Type 2 Gaucher disease: the collodion baby phenotype revisited

Neuronopathic Gaucher disease: Rare in the West, common in the East

Gaucher disease (GD) stands as one of the most prevalent lysosomal disorders, yet neuronopathic GD (nGD) is an uncommon subset characterized by a wide array of clinical manifestations that complicate diagnosis, particularly when neurological symptoms are understated. nGD may manifest as the acute neuronopathic type, or GD type 2 (GD2), either prenatally or within the first weeks to months of life, whereas GD type 3 (GD3) symptoms may emerge at any point during childhood or occasionally in adolescence. The clinical presentation encompasses severe systemic involvement to mild visceral disease, often coupled with a spectrum of progressive neurological signs and symptoms such as cognitive impairment, ataxia, seizures, myoclonus, varying degrees of brainstem dysfunction presenting with stridor, apneic episodes, and/or impaired swallowing. This manuscript aims to provide a comprehensive review of the incidence, distinctive presentations, and diverse clinical phenotypes of nGD across various countries and regions. It will explore the natural history of the neurodegenerative process in GD, shedding light on its various manifestations during infancy and childhood, and offer insights into the diagnostic journey, the challenges faced in the clinical management, and current and investigative therapeutic approaches for GD's neurological variants.

Animal Models for the Study of Gaucher Disease

In Gaucher disease (GD), a relatively common sphingolipidosis, the mutant lysosomal enzyme acid β-glucocerebrosidase (GCase), encoded by the GBA1 gene, fails to properly hydrolyze the sphingolipid glucosylceramide (GlcCer) in lysosomes, particularly of tissue macrophages. As a result, GlcCer accumulates, which, to a certain extent, is converted to its deacylated form, glucosylsphingosine (GlcSph), by lysosomal acid ceramidase. The inability of mutant GCase to degrade GlcSph further promotes its accumulation. The amount of mutant GCase in lysosomes depends on the amount of mutant ER enzyme that shuttles to them. In the case of many mutant GCase forms, the enzyme is largely misfolded in the ER. Only a fraction correctly folds and is subsequently trafficked to the lysosomes, while the rest of the misfolded mutant GCase protein undergoes ER-associated degradation (ERAD). The retention of misfolded mutant GCase in the ER induces ER stress, which evokes a stress response known as the unfolded protein response (UPR). GD is remarkably heterogeneous in clinical manifestation, including the variant without CNS involvement (type 1), and acute and subacute neuronopathic variants (types 2 and 3). The present review discusses animal models developed to study the molecular and cellular mechanisms underlying GD.

The ovine Type II Gaucher disease model recapitulates aspects of human brain disease

Acute neuronopathic (type II) Gaucher disease (GD) is a devastating, untreatable neurological disorder resulting from mutations in the glucocerebrosidase gene (GBA1), with subsequent accumulation of glucosylceramide and glucosylsphingosine. Patients experience progressive decline in neurological function, with onset typically within the first three-to-six months of life and premature death before two years. Mice and drosophila with GD have been described, however little is known about the brain pathology observed in the naturally occurring ovine model of GD. We have characterised pathological changes in GD lamb brain and compared the histological findings to those in GD patient post-mortem tissue, to determine the validity of the sheep as a model of this disease. Five GD and five age-matched unaffected lamb brains were examined. We observed significant expansion of the endo/lysosomal system in GD lamb cingulate gyrus however TPP1 and cathepsin D levels were unchanged or reduced. H&E staining revealed neurons with shrunken, hypereosinophilic cytoplasm and hyperchromatic or pyknotic nuclei (red neurons) that were also shrunken and deeply Nissl stain positive. Amoeboid microglia were noted throughout GD brain. Spheroidal inclusions reactive for TOMM20, ubiquitin and most strikingly, p-Tau were observed in many brain regions in GD lamb brain, potentially indicating disturbed axonal trafficking. Our findings suggest that the ovine model of GD exhibits similar pathological changes to human, mouse, and drosophila type II GD brain, and represents a model suitable for evaluating therapeutic intervention, particularly in utero-targeted approaches.

Combined saposin deficiency: A rare occurrence

Combined saposin deficiency (OMIM #611721), an exceedingly rare lysosomal storage disorder, is caused by a mutation in the gene PSAP. This gene encodes a protein, prosaposin, that cleaves into four constituent proteins, each of which has a role as a cofactor for the enzymes whose deficiency results in Krabbe disease, metachromatic leukodystrophy, Gaucher disease, and Farber disease, respectively. Intact prosaposin itself is essential for neuronal survival. The typical manifestation of combined saposin deficiency is of severe neurological features in the neonatal period, hepatosplenomegaly, thrombocytopenia, and early death. We report, to the best of our knowledge, the first Indian case with these clinical manifestations and confirmation by genetic and enzymatic testing.

Glucocerebrosidase mutations and Parkinson disease

The discovery of glucocerebrosidase (GBA1) mutations as the greatest numerical genetic risk factor for the development of Parkinson disease (PD) resulted in a paradigm shift within the research landscape. Efforts to elucidate the mechanisms behind GBA1-associated PD have highlighted shared pathways in idiopathic PD including the loss and gain-of-function hypotheses, endoplasmic reticulum stress, lipid metabolism, neuroinflammation, mitochondrial dysfunction and altered autophagy-lysosomal pathway responsible for degradation of aggregated and misfolded a-synuclein. GBA1-associated PD exhibits subtle differences in phenotype and disease progression compared to idiopathic counterparts notably an earlier age of onset, faster motor decline and greater frequency of non-motor symptoms (which also constitute a significant aspect of the prodromal phase of the disease). GBA1-targeted therapies have been developed and are being investigated in clinical trials. The most notable are Ambroxol, a small molecule chaperone, and Venglustat, a blood-brain-barrier-penetrant substrate reduction therapy agent. It is imperative that further studies clarify the aetiology of GBA1-associated PD, enabling the development of a greater abundance of targeted therapies in this new era of precision medicine.

