Farber lipogranulomatosis: clinical and molecular genetic analysis reveals a novel mutation in an Indian family

Lysosome function in glomerular health and disease

The lysosome represents an important regulatory platform within numerous vesicle trafficking pathways including the endocytic, phagocytic, and autophagic pathways. Its ability to fuse with endosomes, phagosomes, and autophagosomes enables the lysosome to break down a wide range of both endogenous and exogenous cargo, including macromolecules, certain pathogens, and old or damaged organelles. Due to its center position in an intricate network of trafficking events, the lysosome has emerged as a central signaling node for sensing and orchestrating the cells metabolism and immune response, for inter-organelle and inter-cellular signaling and in membrane repair. This review highlights the current knowledge of general lysosome function and discusses these findings in their implication for renal glomerular cell types in health and disease including the involvement of glomerular cells in lysosomal storage diseases and the role of lysosomes in nongenetic glomerular injuries.

The interaction of ASAH1 and NGF gene involving in neurotrophin signaling pathway contributes to schizophrenia susceptibility and psychopathology

The neurodevelopmental hypothesis of schizophrenia has been widely accepted. In light of our previous microarray data, two neurodevelopment-related genes were focused on inclduing the N-acylsphingosine amidohydrolase 1 gene (ASAH1) and the nerve growth factor gene (NGF). The evidence that ASAH1 and NGF are associated with schizophrenia is far from conclusive. Furthermore, their interactions in schizophrenia have not been investigated. Total 413 patients and 578 controls were included. Eleven single-nucleotide polymorphisms (SNPs) in ASAH1 and NGF were selected. A multifactor dimensionality reduction (MDR) was applied to investigate gene-gene interactions in schizophrenia, and the traditional odds ratio methods was applied to validate it. The effects of ASAH1, NGF and their interaction on the severity of the disease were analyzed by 3 × 3 covariance analysis of (ANCOVA). The biological interaction between ASAH1 and NGF was examined. KEGG was used to identify the related signaling pathways. After correction by Bonferroni, there were no differences in the genotypic, allelic, or haplotypic frequencies of 11 SNPs between patients and controls. However, the interaction of certain SNPs had effect on susceptibility to schizophrenia, including two high-risk and one low-risk genotypic combinations (OR = 1.49 [1.11-2.00]; OR = 1.45 [1.09-1.92], and OR = 0.64 [0.41-0.98]). ASAH1-rs7830490 and its interaction with NGF-rs4332358 were associated with the general psychopathological subscale score (F _adjusted = 3.94, p _adjusted = 0.01; F _adjusted = 2.36, p _adjusted = 0.03). We also found that ASAH1 and NGF interacted with CaMK2B involving in the neurotrophin signaling pathway. Our results suggest that the interaction of ASAH1 and NGF with CaMK2B involved in neurotrophin signaling pathway may contribute to schizophrenia susceptibility and psychopathology.

Acid ceramidase deficiency: Farber disease and SMA-PME

Acid ceramidase (ACDase) deficiency is a spectrum of disorders that includes a rare lysosomal storage disorder called Farber disease (FD) and a rare epileptic disorder called spinal muscular atrophy with progressive myoclonic epilepsy (SMA-PME). Both disorders are caused by mutations in the ASAH1 gene that encodes the lysosomal hydrolase that breaks down the bioactive lipid ceramide. To date, there have been fewer than 200 reported cases of FD and SMA-PME in the literature. Typical textbook manifestations of classical FD include the formation of subcutaneous nodules, accumulation of joint contractures, and development of a hoarse voice. In reality, however, the clinical presentation is much broader. Patients may develop severe pathologies leading to death in infancy or may develop attenuated forms of the disorder wherein they are often misdiagnosed or not diagnosed until adulthood. A clinical variability also exists for SMA-PME, in which patients develop progressive muscle weakness and seizures. Currently, there is no known cure for FD or for SMA-PME. The main treatment is symptom management. In rare cases, treatment may include surgery or hematopoietic stem cell transplantation. Research using disease models has provided insights into the pathology as well as the role of ACDase in the development of these conditions. Recent studies have highlighted possible biomarkers for an effective diagnosis of ACDase deficiency. Ongoing work is being conducted to evaluate the use of recombinant human ACDase (rhACDase) for the treatment of FD. Finally, gene therapy strategies for the treatment of ACDase deficiency are actively being pursued. This review highlights the broad clinical definition and outlines key studies that have improved our understanding of inherited ACDase deficiency-related conditions.

