such as hip dislocations, inguinal hernia, hepatomegaly, joint limitation, and skin changes may be present at birth. Coarse facial features and skeletal abnormalities become more conspicuous with time. The life expectancy of children with this condition is poor, with death usually occurring around the fifth year. A case report of the anesthetic management of gingivectomy with multiple dental extractions in a 5-year-old Omani female with I-cell disease is presented. The problems faced and their management during anesthesia are described.

Mucolipidosis type II (MLII), or I-cell disease, is a rare but severe disorder affecting localization of enzymes to the lysosome, generally resulting in death before the 10th birthday. Although hematopoietic stem cell transplantation (HSCT) has been used to successfully treat some lysosomal storage diseases, only 2 cases have been reported on the use of HSCT to treat MLII. For the first time, we describe the combined international experience in the use of HSCT for MLII in 22 patients. Although 95% of the patients engrafted, overall survival was low, with only 6 patients (27%) alive at last follow-up. The most common cause of death post-transplant was cardiovascular complications, most likely due to disease progression. Survivors were globally delayed in development and often required complex medical support, such as gastrostomy tubes for nutrition and tracheostomy with mechanical ventilation. Although HSCT has demonstrated efficacy in treating some lysosomal storage disorders, the neurologic outcome and survival for patents with MLII were poor. Therefore, new medical and cellular therapies should be sought for these patients. [ABSTRACT FROM AUTHOR]

Abstract: Mucolipidosis type II is an autosomal recessive lysosomal storage disease caused by N-acetylglucosamine-1-phosphotransferese deficiency. We report here pathological findings of an autopsy case of mucolipidosis type II. The patient was an 8-year-old boy with mucolipidosis type II and was complicated with hypertrophic cardiomyopathy. He suddenly developed progressive respiratory failure and finally died. At autopsy, systemic accumulation of undigested lysosomal metabolites was prominent, particularly in the heart, lungs, and dorsal root ganglion. In cardiomyocyte, LC3, an autophagy marker, was positive in the cytoplasm. Ubiquitin, p62, K48 polyubiquitin, and K63 polyubiquitin were also positive in the cytoplasm. Our findings suggest that autophagic dysfunction might be associated with the cardiomyopahty of mucolipidosis type II. [Copyright &y& Elsevier]

Abstract: Mucolipidosis II and III (MLII and MLIII) alpha/beta are rare autosomal recessive lysosomal storage diseases (LSDs) caused by pathogenic variations in the GNPTAB gene. GNPTAB gene codes for the α and β subunits of phosphotransferase, the enzyme responsible for synthesis of the mannose-6-phosphate (M6P) marker that directs lysosomal enzymes to the lysosome. Objectives: The objective of this study is to identify sequence variations of the GNPTAB gene in Brazilian patients with MLII and MLIII alpha/beta. Method: Sequencing of the GNPTAB gene was performed in samples of gDNA extracted from the peripheral blood of patients with MLII/III diagnosed at a national reference center for LSDs. Results: Twelve unrelated patients, from several regions of Brazil, were included in this study. Only one was born of consanguineous parents. All patients were found to carry at least one nonpathogenic variation. Nine causal sequence variations were found: c.242G>T (p.W81L); c.1123C>T (p.R375X); c.1196C>T (p.S399F); c.1208T>C (p.I403T); c.1514G>A (p.C505Y); c.1759C>T (p.R587X); c.2808A>G (p.Y937_M972del, novel mutation); c. 2269_2273delGAAAC (p.E757KfsX2, novel mutation); and c.3503_3504delTC (p.L1168QfsX5). Both pathogenic variations were identified in 8 of 12 patients; in four patients, only one pathogenic variation was identified. Mutation c.3503_3504delTC, located in exon 19, was the most frequent pathogenic variation found (n=11/24 alleles). The deleterious effect of the c.2808A>C mutation on splicing was confirmed by cDNA analysis. Discussion/conclusions: Our findings confirm that the GNPTAB gene presents broad allelic heterogeneity and suggests that, in Brazilian ML II and III patients, screening for mutations should begin at exon 19 of the GNPTAB gene. Further analyses will be conducted on patients in whom both pathogenic mutations have not been found in this study. [Copyright &y& Elsevier]