Promising Effect of High Dose Ambroxol Treatment on Neurocognition and Motor Development in a Patient With Neuropathic Gaucher Disease 2

Gaucher Disease (GD) 2 is a rare inherited lysosomal disorder. Early-onset and rapid progression of neurovisceral symptoms lead to fatal outcome in early childhood. Treatment is symptomatic, a curative therapy is currently not available. This prospective study describes the clinical and biochemical outcome of a GD 2 patient treated with high dose ambroxol from the age of 4 months. Due to progressive hepatosplenomegaly additional enzyme replacement therapy was required 1 year after ambroxol monotherapy was initiated. Detailed clinical follow-up data demonstrated an age-appropriate neurocognitive and motor development but no clear benefit on peripheral organs. Glucosylsphingosine (Lyso-GL1) in cerebrospinal fluid decreased remarkably compared to pre-treatment, whereas Lyso-GL1 and chitotriosidase in blood increased. Ambroxol treatment of patient fibroblasts revealed a significant increase in β-glucocerebrosidase activity in vitro. To our knowledge, this is the first report of a GD 2 patient with age-appropriate cognitive and motor development at 3 years of age. Combination of high dose ambroxol with ERT proved to be a successful approach to manage both visceral and neurological manifestations.

A rare cause of hydrops fetalis in two Gaucher disease type 2 patients with a novel mutation

Gaucher disease type 2 is the most progressive and the rarest form of Gaucher disease, defined as the acute neuronopathic type. We presented two GD2 patients who died before three months of age due to severe septicemia, respiratory and liver failure. One was homozygous for a novel GBA variant c.590 T > A (p.197 K), and the second homozygous for the known GBA mutation c.1505G > A (p.R502H). Ichthyosis, hydrops fetalis, apnea, myoclonic seizures, and hepatosplenomegaly occurred in both patients, but hypertrophic cardiomyopathy was observed only in the second and unilateral cataract in the first patient. Due to the disease's early and rapid neurological progression, we did not administer ERT to our patients. It is strongly believed that early diagnosis is essential, and prenatal diagnosis makes genetic counselling possible for future pregnancies.

Proposal for a 6-step-approach for differential diagnosis of neonatal erythroderma

The broad differential diagnosis of neonatal erythroderma often poses a diagnostic challenge. Mortality of neonatal erythroderma is high due to complications of the erythroderma itself and the occasionally severe and life-threatening underlying disease. Early correct recognition of the underlying cause leads to better treatment and prognosis. Currently, neonatal erythroderma is approached by a case by case basis. The purpose of this scoping review was to develop a diagnostic approach in neonatal erythroderma. After a systematic literature search in Embase (January 1990 - May 2020, 74 cases of neonatal erythroderma were identified, and 50+ diagnoses could be extracted. Main causes were the ichthyoses (40%) and primary immunodeficiencies (35%). Congenital erythroderma was present in 64% (47/74) of the cases, predominantly with congenital ichthyosis (11/11; 100%), Netherton syndrome (12/14, 86%), and Omenn syndrome (11/23, 48%). Time until diagnosis ranged from 102 days to 116 days for cases of non-congenital erythroderma and congenital erythroderma respectively. Among the 74 identified cases a total of 17 patients (23%) died within a mean of 158 days and were related to Omenn syndrome (35%), graft versus host disease (67%), and Netherton syndrome (18%). Disease history and physical examination are summarized in this paper. Age of onset and a collodion membrane can help to narrow the differential diagnoses. Investigations of blood, histology, hair analysis, genetic analysis and clinical imaging are summarized and discussed. A standard blood investigation is proposed and the need for skin biopsies with Lympho-Epithelial Kazal-Type related Inhibitor-staining is highlighted. Overall, this review shows that diagnostic procedures narrow the differential diagnosis in neonatal erythroderma. A 6-step flowchart for the diagnostic approach for neonatal erythroderma during the first month of life is proposed. The approach was made with the support of expert leaders from international multidisciplinary collaborations in the European Reference Network Skin-subthematic group Ichthyosis.

Children with atopic dermatitis show increased activity of β- glucocerebrosidase and stratum corneum levels of glucosylcholesterol that are strongly related to local cytokine milieu

Background

Atopic dermatitis (AD) is characterized by immune dysregulations and an impaired skin barrier, including abnormalities in lipid organization. In the stratum corneum (SC), β‐glucocerebrosidase (GBA) mediates transformation of glucosylceramide (GlcCER) into ceramide (CER) and cholesterol into glucosylcholesterol (GlcChol). Alteration in GBA activity might contribute to skin barrier defects in AD.

Objectives

To investigate GBA activity in the SC of children with AD before and after topical corticosteroid therapy and to compare it with healthy controls; to determine SC levels of GlcCER‐ and CER‐containing hydroxysphingosine base (GlcCER[H] and CER[H], respectively) and GlcChol; and to relate them to disease severity, skin barrier function and the local cytokine milieu.

Methods

Lipid markers and cytokines of innate, T helper 1 and T helper 2 immunity were determined in SC collected from healthy children and from clinically unaffected skin of children with AD, before and after 6 weeks of therapy with topical corticosteroids. AD severity was assessed by Scoring Atopic Dermatitis and skin barrier function by transepidermal water loss (TEWL).

Results

Baseline GBA activity and GlcChol levels were increased in children with AD but declined after therapy. CER[H] levels and the CER[H] to GlcCER[H] ratio were increased in AD. GBA activity and GlcChol correlated with TEWL and levels of multiple cytokines, especially interleukin‐1α and interleukin‐18. GlcChol was strongly associated with disease severity.

Conclusions

We show increased GBA activity and levels of GlcChol in AD. Our data suggest an important role of inflammation in disturbed lipid processing. GBA activity or GlcChol might be useful biomarkers in the monitoring of therapeutic responses in AD.

What is already known about this topic?

Patients with atopic dermatitis (AD) have a reduced skin barrier, mainly caused by altered lipid organization.

The mechanisms underlying these lipid anomalies are not fully understood but likely reflect both genetic abnormalities in AD skin and the local cutaneous inflammatory environment.

What does this study add?

We show increased activity of the ceramide‐generating enzyme β‐glucocerebrosidase in AD. Activity of this enzyme was correlated with the local cytokine milieu and declined after local corticosteroid therapy.

We show that glucosylcholesterol levels in the stratum corneum are increased in AD.

