Wolman's disease. A rare lipidosis with adrenal calcification

Hepatomegaly and Splenomegaly: An Approach to the Diagnosis of Lysosomal Storage Diseases

Clinical findings of hepatomegaly and splenomegaly, the abnormal enlargement of the liver and spleen, respectively, should prompt a broad differential diagnosis that includes metabolic, congestive, neoplastic, infectious, toxic, and inflammatory conditions. Among the metabolic diseases, lysosomal storage diseases (LSDs) are a group of rare and ultrarare conditions with a collective incidence of 1 in 5000 live births. LSDs are caused by genetic variants affecting the lysosomal enzymes, transporters, or integral membrane proteins. As a result, abnormal metabolites accumulate in the organelle, leading to dysfunction. Therapeutic advances, including early diagnosis and disease-targeted management, have improved the life expectancy and quality of life of people affected by certain LSDs. To access these new interventions, LSDs must be considered in patients presenting with hepatomegaly and splenomegaly throughout the lifespan. This review article navigates the diagnostic approach for individuals with hepatosplenomegaly particularly focusing on LSDs. We provide hints in the history, physical exam, laboratories, and imaging that may identify LSDs. Additionally, we discuss molecular testing, arguably the preferred confirmatory test (over biopsy), accompanied by enzymatic testing when feasible.

Rapid proteome-wide prediction of lipid-interacting proteins through ligand-guided structural genomics

Lipids are primary metabolites that play essential roles in multiple cellular pathways. Alterations in lipid metabolism and transport are associated with infectious diseases and cancers. As such, proteins involved in lipid synthesis, trafficking, and modification, are targets for therapeutic intervention. The ability to rapidly detect these proteins can accelerate their biochemical and structural characterization. However, it remains challenging to identify lipid binding motifs in proteins due to a lack of conservation at the amino acids level. Therefore, new bioinformatic tools that can detect conserved features in lipid binding sites are necessary. Here, we present Structure-based Lipid-interacting Pocket Predictor (SLiPP), a structural bioinformatics algorithm that uses machine learning to detect protein cavities capable of binding to lipids in experimental and AlphaFold-predicted protein structures. SLiPP, which can be used at proteome-wide scales, predicts lipid binding pockets with an accuracy of 96.8% and a F1 score of 86.9%. Our analyses revealed that the algorithm relies on hydrophobicity-related features to distinguish lipid binding pockets from those that bind to other ligands. Use of the algorithm to detect lipid binding proteins in the proteomes of various bacteria, yeast, and human have produced hits annotated or verified as lipid binding proteins, and many other uncharacterized proteins whose functions are not discernable from sequence alone. Because of its ability to identify novel lipid binding proteins, SLiPP can spur the discovery of new lipid metabolic and trafficking pathways that can be targeted for therapeutic development.

Loss of lysosomal acid lipase results in mitochondrial dysfunction and fiber switch in skeletal muscles of mice

OBJECTIVE

Lysosomal acid lipase (LAL) is the only enzyme known to hydrolyze cholesteryl esters (CE) and triacylglycerols in lysosomes at an acidic pH. Despite the importance of lysosomal hydrolysis in skeletal muscle (SM), research in this area is limited. We hypothesized that LAL may play an important role in SM development, function, and metabolism as a result of lipid and/or carbohydrate metabolism disruptions.

RESULTS

Mice with systemic LAL deficiency (Lal-/-) had markedly lower SM mass, cross-sectional area, and Feret diameter despite unchanged proteolysis or protein synthesis markers in all SM examined. In addition, Lal-/- SM showed increased total cholesterol and CE concentrations, especially during fasting and maturation. Regardless of increased glucose uptake, expression of the slow oxidative fiber marker MYH7 was markedly increased in Lal-/-SM, indicating a fiber switch from glycolytic, fast-twitch fibers to oxidative, slow-twitch fibers. Proteomic analysis of the oxidative and glycolytic parts of the SM confirmed the transition between fast- and slow-twitch fibers, consistent with the decreased Lal-/- muscle size due to the "fiber paradox". Decreased oxidative capacity and ATP concentration were associated with reduced mitochondrial function of Lal-/- SM, particularly affecting oxidative phosphorylation, despite unchanged structure and number of mitochondria. Impairment in muscle function was reflected by increased exhaustion in the treadmill peak effort test in vivo.

CONCLUSION

We conclude that whole-body loss of LAL is associated with a profound remodeling of the muscular phenotype, manifested by fiber type switch and a decline in muscle mass, most likely due to dysfunctional mitochondria and impaired energy metabolism, at least in mice.

Lysosomal acid lipase deficiency: A rare inherited dyslipidemia but potential ubiquitous factor in the development of atherosclerosis and fatty liver disease

Lysosomal acid lipase (LAL), encoded by the gene LIPA, is the sole neutral lipid hydrolase in lysosomes, responsible for cleavage of cholesteryl esters and triglycerides into their component parts. Inherited forms of complete (Wolman Disease, WD) or partial LAL deficiency (cholesteryl ester storage disease, CESD) are fortunately rare. Recently, LAL has been identified as a cardiovascular risk gene in genome-wide association studies, though the directionality of risk conferred remains controversial. It has also been proposed that the low expression and activity of LAL in arterial smooth muscle cells (SMCs) that occurs inherently in nature is a likely determinant of the propensity of SMCs to form the majority of foam cells in atherosclerotic plaque. LAL also likely plays a potential role in fatty liver disease. This review highlights the nature of LAL gene mutations in WD and CESD, the association of LAL with prediction of cardiovascular risk from genome-wide association studies, the importance of relative LAL deficiency in SMC foam cells, and the need to further interrogate the pathophysiological impact and cell type-specific role of enhancing LAL activity as a novel treatment strategy to reduce the development and induce the regression of ischemic cardiovascular disease and fatty liver.

Molecular markers of brain cholesterol homeostasis are unchanged despite a smaller brain mass in a mouse model of cholesteryl ester storage disease

Lysosomal acid lipase (LAL), encoded by the gene LIPA, facilitates the intracellular processing of lipids by hydrolyzing cholesteryl esters and triacylglycerols present in newly internalized lipoproteins. Loss-of-function mutations in LIPA result in cholesteryl ester storage disease (CESD) or Wolman disease when mutations cause complete loss of LAL activity. Although the phenotype of a mouse CESD model has been extensively characterized, there has not been a focus on the brain at different stages of disease progression. In the current studies, whole-brain mass and the concentrations of cholesterol in both the esterified (EC) and unesterified (UC) fractions were measured in Lal-/- and matching Lal+/+ mice (FVB-N strain) at ages ranging from 14 up to 280 days after birth. Compared to Lal+/+ controls at 50, 68-76, 140-142, and 230-280 days of age, Lal-/- mice had brain weights that averaged approximately 6%, 7%, 18%, and 20% less, respectively. Brain EC levels were higher in the Lal-/- mice at every age, being elevated 27-fold at 230-280 days. Brain UC concentrations did not show a genotypic difference at any age. The elevated brain EC levels in the Lal-/- mice did not reflect EC in residual blood. An mRNA expression analysis for an array of genes involved in the synthesis, catabolism, storage, and transport of cholesterol in the brains of 141-day old mice did not detect any genotypic differences although the relative mRNA levels for several markers of inflammation were moderately elevated in the Lal-/- mice. The possible sites of EC accretion in the central nervous system are discussed.

