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Classifications

Harrison's Part

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Inheritance

1

Autosomal recessive HP:0000007

Wolman disease is inherited as an autosomal recessive disorder caused by biallelic LIPA pathogenic variants that severely reduce or abolish lysosomal acid lipase activity.

Autosomal recessive inheritance

Show evidence (2 references)

PMID:28786388 SUPPORT Human Clinical

"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."

This review directly supports autosomal recessive inheritance and LIPA-mediated lysosomal acid lipase deficiency.

PMID:26225414 SUPPORT Other

"If both parents are known to be heterozygous for a LIPA pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier."

GeneReviews provides the autosomal-recessive sibling recurrence and carrier risks used in family counseling.

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Discussions and Knowledge Gaps

2

Which in-vivo steps connect lysosomal neutral-lipid storage in the adrenal gland to adrenal necrosis and calcification in Wolman disease?

HUMAN MODEL MISMATCH OPEN gap_wolman_adrenal_calcification_mechanism

Attached to

pathophysiology#Adrenal Lipid Storage

Adrenal lipid infiltration, enlargement, and calcification are clinically documented, but the available mechanistic study is a cultured-cell hypothesis involving oxidized LDL uptake, calcium loading, cytotoxicity, and necrosis. It does not establish the sequence or its necessity in affected infants.

Proposed experiments

Human adrenal validation of the oxidized-LDL injury sequence

exp_wolman_adrenal_human_validation

Compare LIPA-deficient and isogenic-corrected human adrenal cortical organoids after matched native- and mildly oxidized-LDL exposures, measuring LDL uptake, lysosomal neutral-lipid storage, calcium dynamics, necrosis, and mineral deposition over time. Compare the resulting molecular and spatial signature with archived adrenal tissue from affected infants and age-matched controls when such tissue is available.

Decision criterion

The cultured-cell mechanism is supported as a bridge to infant adrenal disease if LIPA deficiency produces an ordered excess-uptake, calcium-loading, necrosis, and mineralization sequence that is reversed by isogenic LIPA correction and is concordant with affected-infant adrenal pathology. Storage without the downstream injury sequence, or absence of that signature in affected-infant tissue, would refute the proposed bridge.

Would support

pathophysiology#Adrenal Lipid Storage phenotypes#Adrenal calcification

Would refute

pathophysiology#Adrenal Lipid Storage phenotypes#Adrenal calcification

Show evidence (1 reference)

PMID:8037680 SUPPORT In Vitro

"These findings support the hypothesis that the Wolman-disease adrenal damage (necrosis and calcification) could result from the association of the following events"

The authors explicitly frame the oxidized-LDL mechanism as a hypothesis, leaving its in-vivo role unresolved.

Can liver-directed LIPA AAV safely and durably reproduce the knockout-mouse rescue in infants with rapidly progressive LAL-D?

HUMAN MODEL MISMATCH OPEN gap_wolman_lipa_aav_translation

Attached to

pathophysiology#Lysosomal Acid Lipase Deficiency

Liver-directed AAV produced broad biochemical and survival rescue in Lipa-null mice. The reviewed evidence is preclinical and therefore does not establish infant dosing, organ coverage, durability, vector immunity, or clinical safety.

Proposed experiments

Staged translation of liver-directed LIPA AAV to infantile LAL-D

exp_wolman_lipa_aav_human_translation

Quantify dose, biodistribution, secreted LAL cross-correction, durability, pre-existing and treatment-emergent immunity, and organ toxicity in infant-relevant human hepatocyte-intestinal co-cultures and a nonhuman-primate bridging study. Advance only a candidate meeting prespecified bridging criteria to an early-phase infant study measuring LAL activity, organ lipid burden, liver and gastrointestinal disease, growth, vector immunity, and toxicity.

Decision criterion

Direct translation from the Lipa-null mouse is supported only if a tolerable exposure produces durable therapeutic LAL activity and cross-correction in the bridging systems and concordant biochemical and clinical improvement without unacceptable vector or immune toxicity in treated infants. Failure of organ coverage or durability, or dose-limiting toxicity before therapeutic activity, would refute direct extrapolation of the mouse rescue to infants.

Would support

experimental_models#Lipa-null mouse model with liver-directed LIPA AAV rescue pathophysiology#Lysosomal Acid Lipase Deficiency

Would refute

experimental_models#Lipa-null mouse model with liver-directed LIPA AAV rescue pathophysiology#Lysosomal Acid Lipase Deficiency

Show evidence (1 reference)

PMID:39489913 SUPPORT Model Organism

"These results show that this liver-directed LIPA gene therapy has the potential to be a transformative treatment for LAL-D."

The investigators describe therapeutic potential based on a mouse study; clinical translation remains an open question.

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Pathophysiology

9

LIPA Loss of Function

Biallelic pathogenic variants in LIPA reduce or abolish lysosomal acid lipase activity.

LIPA hgnc:6617

Downstream

Lysosomal Acid Lipase Deficiency Loss of LIPA function reduces or abolishes lysosomal acid lipase activity.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"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."

This review directly links LIPA mutations to reduced or absent lysosomal acid lipase activity.

Lysosomal Acid Lipase Deficiency

Lysosomal acid lipase activity is markedly reduced or absent, removing the essential lysosomal hydrolase required to cleave cholesteryl esters and triglycerides.

LIPA hgnc:6617

neutral lipid catabolic process GO:0046461 ↓ DECREASED triglyceride catabolic process GO:0019433 ↓ DECREASED

sterol ester esterase activity GO:0004771 ↓ DECREASED triacylglycerol lipase activity GO:0004806 ↓ DECREASED

lysosomal lumen GO:0043202

Experimental models

Lipa-null mouse model with liver-directed LIPA AAV rescue OTHER The knockout removes Lipa activity and AAV supplies a functional LIPA transgene.

Downstream

Impaired Lysosomal Cholesteryl Ester and Triglyceride Hydrolysis Deficient lysosomal acid lipase prevents normal lysosomal hydrolysis of cholesteryl esters and triglycerides.

Show evidence (2 references)

PMID:30866656 SUPPORT Human Clinical

"Lysosomal acid lipase (LAL), encoded by the lipase A ( LIPA) gene, hydrolyzes cholesteryl esters and triglycerides to generate free fatty acids and cholesterol in the cell."

This review provides the core enzymatic function that is lost in Wolman disease.

PMID:36204319 SUPPORT Human Clinical

"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."

This review independently supports lysosomal acid lipase as the key lysosomal hydrolase for cholesteryl ester and triglyceride cleavage.

Impaired Lysosomal Cholesteryl Ester and Triglyceride Hydrolysis

Failure of lysosomal acid lipase blocks lysosomal cleavage of cholesteryl esters and triglycerides into free cholesterol and fatty acids.

cholesterol metabolic process GO:0008203 ↓ DECREASED lipid metabolic process GO:0006629 ↓ DECREASED

Downstream

Lysosomal Cholesteryl Ester and Triglyceride Storage Undegraded cholesteryl esters and triglycerides accumulate in lysosomes.

Show evidence (1 reference)

PMID:30866656 SUPPORT Human Clinical

"Lysosomal acid lipase (LAL), encoded by the lipase A ( LIPA) gene, hydrolyzes cholesteryl esters and triglycerides to generate free fatty acids and cholesterol in the cell."

Loss of this lysosomal hydrolysis step is the immediate biochemical consequence of lysosomal acid lipase deficiency.

Lysosomal Cholesteryl Ester and Triglyceride Storage

Cholesteryl esters and triglycerides accumulate within lysosomes of macrophages and parenchymal cells across multiple tissues, establishing the multisystem storage phenotype of Wolman disease.

macrophage CL:0000235 hepatocyte CL:0000182 enterocyte CL:0000584

liver UBERON:0002107 small intestine UBERON:0002108 lymph node UBERON:0000029

Experimental models

Wolman disease patient fibroblast lipid-storage and LAL-transgene rescue model PRIMARY CELL CULTURE The model reports excess intracellular lipid droplets and lysosomes caused by LAL deficiency.

Downstream

Hepatic and Reticuloendothelial Lipid Storage Lipid-laden macrophages and parenchymal cells accumulate in liver and spleen.

Intestinal Lipid Storage Lipid storage in the gastrointestinal tract drives enteric dysfunction.

Adrenal Lipid Storage Neutral-lipid deposition extends to the adrenal glands in Wolman disease.

Show evidence (2 references)

PMID:41599846 SUPPORT Human Clinical

"LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."

This review directly supports multisystem lysosomal cholesteryl ester and triglyceride storage in macrophages and parenchymal cells.

PMID:23624251 SUPPORT Human Clinical

"Lysosomal Acid Lipase (LAL) deficiency is a rare metabolic storage disease, caused by a marked reduction in activity of LAL, which leads to accumulation of cholesteryl esters (CE) and triglycerides (TG) in lysosomes in many tissues."

This human translational study independently supports CE and TG accumulation in lysosomes across many tissues.

Hepatic and Reticuloendothelial Lipid Storage

Storage within hepatocytes and reticuloendothelial macrophages enlarges the liver and spleen and sets up rapidly progressive hepatic injury.

hepatocyte CL:0000182 macrophage CL:0000235

liver UBERON:0002107 spleen UBERON:0002106

Downstream

Progressive Liver Dysfunction Progressive hepatic storage contributes to liver dysfunction and eventual hepatic failure.

Hepatosplenomegaly Hepatic and reticuloendothelial lipid storage clinically manifests as marked hepatosplenomegaly.

Show evidence (1 reference)

PMID:28179030 SUPPORT Human Clinical

"Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"

This infant treatment study summarizes the core hepatic and reticuloendothelial disease burden before effective therapy.

Progressive Liver Dysfunction

Ongoing hepatic lipid storage causes liver dysfunction that can progress to hepatic failure during infancy.

hepatocyte CL:0000182

liver UBERON:0002107

Downstream

Hepatic failure Progressive hepatic dysfunction can advance to hepatic failure in the severe infantile phenotype.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"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."

This review directly connects the severe infantile phenotype to progressive hepatic failure.

Intestinal Lipid Storage

Storage in the gastrointestinal tract injures intestinal tissue and contributes to poor fat tolerance, vomiting, diarrhea, and downstream malabsorption.

enterocyte CL:0000584 macrophage CL:0000235

small intestine UBERON:0002108

Downstream

Malabsorption and Severe Gastrointestinal Dysfunction Intestinal storage produces gastrointestinal disturbance and impaired nutrient absorption.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."

This review supports direct lipid storage within gastrointestinal tissues as a core component of disease biology.

Malabsorption and Severe Gastrointestinal Dysfunction

Intestinal dysfunction produces persistent gastrointestinal symptoms and poor nutrient absorption, driving severe growth failure in infancy.

enterocyte CL:0000584

small intestine UBERON:0002108

Downstream

Malabsorption Severe gastrointestinal dysfunction includes malabsorption.

Diarrhea Gastrointestinal dysfunction commonly manifests as diarrhea.

Vomiting Severe gastrointestinal dysfunction begins early with persistent vomiting.

Steatorrhea Severe gastrointestinal dysfunction manifests as fatty stools in early infantile disease.

Abdominal distention Severe gastrointestinal and abdominal organ disease manifests as early abdominal distention.

Malnutrition Gastrointestinal impairment with vomiting, diarrhea, and malabsorption causes severe nutritional compromise.

Failure to thrive Malabsorption and gastrointestinal dysfunction drive severe infantile growth failure.

Show evidence (2 references)

PMID:41599846 SUPPORT Human Clinical

"Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."

This review directly links gastrointestinal disturbance and growth failure to malabsorption in infantile Wolman disease.

PMID:34020687 SUPPORT Human Clinical

"The gastrointestinal symptoms are particularly improved after HCT, with reduced diarrhoea and vomiting. This allows gradual structured normalisation of diet with improved tolerance of dietary fat. Histologically there are reduced cholesterol clefts, fewer foamy macrophages and an improved..."

Improvement in diarrhea, vomiting, fat tolerance, and villous structure after therapy supports intestinal pathology as a key disease mechanism.

Adrenal Lipid Storage

Lipid deposition involves the adrenal glands and accompanies bilateral adrenal enlargement. The steps connecting storage to necrosis and calcification remain incompletely established.

adrenal gland UBERON:0002369

Downstream

Adrenal calcification Adrenal lipid-storage disease is associated with calcification; oxidized-LDL uptake, cytotoxicity, calcium loading, and necrosis are a proposed intervening mechanism.

Show evidence (1 reference)

PMID:34401013 SUPPORT Human Clinical

"Multiple organs such as adrenal glands, liver, spleen, bone marrow, small bowel loops, and abdominal lymph nodes are infiltrated by the deposition of lipids."

The report directly supports adrenal lipid infiltration as part of multisystem storage.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

13

Blood 2

Anemia HP:0001903

Anemia accompanies severe infantile disease; iron-deficiency anemia can remain a residual problem even among treated survivors.

