Lysosomal Acid Lipase Deficiency: Genetics, Screening, and Preclinical Study.

Lysosomal acid lipase (LAL) is a lysosomal enzyme essential for the degradation of cholesteryl esters through the endocytic pathway. Deficiency of the LAL enzyme encoded by the LIPA gene leads to LAL deficiency (LAL-D) (OMIM 278000), one of the lysosomal storage disorders involving 50-60 genes. Among the two disease subtypes, the severe disease subtype of LAL-D is known as Wolman disease, with typical manifestations involving hepatomegaly, splenomegaly, vomiting, diarrhea, and hematopoietic abnormalities, such as anemia. In contrast, the mild disease subtype of this disorder is known as cholesteryl ester storage disease, with hypercholesterolemia, hypertriglyceridemia, and high-density lipoprotein disappearance. The prevalence of LAL-D is rare, but several treatment options, including enzyme replacement therapy, are available. Accordingly, a number of screening methodologies have been developed for this disorder. This review summarizes the current discussion on LAL-D, covering genetics, screening, and the tertiary structure of human LAL enzyme and preclinical study for the future development of a novel therapy.

Lysosomal acid lipase deficiency in pediatric patients: a scoping review

Abstract Objective: Lysosomal acid lipase deficiency (LAL-D) is an underdiagnosed autosomal recessive disease with onset between the first years of life and adulthood. Early diagnosis is crucial for effective therapy and long-term survival. The objective of this article is to recognize warning signs among the clinical and laboratory characteristics of LAL-D in pediatric patients through a scope review. Sources: Electronic searches in the Embase, PubMed, Livivo, LILACS, Web of Science, Scopus, Google Scholar, Open Gray, and ProQuest Dissertations and Theses databases. The dataset included observational studies with clinical and laboratory characteristics of infants, children and adolescents diagnosed with lysosomal acid lipase deficiency by enzyme activity testing or analysis of mutations in the lysosomal acid lipase gene (LIPA). The reference selection process was performed in two stages. The references were selected by two authors, and the data were extracted in June 2020. Summary of the findings: The initial search returned 1593 studies, and the final selection included 108 studies from 30 countries encompassing 206 patients, including individuals with Wolman disease and cholesteryl ester storage disease (CESD). The most prevalent manifestations in both spectra of the disease were hepatomegaly, splenomegaly, anemia, dyslipidemia, and elevated transaminases. Conclusions: Vomiting, diarrhea, jaundice, and splenomegaly may be correlated, and may serve as a starting point for investigating LAL-D. Familial lymphohistiocytosis should be part of the differential diagnosis with LAL-D, and all patients undergoing upper gastrointestinal endoscopy should be submitted to intestinal biopsy.

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.

Lysosomal acid lipase deficiency in pediatric patients: a scoping review.

OBJECTIVE: Lysosomal acid lipase deficiency (LAL-D) is an underdiagnosed autosomal recessive disease with onset between the first years of life and adulthood. Early diagnosis is crucial for effective therapy and long-term survival. The objective of this article is to recognize warning signs among the clinical and laboratory characteristics of LAL-D in pediatric patients through a scope review. SOURCES: Electronic searches in the Embase, PubMed, Livivo, LILACS, Web of Science, Scopus, Google Scholar, Open Gray, and ProQuest Dissertations and Theses databases. The dataset included observational studies with clinical and laboratory characteristics of infants, children and adolescents diagnosed with lysosomal acid lipase deficiency by enzyme activity testing or analysis of mutations in the lysosomal acid lipase gene (LIPA). The reference selection process was performed in two stages. The references were selected by two authors, and the data were extracted in June 2020. SUMMARY OF THE FINDINGS: The initial search returned 1593 studies, and the final selection included 108 studies from 30 countries encompassing 206 patients, including individuals with Wolman disease and cholesteryl ester storage disease (CESD). The most prevalent manifestations in both spectra of the disease were hepatomegaly, splenomegaly, anemia, dyslipidemia, and elevated transaminases. CONCLUSIONS: Vomiting, diarrhea, jaundice, and splenomegaly may be correlated, and may serve as a starting point for investigating LAL-D. Familial lymphohistiocytosis should be part of the differential diagnosis with LAL-D, and all patients undergoing upper gastrointestinal endoscopy should be submitted to intestinal biopsy.

Loss of function of lysosomal acid lipase (LAL) profoundly impacts osteoblastogenesis and increases fracture risk in humans.