Chronic lung injury and impaired pulmonary function in a mouse model of acid ceramidase deficiency

Farber disease (FD) is a debilitating lysosomal storage disorder (LSD) caused by a deficiency of acid ceramidase (ACDase) activity due to mutations in the gene ASAH1. Patients with ACDase deficiency may develop a spectrum of clinical phenotypes. Severe cases of FD are frequently associated with neurological involvement, failure to thrive, and respiratory complications. Mice homozygous ( Asah1P361R/P361R) for an orthologous patient mutation in Asah1 recapitulate human FD. In this study, we show significant impairment in lung function, including low compliance and increased airway resistance in a mouse model of ACDase deficiency. Impaired lung mechanics in Farber mice resulted in decreased blood oxygenation and increased red blood cell production. Inflammatory cells were recruited to both perivascular and peribronchial areas of the lung. We observed large vacuolated foamy histiocytes that were full of storage material. An increase in vascular permeability led to protein leakage, edema, and impacted surfactant homeostasis in the lungs of Asah1P361R/P361R mice. Bronchial alveolar lavage fluid (BALF) extraction and analysis revealed accumulation of a highly turbid lipoprotein-like substance that was composed in part of surfactants, phospholipids, and ceramides. The phospholipid composition of BALF from Asah1P361R/P361R mice was severely altered, with an increase in both phosphatidylethanolamine (PE) and sphingomyelin (SM). Ceramides were also found at significantly higher levels in both BALF and lung tissue from Asah1P361R/P361R mice when compared with levels from wild-type animals. We demonstrate that a deficiency in ACDase leads to sphingolipid and phospholipid imbalance, chronic lung injury caused by significant inflammation, and increased vascular permeability, leading to impaired lung function.

Accumulation of ordered ceramide-cholesterol domains in farber disease fibroblasts

Farber disease is an inherited metabolic disorder caused by mutations in the acid ceramidase gene, which leads to ceramide accumulation in lysosomes. Farber disease patients display a wide variety of symptoms with most patients eventually displaying signs of nervous system dysfunction. We now present a novel tool that could potentially be used to distinguish between the milder and more severe forms of the disease, namely, an antibody that recognizes a mixed monolayer or bilayer of cholesterol:C16-ceramide, but does not recognize either ceramide or cholesterol by themselves. This antibody has previously been used to detect cholesterol:C16-ceramide domains in a variety of cultured cells. We demonstrate that levels of cholesterol:C16-ceramide domains are significantly elevated in fibroblasts from types 4 and 7 Farber disease patients, and that levels of the domains can be modulated by either reducing ceramide or cholesterol levels. Moreover, these domains are located in membranes of the endomembrane system, and also in two unexpected locations, namely, the mitochondria and the plasma membrane. This study suggests that the ceramide that accumulates in severe forms of Farber disease cells is sequestered to distinct membrane subdomains, which may explain some of the cellular pathology observed in this devastating lysosomal storage disease.

Molecular basis of acid ceramidase deficiency in a neonatal form of Farber disease: identification of the first large deletion in ASAH1 gene

Farber disease, also known as Farber's lipogranulomatosis, is a clinically heterogeneous autosomal recessive disease caused by mutations in the ASAH1 gene. This gene codes for acid ceramidase, a lysosomal heterodimeric enzyme that hydrolyzes ceramide into sphingosine and fatty acid. To date, less than 25 distinct mutations have been identified in Farber patients, but no large deletions have yet been reported. In this work, cultured fibroblasts from a Farber patient with the rare neonatal form of Farber disease were studied to elucidate the molecular basis of this extremely severe phenotype. Direct sequencing of ASAH1 genomic DNA revealed the causative heterozygous mutation in the donor splice site consensus sequence of intron 11, g.24491A > G (c.917 + 4A > G), that resulted in the absence of detectable mRNA. Subsequent analysis of ASAH1 mRNA showed total skipping of exons 3 to 5. Long-range PCR and sequencing led to the identification of a gross deletion of ASAH1 gene, g.8728_18197del (c.126-3941_382 + 1358del) predicting the synthesis of a truncated polypeptide, p.Tyr42_Leu127delinsArgfs*10. Accordingly, no molecular forms corresponding to precursor or proteolytically processed mature protein were observed. These findings indicate that any functionally active acid ceramidase is absent in patient cells, underscoring the severity of the clinical phenotype. Molecular findings in the non-consanguineous parents confirmed the compound heterozygous ASAH1 genotype identified in this Farber case. This work unravels for the first time the mutations underlying the neonatal form of Farber disease and represents the first report of a large deletion identified in the ASAH1 gene. Screening for gross deletions in other patients in whom the mutation present in the second allele had not yet been identified is required to elucidate further its overall contribution for the molecular pathogenesis of this devastating disease.