Clinical and Histologic Liver Improvement in Siblings With Lysosomal Acid Lipase Deficiency After Enzyme Replacement

OBJECTIVES

To assess the effect of long-term (104 weeks) treatment with recombinant sebelipase alpha (rhSA) on serum lipid and hepatic transaminase levels, and liver histopathology in 4 siblings diagnosed with lysosomal acid lipase deficiency (LAL-D).

METHODS

Four male siblings from the same nonconsanguineous parents were diagnosed with the late-onset phenotype of LAL-D in 2015. Liver specimens were obtained by biopsy at baseline and after 104 weeks of enzyme replacement with rhSA (1 mg/kg, IV, every 2 weeks). Hepatic transaminase, lipid and lipoprotein levels were assessed at baseline and sequentially every 16 weeks for 104 weeks. Hepatic steatosis was evaluated from hematoxylin and eosin-stained specimens, and fibrosis was evaluated (Metavir-scoring system) from trichrome-stained specimens obtained at baseline and following 104 weeks of treatment with rhSA.

RESULTS

All 4 siblings had improvement in their serum lipid and hepatic transaminase levels after treatment with rhSA. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels decreased from baseline by an average of 47% and 56%, respectively. The fasting triglyceride and low-density lipoprotein cholesterol (LDL-C) levels decreased from baseline by an average of 43% and 60%, respectively. Hepatic steatosis decreased from baseline grade 3 to posttreatment grade 1. Hepatic fibrosis did not advance following 104 weeks of treatment with rhSA and regressed in 1 sibling.

CONCLUSIONS

Treatment with rhSA for 104 weeks in 4 siblings with LAL-D demonstrated improvement in their hepatic transaminase and serum lipid levels, accompanied by reduction of hepatic steatosis and no progression of fibrosis.

Initial assessment and ongoing monitoring of lysosomal acid lipase deficiency in children and adults: Consensus recommendations from an international collaborative working group

BACKGROUND

Lysosomal acid lipase (LAL) deficiency is an ultra-rare, progressive, autosomal recessive disorder. Functional mutations in LIPA, the gene that encodes LAL, result in accumulation of cholesteryl esters and triglycerides in hepatocytes and in the macrophages of the intestines, vascular endothelial system, and numerous other organs. LAL deficiency has a broad clinical spectrum; children and adults can present with dyslipidemia, liver enzyme elevations, hepatosplenomegaly, hepatic steatosis, liver fibrosis and/or cirrhosis, and vascular disease, which may lead to significant morbidity and premature mortality in some patients. Given the systemic involvement and the wide range of healthcare specialists who manage patients with LAL deficiency, there is a need for guidelines to assess and monitor disease involvement.

OBJECTIVES

To provide a set of recommendations for the initial assessment and ongoing monitoring of patients with LAL deficiency to help physicians in various disciplines effectively manage the disease based on the observed presentation and progression in each case.

METHODS

A group of internationally recognized healthcare specialists with expertise in clinical genetics, pathology, hepatology, gastroenterology, cardiology, and lipidology convened to develop an evidence-based consensus of best practices for the initial assessment and ongoing monitoring of children and adults with LAL deficiency, regardless of treatment status; infants with LAL deficiency have been excluded from these guidelines because they require specialized care.

RESULTS

The authors present guidance for the assessment and monitoring of patients with LAL deficiency based on age and disease manifestations that include the hepatic, cardiovascular, and gastrointestinal systems. A schedule for ongoing monitoring of disease progression is provided. In addition, the need to establish an interdisciplinary and integrated care team to optimize the approach to managing this systemic disease is highlighted.

CONCLUSIONS

There is currently no published guidance on the assessment and monitoring of patients with LAL deficiency. These consensus recommendations for the initial assessment and ongoing monitoring of children and adults with LAL deficiency are intended to help improve the management of these patients.

Lysosomal acid lipase deficiency - early diagnosis is the key

Lysosomal acid lipase deficiency (LAL-D) is an ultra-rare lysosomal storage disease that may present from infancy to late adulthood depending on residual enzyme activity. While the severe form manifests as a rapidly progressive disease with near universal mortality within the first 6 months of life, milder forms frequently go undiagnosed for prolonged periods and typically present with progressive fatty liver disease, enlarged spleen, atherogenic dyslipidemia and premature atherosclerosis. The adult variant of LAL-D is typically diagnosed late or even overlooked due to the unspecific nature of the presenting symptoms, which are similar to common changes observed in the context of the metabolic syndrome. This review is aimed at delineating clinically useful scenarios in which pediatric or adult medicine clinicians should be aware of LAL-D as a differential diagnosis for selected patients. This is particularly relevant as a potentially life-saving enzyme replacement therapy has become available and the diagnosis can easily be ruled out or confirmed using a dried blood spot test.

Hepatocyte-specific lysosomal acid lipase deficiency protects mice from diet-induced obesity but promotes hepatic inflammation

Lysosomal acid lipase (LAL) hydrolyzes cholesteryl esters (CE) and triglycerides (TG) to generate fatty acids (FA) and cholesterol. LAL deficiency (LAL-D) in both humans and mice leads to hepatomegaly, hypercholesterolemia, and shortened life span. Despite its essential role in lysosomal neutral lipid catabolism, the cell type-specific contribution of LAL to disease progression is still elusive. To investigate the role of LAL in the liver in more detail and to exclude the contribution of LAL in macrophages, we generated hepatocyte-specific LAL-deficient mice (Liv-Lipa^−/−) and fed them either chow or high fat/high cholesterol diets (HF/HCD). Comparable to systemic LAL-D, Liv-Lipa^−/− mice were resistant to diet-induced obesity independent of food intake, movement, and energy expenditure. Reduced body weight gain was mainly due to reduced white adipose tissue depots. Furthermore, Liv-Lipa^−/− mice exhibited improved glucose clearance during glucose and insulin tolerance tests compared to control mice. Analysis of hepatic lipid content revealed a massive reduction of TG, whereas CE concentrations were markedly increased, leading to CE crystal formation in the livers of Liv-Lipa^−/− mice. Elevated plasma transaminase activities, increased pro-inflammatory cytokines and chemokines as well as hepatic macrophage infiltration indicated liver inflammation. Our data provide evidence that hepatocyte-specific LAL deficiency is sufficient to alter whole-body lipid and energy homeostasis in mice. We conclude that hepatic LAL plays a pivotal role by preventing liver damage and maintaining lipid and energy homeostasis, especially during high lipid availability.