Show evidence (2 references)

PMID:28179030 SUPPORT Human Clinical

"Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"

This study directly identifies anemia as part of the severe infantile presentation.

PMID:26225414 SUPPORT Other

"However, with early diagnosis and initiation of treatment, long-term survival has improved significantly, although treated individuals may continue to have suboptimal growth, iron deficiency anemia, and lipid accumulation in the gastrointestinal mucosa."

GeneReviews supports iron-deficiency anemia as possible residual morbidity despite treatment.

Thrombocytopenia HP:0001873

GeneReviews recommends periodic complete-blood-count surveillance to assess for thrombocytopenia. The cited guidance does not establish prevalence or a causal intermediate, so this phenotype is deliberately left unlinked.

Show evidence (1 reference)

PMID:26225414 SUPPORT Other

"obtain a complete blood count every six months in children and every six to 12 months in adults to assess for anemia and thrombocytopenia"

GeneReviews surveillance guidance directly identifies thrombocytopenia as a hematologic finding to assess; it does not provide a frequency or causal link.

Cardiovascular 1

Hepatosplenomegaly HP:0001433

Often marked early in the course and coupled to progressive liver dysfunction.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."

This review directly identifies hepatosplenomegaly as a characteristic infantile manifestation.

Digestive 7

Hepatic failure HP:0001399

Severe infantile hepatic disease can progress to hepatic failure within the first months of life.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"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."

This review directly identifies hepatic failure in infantile Wolman disease.

Diarrhea HP:0002014

Persistent diarrhea reflects severe intestinal dysfunction and fat malabsorption.

Show evidence (1 reference)

PMID:28179030 SUPPORT Human Clinical

"Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"

This study directly documents diarrhea as part of the severe infantile phenotype.

Steatorrhea HP:0002570

Fatty stools are an early manifestation of severe intestinal lipid malabsorption.

Show evidence (1 reference)

PMID:26225414 SUPPORT Other

"Infantile-onset LAL-D is rapidly progressive and symptoms arise within the first few days to weeks of life, with persistent vomiting, steatorrhea, and abdominal distention escalating (if untreated) to severe liver dysfunction and death within the first three to six months of life."

GeneReviews directly identifies steatorrhea among the first manifestations of untreated infantile LAL-D.

Vomiting HP:0002013

Persistent vomiting begins early and contributes to nutritional compromise.

Show evidence (1 reference)

PMID:24832708 SUPPORT Human Clinical

"In early onset LAL deficiency, clinical manifestations start in the first few weeks of life with persistent vomiting, failure to thrive, hepatosplenomegaly, liver dysfunction and hepatic failure."

This report directly supports persistent vomiting as an early manifestation of Wolman disease.

Abdominal distention HP:0003270

Abdominal distention appears in the first days to weeks of infantile disease.

Show evidence (1 reference)

PMID:26225414 SUPPORT Other

"Infantile-onset LAL-D is rapidly progressive and symptoms arise within the first few days to weeks of life, with persistent vomiting, steatorrhea, and abdominal distention escalating (if untreated) to severe liver dysfunction and death within the first three to six months of life."

GeneReviews directly supports early abdominal distention in infantile-onset LAL-D.

Malabsorption HP:0002024

Poor intestinal absorption is a major driver of growth failure and dietary intolerance.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."

This review explicitly identifies malabsorption as a driver of growth failure in infantile disease.

Malnutrition HP:0004395

Severe nutritional compromise results from vomiting, diarrhea, and malabsorption in early infancy.

Show evidence (1 reference)

PMID:39770929 SUPPORT Human Clinical

"The infantile-onset form occurs in the first weeks of life and is characterized by malnourishment and failure to thrive due to gastrointestinal impairment (vomiting, diarrhea, malabsorption)"

Expert recommendations directly attribute infant malnourishment to gastrointestinal impairment.

Growth 1

Failure to thrive HP:0001508

Severe early growth failure driven by multisystem disease and malabsorption.

Show evidence (1 reference)

PMID:28179030 SUPPORT Human Clinical

"Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"

This study directly identifies failure to thrive as a hallmark manifestation of infantile Wolman disease.

Other 2

Adrenal calcification HP:0010512

Classic imaging clue when present, though not universal.

Show evidence (1 reference)

PMID:24832708 SUPPORT Human Clinical

"Adrenal calcification is a striking feature but is present in only about 50% of cases."

This case-based review directly supports adrenal calcification as a characteristic but not universal feature of Wolman disease.

Increased inflammatory response HP:0012649

Severe infantile LAL-D can include systemic inflammation, including hemophagocytic lymphohistiocytosis.

Show evidence (1 reference)

PMID:41270440 SUPPORT Human Clinical

"This course includes liver failure, malabsorption and growth failure, and systemic inflammation, such as hemophagocytic lymphohistiocytosis, typically leading to death by 6 months of age if untreated."

The registry report identifies systemic inflammation, including HLH, in rapidly progressive infantile disease.

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Genetic Associations

1

LIPA (Pathogenic Variants)

Gene: LIPA hgnc:6617

Show evidence (2 references)

CGGV:assertion_1691be18-3aa2-46e7-b6a6-e7acafb9f998-2023-04-28T040000.000Z SUPPORT Other

ClinGen classifies the LIPA-lysosomal acid lipase deficiency gene-disease relationship as definitive with autosomal recessive inheritance.

PMID:26225414 SUPPORT Other

"The diagnosis of LAL-D is established in a proband with suggestive findings and biallelic pathogenic variants in LIPA identified by molecular genetic testing and/or deficient lysosomal acid lipase (LAL) enzyme activity in peripheral blood leukocytes or dried blood spots."

GeneReviews directly supports biallelic pathogenic LIPA variants as a molecular route to diagnosis.

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Medical Actions

5

Sebelipase alfa enzyme replacement therapy

Action: enzyme replacement therapy Ontology label: Protein Replacement Therapy NCIT:C16221

Agent: sebelipase alfa NCIT:C152312

Recombinant human lysosomal acid lipase replacement restores proximal enzyme function and substantially improves survival, growth, liver parameters, and other major disease manifestations when started early. Infusion management may require premedication or desensitization, and anti-drug antibodies can attenuate response in some patients.

Mechanism Target:

RESTORES Lysosomal Acid Lipase Deficiency — Sebelipase alfa replaces missing lysosomal acid lipase activity at the proximal defect.

Show evidence (1 reference)

PMID:41270440 SUPPORT Human Clinical

"Sebelipase alfa (KANUMA®; Alexion, AstraZeneca Rare Disease, Boston, MA) is a recombinant human LAL (a hydrolytic lysosomal cholesteryl ester and triacylglycerol-specific enzyme) approved for the treatment of LAL-D"

The registry report identifies sebelipase alfa as recombinant human LAL, directly supporting replacement of the deficient proximal enzyme.

INHIBITS Lysosomal Cholesteryl Ester and Triglyceride Storage — Enzyme replacement lowers the stored neutral-lipid burden downstream of the LAL deficiency.

Show evidence (1 reference)

PMID:23624251 SUPPORT Model Organism

"A significant decrease in hepatic CE was observed in LAL-deficient rats following treatment with sebelipase alfa."

In a LAL-deficient animal model, sebelipase alfa reduced hepatic cholesteryl ester accumulation, supporting direct inhibition of the storage mechanism.

Target Phenotypes: Failure to thrive HP:0001508 Hepatosplenomegaly HP:0001433 Anemia HP:0001903

Show evidence (5 references)

PMID:26225414 SUPPORT Other

"For infantile-onset disease, enzyme replacement therapy with intravenous sebelipase alfa (premedication and desensitization protocols may be necessary) and dietary long-chain fat restriction (fat <1 g/kg/day) with supplementation of fat-soluble vitamins and essential fatty acids is recommended;..."

GeneReviews recommends intravenous sebelipase alfa and explicitly notes possible premedication or desensitization requirements.

PMID:34906190 SUPPORT Human Clinical

"Early ERT initiation allowed 100% survival with positive outcomes."

Long-term cohort follow-up supports strong clinical benefit from early sebelipase alfa initiation.

PMID:33407676 SUPPORT Human Clinical

"The findings of these 2 studies of infants with rapidly progressive LAL-D demonstrated that enzyme replacement therapy with sebelipase alfa prolonged survival with normal psychomotor development, improved growth, hematologic parameters, and liver parameters, and was generally well tolerated,..."

Final pooled study results confirm durable benefit on survival, growth, hematologic measures, and liver disease.

+ 2 more references

Nutritional management with dietary lipid reduction

Action: dietary intervention Ontology label: Dietary Intervention NCIT:C15447

Nutritional management is used alongside enzyme replacement therapy to reduce dietary long-chain fat substrate burden, improve gastrointestinal tolerance, and support growth in infants with severe intestinal disease. Restriction requires supplementation and biochemical monitoring to avoid deficiencies of essential fatty acids and fat-soluble vitamins.

Mechanism Target:

INHIBITS Lysosomal Cholesteryl Ester and Triglyceride Storage — Low-lipid dietary management reduces substrate load and is intended to decrease lipid deposition.

Show evidence (1 reference)

PMID:39770929 SUPPORT Human Clinical

"careful nutritional treatment with a low-lipid diet to decrease lipid deposition and systemic inflammation, leading to better outcomes."

Expert recommendations directly state that the low-lipid diet is intended to decrease lipid deposition and systemic inflammation.

Target Phenotypes: Malabsorption HP:0002024 Failure to thrive HP:0001508 Diarrhea HP:0002014 Vomiting HP:0002013

Show evidence (2 references)

PMID:26225414 SUPPORT Other

"For infantile-onset disease, enzyme replacement therapy with intravenous sebelipase alfa (premedication and desensitization protocols may be necessary) and dietary long-chain fat restriction (fat <1 g/kg/day) with supplementation of fat-soluble vitamins and essential fatty acids is recommended;..."

GeneReviews supplies the infantile dietary restriction, supplementation, and combined-treatment recommendation.

PMID:41599846 SUPPORT Human Clinical

"Treatment takes the two-pronged approach of sebelipase alfa, a human lysosomal acid lipase enzyme replacement therapy (ERT) that improves lipid metabolism, combined with nutritional management."

This review directly frames nutritional management as a standard co-therapy with enzyme replacement in infantile disease.

Hematopoietic stem cell transplantation in selected patients

Action: hematopoietic stem cell transplantation Ontology label: Hematopoietic Cell Transplantation NCIT:C15431

Allogeneic HCT is a specialist, selected-patient option, particularly when enzyme-replacement response is attenuated or a well-matched donor is available. A five-infant multimodal cohort reported gastrointestinal and laboratory improvement in survivors, but one patient died after HCT and historical procedure-related mortality is high; this evidence does not establish HCT as universal first-line therapy.

Target Phenotypes: Diarrhea HP:0002014 Vomiting HP:0002013

Show evidence (5 references)

PMID:34020687 SUPPORT Human Clinical

"The gastrointestinal symptoms are particularly improved after HCT, with reduced diarrhoea and vomiting."

The cohort directly reports improvement in gastrointestinal symptoms after HCT.

PMID:34020687 SUPPORT Human Clinical

"All patients received allogeneic HCT. 4/5 patients are alive, and both disease phenotype and laboratory parameters are improved compared to when they were on ERT alone."

The five-patient cohort supports clinical and laboratory improvement after HCT while retaining the small-cohort boundary.

PMID:34020687 SUPPORT Human Clinical

"In 3/5 an initial response to ERT was attenuated by ADA with associated clinical and laboratory features of deterioration. 1/5 developed anaphylaxis to ERT and the other patient died post HCT with ongoing HLH."

This cohort documents both reasons for considering multimodal therapy and serious adverse outcomes, including post-HCT death.

+ 2 more references

Supportive hematologic care and longitudinal surveillance

Action: Supportive Care NCIT:C15747

Treat anemia and thrombocytopenia conventionally while monitoring growth, diarrhea, liver enzymes, essential fatty acids, fat-soluble vitamins, and blood counts. When treatment efficacy is questioned, assess anti-drug antibodies. Patients with thrombocytopenia should avoid nonsteroidal anti-inflammatory drugs.

Target Phenotypes: Anemia HP:0001903

Show evidence (4 references)

PMID:26225414 SUPPORT Other

"Supportive care: Standard treatment for anemia/thrombocytopenia."

GeneReviews recommends standard supportive treatment of the hematologic manifestations.

PMID:26225414 SUPPORT Other

"For infantile-onset disease, measure weight, length/height, and mid-upper arm circumference in infants/children and weight in adults at each visit; assess for chronic diarrhea and monitor liver enzymes, essential fatty acids, and fat-soluble vitamins (A, D, E, and K) levels every six months"

GeneReviews supplies the growth, gastrointestinal, hepatic, fatty-acid, and vitamin surveillance elements.