Lysosomal acid lipase (LAL) is essential for cholesteryl ester (CE) and triacylglycerol (TAG) hydrolysis in the lysosome. Clinically, an autosomal recessive LIPA mutation causes LAL deficiency (LALD), previously described as Wolman Disease or Cholesteryl Ester Storage Disease (CESD). LAL-D is associated with ectopic lipid accumulation in the liver, small intestine, spleen, adrenal glands, and blood. Considering the importance of unesterified cholesterol and fatty acids in bone metabolism, we hypothesized that LAL is essential for bone formation, and ultimately, skeletal health. To investigate the role of LAL in skeletal homeostasis, we used LAL-deficient (-/-) mice, in vitro osteoblast cultures, and novel clinical data from LAL-D patients. Both male and female LAL-/- mice demonstarted lower trabecular and cortical bone parameters , which translated to reduced biomechanical properties. Further histological analyses revealed that LAL-/- mice had fewer osteoblasts, with no change in osteoclast or marrow adipocyte numbers. In studying the cell-autonomous role of LAL, we observed impaired differentiation of LAL-/- calvarial osteoblasts and in bone marrow stromal cells treated with the LAL inhibitor lalistat. Consistent with LAL's role in other tissues, lalistat resulted in profound lipid puncta accumulation and an altered intracellular lipid profile. Finally, we analyzed a large de-identified national insurance database (i.e. 2016/2017 Optum Clinformatics®) which revealed that adults (≥18 years) with CESD (n = 3076) had a higher odds ratio (OR = 1.21; 95% CI = 1.03-1.41) of all-cause fracture at any location compared to adults without CESD (n = 13.7 M) after adjusting for demographic variables and osteoporosis. These data demonstrate that alterations in LAL have significant clinical implications related to fracture risk and that LAL's modulation of lipid metabolism is a critical for osteoblast function.

Large-scale screening of lipase acid deficiency in at risk population.

BACKGROUND: Lysosomal acid lipase deficiency (LALD, OMIM#278000) is a rare lysosomal disorder with an autosomal recessive inheritance. The main clinical manifestations are related to a progressive accumulation of cholesteryl esters, triglycerides or both within the lysosome in different organs such as the liver, spleen, and cardiovascular system. A wide range of clinical severity is associated with LALD including a severe very rare antenatal/neonatal/infantile phenotype named Wolman disease and a late-onset form named cholesteryl ester storage disease (CESD). METHODS: This study aimed to investigate a cohort of at-risk patients (4174) presenting with clinical or biological signs consistent with LALD using the assessment of LAL activity on dried blood spots. RESULTS: LAL activity was lower than 0.05 nmol/punch/L (cut-off: 0.12) in 19 patients including 13 CESD and 6 Wolman. Molecular study has been conducted in 17 patients and succeeded in identifying 34 mutated alleles. Fourteen unique variants have been characterized, 7 of which are novel. CONCLUSION: This study allowed to identify a series of patients and expanded the molecular spectrum knowledge of LALD. Besides, a new screening criteria grid based on the clinical/biological data from our study and the literature has been proposed in order to enhance the diagnosis rate in at risk populations.

A rare cause of hepatomegaly and dyslipidemia: lysosomal acid lipase deficiency.

BACKGROUND: Lysosomal acid lipase deficiency (LAL-D), also known as cholesteryl ester storage disease or Wolman disease, is a multi-systemic autosomal recessive genetic disorder caused by mutations in the lysosomal acid lipase gene (LIPA). CASE: A 14-year-old female patient was diagnosed as LAL-D with the findings of hepatomegaly, splenomegaly, elevated liver enzyme levels, and abnormal lipid profile. Her sister had similar laboratory and ultrasonographic findings. Both siblings had a homozygous c.894 G > A mutation in the LIPA gene, and their parents were heterozygous for this mutation. CONCLUSIONS: This case is one of the similar reports in the literature regarding clinical, biochemical, and genetic findings. It is well-known that LAL-D has overlapping clinical manifestations, and early diagnosis is quite challenging. Therefore, most patients die in the first year of life. After the determination of novel mutations in LAL-D patients, it is thought that LAL-D can present with heterogeneous signs and symptoms.

A Case of Lysosomal Acid Lipase Deficiency Confirmed by Response to Sebelipase Alfa Therapy.