Microarray analysis of the toxicogenomics and the genotoxic potential of a cationic lipid-based gene delivery nanosystem in human alveolar epithelial a549 cells

ABSTRACT Viral and nonviral vectors have been widely used in gene therapy as delivery reagents for nucleic acids. Toxicity with viral vectors has increasingly led to the search for suitable nonviral vectors, such as cationic lipids/polymers, as potentially safer alternatives. However, little is known about the genomic toxicity of these delivery systems in target cells/tissues. In the current investigation, we report on the toxicogenomics and genotoxicity of cationic lipid Oligofectamine (OF) nanosystems in human alveolar epithelial A549 cells. To investigate the nature and the ontology of the gene expression changes in A549 cells upon treatment with OF nanoliposomes, microarray gene expression profiling methodology was utilized. For microarray analysis, cyanine (Cy3/Cy5)-labeled cDNA samples from treated and untreated cells were hybridized on target arrays housing 200 genes. Both OF and OF-DNA lipoplex induced significant gene expression changes belonging to the different genomic ontologies such as cell defense and apoptosis pathways. Flow cytometry analyses revealed induction of apoptosis in A549 cells treated with these nanosystems that is likely due to interactions and/or deterioration of the cell membranes. However, no DNA damage was detected by the Comet assay. These data suggest that cationic nanoliposomes in the absence of direct DNA damage elicit multiple gene expression changes in A549 cells that may compromise the main goals of gene medicine where only therapy-defined gene changes are required.

A novel mutation in an atypical presentation of the rare infantile Farber disease

BACKGROUND

Farber disease (MIM 228000) is a rare autosomal recessive condition caused by deficiency of lysosomal acid ceramidase (EC 3.5.1.23). The disease presents classically during the infantile period with a characteristic triad of clinical manifestations: (a) painful joints, (b) subcutaneous nodules, and (c) progressive hoarseness due to laryngeal involvement. All cases reported in the literature to date have presented with the above features, except for the neonatal-visceral subtype.

METHODS

Here we describe a 2-year-old female, a product of a non-consanguineous Emirati union, who was quite well until 8 months of age when presented with failure to thrive, developmental delay with relative sparing of cognitive function, cherry-red spot, painful joint, progressive limitation of joint movement, and hoarseness of voice. The sibling of patient died with similar presentation and the nerve biopsy of deceased sibling showed features consistent with Farber disease.

RESULTS

Gene sequencing of the ASAHI gene confirmed the diagnosis of Farber disease. Our patient has two heterozygous novel mutations, one in exon 8 (c.533 T>C) and the other in exon 13 (c.1144 A>C). The carrier status of the parents was confirmed.

CONCLUSIONS

Farber disease is well known for its striking unique triad of symptoms. This study demonstrates that not all the cases essentially present with subcutaneous nodules which is considered a hallmark of the disease.

Novel V97G ASAH1 mutation found in Farber disease patients: unique appearance of the disease with an intermediate severity, and marked early involvement of central and peripheral nervous system

Farber disease is a rare inherited lysosomal storage disorder caused by ceramidase deficiency that leads to accumulation of ceramide in various tissues. Mutations within ASAH1 encoding for acid ceramidase are responsible for the disease. Here we report two siblings with Farber disease who carry a novel V97G with the parents and a sister being asymptomatic carriers. The mutation site was found to be highly conserved among different species using ClustalW2 alignment. Functional prediction tools indicated the mutation to be pathogenic. Electron microscopy based ultrastructural studies using skin biopsy showed inclusion of enlarged lysosomes and presence of the zebra bodies. The T1 weighted magnetic resonance images of the brain indicated diffuse loss of the deep white matter volume predominantly along the occipital horns of the lateral ventricle with subsequent facet dilatation of the supratentorial and infratentorial ventricular system. This is the first report of a detailed clinical and molecular analysis of cases with Farber disease from Saudi Arabia.

Identification of the N-acylsphingosine amidohydrolase 1 gene (ASAH1) for susceptibility to schizophrenia in a Han Chinese population

OBJECTIVES

To study the involvement of the N-acylsphingosine amidohydrolase 1 gene (ASAH1) in the susceptibility to schizophrenia in the Han Chinese population.

METHODS

We performed cDNA microarray analysis to exam the gene expression profile in six schizophrenic patients and six healthy controls. We evaluated the ASAH1 expression levels in 30 subjects with chronic schizophrenia and 30 healthy controls by using real-time polymerase chain reaction (PCR). A total of 254 unrelated probands with schizophrenia and their biological parents were also genotyped at three single nucleotide polymorphisms (SNPs: rs3753118, rs3753116, and rs7830490) of the ASAH1 gene for association analysis.

RESULTS

In the microarray analysis, the ASAH1 gene was down-regulated in all schizophrenic patients compared with healthy controls. In real-time PCR, the ASAH1 expression levels for schizophrenic patients with positive family history were significantly decreased (P = 0.020). In the association analyses, two SNPs (rs7830490 and rs3753118) and one haplotype (rs7830490 (A)-rs3753116 (G)) of ASAH1 showed significant evidence of nominal associations with schizophrenia (P = 0.026; P = 0.046; P = 0.007, respectively). The haplotype remained statistically significant (empirical P = 0.045) after correction for multiple testing.