Abstract: MRI of a female patient with genetically diagnosed I-cell disease at 2weeks, 4 and 8months revealed delayed myelination or hypomyelination with decreased choline on MR spectroscopy. Brain autopsy was performed 2h after death at 14-month-old. Immunoreactivities for myelin basic protein and proteolipid proteins, markers for mature myelin sheath, were reduced in the myelinated fibers and oligodendrocytes in the white matter, indicating the hypomyelination in the central nervous system. I-Cell disease should be added to the list of delayed or hypomyelination conditions, and this neuroimaging finding could be a key for differentiating I-cell disease from the clinically similar disorder of Hurler syndrome characterized by perivascular lacunation. [Copyright &y& Elsevier]

Mucolipidosis type II (ML II) is an autosomal recessive lysosomal targeting disorder that may present with features of hyperparathyroidism. The aim of this study was to describe in detail the clinical cases of ML II presenting to a tertiary referral centre with biochemical and/or radiological features of hyperparathyroidism. There were twenty-three children diagnosed with ML II in the Republic of Ireland from July 1998 to July 2021 inclusive (a 23-year period). The approximate incidence of ML II in the Republic of Ireland is, therefore, 1 per 64,000 live births. Medical records were available and were reviewed for 21 of the 23 children. Five of these had been identified as having biochemical and/or radiological features of hyperparathyroidism. Of these five, three children were born to Irish Traveller parents and two to non-Traveller Irish parents. All five children had radiological features of hyperparathyroidism (on skeletal survey), with evidence of antenatal fractures in three cases and an acute fracture in one. Four children had biochemical features of secondary hyperparathyroidism. Three children received treatment with high dose Vitamin D supplements and two who had antenatal/acute fractures were managed with minimal handling. We observed resolution of secondary hyperparathyroidism in all cases irrespective of treatment. Four of five children with ML II and hyperparathyroidism died as a result of cardiorespiratory failure at ages ranging from 10 months to 7 years. Biochemical and/or radiological evidence of hyperparathyroidism is commonly identified at presentation of ML II. Further studies are needed to establish the pathophysiology and optimal management of hyperparathyroidism in this cohort. Recognition of this association may improve diagnostic accuracy and management, facilitate family counseling and is also important for natural history data. [ABSTRACT FROM AUTHOR]

Mucolipidosis (ML) II alpha/beta and III alpha/beta are autosomal recessive diseases caused by a deficiency of α and/or β subunits of the enzyme N-acetylglucosamine-1-phosphotransferase, which is encoded by the GNPTAB gene. We analyzed the GNPTAB gene in 25 ML II and 15 ML III Japanese patients. In most ML II patients, the clinical conditions ‘stand alone’, ‘walk without support’ and ‘speak single words’ were impaired; however, the frequency of ‘heart murmur’, ‘inguinal hernia’ and ‘hepatomegaly and/or splenomegaly’ did not differ between ML II and III patients. We detected mutations in GNPTAB in 73 of 80 alleles. Fourteen new mutations were c.914_915insA, c.2089_2090insC, c.2427delC, c.2544delA, c.2693delA, c.3310delG, c.3388_3389insC+c.3392C>T, c.3428_3429insA, c.3741_3744delAGAA, p.R334L, p.F374L, p.H956Y, p.N1153S and duplication of exon 2. Previously reported mutations were p.Q104X, p.W894X, p.R1189X and c.2715+1G>A causing skipping of exon 13. Homozygotes or compound heterozygotes of nonsense and frameshift mutations contributed to the severe phenotype. p.F374L, p.N1153S and splicing mutations contributed to the attenuated phenotype, although coupled with nonsense mutation. These results show the effective molecular diagnosis of ML II and III and also provide phenotypic prediction. This is the first and comprehensive report of molecular analysis for ML patients of Japanese origin.Journal of Human Genetics (2009) 54, 145–151; doi:10.1038/jhg.2009.3; published online 6 February 2009 [ABSTRACT FROM AUTHOR]