Lysosomal acid lipase (LAL) deficiency, or cholesterol ester storage disease, is a disorder affecting the breakdown of cholesterol esters and triglycerides within lysosomes. Clinical findings include hepatomegaly, hepatic dysfunction, and dyslipidemia with a wide range of phenotypic variability and age of onset. The available clinical and molecular information of the patient presented herein was consistent with a diagnosis of LAL deficiency, but her LAL activity assay repeatedly showed normal or borderline low results. Her response to enzyme replacement therapy and demonstrable deficiency on a newer specific enzymatic assay ultimately confirmed her diagnosis of LAL deficiency.

Lysosomal Acid Lipase Deficiency: Therapeutic Options.

Lysosomal acid lipase (LAL) deficiency is a metabolic (storage) disorder, encompassing a severe (Wolman disease) and attenuated (Cholesterol ester storage disease) subtype; both inherited as autosomal recessive traits. Cardinal clinical features include the combination of hepatic dysfunction and dyslipidemia, as a consequence of cholesteryl esters and triglyceride accumulation, predominately in the liver and vascular and reticuloendothelial system. Significant morbidity can arise, due to liver failure and/or atherosclerosis; in part related to the severity of the underlying gene defect and corresponding enzyme deficiency. Diagnosis is based on demonstration of decreased LAL enzyme activity, complemented by analysis of the cognate gene defects. Therapeutic options include dietary manipulation and the use of lipid-lowering drugs. Sebelipase alfa, a recombinant enzyme replacement therapy, has garnered regulatory approval, following demonstration of improvements in disease-relevant markers and clinical benefit in clinical trials, which included increased survival in the most severe cases.

Mutations identified in a cohort of Mexican patients with lysosomal acid lipase deficiency.

INTRODUCTION AND OBJECTIVES: Lysosomal acid lipase deficiency (LAL-D) is an autosomal recessive disease caused by mutations in the LIPA gene, located on the long arm of chromosome 10 (10q23.31). Up until now, more than 59 mutations have been described and which are the cause of a very wide clinical spectrum. The goal of this study was to identify the mutations present in Mexican pediatric patients with a diagnosis of LAL-D. MATERIALS AND METHODS: A cross-sectional study was carried out which included all the pediatric patients with LAL-D treated in a tertiary hospital in Mexico from January 2000 to June 2017. RESULTS: Sixteen patients with LAL-D were identified with a disease phenotype marked by the accumulation of cholesteryl esters. Eight distinct variants in the LIPA gene sequence were found, four pathogenic variants and four probably pathogenic. In six individuals, the variants were found in the homozygous state and ten were compound heterozygous. The eight variants were inverted, with five found on exon 4 and the others on exons 2, 8 and 10. The variant c.386A>G;p.His129Arg was the most common, being found in six of the 16 individuals (37.5%), making it much more frequent than what had previously been reported in the literature in proportion to the rest of the variants. The mutation known as E8SJM, which has been the mostly frequently found at the international level, was not the most common among this group of Mexican patients. In conclusion, Mexican patients present a different frequency of mutations associated with LAL-D in comparison to European populations.

Estimation of the prevalence of cholesteryl ester storage disorder in a cohort of patients with clinical features of familial hypercholesterolaemia.

BACKGROUND AND AIM: Familial hypercholesterolaemia is caused by variants in the low-density lipoprotein cholesterol metabolic pathway involving LDLR, APOB and PCSK9 genes. A national genetic testing service in Wales, UK has observed that no familial hypercholesterolaemia variant is found in almost 80% patients with the familial hypercholesterolaemia phenotype. It has recently been suggested that some adult patients with a familial hypercholesterolaemia phenotype may have cholesteryl ester storage disease which can also present as a mixed hyperlipidaemia. The commonest genetic cause of cholesteryl ester storage disease is an exon 8 splice junction variant in the LIPA gene (rs116928232, c.894G>A; E8SJM) previously found to have an allele frequency of 0.0011 (1 in 450 individuals) in a large European population. This study investigated the prevalence of the E8SJM in patients with a familial hypercholesterolaemia phenotype in Wales, UK. METHOD: A total of 1203 patients with a clinical suspicion of familial hypercholesterolaemia but no familial hypercholesterolaemia variant were invited to participate. Of these, 668 patients provided informed written consent. Stored DNA samples from 663 patients were genotyped for the E8SJM variant. RESULTS: Three heterozygotes were identified (allele frequency 0.0023). Whole gene sequencing of the LIPA gene was undertaken in these three individuals, but no other variants were found. Therefore, there were no cholesteryl ester storage disease patients (homozygote or compound heterozygote) identified in this cohort. CONCLUSION: The allele frequency 0.0023 (1 in 221 individuals) for the E8SJM variant was more prevalent in this cohort than in a European population study; however, no cholesteryl ester storage disease homozygotes were identified. We found no evidence to support routine testing for cholesteryl ester storage disease in adult patients with a familial hypercholesterolaemia phenotype.