Lysosomal Acid Lipase Deficiency: Report of Five Cases across the Age Spectrum

Lysosomal acid lipase (LAL) deficiency is an autosomal recessive lysosomal storage disorder caused by mutations in the LIPA gene that leads to premature organ damage and mortality. We present retrospective data from medical records of 5 Brazilian patients, showing the broad clinical spectrum of the disease.

Lysosomal acid lipase deficiency: a form of non-obese fatty liver disease (NOFLD)

INTRODUCTION

With the growing obesity epidemic, nonalcoholic fatty liver disease (NAFLD) is rapidly becoming one of the leading causes of liver disease worldwide. Although obesity is a main risk factor for the development of NAFLD, it can also develop in lean subjects and can be encountered in different clinical setting and in association with an array of genetic, metabolic, nutritional, infectious and drug-induced disorders. Areas covered: This article discusses causes of fatty liver in non-obese subjects focusing on Lysosomal acid lipase deficiency (LAL-D), a commonly overlooked disorder reviewing its prevalence, genetics, pathogenesis, clinical features, diagnosis and treatment. It will also review other causes of non-alcoholic fatty liver disease, which can be encountered in the absence of obesity and metabolic syndrome. Expert commentary: Although the prevalence of LAL-D has been estimated in the range of 1 in 40,000 and 1 in 300,000, this estimate is much more than the identified cases reported in the literature, which suggests that that the disease may be considerably under-diagnosed. There is a pressing need to educate clinicians about the disease, especially with the development of new promising therapeutic modalities.

Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency

Lysosomal acid lipase deficiency is a rare, autosomal recessive condition caused by mutations in the gene encoding lysosomal acid lipase (LIPA) that result in reduced or absent activity of this essential enzyme. The severity of the resulting disease depends on the nature of the underlying mutation and magnitude of its effect on enzymatic function. Wolman's disease is a severe disorder that presents during infancy, resulting in failure to thrive, hepatomegaly, and hepatic failure, and an average life expectancy of less than 4 months. Cholesteryl ester storage disorder arises later in life and is less severe, although the two diseases share many common features, including dyslipidaemia and transaminitis. The prevalence of these diseases has been estimated at one in 40 000 to 300 000, but many cases are undiagnosed and unreported, and awareness among clinicians is low. Lysosomal acid lipase deficiency-which can be diagnosed using dry blood spot testing-is often misdiagnosed as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), hereditary dyslipidaemia, or cryptogenic cirrhosis. There are no formal guidelines for treatment of these patients, and treatment options are limited. In this Review we appraise the existing literature on Wolman's disease and cholesteryl ester storage disease, and discuss available treatments, including enzyme replacement therapy, oral lipid-lowering therapy, stem-cell transplantation, and liver transplantation.

Progression of liver disease in children and adults with lysosomal acid lipase deficiency

BACKGROUND AND OBJECTIVE

Manifestations of the autosomal recessive disorder lysosomal acid lipase deficiency (LAL-D) include hepatomegaly, elevated serum liver enzymes, and progressive liver disease. We report an analysis of time to progression from first clinical manifestation to first documentation of hepatic fibrosis, cirrhosis, or liver transplantation from an observational study of pediatric and adult patients with LAL-D (clinical trial registration: NCT01528917).

METHODS

Data were analyzed from 31 patients with available biopsy data and 1 patient without biopsy data who had undergone liver transplantation. Time to first documentation of fibrosis, cirrhosis, or liver transplantation following the first LAL-D clinical manifestation was estimated using Kaplan-Meier analysis.

RESULTS

The median time to an event was 3.1 years.

CONCLUSIONS

These findings illustrate the progression of liver damage in LAL-D and the elevated risk for liver transplantation among children and adults with LAL-D.

The role of sebelipase alfa in the treatment of lysosomal acid lipase deficiency

Lysosomal acid lipase deficiency (LALD) is a lysosomal storage disorder (LSD) characterized either by infantile onset with fulminant clinical course and very poor prognosis or childhood/adult-onset disease with an attenuated phenotype. The disorder is often misdiagnosed or remains undiagnosed in children and adults due to a rather unspecific clinical presentation with dyslipidemia and steatohepatitis. Until recently, no good treatment options were available for LALD. Despite supportive and symptomatic therapies, death occurred before 1 year of age in patients with infantile-onset disease and patients with childhood/adult-onset LALD suffered from significant complications, such as liver cirrhosis, requiring liver transplantation and early-onset cardiovascular disease. With the recent approval of sebelipase alfa for clinical use in infantile- as well as childhood/adult-onset LALD, a new treatment era for this disorder has begun. Sebelipase alfa is a recombinant human lysosomal acid lipase (LAL), which is administered via the intravenous route. Clinical trials have shown significant improvement of disease parameters such as liver transaminases, hepatomegaly, and dyslipidemia in childhood/adult-onset LALD patients. Treatment of infants with the severe infantile-onset form of the disease has led to improved survival beyond the age of 1 year, and also showed improvement of hepatic and gastrointestinal symptoms, as well as growth. Overall, sebelipase alfa has a favorable safety profile and promises to be a good long-term treatment option for patients with LALD, with significant reduction of disease burden and increased life expectancy.

Neural stem cells for disease modeling of Wolman disease and evaluation of therapeutics

Background

Wolman disease (WD) is a rare lysosomal storage disorder that is caused by mutations in the LIPA gene encoding lysosomal acid lipase (LAL). Deficiency in LAL function causes accumulation of cholesteryl esters and triglycerides in lysosomes. Fatality usually occurs within the first year of life. While an enzyme replacement therapy has recently become available, there is currently no small-molecule drug treatment for WD.

Results

We have generated induced pluripotent stem cells (iPSCs) from two WD patient dermal fibroblast lines and subsequently differentiated them into neural stem cells (NSCs). The WD NSCs exhibited the hallmark disease phenotypes of neutral lipid accumulation, severely deficient LAL activity, and increased LysoTracker dye staining. Enzyme replacement treatment dramatically reduced the WD phenotype in these cells. In addition, δ-tocopherol (DT) and hydroxypropyl-beta-cyclodextrin (HPBCD) significantly reduced lysosomal size in WD NSCs, and an enhanced effect was observed in DT/HPBCD combination therapy.