Mucolipidosis (ML) II (I-cell disease) is a lysosomal storage disorder caused by a deficiency of UDP- N-acetylglucosamine:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase. MLII is an autosomal recessive disease with a carrier rate estimated at 1/39 in Saguenay–Lac-Saint-Jean (SLSJ) (Quebec, Canada), which is the highest frequency documented worldwide. To identify the causing mutation, we sequenced GNPTAB exons in 27 parents of 16 MLII-deceased children from the SLSJ region as obligatory and potential carriers. We also performed a genealogical reconstruction for each parent to evaluate consanguinity levels and genetic contribution of ancestors. Our goal was to identify which parameters could explain the high MLII frequency observed in the SLSJ population. A single mutation (c.3503_3504delTC) was found in all obligatory carriers. In addition, 11 apparent polymorphisms were identified. The mutation was not detected in genomic DNA of 50 unrelated controls. Genealogical data show six founders (three couples) with a higher probability of having introduced the mutation in the population. The frequency of the mutation was increased as a consequence of this founder effect and of the resulting population structure. We suggest that c.3503_3504delTC is the allele causing MLII in the SLSJ population, and its high carrier rate is most likely explained by a founder effect. [ABSTRACT FROM AUTHOR]

Abstract: Mucolipidosis type II (ML II) is a fatal, autosomal recessive, lysosomal storage disorder characterized by severe clinical and radiologic features. ML II results from mutations in alpha and beta subunits, encoded by the GlcNAc-1-phosphotransferase gene (GNPTAB). Most of the 40 different GNPTAB mutations reported so far are insertions and deletions predicting diverse types of aberrant proteins. Alu mobile elements have however never been involved in these events up to now. The Italian ML II patient of our study showed an Alu retrotrasposition in GNPTAB exon 5. The Alu insertion mutation (NM_024312.3:c.555_556insHSU14569) generated a transcript with a skipping of the target exon 5 and a frameshift p.S122fs, causing a premature translation termination codon at position 123. This insertion mutation was found in compound heterozygosity with the frameshift p.S887KfsX33, resulting from a new mono-nucleotide duplication (c.2659dupA) that occurred in GNPTAB exon 13. A possible involvement of cis-splicing elements having an exonic location, such as exon enhancers (ESEs), is discussed as mechanism that led to the production of the aberrant mRNA splicing. [Copyright &y& Elsevier]

Abstract: Background: In cultured fibroblasts from I-cell disease patients the transport of many lysosomal enzymes is defective, and affected cells contain inclusion bodies filled with undegraded substrates. However, the contents of these inclusion bodies have not been well characterized yet. We attempted to identify accumulated substances in cultured I-cell disease fibroblasts cytochemically. Methods: Cultured fibroblasts from I-cell disease patients were double-stained with a monoclonal antibody to lysosome-associated membrane protein-1 (LAMP-1) and that to GM2 ganglioside, or a series of lectins that specifically bind to sugar moieties. Results: The patients'' cells were granularly stained with the antibody to GM2 ganglioside and the lectins including Maakia amurensis, Datura stramonium, and concanavalin A. Their localization was coincident with that of LAMP-1. Conclusions: GM2 ganglioside and various kinds of glycoconjugates having sialic acidα2-3galactose, galactoseβ1-4N-acetylglucosamine and mannose residues accumulate in enlarged lysosomes in I-cell disease fibroblasts. [Copyright &y& Elsevier]

Abstract: Although the role of the cytoplasmic tail of the cation-independent mannose 6-phosphate receptor (CIMPR) has been well established in the receptor trafficking, that of the luminal domain is still controversial. We noticed that the peripheral distribution of GFP, fused to the transmembrane and cytoplasmic domains of CIMPR (G-CIMPR-tail), was distinct from that of endogenous CIMPR or of GFP fused to the full-length CIMPR (G-CIMPR-full). By live-cell imaging, trans-Golgi-network (TGN)-derived transport carriers containing G-CIMPR-full more frequently stopped and overlapped with transferrin-containing endosomes in the peripheral region than those containing G-CIMPR-tail. G-CIMPR-full was recycled back to the perinuclear TGN more slowly than that for G-CIMPR-tail, evidenced by fluorescence recovery after photobleaching analysis. Moreover, endogenous CIMPR and G-CIMPR-full, but not GFP-CIMPR-tail, drastically altered the characteristic distribution after treatment with chloroquine. A mutant receptor, G-CIMPR-full R/A, that cannot recognize the mannose 6-phosphate (M6P)-signal, behaved similarly to G-CIMPR-full, indicating that these differences are not attributable to the M6P-ligands binding situation. Interestingly, we also found that U18666A treatment was able to discriminate the M6P-ligand binding-dependent trafficking of CIMPR. Based on these findings, we propose that the CIMPR luminal domain is required for tight interaction with endocytic compartments, and retention by them, and that there are additional transport steps, in which the binding to M6P-ligands is involved. [Copyright &y& Elsevier]