Screening for lysosomal acid lipase deficiency: A retrospective data mining study and evaluation of screening criteria.

BACKGROUND AND AIMS: Lysosomal acid lipase deficiency (LAL-D) is a lysosomal storage disorder. In severe cases, it can cause life-threatening organ failure due to lipid substrates accumulation. However, mild phenotypes of this disorder are increasingly recognized. The aim of this study is to determine the number of missed LAL-D patients in a large pediatric hospital population. METHODS: In a retrospective data mining study, the medical files of children, who visited the outpatient clinic at a university hospital between 2000 and 2016, with high plasma low density lipoprotein cholesterol (LDL-C) levels, were evaluated. Previously developed LAL-D screening criteria, with lipid and alanine aminotransferase (ALT) values adjusted for children, were used to analyze which children are suspect for LAL-D. For suspicion of LAL-D, at least 3 out of 5 screening criteria had to be met. Subsequently data on presentation and follow-up were collected to determine if the clinical picture was compatible with LAL-D. RESULTS: We identified 2037 children with high LDL-C levels. Of those, 36 children complied with ≥3 screening criteria. Thirty-one of those had an underlying disorder other than LAL-D that explained the abnormalities and, in the 5 remaining children, ALT and lipid levels normalized spontaneously, thus excluding LAL-D. CONCLUSIONS: This study shows that retrospective data mining is unlikely to yield a significant number of LAL-D cases in children. The screening algorithm adjusted for children seems useful and accurate in the selection of children for further testing, suggesting it can be applied prospectively, although further validation is warranted.

Importância da biópsia hepática no diagnóstico da deficiência de lipase ácida lisossomal: relato de caso / Importance of liver biopsy in the diagnosis of lysosomal acid lipase deficiency: a case report

RESUMO Objetivo: Descrever a doença de depósito de ésteres de colesterol (DDEC) e a importância da biópsia hepática na realização do diagnóstico. Descrição do caso: Paciente feminina, dois anos e dez meses de idade, com queixa de aumento do volume abdominal secundário à hepatomegalia há quatro meses. Ultrassonografia abdominal demonstrou hepatomegalia e esteatose hepática. Exames laboratoriais mostraram aumento de enzimas hepáticas e dislipidemia. A biópsia hepática foi compatível com DDEC. Comentários: Embora a medida da atividade enzimática seja o padrão-ouro para o diagnóstico de DDEC, a biópsia hepática é muito útil na investigação de casos suspeitos, particularmente quando há outros diagnósticos diferenciais a serem considerados.

ABSTRACT Objective: To describe a case of cholesteryl ester storage disease (CESD) and discuss the importance of liver biopsy for diagnosis. Case description: A female patient, aged two years and ten months, presented with an increased abdominal volume following hepatomegaly for four months. Abdominal ultrasound demonstrated hepatomegaly and hepatic steatosis. Laboratory tests showed elevated liver serum enzymes and dyslipidemia. Liver biopsy was consistent with CESD. Comments: Although measuring enzyme activity is the gold standard for CESD diagnosis, liver biopsy is very helpful when investigating suspected cases of CESD, particularly upon other differential diagnoses to be considered.

Specific Substrate for the Assay of Lysosomal Acid Lipase.