PMID:26225414 SUPPORT Other

"monitor anti-drug antibody (ADA) concentration for those on enzyme replacement therapy if the ALT and AST levels are >3 times the normal limit or if there are clinical concerns regarding efficacy of treatment"

GeneReviews supports targeted ADA monitoring when biochemical or clinical efficacy is in question.

+ 1 more reference

Genetic counseling and family testing

Action: Genetic Counseling NCIT:C15240

Counsel families about autosomal-recessive recurrence risk, test at-risk relatives promptly so treatment can begin early, and offer carrier, prenatal, or preimplantation testing when familial LIPA variants are known.

Show evidence (2 references)

PMID:26225414 SUPPORT Other

"If the LIPA pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives and prenatal/preimplantation genetic testing are possible."

GeneReviews directly supports family-based carrier and reproductive testing after variant identification.

PMID:26225414 SUPPORT Other

"It is appropriate to evaluate the sibs of a proband in order to identify those who would benefit from early institution of treatment."

GeneReviews supports prompt evaluation of siblings because early treatment changes outcome.

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Biochemical Markers

4

Reduced lysosomal acid lipase activity (DECREASED)

Context: Reduced or absent lysosomal acid lipase activity is the proximal diagnostic enzyme abnormality caused by LIPA pathogenic variants.

Pathograph Readouts

Readout Of Lysosomal Acid Lipase Deficiency Negative Diagnostic

Low LAL enzyme activity reports the proximal lysosomal acid lipase deficiency.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"Lysosomal acid lipase deficiency-which can be diagnosed using dry blood spot testing-is often misdiagnosed as non-alcoholic fatty liver disease"

Dry blood spot LAL enzyme activity assay is the established diagnostic test for the proximal LAL deficiency, supporting low enzyme activity as the diagnostic readout.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"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."

This review directly supports reduced or absent LAL activity as the defining biochemical enzyme abnormality.

Cholesteryl ester storage burden (INCREASED)

Context: Cholesteryl ester storage is a chemical readout of the LAL deficiency neutral-lipid storage lesion.

Pathograph Readouts

Readout Of Lysosomal Cholesteryl Ester and Triglyceride Storage Positive Diagnostic

Increased cholesteryl ester storage reports the core lysosomal neutral-lipid storage lesion.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"LAL is essential for the metabolism of cholesteryl esters and triglycerides. LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes"

LAL deficiency causes intra-lysosomal accumulation of cholesteryl esters, supporting CE burden as a direct readout of the lysosomal neutral-lipid storage lesion.

Readout Of Hepatic and Reticuloendothelial Lipid Storage Positive Monitoring

Cholesteryl ester burden reports hepatic and reticuloendothelial storage biology.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes"

Accumulation in liver and macrophages (reticuloendothelial system) and lymph nodes supports the cholesteryl ester readout reporting on hepatic and reticuloendothelial storage biology.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."

This review supports cholesteryl ester storage as a disease biochemical readout.

Triglyceride storage burden (INCREASED)

Context: Triglyceride storage accompanies cholesteryl ester storage when LAL deficiency blocks lysosomal neutral-lipid hydrolysis.

Pathograph Readouts

Readout Of Lysosomal Cholesteryl Ester and Triglyceride Storage Positive Diagnostic

Increased triglyceride burden reports impaired lysosomal neutral-lipid hydrolysis.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"LAL is essential for the metabolism of cholesteryl esters and triglycerides. LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes"

LAL deficiency causes intra-lysosomal triglyceride accumulation alongside cholesteryl esters, supporting TG burden as a direct readout of the impaired lysosomal neutral-lipid hydrolysis lesion.

Show evidence (1 reference)

PMID:41599846 SUPPORT Human Clinical

"LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."

This review supports triglyceride storage as part of the disease biochemical profile.

Elevated hepatic transaminases (INCREASED)

Context: Transaminitis is a circulating biochemical correlate of hepatic involvement across the LAL deficiency spectrum.

Pathograph Readouts

Readout Of Progressive Liver Dysfunction Positive Monitoring

Elevated transaminases report ongoing hepatocellular injury downstream of hepatic lipid storage.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"although the two diseases share many common features, including dyslipidaemia and transaminitis."

Transaminitis is a shared feature across the LAL deficiency spectrum, supporting elevated transaminases as a circulating readout of progressive hepatocellular injury.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"although the two diseases share many common features, including dyslipidaemia and transaminitis."

This review supports transaminitis as a biochemical manifestation of LAL deficiency.

🔬

Diagnosis

2

Lysosomal acid lipase enzyme activity assay

Deficient LAL activity in a dried blood spot or peripheral-blood leukocytes establishes the biochemical diagnosis in an infant with suggestive findings; dried blood spot analysis provides rapid testing.

laboratory procedure NCIT:C25294

Results: Deficient lysosomal acid lipase activity supports or establishes LAL-D in the appropriate clinical context.

Show evidence (2 references)

PMID:26225414 SUPPORT Other

"The diagnosis of LAL-D is established in a proband with suggestive findings and biallelic pathogenic variants in LIPA identified by molecular genetic testing and/or deficient lysosomal acid lipase (LAL) enzyme activity in peripheral blood leukocytes or dried blood spots."

GeneReviews specifies both accepted specimen types and deficient enzyme activity as an establishing test.

PMID:39770929 SUPPORT Human Clinical

"When LAL-D is suspected, enzyme activity should be determined to confirm the diagnosis, with analysis from a dried blood spot sample being the quickest and most reliable method."

Expert recommendations prioritize dried-blood-spot enzyme analysis for rapid confirmation.

LIPA molecular genetic testing

Identification of biallelic pathogenic LIPA variants establishes the molecular diagnosis and enables carrier, at-risk relative, prenatal, and preimplantation testing.

molecular genetic testing NCIT:C19770

Results: Biallelic pathogenic LIPA variants establish the molecular diagnosis.

Show evidence (1 reference)

PMID:26225414 SUPPORT Other

"The diagnosis of LAL-D is established in a proband with suggestive findings and biallelic pathogenic variants in LIPA identified by molecular genetic testing and/or deficient lysosomal acid lipase (LAL) enzyme activity in peripheral blood leukocytes or dried blood spots."

GeneReviews identifies biallelic pathogenic LIPA variants as an establishing diagnostic result.

🩻

Imaging Findings

1

Bilateral enlarged adrenal glands with stippled calcification on CT

Abdominal CT can show stippled calcification of symmetrically enlarged adrenal glands while preserving the adreniform contour, an important diagnostic clue that is characteristic when present but not universal.

Ct Diagnostic

Adrenal calcification HP:0010512 adrenal gland UBERON:0002369

Show evidence (1 reference)

PMID:34401013 SUPPORT Human Clinical

"The CT scan revealed stippled calcifications of both enlarged adrenal glands, without the distortion of the adreniform shape, fatty liver, splenomegaly and thickened small bowel loops; characteristic imaging findings of Wolman disease."

The case report directly documents the characteristic bilateral adrenal CT pattern and associated abdominal findings.

📈

Progression

3

Neonatal/Early infancy onset

Age: first weeks to months of life

Symptoms begin in early infancy with persistent vomiting, failure to thrive, hepatosplenomegaly, liver dysfunction, and progressive gastrointestinal disease.

Show evidence (1 reference)

PMID:24832708 SUPPORT Human Clinical

"In early onset LAL deficiency, clinical manifestations start in the first few weeks of life with persistent vomiting, failure to thrive, hepatosplenomegaly, liver dysfunction and hepatic failure."

This infant case report and review directly supports early infantile onset with gastrointestinal and hepatic manifestations.

Untreated rapid progression

Age: first year of life

Without treatment, disease progresses rapidly to multiorgan failure and death in infancy.

Show evidence (1 reference)

PMID:34906190 SUPPORT Human Clinical

"Wolman disease (WD), the rapidly progressive phenotype of lysosomal acid lipase (LAL) deficiency, presents in neonates with failure to thrive and hepatosplenomegaly, and leads to multi-organ failure and death before 12 months of age."

This nationwide cohort study summarizes the untreated natural history as rapidly progressive multiorgan failure in infancy.

Treatment-altered long-term course

Age: infancy through childhood

Early diagnosis and sebelipase alfa have enabled multi-year survival and generally normal neurodevelopment, but residual growth, gastrointestinal, hematologic, and treatment-immunogenicity burdens require ongoing follow-up.

Show evidence (3 references)

PMID:26225414 SUPPORT Other

"However, with early diagnosis and initiation of treatment, long-term survival has improved significantly, although treated individuals may continue to have suboptimal growth, iron deficiency anemia, and lipid accumulation in the gastrointestinal mucosa."

GeneReviews directly defines the treatment-altered natural history and residual morbidity.

PMID:26225414 SUPPORT Other

"Those with infantile-onset disease who are treated typically experience normal long-term intellectual and neurodevelopmental outcomes."

GeneReviews supports generally normal long-term neurodevelopment among treated individuals.

PMID:41270440 SUPPORT Human Clinical

"Overall, 27 of 29 (93 %) patients survived during the median observation time (Q1, Q3) of 6.2 years (3.5, 8.4)."

The international registry quantifies multi-year survival among 29 symptomatic infantile patients treated with sebelipase alfa.

📊

Prevalence

1

Worldwide

Unknown Ultra Rare

Wolman disease is described as ultra-rare, but the reviewed sources do not provide a sufficiently robust population denominator for a numeric prevalence.

Show evidence (1 reference)

PMID:39770929 SUPPORT Human Clinical

"Lysosomal acid lipase deficiency (LAL-D) is an ultra-rare lysosomal storage disease with two distinct phenotypes, an infantile-onset form (formerly Wolman disease) and a later-onset form (formerly cholesteryl ester storage disease)."

The expert recommendations characterize infantile-onset LAL-D as part of an ultra-rare disease spectrum without supplying a population rate.

🔀

Differential Diagnoses

1

Conditions with similar clinical presentations that must be differentiated from Wolman Disease:

Cholesteryl ester storage disease MONDO:0019149

Overlapping Features Later-onset lysosomal acid lipase deficiency phenotype that shares LIPA causation and cholesteryl ester/triglyceride storage biology but is clinically less severe and usually presents beyond infancy with chronic liver disease and dyslipidemia.

Show evidence (1 reference)

PMID:28786388 SUPPORT Human Clinical

"Cholesteryl ester storage disorder arises later in life and is less severe, although the two diseases share many common features, including dyslipidaemia and transaminitis."

This review directly supports CESD as the later-onset, less severe sibling phenotype on the same LAL deficiency spectrum.

🧫

Experimental Models

2

Wolman disease patient fibroblast lipid-storage and LAL-transgene rescue model PRIMARY_CELL_CULTURE

Primary fibroblasts from people with Wolman disease model intracellular lipid-droplet and lysosomal abnormalities and permit cell-level testing of LAL rescue. The system demonstrated restoration of lipid homeostasis after delivery of a functional LAL transgene, but does not reproduce whole-organ infant disease.

Organism

human NCBITaxon:9606

Cell source

Primary fibroblasts from patients with Wolman disease

Culture

Patient-derived fibroblast culture

Publication

PMID:40613725

Pathograph links

Lysosomal Cholesteryl Ester and Triglyceride Storage The model reports excess intracellular lipid droplets and lysosomes caused by LAL deficiency.

Show evidence (1 reference)

PMID:40613725 SUPPORT In Vitro

"In particular, we stained WD patients' fibroblasts for intracellular lipid droplets (LD) and lysosomes, and we analyzed staining intensity and granularity, as well as an increased number of LD and lysosomes using fluorescence wide-field microscopy, confocal microscopy, conventional, and image..."

The study directly characterizes the lipid-droplet and lysosomal phenotype in patient fibroblasts.

Findings

Functional LAL transgene delivery restored lipid homeostasis in the cellular model.

"Noteworthy, we showed that lipid homeostasis was restored upon delivery of a functional LAL transgene."

Show evidence (1 reference)

PMID:40613725 SUPPORT In Vitro

"Noteworthy, we showed that lipid homeostasis was restored upon delivery of a functional LAL transgene."

The transgene-rescue experiment directly supports this finding.

Show evidence (1 reference)

PMID:40613725 SUPPORT In Vitro

"Noteworthy, we showed that lipid homeostasis was restored upon delivery of a functional LAL transgene."

The patient-cell experiment directly demonstrates reversal of the measured lipid-homeostasis phenotype by functional LAL.

Lipa-null mouse model with liver-directed LIPA AAV rescue OTHER

Lipa-knockout mice model severe systemic LAL deficiency and were treated at neonatal or 8-week time points with liver-directed LIPA AAV. Rescue of storage, hepatic injury, inflammation, fibrosis, and survival supports preclinical mechanism testing, while human infant safety, immunogenicity, dosing, and durability remain unestablished.