Hyaluronidases are endo-glycosidases that degrade both hyaluronan (hyaluronic acid) (HA) and chondroitin sulfates. Deficiency of hyaluronidase activity has been predicted to result in a phenotype similar to that observed in mucopolysaccharidosis (MPS). In the present study, we surveyed a variety of patients with phenotypes similar to those observed in MPS, but without significant mucopolysacchariduria to determine if some are based on aberrations in serum hyaluronidase (Hyal-1) activity. The study included patients with well-characterized dysmorphic disorders occurring on genetic basis, as well as those of unkown etiology. The purpose of the study was to establish how wide spread were abnormalities in levels of circulating Hyal-1 activity. A simple and sensitive semi-quantitative zymographic procedure was used for the determination of activity. Levels of both ß - N-acetylglucosaminidase and ß -glucuronidase whose activities contribute to the total breakdown of hyaluronan (HA) were also measured, as well as the concentration of circulating HA. Among 48 patients with bone or connective tissue abnormalities, low levels of Hyal-1 activity were found in six patients compared to levels in 100 healthy donors (2.0–3.2 units/μL vs 6(± 1 SE) units/μL). These six patients exhibited a wide spectrum of clinical abnormalities, in particular shortened extremities: they included three patients with unknown causes of clinical symptoms, one patient with Sanfilippo disease, one of the seven patients with achondroplasia, and one with hypophosphotemic rickets. Normal levels of serum Hyal-1 activities were found in patients with Morquio disease, GM1 gangliosidosis, I cell-disease, 6 of the 7 patients with achondroplasia, Marfan's-syndrome and Ehlers-Danlos syndrome. No patient totally lacked serum Hyal-1 activity. Serum HA concentration was elevated in patients with Sanfilippo A and I-cell disease. Determination of serum and leukocyte Hyal-1 and serum HA may be useful to evaluate patients with metabolic and morphogenetic disorders. [ABSTRACT FROM AUTHOR]

Unlabelled: Mucolipidosis II (ML II or I-cell disease ) (OMIM 252500) is an autosomal recessive lysosomal enzyme targeting disorder that usually presents between 6 and 12 months of age with a clinical phenotype resembling Hurler syndrome and a radiological picture of dysostosis multiplex. When ML II is severe enough to be detected in the newborn period, the radiological changes have been described as similar to hyperparathyroidism or rickets. The biological basis of these findings has not been explored and few biochemical measurements have been recorded. We describe three unrelated infants with ML II who had radiological features of intrauterine hyperparathyroidism and biochemical findings consistent with severe secondary neonatal hyperparathyroidism (marked elevation of serum parathyroid hormone and alkaline phosphatase levels). The vitamin D metabolites were not substantially different from normal and repeatedly normal calcium concentrations excluded vitamin D deficiency rickets and neonatal severe hyperparathyroidism secondary to calcium-sensing receptor gene mutations (OMIM 239200). The pathogenesis of severe hyperparathyroidism in the fetus and newborn with ML II is unexplained. We hypothesize that the enzyme targeting defect of ML II interferes with transplacental calcium transport leading to a calcium starved fetus and activation of the parathyroid response to maintain extracellular calcium concentrations within the normal range.Conclusion: Newborns with mucolipidosis II can present with radiological and biochemical signs of hyperparathyroidism. Awareness of this phenomenon may help in avoiding diagnostic pitfalls and establishing a proper diagnosis and therapy. [ABSTRACT FROM AUTHOR]

To better understand the role of lysosomes in apoptosis, we compared the responses to apoptotic stimuli of normal fibroblasts with those of inclusion cells (I-cells), i.e., fibroblasts with impaired function of lysosomal enzymes due to their missorting and ensuing nonlysosomal localization. Although both cell types did undergo apoptosis when exposed to the lysosomotropic detergent MSDH, the redox-cycling quinone naphthazarin, or the protein kinase inhibitor staurosporine, I-cells exerted a markedly decreased response to these agonists than did normal fibroblasts. Furthermore, leupeptin and pepstatin A (inhibitors of cysteine and aspartic proteases, respectively) suppressed staurosporine-induced apoptosis of normal fibroblasts, whereas survival of I-cells was unaffected. These findings give further support for the involvement of lysosomal enzymes in apoptosis and suggest I-cells as a suitable model for studying the role of lysosomes in programmed cell death. [Copyright &y& Elsevier]