Conclusion

The results demonstrate that these WD NSCs are valid cell-based disease models with characteristic disease phenotypes that can be used to evaluate drug efficacy and screen compounds. DT and HPBCD both reduce LysoTracker dye staining in WD cells. The cells may be used to further dissect the pathology of WD, evaluate compound efficacy, and serve as a platform for high-throughput drug screening to identify new compounds for therapeutic development.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-017-0670-9) contains supplementary material, which is available to authorized users.

Managing Cardiovascular Risk in Lysosomal Acid Lipase Deficiency

Lysosomal acid lipase deficiency (LAL-D) is a rare, life-threatening, autosomal recessive, lysosomal storage disease caused by mutations in the LIPA gene, which encodes for lysosomal acid lipase (LAL). This enzyme is necessary for the hydrolysis of cholesteryl ester and triglyceride in lysosomes. Deficient LAL activity causes accumulation of these lipids in lysosomes and a marked decrease in the cytoplasmic free cholesterol concentration, leading to dysfunctional cholesterol homeostasis. The accumulation of neutral lipid occurs predominantly in liver, spleen, and macrophages throughout the body, and the aberrant cholesterol homeostasis causes a marked dyslipidemia. LAL-D is characterized by accelerated atherosclerotic cardiovascular disease (ASCVD) and hepatic microvesicular or mixed steatosis, leading to inflammation, fibrosis, cirrhosis and liver failure. LAL-D presents as a clinical continuum with two phenotypes: the infantile-onset phenotype, formally referred to as Wolman disease, and the later-onset phenotype, formerly referred to as cholesteryl ester storage disease. Infants with LAL-D present within the first few weeks of life with vomiting, diarrhea, hepatosplenomegaly, failure to thrive and rapid progression to liver failure and death by 6-12 months of age. Children and young adults with LAL-D generally present with marked dyslipidemia, hepatic enzyme elevation, hepatomegaly and mixed steatosis by liver biopsy. The average age of the initial signs and symptoms of the later-onset phenotype is about 5 years old. The typical dyslipidemia is a significantly elevated low-density lipoprotein cholesterol (LDL-C) concentration and a low high-density lipoprotein cholesterol (HDL-C) concentration, placing these individuals at heightened risk for premature ASCVD. Diagnosis of the later-onset phenotype of LAL-D requires a heightened awareness of the disease because the dyslipidemia and hepatic transaminase elevation combination are common and overlap with other metabolic disorders. LAL-D should be considered in the differential diagnosis of healthy weight children and young adults with unexplained hepatic transaminase elevation accompanied by an elevated LDL-C level (>160 mg/dL) and low HDL-C level (<35 mg/dL) that is not caused by monogenic and polygenic lipid disorders or secondary factors. Treatment of LAL-D with sebelipase alfa (LAL replacement enzyme) should be considered as the standard of treatment in all individuals diagnosed with LAL-D. Other ASCVD risk factors that may be present (hypertension, tobacco use, diabetes mellitus, etc.) should be managed appropriately, consistent with secondary prevention goals.

Update on lysosomal acid lipase deficiency: Diagnosis, treatment and patient management

Lysosomal acid lipase deficiency (LALD) is an ultra-rare disease caused by a congenital disorder of the lipid metabolism, characterized by the deposition of cholesterol esters and triglycerides in the organism. In patients with no enzyme function, the disease develops during the perinatal period and is invariably associated with death during the first year of life. In all other cases, the phenotype is heterogeneous, although most patients develop chronic liver diseases and may also develop an early cardiovascular disease. Treatment for LALD has classically included the use of supportive measures that do not prevent the progression of the disease. In 2015, regulatory agencies approved the use of a human recombinant LAL for the treatment of LALD. This long-term enzyme replacement therapy has been associated with significant improvements in the hepatic and lipid profiles of patients with LALD, increasing survival rates in infants with a rapidly progressive disease. Both the severity of LALD and the availability of a specific treatment highlight the need to identify these patients in clinical settings, although its low prevalence and the existing clinical overlap with other more frequent pathologies limit its diagnosis. In this paper we set out practical recommendations to identify and monitor patients with LALD, including a diagnostic algorithm, along with an updated treatment.

Lysosomal acid lipase deficiency in all siblings of the same parents

We present 4 normal-weight sibling children with lysosomal acid lipase deficiency (LAL-D). LAL-D was considered in the differential diagnosis based on the absence of secondary causes and primary inherited traits for their marked hyperlipidemia, together with unexplained hepatic transaminase elevation. Residual lysosomal acid lipase activity confirmed the diagnosis. DNA sequencing of LIPA indicated that the siblings were compound heterozygotes (c.894G>A and c.428+1G>A). This case describes the unusual occurrence of all offspring from the same nonconsanguineous mother and father inheriting compound heterozygosity of a recessive trait and the identification of an apparently unique LIPA mutation (c.428+1G>A). It highlights the collaborative effort between a lipidologist and gastroenterologist in developing a differential diagnosis leading to the confirmatory diagnosis of this rare, life-threatening disease. With the availability of an effective enzyme replacement therapy (sebelipase alfa), LAL-D should be entertained in the differential diagnosis of children, adolescents, and young adults with idiopathic hyperlipidemia and unexplained hepatic transaminase elevation.

Targeting Wolman Disease and Cholesteryl Ester Storage Disease: Disease Pathogenesis and Therapeutic Development

Wolman disease (WD) and cholesteryl ester storage disease (CESD) are lysosomal storage diseases (LSDs) caused by a deficiency in lysosomal acid lipase (LAL) due to mutations in the LIPA gene. This enzyme is critical to the proper degradation of cholesterol in the lysosome. LAL function is completely lost in WD while some residual activity remains in CESD. Both are rare diseases with an incidence rate of less than 1/100,000 births for WD and approximate 2.5/100,000 births for CESD. Clinical manifestation of WD includes hepatosplenomegaly, calcified adrenal glands, severe malabsorption and a failure to thrive. As in CESD, histological analysis of WD tissues reveals the accumulation of triglycerides (TGs) and esterified cholesterol (EC) in cellular lysosomes. However, the clinical presentation of CESD is less severe and more variable than WD. This review is to provide an overview of the disease pathophysiology and the current state of therapeutic development for both of WD and CESD. The review will also discuss the application of patient derived iPSCs for further drug discovery.