Organism

mouse NCBITaxon:10090

Publication

PMID:39489913

Pathograph links

Lysosomal Acid Lipase Deficiency The knockout removes Lipa activity and AAV supplies a functional LIPA transgene.

Show evidence (1 reference)

PMID:39489913 SUPPORT Model Organism

"rscAAVrh74.LP1.LIPA treatment elevated LAL enzyme activity above wild-type levels in all tissues tested, including liver, spleen, intestine, muscle, and brain"

The treated knockout model demonstrated systemic biochemical cross-correction after liver-directed LIPA delivery.

Findings

AAV treatment normalized multiple storage and hepatic disease measures in Lipa-null mice.

"normalized many disease measures in Lipa-/- mice when measured at 24 weeks of age, including hepatosplenomegaly, serum transaminase activity, organ triglyceride and cholesterol levels, and biomarkers of liver inflammation and fibrosis."

Show evidence (1 reference)

PMID:39489913 SUPPORT Model Organism

"normalized many disease measures in Lipa-/- mice when measured at 24 weeks of age, including hepatosplenomegaly, serum transaminase activity, organ triglyceride and cholesterol levels, and biomarkers of liver inflammation and fibrosis."

The study directly supports normalization across the listed mouse disease measures.

AAV treatment at 8 weeks significantly extended survival beyond untreated Lipa-null mice.

"AAV treatment at 8 weeks of age with 1 × 1013 vg/kg extended survival significantly, with all AAV-treated mice surviving beyond the maximal lifespan of untreated Lipa-/- mice."

Show evidence (1 reference)

PMID:39489913 SUPPORT Model Organism

"AAV treatment at 8 weeks of age with 1 × 1013 vg/kg extended survival significantly, with all AAV-treated mice surviving beyond the maximal lifespan of untreated Lipa-/- mice."

The report directly supports extended survival after the 8-week intervention.

Show evidence (1 reference)

PMID:39489913 SUPPORT Model Organism

"Treatment at both early (1-2 days) and late (8-week) timepoints with rscAAVrh74.LP1.LIPA, a liver-directed AAV gene therapy, normalized many disease measures in Lipa-/- mice when measured at 24 weeks of age, including hepatosplenomegaly, serum transaminase activity, organ triglyceride and..."

The mouse experiment directly supports broad preclinical biochemical, inflammatory, fibrotic, and organ-level rescue.