The function of glucosylcholesterol and the physiological consequences of increased levels are not clear yet; however, its levels were strongly correlated with skin barrier function: high transepidermal water loss strongly correlated with high levels of glucosylcholesterol.

What is the translational message?

Correction of cutaneous inflammation largely restores alterations in lipid metabolism in the stratum corneum of infants with AD.

Glucocerebrosidase mutations: A paradigm for neurodegeneration pathways

Biallelic (homozygous or compound heterozygous) glucocerebrosidase gene (GBA) mutations cause Gaucher disease, whereas heterozygous mutations are numerically the most important genetic risk factor for Parkinson disease (PD) and are associated with the development of other synucleinopathies, notably Dementia with Lewy Bodies. This phenomenon is not limited to GBA, with converging evidence highlighting further examples of autosomal recessive disease genes increasing neurodegeneration risk in heterozygous mutation carriers. Nevertheless, despite extensive research, the cellular mechanisms by which mutations in GBA, encoding lysosomal enzyme β-glucocerebrosidase (GCase), predispose to neurodegeneration remain incompletely understood. Alpha-synuclein (A-SYN) accumulation, autophagic lysosomal dysfunction, mitochondrial abnormalities, ER stress and neuroinflammation have been proposed as candidate pathogenic pathways in GBA-linked PD. The observation of GCase and A-SYN interactions in PD initiated the development and evaluation of GCase-targeted therapeutics in PD clinical trials.

Inherited disorders of complex lipid metabolism: A clinical review

Over 80 human diseases have been attributed to defects in complex lipid metabolism. A majority of them have been reported recently in the setting of rapid advances in genomic technology and their increased use in clinical settings. Lipids are ubiquitous in human biology and play roles in many cellular and intercellular processes. While inborn errors in lipid metabolism can affect every organ system with many examples of genetic heterogeneity and pleiotropy, the clinical manifestations of many of these disorders can be explained based on the disruption of the metabolic pathway involved. In this review, we will discuss the physiological function of major pathways in complex lipid metabolism, including nonlysosomal sphingolipid metabolism, acylceramide metabolism, de novo phospholipid synthesis, phospholipid remodeling, phosphatidylinositol metabolism, mitochondrial cardiolipin synthesis and remodeling, and ether lipid metabolism as well as common clinical phenotypes associated with each.

Report of a Novel ALOX12B Mutation in Self-Improving Collodion Ichthyosis with an Overview of the Genetic Background of the Collodion Baby Phenotype

Collodion baby is a congenital, transient phenotype encountered in approximately 70–90% of autosomal recessive congenital ichthyosis and is an important entity of neonatal erythroderma. The clinical outcome after this severe condition is variable. Genetic mutations of components of the epidermal lipoxygenase pathway have been implicated in the majority of self-improving collodion ichthyosis (SICI). In SICI, the shedding of the collodion membrane reveals clear skin or only mild residual manifestation of ichthyosis. Here we report the case of a girl born with a severe form of collodion baby phenotype, whose skin almost completely cleared within the first month of life. At the age of 3 years, only mild symptoms of a keratinization disorder remained. However, the severity of erythema and scaling showed mild fluctuations over time. To objectively evaluate the skin changes of the patient, we assessed the ichthyosis severity index. Upon sequencing of the ALOX12B gene, we identified a previously unreported heterozygous nonsense mutation, c.1607G>A (p.Trp536Ter) with the recurrent, heterozygous mutation c.1562A>G (p.Tyr521Cys). Thereby, our findings expand the genotypic spectrum of SICI. In addition, we summarize the spectrum of further genetic diseases that can present at birth as collodion baby, in particular the SICI.

Sphingolipid lysosomal storage diseases: from bench to bedside

Johann Ludwig Wilhelm Thudicum described sphingolipids (SLs) in the late nineteenth century, but it was only in the past fifty years that SL research surged in importance and applicability. Currently, sphingolipids and their metabolism are hotly debated topics in various biochemical fields. Similar to other macromolecular reactions, SL metabolism has important implications in health and disease in most cells. A plethora of SL-related genetic ailments has been described. Defects in SL catabolism can cause the accumulation of SLs, leading to many types of lysosomal storage diseases (LSDs) collectively called sphingolipidoses. These diseases mainly impact the neuronal and immune systems, but other systems can be affected as well. This review aims to present a comprehensive, up-to-date picture of the rapidly growing field of sphingolipid LSDs, their etiology, pathology, and potential therapeutic strategies. We first describe LSDs biochemically and briefly discuss their catabolism, followed by general aspects of the major diseases such as Gaucher, Krabbe, Fabry, and Farber among others. We conclude with an overview of the available and potential future therapies for many of the diseases. We strive to present the most important and recent findings from basic research and clinical applications, and to provide a valuable source for understanding these disorders.

Glucosylated cholesterol in skin: Synthetic role of extracellular glucocerebrosidase

The existence of glucosylated cholesterol (GlcChol) in tissue has recently been recognized. GlcChol is generated from glucosylceramide (GlcCer) and cholesterol through transglucosylation by two retaining β-glucosidases, GBA and GBA2. Given the abundance of GBA, GlcCer and cholesterol in the skin's stratum corneum (SC), we studied the occurrence of GlcChol. A significant amount of GlcChol was detected in SC (6 pmol/mg weight). The ratio GlcChol/GlcCer is higher in SC than epidermis, 0.083 and 0.011, respectively. Examination of GlcChol in patients with Netherton syndrome revealed comparable levels (11 pmol/mg). Concluding, GlcChol was identified as a novel component in SC and is likely locally metabolized by GBA. The physiological function of GlcChol in the SC warrants future investigation.

The natural history of type 2 Gaucher disease in the 21st century: A retrospective study

OBJECTIVE

To gather natural history data to better understand the changing course of type 2 Gaucher disease (GD2) in order to guide future interventional protocols.

METHODS

A structured interview was conducted with parents of living or deceased patients with GD2. Retrospective information obtained included disease presentation, progression, medical and surgical history, medications, family history, management, complications, and cause of death, as well as the impact of disease on families.