BACKGROUND: Deficiency of lysosomal acid lipase (LAL) causes Wolman disease and cholesterol ester storage disease. With the recent introduction of enzyme replacement therapy to manage LAL deficiency comes the need for a reliable assay of LAL enzymatic activity that can be applied to dried blood spots (DBS). METHODS: We prepared and tested a library of analogs of palmitoyl 4-methylumbelifferyl esters to find a highly active and specific substrate for LAL in DBS. The LAL assay was optimized leading to both LC-MS/MS and fluorometric assay of LAL. We tested the new assay on DBS from healthy and LAL-deficient patients. RESULTS: The ester formed between palmitic acid and 4-propyl-8-methyl-7-hydroxycoumarin (P-PMHC) was found to be >98% selective for LAL in DBS based on the sensitivity of its activity to the LAL-specific inactivator Lalistat-2 and the fact that the activity was close to zero using DBS from patients previously shown to be LAL-deficient. Use of P-PMHC and heavy isotope-labeled internal standard with optimized assay conditions led to an approximately 2-fold increase in the specific activity of LAL compared with the previously reported LAL assay. Patients deficient in LAL were readily distinguished from normal persons with the new LAL assay using UPLC-MS/MS or fluorometric assay platforms. CONCLUSIONS: The new assay can measure LAL in DBS with a single measurement compared with the previous method involving 2 assays done in parallel.

[Lysosomal acid lipase deficiency (LAL-D) : Diagnostic and therapeutic options in an underdiagnosed disease]. / Mangel an lysosomaler saurer Lipase (LAL-D) : Diagnostik und aktuelle Therapie einer unterdiagnostizierten Erkrankung.

BACKGROUND AND CLINICAL SETTING: Lysosomal acid lipase deficiency is an autosomal recessive storage disease caused by mutations in the LIPA gene. The accumulation of cholesteryl esters and triglycerides in hepatocytes lead to hepatomegaly with progressive fibrosis and liver cirrhosis. Characteristically, patients have a hepatomegaly combined with high serum levels of cholesterol, LDL-cholesterol and in some cases triglyceride, whereas HDL-cholesterol is decreased. Histologically, hepatocytes show a microvesicular steatosis with typically ballooned Kupffer cells. Even though histological morphology is typical, it is not characteristic. Therefore LAL-D is supposed to be an underdiagnosed disease with a high number of unreported cases misdiagnosed as uncharacteristic fatty liver disease (NASH, NAFLD, cryptogenic liver cirrhosis). Further, there is overlap with other storage diseases, complicating a correct diagnosis. THERAPY: Until recently, different therapeutic options could not prevent development of liver cirrhosis. Patients with Wolman's disease have an especially rapid progression and die within the first six months of life. With the recent development of a new enzyme replacement therapy with sebelipase alfa (Kanuma ®), new therapeutic options with significant improvement of dyslipidemia and reduction of transaminases have become reality. Positive clinical results seem to have the potential to significantly raise life expectancy. CONCLUSION: These new therapeutic options warrant an increase in awareness of LAL-D by clinicians and pathologists. Correct diagnosis of LAL-D is important for effective therapy and long-term survival.

IMPORTANCE OF LIVER BIOPSY IN THE DIAGNOSIS OF LYSOSOMAL ACID LIPASE DEFICIENCY: A CASE REPORT. / IMPORTÂNCIA DA BIÓPSIA HEPÁTICA NO DIAGNÓSTICO DA DEFICIÊNCIA DE LIPASE ÁCIDA LISOSSOMAL: RELATO DE CASO.

OBJECTIVE: To describe a case of cholesteryl ester storage disease (CESD) and discuss the importance of liver biopsy for diagnosis. CASE DESCRIPTION: A female patient, aged two years and ten months, presented with an increased abdominal volume following hepatomegaly for four months. Abdominal ultrasound demonstrated hepatomegaly and hepatic steatosis. Laboratory tests showed elevated liver serum enzymes and dyslipidemia. Liver biopsy was consistent with CESD. COMMENTS: Although measuring enzyme activity is the gold standard for CESD diagnosis, liver biopsy is very helpful when investigating suspected cases of CESD, particularly upon other differential diagnoses to be considered.

OBJETIVO: Descrever a doença de depósito de ésteres de colesterol (DDEC) e a importância da biópsia hepática na realização do diagnóstico. DESCRIçÃO DO CASO: Paciente feminina, dois anos e dez meses de idade, com queixa de aumento do volume abdominal secundário à hepatomegalia há quatro meses. Ultrassonografia abdominal demonstrou hepatomegalia e esteatose hepática. Exames laboratoriais mostraram aumento de enzimas hepáticas e dislipidemia. A biópsia hepática foi compatível com DDEC. COMENTÁRIOS: Embora a medida da atividade enzimática seja o padrão-ouro para o diagnóstico de DDEC, a biópsia hepática é muito útil na investigação de casos suspeitos, particularmente quando há outros diagnósticos diferenciais a serem considerados.