{ }

Source YAML

click to show

name: Wolman Disease
creation_date: '2026-04-14T19:53:03Z'
category: Mendelian
description: >
  Wolman disease is the rapidly progressive infantile phenotype of lysosomal acid
  lipase deficiency caused by biallelic pathogenic variants in LIPA. Near-complete
  loss of lysosomal acid lipase activity blocks lysosomal hydrolysis of cholesteryl
  esters and triglycerides, causing multisystem lipid storage in macrophages and
  parenchymal cells, especially in liver, intestine, spleen, lymphoid tissues,
  and adrenal cortex. The resulting hepatic dysfunction, malabsorption, failure
  to thrive, hepatosplenomegaly, anemia, and adrenal calcification lead to fatal
  multiorgan failure in early infancy if untreated. Early sebelipase alfa plus
  intensive nutritional management has changed survival substantially, although
  growth, gastrointestinal lipid storage, anemia, treatment immunogenicity, and
  other residual morbidity can persist. Wolman disease is the infantile end of
  the LAL-D spectrum, distinct from the later-onset cholesteryl ester storage
  disease phenotype.
disease_term:
  preferred_term: Wolman disease
  term:
    id: MONDO:0019148
    label: Wolman disease
parents:
- Lysosomal Storage Disease
classifications:
  harrisons_chapter:
  - classification_value: ENDOCRINOLOGY_METABOLISM
    notes: >
      Wolman disease is classified with metabolic disorders because its proximal
      lesion is inherited deficiency of the lysosomal neutral-lipid hydrolase LAL.
    evidence:
    - reference: PMID:26225414
      reference_title: Lysosomal Acid Lipase Deficiency.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "The phenotypic spectrum of lysosomal acid lipase deficiency (LAL-D) ranges from an infantile-onset form (previously known as Wolman disease) to childhood/adult-onset forms (previously known as cholesterol ester storage disease [CESD])."
      explanation: GeneReviews identifies Wolman disease as the infantile form of an inherited lysosomal enzyme deficiency, supporting placement in the metabolism chapter.
inheritance:
- name: Autosomal recessive
  description: >
    Wolman disease is inherited as an autosomal recessive disorder caused by
    biallelic LIPA pathogenic variants that severely reduce or abolish lysosomal
    acid lipase activity.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: PMID:28786388
    reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: This review directly supports autosomal recessive inheritance and LIPA-mediated lysosomal acid lipase deficiency.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "If both parents are known to be heterozygous for a LIPA pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier."
    explanation: GeneReviews provides the autosomal-recessive sibling recurrence and carrier risks used in family counseling.
prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: ULTRA_RARE
  notes: >
    Wolman disease is described as ultra-rare, but the reviewed sources do not
    provide a sufficiently robust population denominator for a numeric prevalence.
  evidence:
  - reference: PMID:39770929
    reference_title: Practical Recommendations for the Diagnosis and Management of Lysosomal Acid Lipase Deficiency with a Focus on Wolman Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lysosomal acid lipase deficiency (LAL-D) is an ultra-rare lysosomal storage disease with two distinct phenotypes, an infantile-onset form (formerly Wolman disease) and a later-onset form (formerly cholesteryl ester storage disease)."
    explanation: The expert recommendations characterize infantile-onset LAL-D as part of an ultra-rare disease spectrum without supplying a population rate.
progression:
- phase: Neonatal/Early infancy onset
  age_range: first weeks to months of life
  notes: >
    Symptoms begin in early infancy with persistent vomiting, failure to thrive,
    hepatosplenomegaly, liver dysfunction, and progressive gastrointestinal disease.
  evidence:
  - reference: PMID:24832708
    reference_title: "Infant case of lysosomal acid lipase deficiency: Wolman's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In early onset LAL deficiency, clinical manifestations start in the first few weeks of life with persistent vomiting, failure to thrive, hepatosplenomegaly, liver dysfunction and hepatic failure."
    explanation: This infant case report and review directly supports early infantile onset with gastrointestinal and hepatic manifestations.
- phase: Untreated rapid progression
  age_range: first year of life
  notes: >
    Without treatment, disease progresses rapidly to multiorgan failure and death
    in infancy.
  evidence:
  - reference: PMID:34906190
    reference_title: "Sebelipase alfa enzyme replacement therapy in Wolman disease: a nationwide cohort with up to ten years of follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Wolman disease (WD), the rapidly progressive phenotype of lysosomal acid lipase (LAL) deficiency, presents in neonates with failure to thrive and hepatosplenomegaly, and leads to multi-organ failure and death before 12 months of age."
    explanation: This nationwide cohort study summarizes the untreated natural history as rapidly progressive multiorgan failure in infancy.
- phase: Treatment-altered long-term course
  age_range: infancy through childhood
  notes: >
    Early diagnosis and sebelipase alfa have enabled multi-year survival and
    generally normal neurodevelopment, but residual growth, gastrointestinal,
    hematologic, and treatment-immunogenicity burdens require ongoing follow-up.
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "However, with early diagnosis and initiation of treatment, long-term survival has improved significantly, although treated individuals may continue to have suboptimal growth, iron deficiency anemia, and lipid accumulation in the gastrointestinal mucosa."
    explanation: GeneReviews directly defines the treatment-altered natural history and residual morbidity.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Those with infantile-onset disease who are treated typically experience normal long-term intellectual and neurodevelopmental outcomes."
    explanation: GeneReviews supports generally normal long-term neurodevelopment among treated individuals.
  - reference: PMID:41270440
    reference_title: "Survival, growth, and safety findings in patients with rapidly progressive, infantile-onset LAL-D: Results from the international LAL-D registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Overall, 27 of 29 (93 %) patients survived during the median observation time (Q1, Q3) of 6.2 years (3.5, 8.4)."
    explanation: The international registry quantifies multi-year survival among 29 symptomatic infantile patients treated with sebelipase alfa.
pathophysiology:
- name: LIPA Loss of Function
  biological_scale: MOLECULAR
  description: >
    Biallelic pathogenic variants in LIPA reduce or abolish lysosomal acid lipase
    activity.
  genes:
  - preferred_term: LIPA
    term:
      id: hgnc:6617
      label: LIPA
  downstream:
  - target: Lysosomal Acid Lipase Deficiency
    description: Loss of LIPA function reduces or abolishes lysosomal acid lipase activity.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28786388
      reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "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."
      explanation: This review directly connects LIPA mutations to reduced or absent lysosomal acid lipase activity.
  evidence:
  - reference: PMID:28786388
    reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: This review directly links LIPA mutations to reduced or absent lysosomal acid lipase activity.
- name: Lysosomal Acid Lipase Deficiency
  conforms_to: "lysosomal_substrate_accumulation#Lysosomal Hydrolase or Cofactor Deficiency"
  biological_scale: MOLECULAR
  description: >
    Lysosomal acid lipase activity is markedly reduced or absent, removing the
    essential lysosomal hydrolase required to cleave cholesteryl esters and triglycerides.
  genes:
  - preferred_term: LIPA
    term:
      id: hgnc:6617
      label: LIPA
  molecular_functions:
  - preferred_term: sterol ester esterase activity
    term:
      id: GO:0004771
      label: sterol ester esterase activity
    modifier: DECREASED
  - preferred_term: triacylglycerol lipase activity
    term:
      id: GO:0004806
      label: triacylglycerol lipase activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: neutral lipid catabolic process
    term:
      id: GO:0046461
      label: neutral lipid catabolic process
    modifier: DECREASED
  - preferred_term: triglyceride catabolic process
    term:
      id: GO:0019433
      label: triglyceride catabolic process
    modifier: DECREASED
  cellular_components:
  - preferred_term: lysosomal lumen
    term:
      id: GO:0043202
      label: lysosomal lumen
  downstream:
  - target: Impaired Lysosomal Cholesteryl Ester and Triglyceride Hydrolysis
    description: Deficient lysosomal acid lipase prevents normal lysosomal hydrolysis of cholesteryl esters and triglycerides.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:36204319
      reference_title: "Lysosomal acid lipase deficiency: A rare inherited dyslipidemia but potential ubiquitous factor in the development of atherosclerosis and fatty liver disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "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."
      explanation: This review defines LAL as the lysosomal hydrolase responsible for cleaving cholesteryl esters and triglycerides, supporting the hydrolysis block caused by deficiency.
  evidence:
  - reference: PMID:30866656
    reference_title: "Lysosomal Acid Lipase in Lipid Metabolism and Beyond."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lysosomal acid lipase (LAL), encoded by the lipase A ( LIPA) gene, hydrolyzes cholesteryl esters and triglycerides to generate free fatty acids and cholesterol in the cell."
    explanation: This review provides the core enzymatic function that is lost in Wolman disease.
  - reference: PMID:36204319
    reference_title: "Lysosomal acid lipase deficiency: A rare inherited dyslipidemia but potential ubiquitous factor in the development of atherosclerosis and fatty liver disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: This review independently supports lysosomal acid lipase as the key lysosomal hydrolase for cholesteryl ester and triglyceride cleavage.
- name: Impaired Lysosomal Cholesteryl Ester and Triglyceride Hydrolysis
  biological_scale: MOLECULAR
  description: >
    Failure of lysosomal acid lipase blocks lysosomal cleavage of cholesteryl esters
    and triglycerides into free cholesterol and fatty acids.
  biological_processes:
  - preferred_term: cholesterol metabolic process
    term:
      id: GO:0008203
      label: cholesterol metabolic process
    modifier: DECREASED
  - preferred_term: lipid metabolic process
    term:
      id: GO:0006629
      label: lipid metabolic process
    modifier: DECREASED
  chemical_entities:
  - preferred_term: cholesteryl ester
    term:
      id: CHEBI:17002
      label: cholesteryl ester
  - preferred_term: triglyceride
    term:
      id: CHEBI:17855
      label: triglyceride
  downstream:
  - target: Lysosomal Cholesteryl Ester and Triglyceride Storage
    description: Undegraded cholesteryl esters and triglycerides accumulate in lysosomes.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:23624251
      reference_title: "Hepatic cholesteryl ester accumulation in lysosomal acid lipase deficiency: non-invasive identification and treatment monitoring by magnetic resonance."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Lysosomal Acid Lipase (LAL) deficiency is a rare metabolic storage disease, caused by a marked reduction in activity of LAL, which leads to accumulation of cholesteryl esters (CE) and triglycerides (TG) in lysosomes in many tissues."
      explanation: Human LAL deficiency data directly support lysosomal cholesteryl ester and triglyceride storage downstream of reduced LAL activity.
  evidence:
  - reference: PMID:30866656
    reference_title: "Lysosomal Acid Lipase in Lipid Metabolism and Beyond."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lysosomal acid lipase (LAL), encoded by the lipase A ( LIPA) gene, hydrolyzes cholesteryl esters and triglycerides to generate free fatty acids and cholesterol in the cell."
    explanation: Loss of this lysosomal hydrolysis step is the immediate biochemical consequence of lysosomal acid lipase deficiency.
- name: Lysosomal Cholesteryl Ester and Triglyceride Storage
  conforms_to: "lysosomal_substrate_accumulation#Lysosomal Substrate Accumulation"
  biological_scale: CELLULAR
  description: >
    Cholesteryl esters and triglycerides accumulate within lysosomes of macrophages
    and parenchymal cells across multiple tissues, establishing the multisystem
    storage phenotype of Wolman disease.
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  - preferred_term: enterocyte
    term:
      id: CL:0000584
      label: enterocyte
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  - preferred_term: small intestine
    term:
      id: UBERON:0002108
      label: small intestine
  - preferred_term: lymph node
    term:
      id: UBERON:0000029
      label: lymph node
  chemical_entities:
  - preferred_term: cholesteryl ester
    term:
      id: CHEBI:17002
      label: cholesteryl ester
  - preferred_term: triglyceride
    term:
      id: CHEBI:17855
      label: triglyceride
  downstream:
  - target: Hepatic and Reticuloendothelial Lipid Storage
    description: Lipid-laden macrophages and parenchymal cells accumulate in liver and spleen.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."
      explanation: The review directly identifies lipid storage in macrophages and parenchymal cells, including liver and lymphoid tissues.
  - target: Intestinal Lipid Storage
    description: Lipid storage in the gastrointestinal tract drives enteric dysfunction.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."
      explanation: The same tissue-distribution statement directly supports gastrointestinal tract lipid storage.
  - target: Adrenal Lipid Storage
    description: Neutral-lipid deposition extends to the adrenal glands in Wolman disease.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:34401013
      reference_title: CT features of Wolman disease (lysosomal acid lipase enzyme deficiency) - A case report.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Multiple organs such as adrenal glands, liver, spleen, bone marrow, small bowel loops, and abdominal lymph nodes are infiltrated by the deposition of lipids."
      explanation: The radiology case review explicitly includes the adrenal glands among organs infiltrated by lipid deposition.
  evidence:
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."
    explanation: This review directly supports multisystem lysosomal cholesteryl ester and triglyceride storage in macrophages and parenchymal cells.
  - reference: PMID:23624251
    reference_title: "Hepatic cholesteryl ester accumulation in lysosomal acid lipase deficiency: non-invasive identification and treatment monitoring by magnetic resonance."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lysosomal Acid Lipase (LAL) deficiency is a rare metabolic storage disease, caused by a marked reduction in activity of LAL, which leads to accumulation of cholesteryl esters (CE) and triglycerides (TG) in lysosomes in many tissues."
    explanation: This human translational study independently supports CE and TG accumulation in lysosomes across many tissues.
- name: Hepatic and Reticuloendothelial Lipid Storage
  biological_scale: TISSUE
  description: >
    Storage within hepatocytes and reticuloendothelial macrophages enlarges the
    liver and spleen and sets up rapidly progressive hepatic injury.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  - preferred_term: spleen
    term:
      id: UBERON:0002106
      label: spleen
  downstream:
  - target: Progressive Liver Dysfunction
    description: Progressive hepatic storage contributes to liver dysfunction and eventual hepatic failure.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - hepatic inflammation
    - hepatic fibrosis
    evidence:
    - reference: PMID:28179030
      reference_title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"
      explanation: The infant treatment study links hepatosplenomegaly and rapidly progressive liver disease in the severe LAL-D phenotype.
    - reference: PMID:39489913
      reference_title: Liver-directed AAV gene therapy normalizes disease symptoms and provides cross-correction in a model of lysosomal acid lipase deficiency.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "normalized many disease measures in Lipa-/- mice when measured at 24 weeks of age, including hepatosplenomegaly, serum transaminase activity, organ triglyceride and cholesterol levels, and biomarkers of liver inflammation and fibrosis."
      explanation: Concurrent rescue of organ lipid burden, transaminases, inflammation, and fibrosis in Lipa-null mice supports inflammatory and fibrotic intermediates between storage and liver dysfunction.
  - target: Hepatosplenomegaly
    description: Hepatic and reticuloendothelial lipid storage clinically manifests as marked hepatosplenomegaly.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28179030
      reference_title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"
      explanation: The study identifies massive hepatosplenomegaly as a hallmark manifestation of infantile LAL-D.
  evidence:
  - reference: PMID:28179030
    reference_title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"
    explanation: This infant treatment study summarizes the core hepatic and reticuloendothelial disease burden before effective therapy.
- name: Progressive Liver Dysfunction
  biological_scale: TISSUE
  description: >
    Ongoing hepatic lipid storage causes liver dysfunction that can progress to
    hepatic failure during infancy.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  evidence:
  - reference: PMID:28786388
    reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: This review directly connects the severe infantile phenotype to progressive hepatic failure.
  downstream:
  - target: Hepatic failure
    description: Progressive hepatic dysfunction can advance to hepatic failure in the severe infantile phenotype.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28786388
      reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "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."
      explanation: The review directly links the severe infantile phenotype to hepatic failure.
- name: Intestinal Lipid Storage
  biological_scale: TISSUE
  description: >
    Storage in the gastrointestinal tract injures intestinal tissue and contributes
    to poor fat tolerance, vomiting, diarrhea, and downstream malabsorption.
  cell_types:
  - preferred_term: enterocyte
    term:
      id: CL:0000584
      label: enterocyte
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  locations:
  - preferred_term: small intestine
    term:
      id: UBERON:0002108
      label: small intestine
  downstream:
  - target: Malabsorption and Severe Gastrointestinal Dysfunction
    description: Intestinal storage produces gastrointestinal disturbance and impaired nutrient absorption.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - foamy macrophage infiltration
    - intestinal villous injury
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."
      explanation: The review links infantile LAL-D gastrointestinal disturbance with malabsorption-driven growth failure.
    - reference: PMID:34020687
      reference_title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Histologically there are reduced cholesterol clefts, fewer foamy macrophages and an improved villous structure."
      explanation: Histologic improvement in cholesterol clefts, foamy macrophages, and villous structure after treatment supports the named tissue intermediates.
  evidence:
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."
    explanation: This review supports direct lipid storage within gastrointestinal tissues as a core component of disease biology.
- name: Malabsorption and Severe Gastrointestinal Dysfunction
  biological_scale: ORGANISM
  description: >
    Intestinal dysfunction produces persistent gastrointestinal symptoms and poor
    nutrient absorption, driving severe growth failure in infancy.
  cell_types:
  - preferred_term: enterocyte
    term:
      id: CL:0000584
      label: enterocyte
  locations:
  - preferred_term: small intestine
    term:
      id: UBERON:0002108
      label: small intestine
  evidence:
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."
    explanation: This review directly links gastrointestinal disturbance and growth failure to malabsorption in infantile Wolman disease.
  - reference: PMID:34020687
    reference_title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The gastrointestinal symptoms are particularly improved after HCT, with reduced diarrhoea and vomiting. This allows gradual structured normalisation of diet with improved tolerance of dietary fat. Histologically there are reduced cholesterol clefts, fewer foamy macrophages and an improved villous structure."
    explanation: Improvement in diarrhea, vomiting, fat tolerance, and villous structure after therapy supports intestinal pathology as a key disease mechanism.
  downstream:
  - target: Malabsorption
    description: Severe gastrointestinal dysfunction includes malabsorption.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."
      explanation: The review explicitly states that malabsorption drives growth failure in rapidly progressive infantile LAL-D.
  - target: Diarrhea
    description: Gastrointestinal dysfunction commonly manifests as diarrhea.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:28179030
      reference_title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"
      explanation: The infant LAL-D study directly lists diarrhea among the severe gastrointestinal manifestations.
  - target: Vomiting
    description: Severe gastrointestinal dysfunction begins early with persistent vomiting.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:24832708
      reference_title: "Infant case of lysosomal acid lipase deficiency: Wolman's disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In early onset LAL deficiency, clinical manifestations start in the first few weeks of life with persistent vomiting, failure to thrive, hepatosplenomegaly, liver dysfunction and hepatic failure."
      explanation: This case-based review directly supports persistent vomiting as an early gastrointestinal manifestation.
  - target: Steatorrhea
    description: Severe gastrointestinal dysfunction manifests as fatty stools in early infantile disease.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:26225414
      reference_title: Lysosomal Acid Lipase Deficiency.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Infantile-onset LAL-D is rapidly progressive and symptoms arise within the first few days to weeks of life, with persistent vomiting, steatorrhea, and abdominal distention escalating (if untreated) to severe liver dysfunction and death within the first three to six months of life."
      explanation: GeneReviews identifies steatorrhea as an early gastrointestinal manifestation of infantile-onset LAL-D.
  - target: Abdominal distention
    description: Severe gastrointestinal and abdominal organ disease manifests as early abdominal distention.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:26225414
      reference_title: Lysosomal Acid Lipase Deficiency.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Infantile-onset LAL-D is rapidly progressive and symptoms arise within the first few days to weeks of life, with persistent vomiting, steatorrhea, and abdominal distention escalating (if untreated) to severe liver dysfunction and death within the first three to six months of life."
      explanation: GeneReviews directly places abdominal distention in the early gastrointestinal presentation while the specific intermediates remain unresolved.
  - target: Malnutrition
    description: Gastrointestinal impairment with vomiting, diarrhea, and malabsorption causes severe nutritional compromise.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:39770929
      reference_title: Practical Recommendations for the Diagnosis and Management of Lysosomal Acid Lipase Deficiency with a Focus on Wolman Disease.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The infantile-onset form occurs in the first weeks of life and is characterized by malnourishment and failure to thrive due to gastrointestinal impairment (vomiting, diarrhea, malabsorption)"
      explanation: Expert recommendations explicitly attribute malnourishment and failure to thrive to gastrointestinal impairment.
  - target: Failure to thrive
    description: Malabsorption and gastrointestinal dysfunction drive severe infantile growth failure.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."
      explanation: The review directly connects malabsorption to growth failure in infantile-onset LAL-D.
- name: Adrenal Lipid Storage
  biological_scale: TISSUE
  description: >
    Lipid deposition involves the adrenal glands and accompanies bilateral adrenal
    enlargement. The steps connecting storage to necrosis and calcification remain
    incompletely established.
  locations:
  - preferred_term: adrenal gland
    term:
      id: UBERON:0002369
      label: adrenal gland
  evidence:
  - reference: PMID:34401013
    reference_title: CT features of Wolman disease (lysosomal acid lipase enzyme deficiency) - A case report.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Multiple organs such as adrenal glands, liver, spleen, bone marrow, small bowel loops, and abdominal lymph nodes are infiltrated by the deposition of lipids."
    explanation: The report directly supports adrenal lipid infiltration as part of multisystem storage.
  downstream:
  - target: Adrenal calcification
    description: >
      Adrenal lipid-storage disease is associated with calcification; oxidized-LDL
      uptake, cytotoxicity, calcium loading, and necrosis are a proposed intervening mechanism.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:8037680
      reference_title: "New pathogenetic hypothesis for Wolman disease: possible role of oxidized low-density lipoproteins in adrenal necrosis and calcification."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "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."
      explanation: Human cultured-cell experiments support a mechanistic hypothesis, but do not establish the full causal sequence in infants in vivo.
phenotypes:
- name: Failure to thrive
  category: Growth
  notes: Severe early growth failure driven by multisystem disease and malabsorption.
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: PMID:28179030
    reference_title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"
    explanation: This study directly identifies failure to thrive as a hallmark manifestation of infantile Wolman disease.
- name: Hepatosplenomegaly
  category: Gastrointestinal
  diagnostic: true
  notes: Often marked early in the course and coupled to progressive liver dysfunction.
  phenotype_term:
    preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  evidence:
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."
    explanation: This review directly identifies hepatosplenomegaly as a characteristic infantile manifestation.
- name: Hepatic failure
  category: Hepatic
  notes: Severe infantile hepatic disease can progress to hepatic failure within the first months of life.
  phenotype_term:
    preferred_term: Hepatic failure
    term:
      id: HP:0001399
      label: Hepatic failure
  evidence:
  - reference: PMID:28786388
    reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: This review directly identifies hepatic failure in infantile Wolman disease.
- name: Diarrhea
  category: Gastrointestinal
  notes: Persistent diarrhea reflects severe intestinal dysfunction and fat malabsorption.
  phenotype_term:
    preferred_term: Diarrhea
    term:
      id: HP:0002014
      label: Diarrhea
  evidence:
  - reference: PMID:28179030
    reference_title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"
    explanation: This study directly documents diarrhea as part of the severe infantile phenotype.
- name: Steatorrhea
  category: Gastrointestinal
  notes: Fatty stools are an early manifestation of severe intestinal lipid malabsorption.
  phenotype_term:
    preferred_term: Steatorrhea
    term:
      id: HP:0002570
      label: Steatorrhea
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Infantile-onset LAL-D is rapidly progressive and symptoms arise within the first few days to weeks of life, with persistent vomiting, steatorrhea, and abdominal distention escalating (if untreated) to severe liver dysfunction and death within the first three to six months of life."
    explanation: GeneReviews directly identifies steatorrhea among the first manifestations of untreated infantile LAL-D.
- name: Vomiting
  category: Gastrointestinal
  notes: Persistent vomiting begins early and contributes to nutritional compromise.
  phenotype_term:
    preferred_term: Vomiting
    term:
      id: HP:0002013
      label: Vomiting
  evidence:
  - reference: PMID:24832708
    reference_title: "Infant case of lysosomal acid lipase deficiency: Wolman's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In early onset LAL deficiency, clinical manifestations start in the first few weeks of life with persistent vomiting, failure to thrive, hepatosplenomegaly, liver dysfunction and hepatic failure."
    explanation: This report directly supports persistent vomiting as an early manifestation of Wolman disease.
- name: Abdominal distention
  category: Gastrointestinal
  notes: Abdominal distention appears in the first days to weeks of infantile disease.
  phenotype_term:
    preferred_term: Abdominal distention
    term:
      id: HP:0003270
      label: Abdominal distention
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Infantile-onset LAL-D is rapidly progressive and symptoms arise within the first few days to weeks of life, with persistent vomiting, steatorrhea, and abdominal distention escalating (if untreated) to severe liver dysfunction and death within the first three to six months of life."
    explanation: GeneReviews directly supports early abdominal distention in infantile-onset LAL-D.
- name: Malabsorption
  category: Gastrointestinal
  notes: Poor intestinal absorption is a major driver of growth failure and dietary intolerance.
  phenotype_term:
    preferred_term: Malabsorption
    term:
      id: HP:0002024
      label: Malabsorption
  evidence:
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infants with rapidly progressive LAL-D present with gastrointestinal disturbance, adrenomegaly with calcification, hepatosplenomegaly, growth failure due to malabsorption, and systemic inflammation."
    explanation: This review explicitly identifies malabsorption as a driver of growth failure in infantile disease.
- name: Malnutrition
  category: Growth
  notes: Severe nutritional compromise results from vomiting, diarrhea, and malabsorption in early infancy.
  phenotype_term:
    preferred_term: Malnutrition
    term:
      id: HP:0004395
      label: Malnutrition
  evidence:
  - reference: PMID:39770929
    reference_title: Practical Recommendations for the Diagnosis and Management of Lysosomal Acid Lipase Deficiency with a Focus on Wolman Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The infantile-onset form occurs in the first weeks of life and is characterized by malnourishment and failure to thrive due to gastrointestinal impairment (vomiting, diarrhea, malabsorption)"
    explanation: Expert recommendations directly attribute infant malnourishment to gastrointestinal impairment.
- name: Adrenal calcification
  category: Endocrine
  diagnostic: true
  notes: Classic imaging clue when present, though not universal.
  phenotype_term:
    preferred_term: Adrenal calcification
    term:
      id: HP:0010512
      label: Adrenal calcification
  evidence:
  - reference: PMID:24832708
    reference_title: "Infant case of lysosomal acid lipase deficiency: Wolman's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Adrenal calcification is a striking feature but is present in only about 50% of cases."
    explanation: This case-based review directly supports adrenal calcification as a characteristic but not universal feature of Wolman disease.
- name: Increased inflammatory response
  category: Immunologic
  notes: >
    Severe infantile LAL-D can include systemic inflammation, including
    hemophagocytic lymphohistiocytosis.
  phenotype_term:
    preferred_term: Increased inflammatory response
    term:
      id: HP:0012649
      label: Increased inflammatory response
  evidence:
  - reference: PMID:41270440
    reference_title: "Survival, growth, and safety findings in patients with rapidly progressive, infantile-onset LAL-D: Results from the international LAL-D registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This course includes liver failure, malabsorption and growth failure, and systemic inflammation, such as hemophagocytic lymphohistiocytosis, typically leading to death by 6 months of age if untreated."
    explanation: The registry report identifies systemic inflammation, including HLH, in rapidly progressive infantile disease.
- name: Anemia
  category: Hematologic
  notes: >
    Anemia accompanies severe infantile disease; iron-deficiency anemia can
    remain a residual problem even among treated survivors.
  phenotype_term:
    preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: PMID:28179030
    reference_title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infants presenting with lysosomal acid lipase deficiency have marked failure to thrive, diarrhea, massive hepatosplenomegaly, anemia, rapidly progressive liver disease, and death typically in the first 6 months of life"
    explanation: This study directly identifies anemia as part of the severe infantile presentation.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "However, with early diagnosis and initiation of treatment, long-term survival has improved significantly, although treated individuals may continue to have suboptimal growth, iron deficiency anemia, and lipid accumulation in the gastrointestinal mucosa."
    explanation: GeneReviews supports iron-deficiency anemia as possible residual morbidity despite treatment.
- name: Thrombocytopenia
  category: Hematologic
  notes: >
    GeneReviews recommends periodic complete-blood-count surveillance to assess for
    thrombocytopenia. The cited guidance does not establish prevalence or a causal
    intermediate, so this phenotype is deliberately left unlinked.
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "obtain a complete blood count every six months in children and every six to 12 months in adults to assess for anemia and thrombocytopenia"
    explanation: >
      GeneReviews surveillance guidance directly identifies thrombocytopenia as a
      hematologic finding to assess; it does not provide a frequency or causal link.
imaging_findings:
- name: Bilateral enlarged adrenal glands with stippled calcification on CT
  modality: CT
  description: >
    Abdominal CT can show stippled calcification of symmetrically enlarged adrenal
    glands while preserving the adreniform contour, an important diagnostic clue
    that is characteristic when present but not universal.
  imaging_finding_term:
    preferred_term: Adrenal calcification
    term:
      id: HP:0010512
      label: Adrenal calcification
  located_in:
    preferred_term: adrenal gland
    term:
      id: UBERON:0002369
      label: adrenal gland
  diagnostic: true
  evidence:
  - reference: PMID:34401013
    reference_title: CT features of Wolman disease (lysosomal acid lipase enzyme deficiency) - A case report.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The CT scan revealed stippled calcifications of both enlarged adrenal glands, without the distortion of the adreniform shape, fatty liver, splenomegaly and thickened small bowel loops; characteristic imaging findings of Wolman disease."
    explanation: The case report directly documents the characteristic bilateral adrenal CT pattern and associated abdominal findings.
biochemical:
- name: Reduced lysosomal acid lipase activity
  presence: DECREASED
  context: >
    Reduced or absent lysosomal acid lipase activity is the proximal diagnostic
    enzyme abnormality caused by LIPA pathogenic variants.
  readouts:
  - target: Lysosomal Acid Lipase Deficiency
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Low LAL enzyme activity reports the proximal lysosomal acid lipase deficiency.