I-cell disease (Mucolipidosis II) is one of the lysosomal storage diseases which presents in the neonatal period, and within six months will phenotypically resemble the severe forms of the group of disorders called the "mucopolysaccharidoses" but without mucopolysacchariduria. In Mucolipidosis II, fibrocytes exhibit "abnormal lysosomes". Activities of several lysosomal enzymes are low in fibroblast cultures but high in mucolipidosis II serum. We present a patient with I-cell disease diagnosed on the basis of clinical, radiological and biochemical features. The mother of this child was pregnant and the fetus was also found to be affected. [ABSTRACT FROM AUTHOR]

Inclusion-cell disease (mucolipidosis II/I-cell disease) is a lysosomal storage disease characterized by a constellation of physical findings which complicate airway management. There is currently a deficit of published literature describing appropriate strategies for acute management of these children's airways. This paper details emergency and anesthetic airway management concerns and potential solutions in a small series of children with I-cell disease. [ABSTRACT FROM AUTHOR]

In a case of infantile mucolipidosis type II (I-cell disease), storage was identified at autopsy in serous-type secretory cells in exocrine pancreas, in the tracheal and sublingual salivary glands and in the chief (zymogenic) cells of the gastric oxyntic glands, suggesting a systemic involvement of this type of secretory cells. The content of specific secretory granules was inversely proportional to the intensity of the storage process. The mucus-producing cells were not affected. The serous glandular system is a novel storage site in I-cell disease. Review of archival material in three further cases confirmed the findings. [ABSTRACT FROM AUTHOR]

Mannose 6-phosphate is a recognition marker used by many newly made acid hydrolases for their transport to lyso-somes. Previously, we investigated the incorporation of Pi into α-L-fucosidase of lymphoid cell lines from a healthy individual (control) and an I-cell disease patient [DiCioccio and Miller, , 1, 595–604 (1991)]. Phosphoserine was found in immunoprecipitable α-L-fucosidase of both control and I-cell lymphoid cells, but mannose 6-phosphate was identified only in enzyme of control cells. Extension of this investigation to lymphoid cultures of a pseudo-Hurler polydystrophy patient also identified only phosphoserine in α-L-fucosidase. Using [H] mannose instead of Pi, the precise identification of mannose 6-phosphate in α-L-fucosidase of control cells, and its absence in α-L-fucosidase of I-cell and pseudo-Hurler cells, was established. The stoichiometry of phosphorylation of α-L-fucosidase in I-cell, pseudo-Hurler and control lymphoid cells was 3, 4 and 10 mol Pi/mol enzyme, respectively. α-L-Fucosidase was located in lysosomes isolated from control, I-cell and pseudo-Hurler lymphoid cells by subcelluar fractionation on Percoll density gradients. Both I-cell and pseudo-Hurler lymphoid cells displayed normal intralysosomal activity of α-L-fucosidase despite lack of the mannose 6-phosphate marker. Thus, I-cell and pseudo-Hurler lymphoid cells must possess a mannose 6-phosphate-independent mechanism for directing α-L-fucosidase to lysosomes. Phosphorylation of α-L-fucosidase in pseudo-Hurler and I-cell lymphoid cultures was found almost exclusively in intracellular and not in extracellular enzyme, suggesting that phosphoserine may participate in the localization of α-L-fucosidase in lysosomes of these cells. [ABSTRACT FROM PUBLISHER]