RESULTS

Data from 23 patients were analyzed (20 deceased and 3 living), showing a mean age at death of 19.2 months, ranging from 3 to 55 months. Fourteen patients were treated with enzyme replacement therapy, 2 were treated with substrate reduction therapy, and 3 underwent bone marrow transplantation. Five patients received ambroxol and one was on N-acetylcysteine, both considered experimental treatments. Fifteen patients had gastrostomy tubes placed; 10 underwent tracheostomies. Neurologic disease manifestations included choking episodes, myoclonic jerks, autonomic dysfunction, apnea, seizures, and diminished blinking, all of which worsened as disease progressed.

CONCLUSIONS

Current available therapies appear to prolong life but do not alter neurologic manifestations. Despite aggressive therapeutic interventions, GD2 remains a progressive disorder with a devastating prognosis that may benefit from new treatment approaches.

Glucocerebrosidase: Functions in and Beyond the Lysosome

Glucocerebrosidase (GCase) is a retaining β-glucosidase with acid pH optimum metabolizing the glycosphingolipid glucosylceramide (GlcCer) to ceramide and glucose. Inherited deficiency of GCase causes the lysosomal storage disorder named Gaucher disease (GD). In GCase-deficient GD patients the accumulation of GlcCer in lysosomes of tissue macrophages is prominent. Based on the above, the key function of GCase as lysosomal hydrolase is well recognized, however it has become apparent that GCase fulfills in the human body at least one other key function beyond lysosomes. Crucially, GCase generates ceramides from GlcCer molecules in the outer part of the skin, a process essential for optimal skin barrier property and survival. This review covers the functions of GCase in and beyond lysosomes and also pays attention to the increasing insight in hitherto unexpected catalytic versatility of the enzyme.

Ophthalmic manifestations of Gaucher disease: the most common lysosomal storage disorder

Gaucher disease (GD) results from a deficiency of glucocerebrosidase activity and the subsequent accumulation of the enzyme's metabolites, principally glucosylsphingosine and glucosylceramide. There are three principal forms: Type I, which is the most common, is usually considered non-neuronopathic. Type II, III and IIIc manifest earlier and have neurological sequelae due to markedly reduced enzyme activity. Gaucher's can be associated with ophthalmological sequelae but these have not been systematically reviewed. We therefore performed a comprehensive literature review of all such ophthalmic abnormalities associated with the different types of Gaucher disease. We systematically searched the literature (1950 - present) for functional and structural ocular abnormalities arising in patients with Gaucher disease and found that all subtypes can be associated with ophthalmic abnormalities; these range from recently described intraocular lesions to disease involving the adnexae, peripheral nerves and brain. In summary, Gaucher can affect most parts of the eye. Rarely is it sight-threatening; some but not all manifestations are amenable to treatment, including with enzyme replacement and substrate reduction therapy. Retinal involvement is rare but patients with ocular manifestations should be monitored and treated early to reduce the risk of progression and further complications. As Gaucher disease is also associated with Parkinsons disease and may also confer an increased risk of malignancy (particularly haematological forms and melanoma), any ocular abnormalities should be fully investigated to exclude these potential underlying conditions.

A Neonatal Case With Perinatal Lethal Gaucher Disease Associated With Missense G234E and H413P Heterozygous Mutations

Perinatal lethal Gaucher disease (PLGD), a particular and serious form of type 2 Gaucher disease (GD), often causes lethality in utero or death within hours after birth. The typical clinical manifestations include non-immune hydrops fetalis (NIHF), premature birth, fetal growth restriction, fetal intrauterine death, or neonatal distress and rapid death after birth. Here, we present a premature neonate with GD whose main clinical manifestations included intrauterine growth retardation, anasarca, facial dysmorphia, ichthyosis, respiratory distress, hepatosplenomegaly, joint contractures, myoclonus, refractory thrombocytopenia, anemia, elevated levels of liver enzymes, bile acid and direct bilirubin, cholestasis, pulmonary hypoplasia, intracranial hemorrhage, and abnormal electroencephalogram. The activity of β- glucocerebrosidase was 0 in the peripheral white blood cells of the neonate. The sequencing analysis identified the presence of missense G234E and H413P heterozygous mutations in glucerebrosidase (GBA) exon 7 and 10, with the latter first observed to be associated with PLGD. This infant died at 73 days of age.

Type 2 Gaucher disease in an infant despite a normal maternal glucocerebrosidase gene

Gaucher disease (GD) is a recessively inherited autosomal lysosomal storage disease, the most severe of which is type 2, an acute neuronopathic form. We report an affected infant who inherited one mutant allele, Arg257Gln (c.887G>A; p.Arg296Gln) from his father, while the second, Gly202Arg (c.721G>A; p.Gly241Arg) arose by either maternal germline mosaicism or as a de novo mutation. This is the first time mutation Gly202Arg has been reported to be inherited non-traditionally. This report is part of a growing literature suggesting that GD can be inherited via germline or de novo mutations, and emphasizes that it is critical for clinicians to consider such inheritance when making diagnostic decisions or providing genetic counseling.

In situ visualization of glucocerebrosidase in human skin tissue: zymography versus activity-based probe labeling

Epidermal β-glucocerebrosidase (GBA1), an acid β-glucosidase normally located in lysosomes, converts (glucosyl)ceramides into ceramides, which is crucial to generate an optimal barrier function of the outermost skin layer, the stratum corneum (SC). Here we report on two developed in situ methods to localize active GBA in human epidermis: i) an optimized zymography method that is less labor intensive and visualizes enzymatic activity with higher resolution than currently reported methods using either substrate 4-methylumbelliferyl-β-D-glucopyranoside or resorufin-β-D-glucopyranoside; and ii) a novel technique to visualize active GBA1 molecules by their specific labeling with a fluorescent activity-based probe (ABP), MDW941. The latter method pro-ved to be more robust and sensitive, provided higher resolution microscopic images, and was less prone to sample preparation effects. Moreover, in contrast to the zymography substrates that react with various β-glucosidases, MDW941 specifically labeled GBA1. We demonstrate that active GBA1 in the epidermis is primarily located in the extracellular lipid matrix at the interface of the viable epidermis and the lower layers of the SC. With ABP-labeling, we observed reduced GBA1 activity in 3D-cultured skin models when supplemented with the reversible inhibitor, isofagomine, irrespective of GBA expression. This inhibition affected the SC ceramide composition: MS analysis revealed an inhibitor-dependent increase in the glucosylceramide:ceramide ratio.