    evidence:
    - reference: PMID:28786388
      reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Lysosomal acid lipase deficiency-which can be diagnosed using dry blood spot testing-is often misdiagnosed as non-alcoholic fatty liver disease"
      explanation: Dry blood spot LAL enzyme activity assay is the established diagnostic test for the proximal LAL deficiency, supporting low enzyme activity as the diagnostic readout.
  evidence:
  - reference: PMID:28786388
    reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: This review directly supports reduced or absent LAL activity as the defining biochemical enzyme abnormality.
- name: Cholesteryl ester storage burden
  presence: INCREASED
  context: >
    Cholesteryl ester storage is a chemical readout of the LAL deficiency
    neutral-lipid storage lesion.
  biomarker_term:
    preferred_term: cholesteryl ester
    term:
      id: CHEBI:17002
      label: cholesteryl ester
  readouts:
  - target: Lysosomal Cholesteryl Ester and Triglyceride Storage
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Increased cholesteryl ester storage reports the core lysosomal neutral-lipid storage lesion.
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "LAL is essential for the metabolism of cholesteryl esters and triglycerides. LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes"
      explanation: LAL deficiency causes intra-lysosomal accumulation of cholesteryl esters, supporting CE burden as a direct readout of the lysosomal neutral-lipid storage lesion.
  - target: Hepatic and Reticuloendothelial Lipid Storage
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: MONITORING
    interpretation: Cholesteryl ester burden reports hepatic and reticuloendothelial storage biology.
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes"
      explanation: Accumulation in liver and macrophages (reticuloendothelial system) and lymph nodes supports the cholesteryl ester readout reporting on hepatic and reticuloendothelial storage biology.
  evidence:
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."
    explanation: This review supports cholesteryl ester storage as a disease biochemical readout.
- name: Triglyceride storage burden
  presence: INCREASED
  context: >
    Triglyceride storage accompanies cholesteryl ester storage when LAL
    deficiency blocks lysosomal neutral-lipid hydrolysis.
  biomarker_term:
    preferred_term: triglyceride
    term:
      id: CHEBI:17855
      label: triglyceride
  readouts:
  - target: Lysosomal Cholesteryl Ester and Triglyceride Storage
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Increased triglyceride burden reports impaired lysosomal neutral-lipid hydrolysis.
    evidence:
    - reference: PMID:41599846
      reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "LAL is essential for the metabolism of cholesteryl esters and triglycerides. LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes"
      explanation: LAL deficiency causes intra-lysosomal triglyceride accumulation alongside cholesteryl esters, supporting TG burden as a direct readout of the impaired lysosomal neutral-lipid hydrolysis lesion.
  evidence:
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LAL deficiency leads to the accumulation of cholesteryl esters and triglycerides within the lysosomes, macrophages, and parenchymal cells in most tissue types, including those in the liver, gastrointestinal tract, and lymph nodes but excluding the central nervous system."
    explanation: This review supports triglyceride storage as part of the disease biochemical profile.
- name: Elevated hepatic transaminases
  presence: INCREASED
  context: >
    Transaminitis is a circulating biochemical correlate of hepatic involvement
    across the LAL deficiency spectrum.
  readouts:
  - target: Progressive Liver Dysfunction
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: MONITORING
    interpretation: Elevated transaminases report ongoing hepatocellular injury downstream of hepatic lipid storage.
    evidence:
    - reference: PMID:28786388
      reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "although the two diseases share many common features, including dyslipidaemia and transaminitis."
      explanation: Transaminitis is a shared feature across the LAL deficiency spectrum, supporting elevated transaminases as a circulating readout of progressive hepatocellular injury.
  evidence:
  - reference: PMID:28786388
    reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "although the two diseases share many common features, including dyslipidaemia and transaminitis."
    explanation: This review supports transaminitis as a biochemical manifestation of LAL deficiency.
genetic:
- name: LIPA
  gene_term:
    preferred_term: LIPA
    term:
      id: hgnc:6617
      label: LIPA
  association: Pathogenic Variants
  evidence:
  - reference: CGGV:assertion_1691be18-3aa2-46e7-b6a6-e7acafb9f998-2023-04-28T040000.000Z
    reference_title: "LIPA / lysosomal acid lipase deficiency (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "LIPA | HGNC:6617 | lysosomal acid lipase deficiency | MONDO:0800449 | AR | Definitive"
    explanation: ClinGen classifies the LIPA-lysosomal acid lipase deficiency gene-disease relationship as definitive with autosomal recessive inheritance.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The diagnosis of LAL-D is established in a proband with suggestive findings and biallelic pathogenic variants in LIPA identified by molecular genetic testing and/or deficient lysosomal acid lipase (LAL) enzyme activity in peripheral blood leukocytes or dried blood spots."
    explanation: GeneReviews directly supports biallelic pathogenic LIPA variants as a molecular route to diagnosis.
diagnosis:
- name: Lysosomal acid lipase enzyme activity assay
  description: >
    Deficient LAL activity in a dried blood spot or peripheral-blood leukocytes
    establishes the biochemical diagnosis in an infant with suggestive findings;
    dried blood spot analysis provides rapid testing.
  diagnosis_term:
    preferred_term: laboratory procedure
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  results: Deficient lysosomal acid lipase activity supports or establishes LAL-D in the appropriate clinical context.
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The diagnosis of LAL-D is established in a proband with suggestive findings and biallelic pathogenic variants in LIPA identified by molecular genetic testing and/or deficient lysosomal acid lipase (LAL) enzyme activity in peripheral blood leukocytes or dried blood spots."
    explanation: GeneReviews specifies both accepted specimen types and deficient enzyme activity as an establishing test.
  - reference: PMID:39770929
    reference_title: Practical Recommendations for the Diagnosis and Management of Lysosomal Acid Lipase Deficiency with a Focus on Wolman Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "When LAL-D is suspected, enzyme activity should be determined to confirm the diagnosis, with analysis from a dried blood spot sample being the quickest and most reliable method."
    explanation: Expert recommendations prioritize dried-blood-spot enzyme analysis for rapid confirmation.
- name: LIPA molecular genetic testing
  description: >
    Identification of biallelic pathogenic LIPA variants establishes the molecular
    diagnosis and enables carrier, at-risk relative, prenatal, and preimplantation testing.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
  results: Biallelic pathogenic LIPA variants establish the molecular diagnosis.
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "The diagnosis of LAL-D is established in a proband with suggestive findings and biallelic pathogenic variants in LIPA identified by molecular genetic testing and/or deficient lysosomal acid lipase (LAL) enzyme activity in peripheral blood leukocytes or dried blood spots."
    explanation: GeneReviews identifies biallelic pathogenic LIPA variants as an establishing diagnostic result.
treatments:
- name: Sebelipase alfa enzyme replacement therapy
  description: >
    Recombinant human lysosomal acid lipase replacement restores proximal enzyme
    function and substantially improves survival, growth, liver parameters, and
    other major disease manifestations when started early. Infusion management
    may require premedication or desensitization, and anti-drug antibodies can
    attenuate response in some patients.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: enzyme replacement therapy
    term:
      id: NCIT:C16221
      label: Protein Replacement Therapy
    therapeutic_agent:
    - preferred_term: sebelipase alfa
      term:
        id: NCIT:C152312
        label: Sebelipase Alfa
  target_mechanisms:
  - target: Lysosomal Acid Lipase Deficiency
    treatment_effect: RESTORES
    description: Sebelipase alfa replaces missing lysosomal acid lipase activity at the proximal defect.
    evidence:
    - reference: PMID:41270440
      reference_title: "Survival, growth, and safety findings in patients with rapidly progressive, infantile-onset LAL-D: Results from the international LAL-D registry."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Sebelipase alfa (KANUMA®; Alexion, AstraZeneca Rare Disease, Boston, MA) is a recombinant human LAL (a hydrolytic lysosomal cholesteryl ester and triacylglycerol-specific enzyme) approved for the treatment of LAL-D"
      explanation: The registry report identifies sebelipase alfa as recombinant human LAL, directly supporting replacement of the deficient proximal enzyme.
  - target: Lysosomal Cholesteryl Ester and Triglyceride Storage
    treatment_effect: INHIBITS
    description: Enzyme replacement lowers the stored neutral-lipid burden downstream of the LAL deficiency.
    evidence:
    - reference: PMID:23624251
      reference_title: "Hepatic cholesteryl ester accumulation in lysosomal acid lipase deficiency: non-invasive identification and treatment monitoring by magnetic resonance."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "A significant decrease in hepatic CE was observed in LAL-deficient rats following treatment with sebelipase alfa."
      explanation: In a LAL-deficient animal model, sebelipase alfa reduced hepatic cholesteryl ester accumulation, supporting direct inhibition of the storage mechanism.
  target_phenotypes:
  - preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  - preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  - preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "For infantile-onset disease, enzyme replacement therapy with intravenous sebelipase alfa (premedication and desensitization protocols may be necessary) and dietary long-chain fat restriction (fat <1 g/kg/day) with supplementation of fat-soluble vitamins and essential fatty acids is recommended; some affected individuals may also benefit from hematopoietic stem cell transplantation."
    explanation: GeneReviews recommends intravenous sebelipase alfa and explicitly notes possible premedication or desensitization requirements.
  - reference: PMID:34906190
    reference_title: "Sebelipase alfa enzyme replacement therapy in Wolman disease: a nationwide cohort with up to ten years of follow-up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Early ERT initiation allowed 100% survival with positive outcomes."
    explanation: Long-term cohort follow-up supports strong clinical benefit from early sebelipase alfa initiation.
  - reference: PMID:33407676
    reference_title: "Long-term survival with sebelipase alfa enzyme replacement therapy in infants with rapidly progressive lysosomal acid lipase deficiency: final results from 2 open-label studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The findings of these 2 studies of infants with rapidly progressive LAL-D demonstrated that enzyme replacement therapy with sebelipase alfa prolonged survival with normal psychomotor development, improved growth, hematologic parameters, and liver parameters, and was generally well tolerated, with an acceptable safety profile."
    explanation: Final pooled study results confirm durable benefit on survival, growth, hematologic measures, and liver disease.
  - reference: PMID:41270440
    reference_title: "Survival, growth, and safety findings in patients with rapidly progressive, infantile-onset LAL-D: Results from the international LAL-D registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Eleven (38 %) patients experienced adverse events potentially related to sebelipase alfa, which were generally not severe and most resolved."
    explanation: The 29-patient international registry provides treatment-specific safety context rather than implying absence of risk.
  - reference: PMID:41270440
    reference_title: "Survival, growth, and safety findings in patients with rapidly progressive, infantile-onset LAL-D: Results from the international LAL-D registry."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Four patients among 7 tested developed antidrug antibodies, and 3 had positive results for neutralizing antidrug antibodies."
    explanation: Registry testing documents clinically relevant immunogenicity that warrants monitoring when efficacy is questioned.
- name: Nutritional management with dietary lipid reduction
  description: >
    Nutritional management is used alongside enzyme replacement therapy to reduce
    dietary long-chain fat substrate burden, improve gastrointestinal tolerance,
    and support growth in infants with severe intestinal disease. Restriction
    requires supplementation and biochemical monitoring to avoid deficiencies of
    essential fatty acids and fat-soluble vitamins.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: dietary intervention
    term:
      id: NCIT:C15447
      label: Dietary Intervention
  target_mechanisms:
  - target: Lysosomal Cholesteryl Ester and Triglyceride Storage
    treatment_effect: INHIBITS
    description: Low-lipid dietary management reduces substrate load and is intended to decrease lipid deposition.
    evidence:
    - reference: PMID:39770929
      reference_title: Practical Recommendations for the Diagnosis and Management of Lysosomal Acid Lipase Deficiency with a Focus on Wolman Disease.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "careful nutritional treatment with a low-lipid diet to decrease lipid deposition and systemic inflammation, leading to better outcomes."
      explanation: Expert recommendations directly state that the low-lipid diet is intended to decrease lipid deposition and systemic inflammation.
  target_phenotypes:
  - preferred_term: Malabsorption
    term:
      id: HP:0002024
      label: Malabsorption
  - preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  - preferred_term: Diarrhea
    term:
      id: HP:0002014
      label: Diarrhea
  - preferred_term: Vomiting
    term:
      id: HP:0002013
      label: Vomiting
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "For infantile-onset disease, enzyme replacement therapy with intravenous sebelipase alfa (premedication and desensitization protocols may be necessary) and dietary long-chain fat restriction (fat <1 g/kg/day) with supplementation of fat-soluble vitamins and essential fatty acids is recommended; some affected individuals may also benefit from hematopoietic stem cell transplantation."
    explanation: GeneReviews supplies the infantile dietary restriction, supplementation, and combined-treatment recommendation.
  - reference: PMID:41599846
    reference_title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Treatment takes the two-pronged approach of sebelipase alfa, a human lysosomal acid lipase enzyme replacement therapy (ERT) that improves lipid metabolism, combined with nutritional management."
    explanation: This review directly frames nutritional management as a standard co-therapy with enzyme replacement in infantile disease.
- name: Hematopoietic stem cell transplantation in selected patients
  description: >
    Allogeneic HCT is a specialist, selected-patient option, particularly when
    enzyme-replacement response is attenuated or a well-matched donor is available.
    A five-infant multimodal cohort reported gastrointestinal and laboratory
    improvement in survivors, but one patient died after HCT and historical
    procedure-related mortality is high; this evidence does not establish HCT as
    universal first-line therapy.
  therapeutic_modality: CELL_THERAPY
  treatment_term:
    preferred_term: hematopoietic stem cell transplantation
    term:
      id: NCIT:C15431
      label: Hematopoietic Cell Transplantation
  target_phenotypes:
  - preferred_term: Diarrhea
    term:
      id: HP:0002014
      label: Diarrhea
  - preferred_term: Vomiting
    term:
      id: HP:0002013
      label: Vomiting
  evidence:
  - reference: PMID:34020687
    reference_title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The gastrointestinal symptoms are particularly improved after HCT, with reduced diarrhoea and vomiting."
    explanation: The cohort directly reports improvement in gastrointestinal symptoms after HCT.
  - reference: PMID:34020687
    reference_title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients received allogeneic HCT. 4/5 patients are alive, and both disease phenotype and laboratory parameters are improved compared to when they were on ERT alone."
    explanation: The five-patient cohort supports clinical and laboratory improvement after HCT while retaining the small-cohort boundary.
  - reference: PMID:34020687
    reference_title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In 3/5 an initial response to ERT was attenuated by ADA with associated clinical and laboratory features of deterioration. 1/5 developed anaphylaxis to ERT and the other patient died post HCT with ongoing HLH."
    explanation: This cohort documents both reasons for considering multimodal therapy and serious adverse outcomes, including post-HCT death.
  - reference: PMID:34020687
    reference_title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Multimodal therapy should be considered a new paradigm of treatment for Wolman disease patients where there is an attenuated response to ERT, and for all patients where there is a well-matched transplant donor"
    explanation: The authors recommend consideration in these settings, but the evidence is a single five-patient cohort and does not establish universal benefit.
  - reference: PMID:34020687