A novel transgenic mouse model of lysosomal storage disorder

Knockout technology has proven useful for delineating functional roles of specific genes. Here we describe and provide an explanation for striking pathology that occurs in a subset of genetically engineered mice expressing a rat Ca_Vβ2a transgene under control of the cardiac α-myosin heavy chain promoter. Lesions were limited to mice homozygous for transgene and independent of native Cacnb2 genomic copy number. Gross findings included an atrophied pancreas; decreased adipose tissue; thickened, orange intestines; and enlarged liver, spleen, and abdominal lymph nodes. Immune cell infiltration and cell engulfment by macrophages were associated with loss of pancreatic acinar cells. Foamy macrophages diffusely infiltrated the small intestine's lamina propria, while similar macrophage aggregates packed liver and splenic red pulp sinusoids. Periodic acid-Schiff-positive, diastase-resistant, iron-negative, Oil Red O-positive, and autofluorescent cytoplasm was indicative of a lipid storage disorder. Electron microscopic analysis revealed liver sinusoids distended by clusters of macrophages containing intracellular myelin "swirls" and hepatocytes with enlarged lysosomes. Additionally, build up of cholesterol, cholesterol esters, and triglycerides, along with changes in liver metabolic enzyme levels, were consistent with a lipid processing defect. Because of this complex pathology, we examined the transgene insertion site. Multiple transgene copies inserted into chromosome 19; at this same site, an approximate 180,000 base pair deletion occurred, ablating cholesterol 25-hydroxylase and partially deleting lysosomal acid lipase and CD95 Loss of gene function can account for the altered lipid processing, along with hypertrophy of the immune system, which define this phenotype, and serendipitously provides a novel mouse model of lysosomal storage disorder.

Lysosomal acid lipase regulates VLDL synthesis and insulin sensitivity in mice

AIMS/HYPOTHESIS

Lysosomal acid lipase (LAL) hydrolyses cholesteryl esters and triacylglycerols (TG) within lysosomes to mobilise NEFA and cholesterol. Since LAL-deficient (Lal (-/-) ) mice suffer from progressive loss of adipose tissue and severe accumulation of lipids in hepatic lysosomes, we hypothesised that LAL deficiency triggers alternative energy pathway(s).

METHODS

We studied metabolic adaptations in Lal (-/-) mice.

RESULTS

Despite loss of adipose tissue, Lal (-/-) mice show enhanced glucose clearance during insulin and glucose tolerance tests and have increased uptake of [(3)H]2-deoxy-D-glucose into skeletal muscle compared with wild-type mice. In agreement, fasted Lal (-/-) mice exhibit reduced glucose and glycogen levels in skeletal muscle. We observed 84% decreased plasma leptin levels and significantly reduced hepatic ATP, glucose, glycogen and glutamine concentrations in fed Lal (-/-) mice. Markedly reduced hepatic acyl-CoA concentrations decrease the expression of peroxisome proliferator-activated receptor α (PPARα) target genes. However, treatment of Lal (-/-) mice with the PPARα agonist fenofibrate further decreased plasma TG (and hepatic glucose and glycogen) concentrations in Lal (-/-) mice. Depletion of hepatic nuclear factor 4α and forkhead box protein a2 in fasted Lal (-/-) mice might be responsible for reduced expression of microsomal TG transfer protein, defective VLDL synthesis and drastically reduced plasma TG levels.

CONCLUSIONS/INTERPRETATION

Our findings indicate that neither activation nor inactivation of PPARα per se but rather the availability of hepatic acyl-CoA concentrations regulates VLDL synthesis and subsequent metabolic adaptations in Lal (-/-) mice. We conclude that decreased plasma VLDL production enhances glucose uptake into skeletal muscle to compensate for the lack of energy supply.

Rapid progression and mortality of lysosomal acid lipase deficiency presenting in infants

PURPOSE

The purpose of this study was to enhance understanding of lysosomal acid lipase deficiency (LALD) in infancy.

METHODS

Investigators reviewed medical records of infants with LALD and summarized data for the overall population and for patients with and without early growth failure (GF). Kaplan-Meier survival analyses were conducted for the overall population and for treated and untreated patients.

RESULTS

Records for 35 patients, 26 with early GF, were analyzed. Prominent symptom manifestations included vomiting, diarrhea, and steatorrhea. Median age at death was 3.7 months; estimated probability of survival past age 12 months was 0.114 (95% confidence interval (CI): 0.009-0.220). Among patients with early GF, median age at death was 3.5 months; estimated probability of survival past age 12 months was 0.038 (95% CI: 0.000-0.112). Treated patients (hematopoietic stem cell transplant (HSCT), n = 9; HSCT and liver transplant, n = 1) in the overall population and the early GF subset survived longer than untreated patients, but survival was still poor (median age at death, 8.6 months).

CONCLUSIONS

These data confirm and expand earlier insights on the progression and course of LALD presenting in infancy. Despite variations in the nature, onset, and severity of clinical manifestations, and treatment attempts, clinical outcome was poor.Genet Med 18 5, 452-458.

Clinical Features of Lysosomal Acid Lipase Deficiency

OBJECTIVE

The aim of this study was to characterize key clinical manifestations of lysosomal acid lipase deficiency (LAL D) in children and adults.

METHODS

Investigators reviewed medical records of LAL D patients ages ≥5 years, extracted historical data, and obtained prospective laboratory and imaging data on living patients to develop a longitudinal dataset.

RESULTS

A total of 49 patients were enrolled; 48 had confirmed LAL D. Mean age at first disease-related abnormality was 9.0 years (range 0-42); mean age at diagnosis was 15.2 years (range 1-46). Twenty-nine (60%) were male patients, and 27 (56%) were <20 years of age at the time of consent/assent. Serum transaminases were elevated in most patients with 458 of 499 (92%) of alanine aminotransferase values and 265 of 448 (59%) of aspartate aminotransferase values above the upper limit of normal. Most patients had elevated low-density lipoprotein (64% patients) and total cholesterol (63%) at baseline despite most being on lipid-lowering therapies, and 44% had high-density lipoprotein levels below the lower limit of normal. More than half of the patients with liver biopsies (n = 31, mean age 13 years) had documented evidence of steatosis (87%) and/or fibrosis (52%). Imaging assessments revealed that the median liver volume was ∼1.15 multiples of normal (MN) and median spleen volume was ∼2.2 MN. Six (13%) patients had undergone a liver transplant (ages 9-43.5 years).

CONCLUSION

This study provides the largest longitudinal case review of patients with LAL D and confirms that LAL D is predominantly a pediatric disease causing early and progressive hepatic dysfunction associated with dyslipidemia that often leads to liver failure and transplantation.