Insights into the structural biology of Gaucher disease

Gaucher disease, the most common lysosomal storage disorder, is caused by mutations in the gene encoding the acid-β-glucosidase lysosomal hydrolase enzyme that cleaves glucocerebroside into glucose and ceramide. Reduced enzyme activity and impaired structural stability arise due to >300 known disease-causing mutations. Several of these mutations have also been associated with an increased risk of Parkinson disease (PD). Since the discovery of the acid-β-glucosidase X-ray structure, there have been major advances in our understanding of the structural properties of the protein. Analysis of specific residues has provided insight into their functional and structural importance and provided insight into the pathogenesis of Gaucher disease and the contribution to PD. Disease-causing mutations are positioned throughout the acid-β-glucosidase structure, with many located far from the active site and thus retaining some enzymatic activity however, thus far no clear relationship between mutation location and disease severity has been established. Here, we review the crystal structure of acid-β-glucosidase, while highlighting important structural aspects of the protein in detail. This review discusses the structural stability of acid-β-glucosidase, which can be altered by pH and glycosylation, and explores the relationship between known Gaucher disease and PD mutations, structural stability and disease severity.

Case report of unexpected gastrointestinal involvement in type 1 Gaucher disease: comparison of eliglustat tartrate treatment and enzyme replacement therapy

BACKGROUND

Gastrointestinal involvement in Gaucher disease is very rare, and appears to be unresponsive to enzyme replacement therapy (ERT).

CASE PRESENTATION

Here, we describe identical twin, splenectomized, non-neuronopathic Gaucher patients on long-term ERT for 9 years, who complained of epigastric discomfort due to Gaucher cell infiltration of the gastroduodenal mucosa. Rare compound heterozygous mutations (p.Arg48Trp and p.Arg257Gln) of the GBA gene were found in both. Improvement in the gastroduodenal infiltration and reduced chitotriosidase levels were observed in one who switched to eliglustat tartrate for 1 year, whereas the other one who maintained ERT showed no improvement of chitotriosidase level and persistent duodenal lesions.

CONCLUSION

This shows that eliglustat might be an effective treatment for Gaucher disease patients having lesions resistant to ERT.

Gaucher Disease Type 2 Presenting with Collodion Membrane and Blueberry Muffin Lesions

Collodion membrane is most closely associated with forms of autosomal recessive congenital ichthyosis, but the differential diagnosis includes many other less common etiologies. Herein we present a case of Gaucher disease (GD) type 2 in a neonate presenting with collodion membrane in addition to blueberry muffin lesions. The clinical presentation and etiology of GD and the differential diagnoses for collodion membrane and blueberry muffin lesions are briefly reviewed.

The eye and the skin in nonendocrine metabolic disorders

As metabolism is controlled by the input of genes and the environment, metabolic disorders result from some disturbance in the interaction between genes and environmental factors. Many metabolic disorders consist in congenital enzyme deficiencies, also known as "inborn errors of metabolism," that may be disabling or cause severe illness and death and are predominantly inherited in an autosomal recessive fashion. The deposit in cells and tissues of storage substances from errors in metabolic processes may produce a wide variety of disorders affecting different organs and functions, with different degrees of severity, and often present around the time of birth or early childhood. Distinctive ocular and skin manifestations accompany many metabolic diseases and may provide clues for their diagnosis and evolution.

Variants associated with Gaucher disease in multiple system atrophy

OBJECTIVE

Glucocerebrosidase gene (GBA) variants that cause Gaucher disease are associated with Parkinson disease (PD) and dementia with Lewy bodies (DLB). To investigate the role of GBA variants in multiple system atrophy (MSA), we analyzed GBA variants in a large case-control series.

METHODS

We sequenced coding regions and flanking splice sites of GBA in 969 MSA patients (574 Japanese, 223 European, and 172 North American) and 1509 control subjects (900 Japanese, 315 European, and 294 North American). We focused solely on Gaucher-disease-causing GBA variants.

RESULTS

In the Japanese series, we found nine carriers among the MSA patients (1.65%) and eight carriers among the control subjects (0.89%). In the European series, we found three carriers among the MSA patients (1.35%) and two carriers among the control subjects (0.63%). In the North American series, we found five carriers among the MSA patients (2.91%) and one carrier among the control subjects (0.34%). Subjecting each series to a Mantel-Haenszel analysis yielded a pooled odds ratio (OR) of 2.44 (95% confidence interval [CI], 1.14-5.21) and a P-value of 0.029 without evidence of significant heterogeneity. Logistic regression analysis yielded similar results, with an adjusted OR of 2.43 (95% CI 1.15-5.37) and a P-value of 0.022. Subtype analysis showed that Gaucher-disease-causing GBA variants are significantly associated with MSA cerebellar subtype (MSA-C) patients (P = 7.3 × 10(-3)).

INTERPRETATION

The findings indicate that, as in PD and DLB, Gaucher-disease-causing GBA variants are associated with MSA.

The clinical management of Type 2 Gaucher disease

Gaucher disease, the inherited deficiency of the enzyme glucocerebrosidase, is the most common of the lysosomal storage disorders. Type 2 Gaucher disease, the most severe and progressive form, manifests either prenatally or in the first months of life, followed by death within the first years of life. The rarity of the many lysosomal storage disorders makes their diagnosis a challenge, especially in the newborn period when the focus is often on more prevalent illnesses. Thus, a heightened awareness of the presentation of these rare diseases is necessary to ensure their timely consideration. This review, designed to serve as a guide to physicians treating newborns and infants with Gaucher disease, discusses the presenting manifestations of Type 2 Gaucher disease, the diagnostic work-up, associated genotypes and suggestions for management. We also address the ethical concerns that may arise with this progressive and lethal disorder, since currently available treatments may prolong life, but do not impact the neurological manifestations of the disease.