We previously reported that I-cell disease lymphoblasts maintain normal or near-normal intracellular levels of lysosomal enzymes, even though -acetylglucosamine-1-phosphotransferase activity is severely depressed or absent (Little , 248, 151–159, 1987). The present study, employing subcellular fractionation on colloidal silica gradients, indicates that both light and heavy lysosomes isolated from I-cell disease and pseudo-Hurler polydystrophy lymphoblasts possess normal specific activity levels of -acetyl-β-D-hexosaminidase, α-D-mannosidase and β-D-glucuronidase. These current findings are in contrast to those of cultured fibroblasts from the same patients, where decreased intralysosomal enzyme activities are found. Column chromatography on revealed that N-acetyl-β-D-hexosaminidase in both heavy and light I-cell disease lysosomal fractions from lymphoblasts possesses an increased number of accessible galactose residues (30–50%) as compared to the enzyme from the corresponding normal controls. Endo-β--acetylglucos-aminidase H treatment of -acetyl-β-D-hexosaminidase from the I-cell lysosomal fractions suggests that the majority of newly synthesized high-mannose-type oligosaccharide chains are modified to complex-type carbohydrates prior to being transported to lysosomes. This result from lymphoblasts differs from previous findings with fibroblasts, where -acetyl-β-D-hexosaminidase from I-cell disease and pseudo-Hurler polydystrophy lysosomes exhibited properties associated with predominantly high-mannose-type oligosaccharide chains. The current results imply that different cell types may modify the carbohydrate side chains of lysosomal enzymes in a differential manner, and that selected cell types may also employ mechanisms other than the mannose-6-phosphate pathway for targeting lysosomal enzymes to lysosomes. [ABSTRACT FROM PUBLISHER]

-Acetylglucosamine 1-phosphotransferase is a key enzyme required for synthesis of the mannose 6-phosphate recognition marker that is used by many newly made acid hydrolases for their transport to lysosomes. It has previously been found that lymphoid cells from patients with I-cell disease and pseudo-Hurler polydystrophy have nearly normal intracellular and intralysosomal activities of several lysosomal acid hydrolases, despite a deficiency of -acetylglucosamine 1-phosphotransferase. These results suggest that lymphoid cells may provide an important system to investigate alternate mechanisms for targeting newly made acid hydrolases to lysosomes. In the present study, the biosynthesis, processing and secretion of α-L-fucosidase in I-cell and pseudoHurler lymphoid cells was used as a model system to study the existence of such mechanisms. The level of intracellular α-L-fucosidase protein in exponentially growing I-cell or pseudo-Hurler lymphoid cultures was statistically indistinguishable from the mean of 19 control cultures. A 1.5 h [S]methionine pulse experiment showed that α-L-fucosidase is initially sythesized by I-cell, pseudo-Hurler and control cultures as an intracellular form (M = 58 000). Companion cultures chased with methionine from 2 to 21 h processed the enzyme to an intracellular form (M = 60 000) and an extracellular form (M = 62 000). All enzyme forms were glycoproteins with polypeptide chains of Mr 52 000. In control cells incubated with radioactive inorganic phosphate (Pi), <1% of the Pi incorporated into α-L-fucosidase was associated with carbohydrate chains and >99% with polypeptide chains. In I-cell disease lymphoid cells, the Pi incorporated into α-L-fucosidase was associated solely with polypeptide chains. A qualitative analysis of phosphorylated residues identified phosphoserine in α-L-fucosidase from control and I-cell lymphoid cells. Only α-L-fucosidase from control cells contained mannose 6-phosphate. These results are consistent with the proposal that I-cell lymphoid cells may use a mannose 6-phosphate-independent mechanism for routing α-L-fucosidase. Additional metabolic labelling experiments demonstrated the presence of P-labelled α-L-fucosidase in both cells and medium of a control lymphoid culture, but only in cells of an I-cell lymphoid culture. In contrast, α-L-fucosidase labelled with [S]methionine was found in cells and medium of control and I-cell lymphoid cultures. Since phosphoserine was only found to occur in intracellular, but not in extracellular α-L-fucosidase of the I-cell culture, we speculate that phosphoserine may be involved in intracellular retention of α-L-fucosidase in I-cell lymphoid cells. [ABSTRACT FROM PUBLISHER]

Fibroblasts derived from patients with I-cell disease have been shown to accumulate many natural substrates including a three to fourfold increase in sialic acid content compared to that found in normal fibroblasts. This diverse accumulation of storage material is due to a massive deficiency of multiple lysosomal hydrolases as they are preferentially excreted into the culture fluid. There is evidence that the I-cell plasma membrane itself is abnormal with respect to certain transferase activities and in its sensitivity to freezing and Triton X-100. In this study, we have shown that a neuraminidase-sensitive substrate, and perhaps others in I-cell fibroblasts, contribute to an increased electronegativity of the I-cell fibroblast surface and to the cells' sensitivity to freezing. We also found that neuraminidase treatment of I-cell fibroblasts before preservative freezing in liquid nitrogen enables the cells to adapt more easily to subculture upon thawing. [ABSTRACT FROM AUTHOR]