A Phase 3 Trial of Sebelipase Alfa in Lysosomal Acid Lipase Deficiency

BACKGROUND

Lysosomal acid lipase is an essential lipid-metabolizing enzyme that breaks down endocytosed lipid particles and regulates lipid metabolism. We conducted a phase 3 trial of enzyme-replacement therapy in children and adults with lysosomal acid lipase deficiency, an underappreciated cause of cirrhosis and severe dyslipidemia.

METHODS

In this multicenter, randomized, double-blind, placebo-controlled study involving 66 patients, we evaluated the safety and effectiveness of enzyme-replacement therapy with sebelipase alfa (administered intravenously at a dose of 1 mg per kilogram of body weight every other week); the placebo-controlled phase of the study was 20 weeks long and was followed by open-label treatment for all patients. The primary end point was normalization of the alanine aminotransferase level. Secondary end points included additional disease-related efficacy assessments, safety, and side-effect profile.

RESULTS

Substantial disease burden at baseline included a very high level of low-density lipoprotein cholesterol (≥190 mg per deciliter) in 38 of 66 patients (58%) and cirrhosis in 10 of 32 patients (31%) who underwent biopsy. A total of 65 of the 66 patients who underwent randomization completed the double-blind portion of the trial and continued with open-label treatment. At 20 weeks, the alanine aminotransferase level was normal in 11 of 36 patients (31%) in the sebelipase alfa group and in 2 of 30 (7%) in the placebo group (P=0.03), with mean changes from baseline of -58 U per liter versus -7 U per liter (P<0.001). With respect to prespecified key secondary efficacy end points, we observed improvements in lipid levels and reduction in hepatic fat content (P<0.001 for all comparisons, except P=0.04 for triglycerides). The number of patients with adverse events was similar in the two groups; most events were mild and were considered by the investigator to be unrelated to treatment.

CONCLUSIONS

Sebelipase alfa therapy resulted in a reduction in multiple disease-related hepatic and lipid abnormalities in children and adults with lysosomal acid lipase deficiency. (Funded by Synageva BioPharma and others; ARISE ClinicalTrials.gov number, NCT01757184.).

Sebelipase alfa over 52 weeks reduces serum transaminases, liver volume and improves serum lipids in patients with lysosomal acid lipase deficiency

BACKGROUND & AIMS

Lysosomal acid lipase deficiency is an autosomal recessive enzyme deficiency resulting in lysosomal accumulation of cholesteryl esters and triglycerides. LAL-CL04, an ongoing extension study, investigates the long-term effects of sebelipase alfa, a recombinant human lysosomal acid lipase.

METHODS

Sebelipase alfa (1mg/kg or 3mg/kg) was infused every-other-week to eligible subjects. Safety and tolerability assessments, including liver function, lipid profiles and liver volume assessment, were carried out at regular intervals.

RESULTS

216 infusions were administered to eight adult subjects through week 52 during LAL-CL04. At week 52, mean alanine aminotransferase and aspartate aminotransferase levels were normal with mean change from baseline of -58% and -40%. Mean changes for low-density lipoprotein, total cholesterol, triglyceride and high-density lipoprotein were -60%, -39%, -36%, and +29%, respectively. Mean liver volume by magnetic resonance imaging and hepatic proton density fat fraction decreased (12% and 55%, respectively). Adverse events were mainly mild and unrelated to sebelipase alfa. Infusion-related reactions were uncommon: three events of moderate severity were reported in two subjects; one patient's event was suggestive of a hypersensitivity-like reaction, but additional testing did not confirm this, and the subject has successfully re-started sebelipase alfa. Of samples tested to date, no anti-drug antibodies have been detected.

CONCLUSIONS

Long-term dosing with sebelipase alfa in lysosomal acid lipase-deficient patients is well tolerated and produces sustained reductions in transaminases, improvements in serum lipid profile and reduction in the hepatic fat fraction. A randomized, placebo-controlled phase 3 trial in children and adults is underway (ARISE: NCT01757184).

Lysosomal acid lipase deficiency--an under-recognized cause of dyslipidaemia and liver dysfunction

Lysosomal acid lipase deficiency (LAL-D) is a rare autosomal recessive lysosomal storage disease caused by deleterious mutations in the LIPA gene. The age at onset and rate of progression vary greatly and this may relate to the nature of the underlying mutations. Patients presenting in infancy have the most rapidly progressive disease, developing signs and symptoms in the first weeks of life and rarely surviving beyond 6 months of age. Children and adults typically present with some combination of dyslipidaemia, hepatomegaly, elevated transaminases, and microvesicular hepatosteatosis on biopsy. Liver damage with progression to fibrosis, cirrhosis and liver failure occurs in a large proportion of patients. Elevated low-density lipoprotein cholesterol levels and decreased high-density lipoprotein cholesterol levels are common features, and cardiovascular disease may manifest as early as childhood. Given that these clinical manifestations are shared with other cardiovascular, liver and metabolic diseases, it is not surprising that LAL-D is under-recognized in clinical practice. This article provides practical guidance to lipidologists, endocrinologists, cardiologists and hepatologists on how to recognize individuals with this life-limiting disease. A diagnostic algorithm is proposed with a view to achieving definitive diagnosis using a recently developed blood test for lysosomal acid lipase. Finally, current management options are reviewed in light of the ongoing development of enzyme replacement therapy with sebelipase alfa (Synageva BioPharma Corp., Lexington, MA, USA), a recombinant human lysosomal acid lipase enzyme.

Cholesteryl ester storage disease: review of the findings in 135 reported patients with an underdiagnosed disease

Cholesteryl ester storage disease (CESD) is caused by deficient lysosomal acid lipase (LAL) activity, predominantly resulting in cholesteryl ester (CE) accumulation, particularly in the liver, spleen, and macrophages throughout the body. The disease is characterized by microvesicular steatosis leading to liver failure, accelerated atherosclerosis and premature demise. Although CESD is rare, it is likely that many patients are unrecognized or misdiagnosed. Here, the findings in 135 CESD patients described in the literature are reviewed. Diagnoses were based on liver biopsies, LAL deficiency and/or LAL gene (LIPA) mutations. Hepatomegaly was present in 99.3% of patients; 74% also had splenomegaly. When reported, most patients had elevated serum total cholesterol, LDL-cholesterol, triglycerides, and transaminases (AST, ALT, or both), while HDL-cholesterol was decreased. All 112 liver biopsied patients had the characteristic pathology, which is progressive, and includes microvesicular steatosis, which leads to fibrosis, micronodular cirrhosis, and ultimately to liver failure. Pathognomonic birefringent CE crystals or their remnant clefts were observed in hepatic cells. Extrahepatic manifestations included portal hypertension, esophageal varices, and accelerated atherosclerosis. Liver failure in 17 reported patients resulted in liver transplantation and/or death. Genotyping identified 31 LIPA mutations in 55 patients; 61% of mutations were the common exon 8 splice-junction mutation (E8SJM(-1G>A)), for which 18 patients were homozygous. Genotype/phenotype correlations were limited; however, E8SJM(-1G>A) homozygotes typically had early-onset, slowly progressive disease. Supportive treatment included cholestyramine, statins, and, ultimately, liver transplantation. Recombinant LAL replacement was shown to be effective in animal models, and recently, a phase I/II clinical trial demonstrated its safety and indicated its potential metabolic efficacy.