A review of the diverse genetic disorders in the Lebanese population: highlighting the urgency for community genetic services

The review lists the genetic diseases reported in Lebanese individuals, surveys genetic programs and services, and highlights the absence of basic genetic health services at the individual and community level. The incidence of individual diseases is not determined, yet the variety of genetic diseases reported is tremendous, most of which follow autosomal recessive inheritance reflecting the social norms in the population, including high rates of consanguinity, which favor the increase in incidence of these diseases. Genetic services including all activities for the diagnosis, care, and prevention of genetic diseases at community level are extremely inadequate. Services are limited to some clinical and laboratory diagnostic services with no genetic counseling. These services are localized within the capital thus preventing their accessibility to high-risk communities. Screening programs, which are at the core of public health prevention services, are minimal and not nationally mandated. The absence of adequate genetic services is attributed to many factors undermining the importance of genetic diseases and their burden on society, the most important of which is genetic illiteracy at all levels of the population, including high-risk families, the general public, and most importantly health care providers and public health officials. Thus, a country like Lebanon, where genetic diseases are expected to be highly prevalent, is in utmost need for community genetics services. Strategies need to be developed to familiarize public health officials and medical professionals with medical genetics leading to a public health infrastructure that delivers community genetics services for the prevention and care of genetic disorders at community level.

Gaucher disease

Gaucher disease is the commonest lysosomal storage disease seen in India and worldwide. It should be considered in any child or adult with an unexplained splenohepatomegaly and cytopenia which are seen in the three types of Gaucher disease. Type 1 is the non-neuronopathic form and type 2 and 3 are the neuronopathic forms. Type 2 is a more severe neuronopathic form leading to mortality by 2 years of age. Definitive diagnosis is made by a blood test-the glucocerebrosidase assay. There is no role for histological examination of the bone marrow, liver or spleen for diagnosis of the disease. Molecular studies for mutations are useful for confirming diagnosis, screening family members and prognosticating the disease. A splenectomy should not be performed except for palliation or when there is no response to enzyme replacement treatment or no possibility of getting any definitive treatment. Splenectomy may worsen skeletal and lung manifestations in Gaucher disease. Enzyme replacement therapy (ERT) has completely revolutionized the prognosis and is now the standard of care for patients with this disease. Best results are seen in type 1 disease with good resolution of splenohepatomegaly, cytopenia and bone symptoms. Neurological symptoms in type 3 disease need supportive care. ERT is of no benefit in type 2 disease. Monitoring of patients on ERT involves evaluation of growth, blood counts, liver and spleen size and biomarkers such as chitotriosidase which reflect the disease burden. Therapy with ERT is very expensive and though patients in India have so far got the drug through a charitable access programme, there is a need for the government to facilitate access to treatment for this potentially curable disease. Bone marrow transplantation is an inferior option but may be considered when access to expensive ERT is not possible.

Gaucher disease: a diagnostic challenge for internists

Gaucher disease (GD), the most common inherited lysosomal storage disorder, is a multiorgan disease due to an autosomal recessive defect of the gene encoding glucocerebrosidase enzyme, responsible for the accumulation of glucosylceramide (glucocerebroside) into reticuloendothelial cells, particularly in the liver, spleen and bone marrow. GD is a clinically heterogeneous disorder and it is conventionally classified in type 1 (non-neuronopathic disease), types 2 and 3 (acute and chronic neuronopathic disease, respectively). Features of clinical presentation and organ involvement as well as age, at presentation are highly variable among affected patients. Splenomegaly and/or thrombocytopenia are the most common presenting features either as incidental findings during routine blood count or physical examination. Other possible clinical manifestations can be hepatomegaly with abnormal liver function tests, bone pain often associated with skeletal complications (pathological fractures, avascular necrosis, osteopenia), pulmonary hypertension and, in neuronopathic forms, neurological manifestations (dysfunction of eye motility, mild mental retardation, behavioural difficulties, choreoathetosis and cramp attacks). For all these reasons GD diagnosis is often a real challenge for internists. In the presence of clinical suspicion of GD, the diagnosis has to be confirmed measuring the betaglucocerebrosidase activity in the peripheral leukocytes and by molecular analysis. Each patient needs an accurate initial multisystemic assessment, staging the damage of all the possible organs involved, and the burden of the disease, followed by regular followup. The correct and early diagnosis permits to treat patients properly, avoiding the complications of the disease.

Novel frameshift mutation (Pro171fsX21) in neonatal type 2 Gaucher's disease

Gaucher's disease is caused by a deficiency of glucocerebrosidase (GBA) and results in the accumulation of glucocerebroside within macrophages. We report on a 33(+2) gestational week premature infant whose family history was significant for a previously undiagnosed premature sibling with similar clinical features, including severe hydrops fetalis, hepatosplenomegaly, skin lesions at birth followed by death. The diagnosis of Gaucher's disease type 2 in the present case was based on postmortem pathological findings and a subsequent gene analysis that indicated a heterozygous condition for the novel deletion mutation at GBA cDNA nucleotide position 630 resulting in the frameshift (Pro171fsX21) in exon 6 and a G→A transition mutation at GBA cDNA nucleotide position 887 (Arg257Gln) in exon 7.

[Enzyme replacement therapy for Gaucher disease introduced in late adulthood]

Gaucher disease is the most prevalent lysosomal storage disorder caused by recessive mutation of the beta-glucocerebrosidase gene, which leads to massive lysosomal accumulation of glucocerebrosids especially in macrophages of bone marrow, liver and spleen. The most common presenting signs and symptoms are hepatosplenomegaly, bone pain, pathologic fractures, fatigue, bleeding tendency and recurrent infections. Regular enzyme replacement therapy which is available since 1992 in Hungary successfully reverses the symptoms of the disorder, including hematological abnormalities, bone infiltration and hepatosplenomegaly. Authors present here two cases diagnosed in late adulthood to emphasize the importance of early diagnosis and treatment.