    reference_title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hematopoietic stem cell transplant (HCT) had been historically the only treatment available but has a high procedure-related mortality because of disease progression and disease-associated morbidities."
    explanation: The authors explicitly identify serious historical transplant risk, supporting careful selection and counseling.
- name: Supportive hematologic care and longitudinal surveillance
  description: >
    Treat anemia and thrombocytopenia conventionally while monitoring growth,
    diarrhea, liver enzymes, essential fatty acids, fat-soluble vitamins, and
    blood counts. When treatment efficacy is questioned, assess anti-drug
    antibodies. Patients with thrombocytopenia should avoid nonsteroidal
    anti-inflammatory drugs.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Supportive care: Standard treatment for anemia/thrombocytopenia."
    explanation: GeneReviews recommends standard supportive treatment of the hematologic manifestations.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "For infantile-onset disease, measure weight, length/height, and mid-upper arm circumference in infants/children and weight in adults at each visit; assess for chronic diarrhea and monitor liver enzymes, essential fatty acids, and fat-soluble vitamins (A, D, E, and K) levels every six months"
    explanation: GeneReviews supplies the growth, gastrointestinal, hepatic, fatty-acid, and vitamin surveillance elements.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "monitor anti-drug antibody (ADA) concentration for those on enzyme replacement therapy if the ALT and AST levels are >3 times the normal limit or if there are clinical concerns regarding efficacy of treatment"
    explanation: GeneReviews supports targeted ADA monitoring when biochemical or clinical efficacy is in question.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Those with thrombocytopenia should avoid use of nonsteroidal anti-inflammatory drugs."
    explanation: GeneReviews provides the specific medication-avoidance safety recommendation.
- name: Genetic counseling and family testing
  description: >
    Counsel families about autosomal-recessive recurrence risk, test at-risk
    relatives promptly so treatment can begin early, and offer carrier,
    prenatal, or preimplantation testing when familial LIPA variants are known.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "If the LIPA pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives and prenatal/preimplantation genetic testing are possible."
    explanation: GeneReviews directly supports family-based carrier and reproductive testing after variant identification.
  - reference: PMID:26225414
    reference_title: Lysosomal Acid Lipase Deficiency.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "It is appropriate to evaluate the sibs of a proband in order to identify those who would benefit from early institution of treatment."
    explanation: GeneReviews supports prompt evaluation of siblings because early treatment changes outcome.
differential_diagnoses:
- name: Cholesteryl ester storage disease
  description: >
    Later-onset lysosomal acid lipase deficiency phenotype that shares LIPA causation
    and cholesteryl ester/triglyceride storage biology but is clinically less severe
    and usually presents beyond infancy with chronic liver disease and dyslipidemia.
  disease_term:
    preferred_term: cholesteryl ester storage disease
    term:
      id: MONDO:0019149
      label: cholesteryl ester storage disease
  evidence:
  - reference: PMID:28786388
    reference_title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cholesteryl ester storage disorder arises later in life and is less severe, although the two diseases share many common features, including dyslipidaemia and transaminitis."
    explanation: This review directly supports CESD as the later-onset, less severe sibling phenotype on the same LAL deficiency spectrum.
experimental_models:
- name: Wolman disease patient fibroblast lipid-storage and LAL-transgene rescue model
  description: >
    Primary fibroblasts from people with Wolman disease model intracellular
    lipid-droplet and lysosomal abnormalities and permit cell-level testing of LAL
    rescue. The system demonstrated restoration of lipid homeostasis after delivery
    of a functional LAL transgene, but does not reproduce whole-organ infant disease.
  experimental_model_type: PRIMARY_CELL_CULTURE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  conditions:
  - Wolman disease
  - LAL transgene rescue
  cell_source: Primary fibroblasts from patients with Wolman disease
  culture_system: Patient-derived fibroblast culture
  publication: PMID:40613725
  modeled_mechanisms:
  - target: Lysosomal Cholesteryl Ester and Triglyceride Storage
    description: The model reports excess intracellular lipid droplets and lysosomes caused by LAL deficiency.
    evidence:
    - reference: PMID:40613725
      reference_title: Advanced Imaging and Cytometric Techniques to Characterize Lipid Accumulation in Wolman Disease.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "In particular, we stained WD patients' fibroblasts for intracellular lipid droplets (LD) and lysosomes, and we analyzed staining intensity and granularity, as well as an increased number of LD and lysosomes using fluorescence wide-field microscopy, confocal microscopy, conventional, and image flow cytometry."
      explanation: The study directly characterizes the lipid-droplet and lysosomal phenotype in patient fibroblasts.
  findings:
  - statement: Functional LAL transgene delivery restored lipid homeostasis in the cellular model.
    supporting_text: "Noteworthy, we showed that lipid homeostasis was restored upon delivery of a functional LAL transgene."
    evidence:
    - reference: PMID:40613725
      reference_title: Advanced Imaging and Cytometric Techniques to Characterize Lipid Accumulation in Wolman Disease.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Noteworthy, we showed that lipid homeostasis was restored upon delivery of a functional LAL transgene."
      explanation: The transgene-rescue experiment directly supports this finding.
  evidence:
  - reference: PMID:40613725
    reference_title: Advanced Imaging and Cytometric Techniques to Characterize Lipid Accumulation in Wolman Disease.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Noteworthy, we showed that lipid homeostasis was restored upon delivery of a functional LAL transgene."
    explanation: The patient-cell experiment directly demonstrates reversal of the measured lipid-homeostasis phenotype by functional LAL.
- name: Lipa-null mouse model with liver-directed LIPA AAV rescue
  description: >
    Lipa-knockout mice model severe systemic LAL deficiency and were treated at
    neonatal or 8-week time points with liver-directed LIPA AAV. Rescue of storage,
    hepatic injury, inflammation, fibrosis, and survival supports preclinical
    mechanism testing, while human infant safety, immunogenicity, dosing, and
    durability remain unestablished.
  experimental_model_type: OTHER
  organism:
    preferred_term: mouse
    term:
      id: NCBITaxon:10090
      label: Mus musculus
  conditions:
  - Homozygous Lipa knockout
  - Liver-directed rscAAVrh74.LP1.LIPA treatment
  publication: PMID:39489913
  modeled_mechanisms:
  - target: Lysosomal Acid Lipase Deficiency
    description: The knockout removes Lipa activity and AAV supplies a functional LIPA transgene.
    evidence:
    - reference: PMID:39489913
      reference_title: Liver-directed AAV gene therapy normalizes disease symptoms and provides cross-correction in a model of lysosomal acid lipase deficiency.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "rscAAVrh74.LP1.LIPA treatment elevated LAL enzyme activity above wild-type levels in all tissues tested, including liver, spleen, intestine, muscle, and brain"
      explanation: The treated knockout model demonstrated systemic biochemical cross-correction after liver-directed LIPA delivery.
  findings:
  - statement: AAV treatment normalized multiple storage and hepatic disease measures in Lipa-null mice.
    supporting_text: "normalized many disease measures in Lipa-/- mice when measured at 24 weeks of age, including hepatosplenomegaly, serum transaminase activity, organ triglyceride and cholesterol levels, and biomarkers of liver inflammation and fibrosis."
    evidence:
    - reference: PMID:39489913
      reference_title: Liver-directed AAV gene therapy normalizes disease symptoms and provides cross-correction in a model of lysosomal acid lipase deficiency.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "normalized many disease measures in Lipa-/- mice when measured at 24 weeks of age, including hepatosplenomegaly, serum transaminase activity, organ triglyceride and cholesterol levels, and biomarkers of liver inflammation and fibrosis."
      explanation: The study directly supports normalization across the listed mouse disease measures.
  - statement: AAV treatment at 8 weeks significantly extended survival beyond untreated Lipa-null mice.
    supporting_text: "AAV treatment at 8 weeks of age with 1 × 1013 vg/kg extended survival significantly, with all AAV-treated mice surviving beyond the maximal lifespan of untreated Lipa-/- mice."
    evidence:
    - reference: PMID:39489913
      reference_title: Liver-directed AAV gene therapy normalizes disease symptoms and provides cross-correction in a model of lysosomal acid lipase deficiency.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "AAV treatment at 8 weeks of age with 1 × 1013 vg/kg extended survival significantly, with all AAV-treated mice surviving beyond the maximal lifespan of untreated Lipa-/- mice."
      explanation: The report directly supports extended survival after the 8-week intervention.
  evidence:
  - reference: PMID:39489913
    reference_title: Liver-directed AAV gene therapy normalizes disease symptoms and provides cross-correction in a model of lysosomal acid lipase deficiency.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Treatment at both early (1-2 days) and late (8-week) timepoints with rscAAVrh74.LP1.LIPA, a liver-directed AAV gene therapy, normalized many disease measures in Lipa-/- mice when measured at 24 weeks of age, including hepatosplenomegaly, serum transaminase activity, organ triglyceride and cholesterol levels, and biomarkers of liver inflammation and fibrosis."
    explanation: The mouse experiment directly supports broad preclinical biochemical, inflammatory, fibrotic, and organ-level rescue.
discussions:
- discussion_id: gap_wolman_adrenal_calcification_mechanism
  prompt: >
    Which in-vivo steps connect lysosomal neutral-lipid storage in the adrenal
    gland to adrenal necrosis and calcification in Wolman disease?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Adrenal Lipid Storage
  rationale: >
    Adrenal lipid infiltration, enlargement, and calcification are clinically
    documented, but the available mechanistic study is a cultured-cell hypothesis
    involving oxidized LDL uptake, calcium loading, cytotoxicity, and necrosis.
    It does not establish the sequence or its necessity in affected infants.
  proposed_experiments:
  - experiment_id: exp_wolman_adrenal_human_validation
    name: Human adrenal validation of the oxidized-LDL injury sequence
    description: >
      Compare LIPA-deficient and isogenic-corrected human adrenal cortical organoids
      after matched native- and mildly oxidized-LDL exposures, measuring LDL uptake,
      lysosomal neutral-lipid storage, calcium dynamics, necrosis, and mineral
      deposition over time. Compare the resulting molecular and spatial signature
      with archived adrenal tissue from affected infants and age-matched controls
      when such tissue is available.
    decision_criterion: >
      The cultured-cell mechanism is supported as a bridge to infant adrenal disease
      if LIPA deficiency produces an ordered excess-uptake, calcium-loading,
      necrosis, and mineralization sequence that is reversed by isogenic LIPA
      correction and is concordant with affected-infant adrenal pathology. Storage
      without the downstream injury sequence, or absence of that signature in
      affected-infant tissue, would refute the proposed bridge.
    would_support:
    - pathophysiology#Adrenal Lipid Storage
    - phenotypes#Adrenal calcification
    would_refute:
    - pathophysiology#Adrenal Lipid Storage
    - phenotypes#Adrenal calcification
  evidence:
  - reference: PMID:8037680
    reference_title: "New pathogenetic hypothesis for Wolman disease: possible role of oxidized low-density lipoproteins in adrenal necrosis and calcification."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "These findings support the hypothesis that the Wolman-disease adrenal damage (necrosis and calcification) could result from the association of the following events"
    explanation: The authors explicitly frame the oxidized-LDL mechanism as a hypothesis, leaving its in-vivo role unresolved.
- discussion_id: gap_wolman_lipa_aav_translation
  prompt: >
    Can liver-directed LIPA AAV safely and durably reproduce the knockout-mouse
    rescue in infants with rapidly progressive LAL-D?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Lysosomal Acid Lipase Deficiency
  rationale: >
    Liver-directed AAV produced broad biochemical and survival rescue in Lipa-null
    mice. The reviewed evidence is preclinical and therefore does not establish
    infant dosing, organ coverage, durability, vector immunity, or clinical safety.
  proposed_experiments:
  - experiment_id: exp_wolman_lipa_aav_human_translation
    name: Staged translation of liver-directed LIPA AAV to infantile LAL-D
    description: >
      Quantify dose, biodistribution, secreted LAL cross-correction, durability,
      pre-existing and treatment-emergent immunity, and organ toxicity in
      infant-relevant human hepatocyte-intestinal co-cultures and a nonhuman-primate
      bridging study. Advance only a candidate meeting prespecified bridging criteria
      to an early-phase infant study measuring LAL activity, organ lipid burden,
      liver and gastrointestinal disease, growth, vector immunity, and toxicity.
    decision_criterion: >
      Direct translation from the Lipa-null mouse is supported only if a tolerable
      exposure produces durable therapeutic LAL activity and cross-correction in the
      bridging systems and concordant biochemical and clinical improvement without
      unacceptable vector or immune toxicity in treated infants. Failure of organ
      coverage or durability, or dose-limiting toxicity before therapeutic activity,
      would refute direct extrapolation of the mouse rescue to infants.
    would_support:
    - experimental_models#Lipa-null mouse model with liver-directed LIPA AAV rescue
    - pathophysiology#Lysosomal Acid Lipase Deficiency
    would_refute:
    - experimental_models#Lipa-null mouse model with liver-directed LIPA AAV rescue
    - pathophysiology#Lysosomal Acid Lipase Deficiency
  evidence:
  - reference: PMID:39489913
    reference_title: Liver-directed AAV gene therapy normalizes disease symptoms and provides cross-correction in a model of lysosomal acid lipase deficiency.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "These results show that this liver-directed LIPA gene therapy has the potential to be a transformative treatment for LAL-D."
    explanation: The investigators describe therapeutic potential based on a mouse study; clinical translation remains an open question.
references:
- reference: CGGV:assertion_1691be18-3aa2-46e7-b6a6-e7acafb9f998-2023-04-28T040000.000Z
  title: "LIPA / lysosomal acid lipase deficiency (Definitive)"
- reference: PMID:28786388
  title: "Wolman's disease and cholesteryl ester storage disorder: the phenotypic spectrum of lysosomal acid lipase deficiency."
- reference: PMID:30866656
  title: "Lysosomal Acid Lipase in Lipid Metabolism and Beyond."
- reference: PMID:36204319
  title: "Lysosomal acid lipase deficiency: A rare inherited dyslipidemia but potential ubiquitous factor in the development of atherosclerosis and fatty liver disease."
- reference: PMID:41599846
  title: "Best Practices for the Nutritional Management of Infantile-Onset Lysosomal Acid Lipase Deficiency: A Case-Based Discussion."
- reference: PMID:23624251
  title: "Hepatic cholesteryl ester accumulation in lysosomal acid lipase deficiency: non-invasive identification and treatment monitoring by magnetic resonance."
- reference: PMID:28179030
  title: "Survival in infants treated with sebelipase Alfa for lysosomal acid lipase deficiency: an open-label, multicenter, dose-escalation study."
- reference: PMID:34906190
  title: "Sebelipase alfa enzyme replacement therapy in Wolman disease: a nationwide cohort with up to ten years of follow-up."
- reference: PMID:33407676
  title: "Long-term survival with sebelipase alfa enzyme replacement therapy in infants with rapidly progressive lysosomal acid lipase deficiency: final results from 2 open-label studies."
- reference: PMID:24832708
  title: "Infant case of lysosomal acid lipase deficiency: Wolman's disease."
- reference: PMID:34020687
  title: "Enzyme replacement therapy and hematopoietic stem cell transplant: a new paradigm of treatment in Wolman disease."
- reference: PMID:26225414
  title: Lysosomal Acid Lipase Deficiency.
  tags:
  - GeneReviews
- reference: PMID:39770929
  title: Practical Recommendations for the Diagnosis and Management of Lysosomal Acid Lipase Deficiency with a Focus on Wolman Disease.
- reference: PMID:41270440
  title: "Survival, growth, and safety findings in patients with rapidly progressive, infantile-onset LAL-D: Results from the international LAL-D registry."
- reference: PMID:34401013
  title: CT features of Wolman disease (lysosomal acid lipase enzyme deficiency) - A case report.
- reference: PMID:8037680
  title: "New pathogenetic hypothesis for Wolman disease: possible role of oxidized low-density lipoproteins in adrenal necrosis and calcification."
- reference: PMID:40613725
  title: Advanced Imaging and Cytometric Techniques to Characterize Lipid Accumulation in Wolman Disease.
- reference: PMID:39489913
  title: Liver-directed AAV gene therapy normalizes disease symptoms and provides cross-correction in a model of lysosomal acid lipase deficiency.

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References & Deep Research