Intractable ascites as a manifestation of Wolman's disease: report of two sibs

Wolman disease (WD) is a rare, inherited, rapidly fatal condition presenting in early infancy. The disease manifests in the first month of life with failure to thrive, vomiting, diarrhea, abdominal distension, hepatosplenomegaly and bilateral adrenal calcification and is nearly always fatal before the age of 1 year. Barring a case report of isolated fetal ascites, there is no report of intractable ascites as the presentation of WD till date. We report two siblings with WD who both had intractable ascites and required therapeutic paracentesis, albumin infusion, and diuretics to control tense ascites. Although rare, WD should be considered in the differential diagnosis of infantile ascites.

An autopsy case of infantile GM1 gangliosidosis with adrenal calcification

We describe an autopsy case of a 1-year-old male baby presenting with failure to gain milestones, floppiness, and reddish skin lesions since birth. Fundoscopic examination revealed bilateral cherry-red spots in the macula. The baby died of respiratory failure and autopsy revealed numerous ballooned neurons and astrocytes with cytoplasmic storage material seen throughout central white matter, basal ganglia, cerebellum, choroid plexus, and brain stem. There was neuronal degeneration with loss of myelin in central white matter with axonal degeneration as well. The storage material was weakly positive with PAS and oil red-O stains. Ultrastructurally, multilayered lamellated bodies were seen within the ballooned neurons. Biochemical analysis of lysosomal enzymes done in leucocytes revealed β-galactosidase deficiency that is consistent with GM1 gangliosidosis. Extensive visceral deposition of similar material was also seen. Remarkably, both adrenals revealed extensive medullary calcification, which has not been reported in this lysosomal storage disorder, to the best of our knowledge.

Wolman disease: diagnosis by leucocyte acid lipase estimation

Wolman disease is a rare fatal autosomal recessive disorder caused by absence of acid lipase enzyme leading to accumulation of cholesterol ester. Hepatosplenomegaly is a constant feature and occurs as early as fourth day of life. Progressive mental deterioration may occur after few weeks of onset of symptoms. Adrenal calcification seen on X-ray abdomen, USG or CT scan is the hallmark of Wolman disease. For the first time in Indian literature, the authors report a case of Wolman disease that was confirmed by acid lipase enzyme estimation.

Wolman disease and cholesteryl ester storage disease diagnosed by histological and ultrastructural examination of intestinal and liver biopsy

Deficient activity of lysosomal acid lipase (LAL) results in massive accumulation of cholesteryl esters and triglycerides in most tissues of the body. The deficiency state is expressed in two major phenotypes: Wolman disease (WD) and cholesteryl ester storage disease (CESD). WD occurs in infancy and is nearly always fatal before the age of 1 year, whereas CESD can be more benign and may not be detected until adulthood. Since there are no specific routine laboratory observations that suggest these metabolic diseases, diagnosis is based on the clinical picture combined with LAL deficiency in cultured skin fibroblasts or peripheral lymphocytes. Both disorders are rather rare, considering that about a hundred of cases have been described up to now. This study describes the histological and ultrastructural aspects disclosed by intestinal or liver biopsy in three cases of WD and in two cases of CESD. Furthermore, it emphasizes the role of morphological findings in pointing the diagnosis towards a metabolic storage disease.

New pathogenetic hypothesis for Wolman disease: possible role of oxidized low-density lipoproteins in adrenal necrosis and calcification

Wolman disease in an inherited metabolic disease, characterized by a severe deficiency of the acid lipase and a massive lysosomal storage of triacylglycerols and cholesteryl esters, associated with hepatosplenomegaly, adrenal calcification and nearly always fatal in the first year of life. Cultured human lymphoblastoid cells and human adrenal cells are able to promote the formation of mildly oxidized low-density lipoproteins (LDL), which in turn exhibit a non-negligible cytotoxic effect on these cells. In contrast, fibroblasts induce only very low levels of LDL oxidation. Comparative experiments have shown that the cytotoxic effect of oxidized LDL was higher to Wolman-disease cells than to controls. The oxidative ability of Wolman cells was similar to that of normal ones. The over-cytotoxicity of mildly oxidized LDL to Wolman cells resulted from the higher uptake of mildly oxidized LDL through the LDL-receptor pathway, which is only poorly down-regulated in Wolman cells subsequently to the block of the lysosomal degradation of LDL-cholesteryl esters. In cultured adrenal cells, oxidized LDL induced a sustained rise in intracellular [Ca2+] which is directly involved in the cellular damage and cell death induced by oxidized LDL [Nègre-Salvayre and Salvayre (1992) Biochim. Biophys. Acta 1123, 207-215]. This Ca2+ peak is followed by a dramatic deposition of calcium in damaged or/and dead cultured adrenal cells, quite similar to that observed in Wolman-disease adrenal cortex. The cell-induced LDL oxidation and the subsequent cytotoxic effect can be prevented, at least in part, by antioxidants such as alpha-tocopherol and nordihydroguaiaretic acid. These findings support the hypothesis that the Wolman-disease adrenal damage (necrosis and calcification) could result from the association of the following events: mild oxidation of LDL by adrenal cells, over-uptake of mildly oxidized LDL by Wolman cells (resulting from the block of the lysosomal degradation of cholesteryl esters in Wolman cells), and cytotoxicity related to the amount of mildly oxidized LDL internalized by cells. The reported data also suggest that LDL oxidation induced by adrenal cells and their subsequent cytotoxicity can be prevented (in part) by antioxidants, and the potential therapeutic use of antioxidants in Wolman disease is discussed.