Recognition and diagnosis of neuro-ichthyotic syndromes

The combination of neurologic disease and ichthyosis defines a heterogeneous group of rare inherited disorders that present in infancy through early adulthood. Although affected patients share the cutaneous feature of ichthyosis, there is variability in the nature and severity of neurologic disease. Impaired cognition, spasticity, sensorineural deafness, visual impairment, and/or seizures are the primary neurologic findings. Most of these disorders are caused by genetic defects in lipid metabolism, glycoprotein synthesis, or intracellular vesicle trafficking. The clinical features of some of the neuro-ichthyoses are distinct enough to allow their clinical recognition, but confirmatory biochemical or genetic tests are necessary for accurate diagnosis. Treatment of the ichthyosis is largely symptomatic, and except for Refsum's disease, there are no effective pathogenesis-based therapies for the neurologic disease.

Glucosidase acid beta gene mutations in Egyptian children with Gaucher disease and relation to disease phenotypes

INTRODUCTION

More than 200 mutations have been found in patients with Gaucher disease (GD) and some mutations usually have a high frequency in certain populations. Genotype/phenotype correlation in patients with GD has not been established. This study was designed to determine underlying mutations in Egyptian children with GD and to assess their relation to disease phenotypes.

METHODS

This study comprised 17 patients with GD and 10 healthy controls. Thirteen patients were type 1 GD, 2 type 2, and 2 type 3. DNA was extracted from peripheral blood leukocytes. Exons 9 and 10 were amplified by polymerase chain reaction, and deoxyribonucleic acid sequencing was done with an ABI 310 genetic analyzer.

RESULTS

Wild type allele was detected in 95% (19/20) and a normal variant in 5% (1/20) of controls. L444P allele was encountered in 50% (13/26) of the alleles in type 1 patients, H451P in 7.7% (2/26) and recombinant alleles (RecNcil, RecNcil + M450L, RecFs, RecFs + M450L) in 34.6% (9/26). L444P and Rec alleles each occurred in 50% (2/4) of type 2 and 3 patients. A new mutation was seen in this study {g.7336A>C, (M450L)} and 2 mutant alleles were not determined. Type 1 GD patients had L444P/L444P genotype (23.1%) and Rec alleles/L444P (53.8%), while type 2 and 3 GD patients had Rec alleles/L444P genotypes (100%) with a poor phenotype/genotype correlation.

CONCLUSIONS

L444P and Rec alleles are common in the studied patients. Novel mutations are continuously detected, adding to the expanding panel of GD mutations. No significant genotype-phenotype association was observed.

Gaucher disease with prenatal onset and perinatal death due to compound heterozygosity for the missense R131C and null Rec Nci I GBA mutations

Gaucher disease is an autosomal recessive disorder resulting from deficient activity of the lysosomal enzyme glucocerebrosidase (GBA, E.C.3.2.1.45). Three clinical forms of Gaucher disease have been described: type 1, nonneuronopathic; type 2, acute neuronopathic; and type 3, subacute neuronopathic (OMIM 230800, 230900, 231000). Over the past decade, recognition of a distinct, perinatal lethal form of Gaucher disease (PLGD) has led researchers and clinicians to evaluate Gaucher disease in the differential diagnosis of congenital ichthyosis and nonimmune hydrops fetalis. To date, more than 30 cases of PLGD have been genotyped and reported. It has been observed that homozygosity for recombinant GBA alleles, which are fundamentally null alleles, leads to early lethality, usually in utero or during the 1st few days of life, whereas genotypes involving a recombinant allele and a missense mutation may be less detrimental. Here, we report a case of Gaucher disease with prenatal onset and death within hours of birth, likely due to compound heterozygosity for the GBA Rec Nci I null allele and a R131C missense mutation. In view of the patient's severe clinical course, and based on reviews of other PLGD cases, we postulate that a missense mutation that abruptly disrupts the structure/function of GBA, in combination with a null allele, may result in early lethality in patients with PLGD. We also speculate that R131C is an extremely severe mutation that has occurred more than once in different populations and, in either the homozygous form or heterozygous with another severe mutation, will result in a poor prognosis.

Congenital ichthyosis in severe type II Gaucher disease with a homozygous null mutation

This paper describes a neonate with type II Gaucher disease. The phenotype was unusually severe with congenital ichthyosis, hepatosplenomegaly, muscular hypotonia, myoclonus and respiratory failure. Electron microscopy of the skin revealed lamellar body contents in the stratum corneum interstices, appearances considered to be typical of type II Gaucher disease. The baby died from respiratory failure 1 month postpartum having made no neurological progress. Molecular analysis identified a previously not reported homozygous null mutation, c.1505G→A of the β-glucocerebrosidase gene.

A reappraisal of Gaucher disease-diagnosis and disease management algorithms

Type 1 (non-neuronopathic) Gaucher disease was the first lysosomal storage disorder for which an effective enzyme replacement therapy was developed and it has become a prototype for treatments for related orphan diseases. There are currently four treatment options available to patients with Gaucher disease, nevertheless, almost 25% of Type 1 Gaucher patients do not gain timely access to therapy because of delays in diagnosis after the onset of symptoms. Diagnosis of Gaucher disease by enzyme testing is unequivocal, but the rarity of the disease and nonspecific and heterogeneous nature of Gaucher disease symptoms may impede consideration of this disease in the differential diagnosis. To help promote timely diagnosis and optimal management of the protean presentations of Gaucher disease, a consensus meeting was convened to develop algorithms for diagnosis and disease management for Gaucher disease.

A newborn case with perinatal-lethal Gaucher disease due to R463H homozygosity complicated by C677T homozygosity in the MTHFR gene

Perinatal-lethal Gaucher disease is very rare and is considered a variant of type 2 Gaucher disease that occurs in the neonatal period. The most distinct features of perinatal-lethal Gaucher disease are non-immune hydrops fetalis, in utero fetal demise and neonatal distress. In some cases without hydrops, neurological signs occur in the first week of life and lead to death within 3 months. Less common signs of the disease are hepatosplenomegaly, ichthyosis, arthrogryposis and facial dysmorphy. We describe a preterm neonate with Gaucher disease homozygous for R463H mutation in GBA gene who showed severe neurologic signs in addition to refractory thrombocytopenia, hepatosplenomagaly, direct hyperbilirubinemia, facial dysmorphy and ichthyosiform skin abnormalities in addition to having thrombosis in portal and splenic veins possibly due to homozygosity for C677T mutation in MTHFR gene. To the best of our knowledge, this is the first case homozygous for the GBA R463H mutation resulting in Gaucher disease with a concomitant homozygous MTHFR C677T mutation.