Six antibiotics, pefloxacin (Peflacine), fosfomycin (Fosfocine), teicoplanin (Targocid), vancomycin (Vancocine), ceftazidime (Fortum), piperacillin (Piperilline), that may be used as a systematic coverage during bone marrow transplantation have been tested on dermal fibroblasts of one control subject and two I-cell disease patients, along with five subcultures, corresponding to 5 weeks of culture. The possible toxicity of these molecules was assessed. The evaluation of lysosomal enzyme sphingomyelinase activity, detection of free intracellular cholesterol and the light- and electron-microscopic examination of treated cells were used as measures of metabolic interference and cytotoxicity. Our study shows that despite a lack of any metabolic sign of interference (no modification in enzyme activity, no increase in free intracellular cholesterol), all the antibiotics tested induced a cytotoxic effect which was notably amplified in the I-cell populations. This may be due to the lysosomal lipid storage of these cells which modifies the relationship between the antibiotic and the cell by inducing a different kind of lipid–antibiotic interference. [ABSTRACT FROM AUTHOR]

Mannose 6-phosphate receptor deficient mice were generated by crossing mice carrying null alleles for Igf2 and the 300 kDa and 46 kDa mannose 6-phosphate receptors, Mpr300 and Mpr46. Pre- and perinatal lethality of mice nullizygous for Igf2, Mpr300 and Mpr46 was increased. Triple deficient mice surviving the first postnatal day had normal viability and developed a phenotype resembling human I-cell disease. The triple deficient mice were characterized by dwarfism, facial dysplasia, waddling gait, dysostosis multiplex, elevated lysosomal enzymes in serum and histological signs of lysosomal storage predominantly in fibroblasts, but also in parenchymal cells of brain and liver. A paternally inherited Mpr300 wild type allele that is normally inactive in mice due to imprinting was reactivated in some tissues of mice lacking IGF II and MPR 46 and carrying a maternal Mpr300 null allele. Inspite of the partial reactivation the phenotype of these mice was similar to that of triple deficient mice. [ABSTRACT FROM AUTHOR]

Histological examination of the bones obtained on autopsy of a 5-month-old child with mucolipidosis II (I-cell disease) revealed inhibition of the growth plate calcification with defective vascular invasion and signs of hyperparathyroidism. These findings are the chondro-osseous basis of the early radiological ricket-like appearance of bones in the neonatal period or soon thereafter. Whether the early skeletal abnormalities of mucolipidosis II result from a primary enzymatic defect of cartilage and bone cells or from factors controlling bone metabolism deserves further study. [ABSTRACT FROM AUTHOR]

We are reporting a rare case of I-cell disease presenting with craniosynostosis. An 11-month-old child presented with abnormal head shape, developmental delay and bent bones. We planned for corrective surgery for craniosynostosis, but on genetic analysis I-cell disease was confirmed. After explaining the prognosis of I-cell disease, parents denied surgery. This case report emphasizes the fact that syndromic evaluation of craniosynostosis is very much essential before proceeding for corrective surgery. [ABSTRACT FROM AUTHOR]

Mucolipidosis II and III (ML II/III) are caused by a deficiency of uridine-diphosphate N-acetylglucosamine: lysosomal-enzyme-N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase, EC2.7.8.17), which tags lysosomal enzymes with a mannose 6-phosphate (M6P) marker for transport to the lysosome. The process is performed by a sequential two-step process: first, GlcNAc-1-phosphotransferase catalyzes the transfer of GlcNAc-1-phosphate to the selected mannose residues on lysosomal enzymes in the cis-Golgi network. The second step removes GlcNAc from lysosomal enzymes by N-acetylglucosamine-1-phosphodiester α-N-acetylglucosaminidase (uncovering enzyme) and exposes the mannose 6-phosphate (M6P) residues in the trans-Golgi network, in which the enzymes are targeted to the lysosomes by M6Preceptors. A deficiency of GlcNAc-1-phosphotransferase causes the hypersecretion of lysosomal enzymes out of cells, resulting in a shortage of multiple lysosomal enzymes within lysosomes. Due to a lack of GlcNAc-1-phosphotransferase, the accumulation of cholesterol, phospholipids, glycosaminoglycans (GAGs), and other undegraded substrates occurs in the lysosomes. Clinically, ML II and ML III exhibit quite similar manifestations to mucopolysaccharidoses (MPSs), including specific skeletal deformities known as dysostosis multiplex and gingival hyperplasia. The life expectancy is less than 10 years in the severe type, and there is no definitive treatment for this disease. In this review, we have described the updated diagnosis and therapy on ML II/III. [ABSTRACT FROM AUTHOR]