A splice junction mutation causes deletion of a 72-base exon from the mRNA for lysosomal acid lipase in a patient with cholesteryl ester storage disease

The genetic defect leading to cholesteryl ester storage disease (CESD) has been determined in a 12-yr-old patient. Lysosomal acid lipase (LAL) activity in cultured skin fibroblasts was reduced to approximately 9% of control fibroblasts. Plasma cholesterol (255 mg/dl) and LDL-cholesterol (215 mg/dl) were elevated whereas HDL-cholesterol was reduced (19 mg/dl). Triglycerides were moderately elevated (141 mg/dl). There were no clinical abnormalities with the exception of hepatosplenomegaly. Both parents have reduced LAL activity in white blood cells. PCR analysis of the LAL mRNA from the propositus revealed a single slightly smaller mRNA species in skin fibroblasts as well as in leukocytes. The mother of the patient and his older brother had two mRNA species: one of normal size and one of the same size as the propositus. The father has a LAL mRNA of normal size only. Sequence analysis of a PCR-amplified cDNA fragment showed a 72-bp in-frame deletion resulting in the loss of the codons for amino acids 254-277. Analysis of genomic DNA revealed that the 72 bp represent an exon, indicating that the deletion in the mRNA is caused by defective splicing. Sequence analysis of the patient's genomic DNA revealed a G-->A substitution in the last nucleotide of the 72-bp exon in one of his alleles. The mutant allele was shown to cosegregate with the truncated mRNA in the pedigree, providing further evidence that the G-->A substitution causes aberrant splicing and exon skipping. No normal-sized mRNA is detectable in the propositus even though he is not homozygous for the splice site mutation. This can be only accounted for by assuming that he is a compound heterozygote with a null allele inherited from his father. In summary, the data presented provide evidence that deletion of the codons for amino acids 254-277 in the LAL mRNA in combination with a null allele cause the clinical expression of CESD in our patient.

Cholesteryl ester storage disease: hepatopathology and effects of therapy with lovastatin

We describe three patients with cholesteryl ester storage disease. Diagnosis was confirmed by demonstrating a deficiency in lysosomal acid cholesteryl hydrolase activity in cultured skin fibroblasts from each of these patients. All had hepatomegaly, elevated serum aminotransferase activities and hyperlipoproteinemia. Histological examination of liver biopsy specimens before treatment revealed accumulation of fat within hepatocytes, bile duct epithelium and endothelial and Kupffer cells. Cholesterol crystals were recognized by their birefringence in frozen sections. A striking feature was the presence of markedly hypertrophied Kupffer cells and portal macrophages with foamy, tan-colored cytoplasm that stained readily with the periodic acid-Schiff reagent and aldehyde fuchsin. Periportal fibrosis was noted in all cases; incomplete cirrhosis was present in one case. Distinctive and hitherto undescribed lysosomal accumulations of triglyceride and cholesterol crystals were noted. The patients were treated with lovastatin, a cholesterol-lowering agent, for at least 12 mo. No significant changes were seen in serum lipoprotein concentrations or liver histopathology after therapy. Thus lovastatin did not have an obviously beneficial effect on abnormal lipid metabolism in these patients.

Relative fluorescence of normal and acid lipase-deficient cultured fibroblasts following administration of pyrene decanoic acid

Skin fibroblasts, derived from normal individuals or patients with Wolman's disease (an autosomal recessive disorder due to acid lysosomal lipase deficiency) were incubated with the fluorescent fatty acid, pyrene-decanoic acid (P10). Measurements of the fluorescence intensities of the total lipid extracts indicated that equal quantities of P10 were incorporated into both cell types. The fluorescence emitted by the intact cells was subsequently recorded in a fluorescence microscope equipped with a microdetector unit, which permitted determination of the fluorescence emitted by the intact cell or by specific regions thereof. The fluorescence intensities emitted by the lipidotic cells exceeded those of their normal counterparts 2- and 5-fold when comparing the entire cells or the perinuclear region, respectively. The cells were then subjected to subcellular fractionation and an analysis of the fractions revealed that up to 85-90% of the fluorescence of the lysosome-mitochondrial pellet was derived from free pyrenedecanoic acid; the latter contributed only 15-18% to the fluorescence of the homogenate or the cytosol. There was no difference in the fluorescence of the lipid extracts from the respective fractions of the lipidotic or normal cells. However, the fluorescence emitted by the intact lysosome-mitochondrial fraction of the lipidotic cells exceeded that of its normal counterpart 2.5-fold. These data suggest that the increased fluorescence intensity of the intact lipidotic cells resulted from a higher quantum yield of free P10 molecules solubilized in the hydrophobic environment of their neutral lipid-containing storage granules.

Cholesteryl ester storage disease: pathologic changes in an affected fetus

The prenatal diagnosis of cholesteryl ester storage disease, a rare autosomal recessive disorder, was made by demonstration of deficient lysosomal acid lipase activity in cultured amniocytes from an at-risk fetus. The histochemical and ultrastructural changes in the affected fetus (at 17 gestational weeks) are described and compared to findings in liver and duodenal biopsy specimens from a 9-year-old homozygous female. Massive lysosomal cholesterol and lipid accumulation was demonstrated in fetal hepatocytes, adrenal cells and syncytiotrophoblasts. Of particular note was the observation of extensive necrosis in the fetal adrenal glands. Necrosis of the adrenals may precede the calcification observed in some patients with cholesteryl ester storage disease and in most patients with Wolman disease, an allelic variant due to lysosomal acid lipase deficiency. Fibrosis of the liver and lipid accumulation in macrophages in liver and duodenum, which were present in the 9-year-old homozygote, were not observed in the affected fetus, and therefore, may represent later manifestations of the disease.

Cholesterol ester storage disease in an adult presenting with sea-blue histiocytosis

An adult patient is described with hepatomegaly and sea-blue histiocytes in the bone marrow. A diagnosis of cholesterol ester storage disease was established following enzyme and lipid analyses on liver biopsy and cultured skin fibroblasts. Acid esterase activity was deficient (approx. 5% of controls) in liver and fibroblasts using [14C]-triolein or 4-methylumbelliferyl palmitate as substrates. Cholesterol ester levels were raised about 70-fold in liver, whereas triglyceride levels were only marginally raised. Marked accumulation of cholesterol esters was also demonstrated in cultured fibroblasts. Clinically, the patient responded favourably to phenobarbitone treatment. However, this was not reflected in liver acid esterase or lipid levels.

Deficient activity of hepatic acid lipase in cholesterol ester storage disease

Absence of lysosomal acid lipase activity in the liver is described in cholesterol ester storage disease and Wolman's disease. This enzyme deficiency may result in the excess hepatic cholesterol ester found in both conditions. However, clinical, genetic, and histopathologic differences suggest that the two conditions are separate diseases not completely explained by deficient enzyme activity.