Review of the safety and efficacy of imiglucerase treatment of Gaucher disease

Most patients who suffer from symptomatic Gaucher disease will benefit from enzyme replacement therapy (ERT) with imiglucerase. The safety profile is excellent, only a small percentage of those exposed developing antibodies; similarly, very few patients require pre-medication for allergic reactions. Within 3 to 5 years of imiglucerase therapy, best documented at doses of 30 to 60 units/kg/infusion, hepatosplenomegaly can be expected to be reduced so that the liver volume will be maintained at 1 to 1.5 times normal (30% to 40% reduction from advent of ERT) and spleen volume to </= 2 to 8 times normal (50% to 60% reduction from advent of ERT). For anemic and thrombocytopenic patients, with 2 to 5 years of imiglucerase, hemoglobin levels are expected to be >/= 11 g/dL for women and children and >/= 12 g/dL for men; and platelet counts in patients with an intact spleen, depending on the baseline value, should approximately be doubled. Bone crises and bone pain but not irreversible skeletal damage will improve in most patients. Nonetheless, some features and some symptomatic patients apparently do not respond equally well and/or perhaps inadequately. The benefit for patients with the neuronopathic forms is primarily in improved visceral and hematological signs and symptoms. There are still several unresolved issues, the high per-unit cost being an important one, which have spurred the development of biosimilar enzymes as well as chaperone therapies currently in clinical trials.

Review of the safety and efficacy of imiglucerase treatment of Gaucher disease

Most patients who suffer from symptomatic Gaucher disease will benefit from enzyme replacement therapy (ERT) with imiglucerase. The safety profile is excellent, only a small percentage of those exposed developing antibodies; similarly, very few patients require pre-medication for allergic reactions. Within 3 to 5 years of imiglucerase therapy, best documented at doses of 30 to 60 units/kg/infusion, hepatosplenomegaly can be expected to be reduced so that the liver volume will be maintained at 1 to 1.5 times normal (30% to 40% reduction from advent of ERT) and spleen volume to </= 2 to 8 times normal (50% to 60% reduction from advent of ERT). For anemic and thrombocytopenic patients, with 2 to 5 years of imiglucerase, hemoglobin levels are expected to be >/= 11 g/dL for women and children and >/= 12 g/dL for men; and platelet counts in patients with an intact spleen, depending on the baseline value, should approximately be doubled. Bone crises and bone pain but not irreversible skeletal damage will improve in most patients. Nonetheless, some features and some symptomatic patients apparently do not respond equally well and/or perhaps inadequately. The benefit for patients with the neuronopathic forms is primarily in improved visceral and hematological signs and symptoms. There are still several unresolved issues, the high per-unit cost being an important one, which have spurred the development of biosimilar enzymes as well as chaperone therapies currently in clinical trials.

Gaucher disease: The importance of early diagnosis and therapy

A Gaucher-kór a leggyakoribb lizoszomális tárolási betegség, amelyet a glukocerebrozidáz nevű lizoszomális enzim elégtelen működése okoz. A nemzetközi Gaucher-regiszterben 2006 végén 4584 beteget tartottak nyilván, közülük 34 volt magyar. A betegségnek három típusa van: nem neuropathiás (1. típus), akut neuropathiás (2. típus) és krónikus neuropathiás (3. típus). Ezek közül a nem neuropathiás típus a leggyakoribb, amelynek klinikai megjelenési formái nagy változatosságot mutatnak, és a tünetek a betegek több mint felében tízéves kor előtt jelentkeznek. A gyermekkori manifesztáció rendszerint súlyosabb fenotípusra utal, az irreverzíbilis komplikációk kialakulásának a veszélye nagy. A biztonságos és hatékony enzimszubsztitúciós kezelést 1991 óta alkalmazzák, Magyarországon 1992 óta elérhető. Az optimális dózisban történő korai kezelés megállítja a betegség progresszióját, a korábban kialakult visceralis és hematológiai eltérésekben regressziót idéz elő, megelőzi az irreverzíbilis csontelváltozások kialakulását, és biztosítja a betegek jó életminőségét. A szerzők három, korai gyermekkorban diagnosztizált Gaucher-kóros betegük kórtörténetét mutatják be. Felhívják a figyelmet a korai diagnózis és az irreverzíbilis komplikációk kialakulása előtt elkezdett kezelés fontosságára. A kórkép időben történő felismerése nagy kihívást jelent a gyermekgyógyászok számára.

Pathogenesis of permeability barrier abnormalities in the ichthyoses: inherited disorders of lipid metabolism

Many of the ichthyoses are associated with inherited disorders of lipid metabolism. These disorders have provided unique models to dissect physiologic processes in normal epidermis and the pathophysiology of more common scaling conditions. In most of these disorders, a permeability barrier abnormality "drives" pathophysiology through stimulation of epidermal hyperplasia. Among primary abnormalities of nonpolar lipid metabolism, triglyceride accumulation in neutral lipid storage disease as a result of a lipase mutation provokes a barrier abnormality via lamellar/nonlamellar phase separation within the extracellular matrix of the stratum corneum (SC). Similar mechanisms account for the barrier abnormalities (and subsequent ichthyosis) in inherited disorders of polar lipid metabolism. For example, in recessive X-linked ichthyosis (RXLI), cholesterol sulfate (CSO(4)) accumulation also produces a permeability barrier defect through lamellar/nonlamellar phase separation. However, in RXLI, the desquamation abnormality is in part attributable to the plurifunctional roles of CSO(4) as a regulator of both epidermal differentiation and corneodesmosome degradation. Phase separation also occurs in type II Gaucher disease (GD; from accumulation of glucosylceramides as a result of to beta-glucocerebrosidase deficiency). Finally, failure to assemble both lipids and desquamatory enzymes into nascent epidermal lamellar bodies (LBs) accounts for both the permeability barrier and desquamation abnormalities in Harlequin ichthyosis (HI). The barrier abnormality provokes the clinical phenotype in these disorders not only by stimulating epidermal proliferation, but also by inducing inflammation.