Mucolipidosis type II (MLII) is a rare lysosomal storage disorder caused by defective trafficking of lysosomal enzymes. Severe skeletal manifestations are a hallmark of the disease including hip dysplasia. This study aims to describe hip morphology and the natural course of hip pathologies in MLII by systematic evaluation of plain radiographs, ultrasounds and magnetic resonance imaging (MRI). An international two-centered study was performed by retrospective chart review. All MLII patients with at least one pelvic radiograph were included. A total of 16 patients were followed over a mean of 3.5 years (range 0.2–10.7 years). Typical age-dependent radiographic signs identified were femoral cloaking (7/16), rickets/hyperparathyroidism-like changes (6/16) and constrictions of the supra-acetabular part of the os ilium (16/16) and the femoral neck (7/16). The course of acetabular and migration indexes (AI, MI) significantly increased in female patients. However, in the overall group, there was no relevant progression of acetabular dysplasia with a mean AI of 23.0 (range 5°–41°) and 23.7° (range 5°–40°) at the first and last assessments, respectively. Better knowledge on hip morphology in MLII could lead to earlier diagnosis, improved clinical management and enables assessment of effects of upcoming therapies on the skeletal system. [ABSTRACT FROM AUTHOR]

Background: Inclusion cell disease (I-cell) is a rare autosomal recessive metabolic disease involving multiple organ systems, associated with a severely restricted life expectancy. No curative therapy is currently available, with management aimed at symptom palliation., Methods: We present a retrospective, single-centre, case series of children referred to a tertiary paediatric metabolic service. The clinical presentation, demographics, genetics and natural history of the condition are investigated., Results: Five patients with I-cell disease were referred over a 10-year period. All patients were born with dysmorphic features and had a family history of I-cell disease on further exploration. Phenotypic variation was seen within patients with the same genetic profile. Airway problems were common with 100% of the documented sleep oximetry studies suggesting sleep-disordered breathing. Of the two patients who had tracheal intubation anaesthetic difficulties we encountered, one required intraoperative reintubation, and one suffered a failed intubation with subsequent death. All five patients required oxygen therapy with the use of CPAP and BiPAP also seen. Feeding issues were almost universal with four of the five patients requiring nasogastric feeding. Four patients had died in the 10-year period with a mean life expectancy of 36 months. Cause of death for three of the four patients was respiratory failure., Conclusions: Airway problems, including sleep-disordered breathing, were ubiquitous in this cohort of children. Any intervention requiring a general anaesthetic needs careful multidisciplinary consideration due to significant associated risks and possibly death. Management as a result is generally non-surgical and symptomatic. This case series demonstrates universal involvement of the airway and respiratory systems, an important consideration when selecting meaningful outcomes for future effectiveness studies of novel therapies.

Abstract: Mucolipidosis II (Inclusion cell or I-cell disease) is an autosomal recessive lysosomal storage disorder clinically comparable to the mucopolysaccharidoses (MPS), characterized by progressive respiratory and neurologic deterioration. Sleep problems, especially obstructive sleep apnea (OSA) and disrupted sleep architecture, are observed in other lysosomal storage diseases but have not been described in mucolipidosis II. We report the progression of polysomnographic abnormalities in a child with mucolipidosis II, demonstrated by worsening sleep-related hypoventilation, OSA, and sleep state fragmentation despite advancing PAP therapy. Background slowing and reduction in spindle activity on limited EEG may reflect progressive CNS disease affecting thalamic neurons., (© 2016 American Academy of Sleep Medicine)

A severe form of I-cell disease (mucolipidosis II) can present in the newborn period as multiple fractures. The bone disease in these patients is believed to be due to hyperparathyroidism. We report a case where bone disease was present at birth but the parathyroid hormone levels were initially normal and did not increase until 37 d of age. Supplemention with vitamin D was needed to normalize the parathyroid hormone levels despite adequate intake of vitamin D, calcium and phosphorus. We suggest that in patients with I-cell disease, continued evaluation for hyperparathyroidism may be necessary despite initial normal parathyroid hormone levels.