CONCLUSIONS

This study supports that the ASAH1 gene may be a potential candidate gene for schizophrenia in Han Chinese subjects.

Farber lipogranulomatosis type 1--late presentation and early death in a Croatian boy with a novel homozygous ASAH1 mutation

BACKGROUND

We report a boy with an unusually late presentation of Farber lipogranulomatosis type l.

CASE STUDY

The first symptoms appeared at the end of the first year of life in the form of joint swelling; other symptoms such as cherry-red spot, hoarseness, subcutaneous nodules appeared much later. The history of the disease, from the first symptoms till his early death, lasted 26.5 months. The neuronal dysfunction accompanied by the rapid neurological deterioration with seizures and myoclonias, rather than the general dystrophy, seemed to limit the duration of disease in our patient and provoked his early death. Diagnosis was confirmed by analysis of ceramide metabolism in cultured fibroblasts and of the ASAH1 gene, which indicated homozygosity for a novel point mutation.

CONCLUSION

The deficient activity of acid ceramidase correlated well with poor prognosis of the disease in our boy, in contrast to late appearance of dermal nodules and the subsequent severe clinical course with fatal outcome. Farber lipogranulomatosis should be suspected in children with joint swelling as the first and only symptom of disease. In order to advance our knowledge towards establishing genotype-phenotype correlations in Farber's disease, detailed analysis of the ASAH1 gene is needed.

Lysosomal storage disorders in the newborn

Lysosomal storage disorders are rare inborn errors of metabolism, with a combined incidence of 1 in 1500 to 7000 live births. These relatively rare disorders are seldom considered when evaluating a sick newborn. A significant number of the >50 different lysosomal storage disorders, however, do manifest in the neonatal period and should be part of the differential diagnosis of several perinatal phenotypes. We review the earliest clinical features, diagnostic tests, and treatment options for lysosomal storage disorders that can present in the newborn. Although many of the lysosomal storage disorders are characterized by a range in phenotypes, the focus of this review is on the specific symptoms and clinical findings that present in the perinatal period, including neurologic, respiratory, endocrine, and cardiovascular manifestations, dysmorphic features, hepatosplenomegaly, skin or ocular involvement, and hydrops fetalis/congenital ascites. A greater awareness of these features may help to reduce misdiagnosis and promote the early detection of lysosomal storage disorders. Implementing therapy at the earliest stage possible is crucial for several of the lysosomal storage disorders; hence, an early appreciation of these disorders by physicians who treat newborns is essential.

Farber's disease type IV presenting with cholestasis and neonatal liver failure: report of two cases

We report 2 siblings diagnosed with Farber's disease type IV. Type IV is a subtype of Farber's disease that presents in the neonatal period and usually initially lacks the triad of symptoms, including painful and deformed joints, subcutaneous nodules, and hoarse cry, classically seen in the other subtypes. While it is well known that all neonates with type IV present with hepatomegaly, a previously unrecognized presentation is that of cholestatic jaundice and rapidly evolving liver failure. We describe 2 siblings who presented with jaundice in the neonatal period and discuss the clinical data and variation in pathologic findings that should be considered for the diagnosis.

Population genetic analysis of the N-acylsphingosine amidohydrolase gene associated with mental activity in humans

To understand the evolution of human mental activity, we performed population genetic analyses of nucleotide sequences ( approximately 11 kb) from a worldwide sample of 60 chromosomes of the N-acylsphingosine amidohydrolase (ASAH1) gene. ASAH1 hydrolyzes ceramides and regulates neuronal development, and its deficiency often results in mental retardation. In the region ( approximately 4.4 kb) encompassing exons 3 and 4 of this gene, two distinct lineages (V and M) have been segregating in the human population for 2.4 +/- 0.4 million years (MY). The persistence of these two lineages is attributed to ancient population structure of humans in Africa. However, all haplotypes belonging to the V lineage exhibit strong linkage disequilibrium, a high frequency (62%), and small nucleotide diversity (pi = 0.05%). These features indicate a signature of positive Darwinian selection for the V lineage. Compared with the orthologs in mammals and birds, it is only Val at amino acid site 72 that is found exclusively in the V lineage in humans, suggesting that this Val is a likely target of positive selection. Computer simulation confirms that demographic models of modern humans except for the ancient population structure cannot explain the presence of two distinct lineages, and neutrality is incompatible with the observed small genetic variation of the V lineage at ASAH1. On the basis of the above observations, it is argued that positive selection is possibly operating on ASAH1 in the modern human population.