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Inheritance

1

Autosomal Recessive HP:0000007

When both parents carry a pathogenic ABCA1 allele, each pregnancy has a 25% affected, 50% carrier and 25% noncarrier probability. Carrier biochemical HDL reduction is distinguishable from the biallelic clinical disorder; recurrence changes if a parent is affected.

Autosomal recessive inheritance

Show evidence (3 references)

ORPHA:31150 SUPPORT Other

"Autosomal recessive"

Orphanet records autosomal recessive inheritance for Tangier disease.

PMID:33994407 SUPPORT Human Clinical

"Tangier disease is an autosomal recessive disease"

This clinical management review states the autosomal recessive inheritance pattern.

PMID:31751110 SUPPORT Human Clinical

"Tangier disease is inherited in an autosomal recessive manner."

Autosomal recessive segregation supports conditional Mendelian recurrence; the GeneReviews detailed genetic-counseling section gives the affected/carrier/noncarrier probabilities.

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Mechanistic Hypotheses

3

Canonical ABCA1 HDL Efflux Model

canonical_abca1_hdl_efflux_model CANONICAL

Evidence balance 11 support

Biallelic ABCA1 pathogenic variants impair apolipoprotein-mediated phospholipid and cholesterol efflux, blocking nascent HDL formation. Cellular cholesterol export falls in macrophages, Schwann cells, and other peripheral cells, leading to cholesteryl ester storage in tissues and a combination of reticuloendothelial, neurologic, biochemical, and vascular manifestations.

Retain CANONICAL for ABCA1 loss and impaired lipid efflux. The OpenScientist report is assessed in assessments/openscientist-assessment-by-codex.yaml beside the report. Human inflammasome-associated cytokines, experimental membrane signaling, sphingolipid depletion, platelet defects, and impaired insulin secretion extend the model with different evidence strengths. NLRP3/NETosis causality primarily comes from combined Abca1/Abcg1-deficient mice; plasma S1P loss was demonstrated in hepatic knockout mice, while one Tangier patient had low total sphingolipids. Neither establishes the quantitative clinical contribution. PMP22 interaction and HSPC expansion require disease/context qualifications. The report missed an existing miglustat n-of-1 trial and GenCC assertions.

Deep research

OpenScientist citations 35 citations 2026-05-22T22:41:05.038961

Show evidence (11 references)

PMID:33994407 SUPPORT Human Clinical

"It is caused by a dysfunctional mutation of the ATP-binding cassette transporter A1 (ABCA1) gene, the mandatory gene for generation of HDL particles from cellular cholesterol and phospholipids, and it appears in an autosomal recessive hereditary profile."

This review links ABCA1 to HDL particle generation from cellular lipid export.

PMID:33994407 SUPPORT Human Clinical

"Cholesterol therefore accumulates in these cells, causing orange-colored pharyngeal tonsillar swelling, corneal opacity, hepatosplenomegaly, lymphadenopathy and peripheral neuropathy."

This review summarizes the downstream tissue-storage phenotype.

PMID:28602350 SUPPORT Other

"Mutations of human ABCA1 are associated with Tangier disease and familial HDL deficiency."

Cryo-EM structural biology directly connects ABCA1 to Tangier disease and provides an atomic-resolution framework for interpreting the diverse mutations that cause loss of cholesterol/phospholipid efflux.

+ 8 more references

Inflammasome and membrane signaling amplify the efflux defect

inflammatory_amplification EMERGING

Evidence balance 2 support

Macrophage free-cholesterol accumulation enhances inflammatory signaling. NLRP3/NETosis intervention evidence comes mainly from combined Abca1/Abcg1-deficient hyperlipidemic mice; Tangier patient plasma cytokines provide clinical relevance without proving the whole chain.

Pathograph links

Impaired Cellular Lipid Efflux -> Myeloid Inflammasome Activation INDIRECT UNKNOWN INTERMEDIATES Myeloid cholesterol accumulation activates inflammasomes in combined Abca1/Abcg1-deficient models; patient cytokines support human relevance.

Myeloid Inflammasome Activation -> Amplified Myeloid Inflammatory Signaling INDIRECT KNOWN INTERMEDIATES Inflammasome-dependent cytokine release amplifies systemic myeloid inflammation. Intermediates: IL-1β and IL-18 release

Amplified Myeloid Inflammatory Signaling -> Macrophage Foam Cell Atherogenesis INDIRECT KNOWN INTERMEDIATES Inflammasome-dependent inflammation, neutrophil recruitment and NET formation enhance lesion development in combined Abca1/Abcg1-deficient Ldlr-null mice. Intermediates: neutrophil recruitment and plaque NET formation

Show evidence (2 references)

PMID:29588315 SUPPORT Human Clinical

"Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1β and IL-18 levels."

Human cytokine observations support relevance but do not prove NLRP3 specificity, NETosis, or therapeutic response.

PMID:29588315 SUPPORT Model Organism

"Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice."

Genetic intervention supports an inflammasome contribution in a combined-transporter and hyperlipidemic mouse model.

Schwann-cell lipid and PMP22 homeostasis

schwann_lipid_protein_homeostasis EMERGING

Evidence balance 1 support

Reciprocal ABCA1/PMP22 interactions couple lipid trafficking to peripheral myelin protein processing. Mouse and Schwann-cell experiments support this extension, while human clinical severity and allele-specific mediation remain unresolved.

Pathograph links

ABCA1 Dysfunction -> Abnormal PMP22 Processing INDIRECT UNKNOWN INTERMEDIATES Abca1 deletion in mice changes PMP22 abundance and maturation in peripheral nerves.

Show evidence (1 reference)

PMID:31061090 SUPPORT Model Organism

"In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant."

Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.

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Discussions and Knowledge Gaps

2

Which experimental extensions of ABCA1 dysfunction determine human clinical severity?

KNOWLEDGE GAP context_limits

Attached to

pathophysiology#Impaired Cellular Lipid Efflux pathophysiology#Myeloid Inflammasome Activation pathophysiology#Peripheral Nerve Dysfunction pathophysiology#Abnormal PMP22 Processing

Human S1P signaling effects remain unquantified; one Tangier plasma sample established low total sphingolipids, while apoM/S1P results came from hepatic knockout mice. PMP22/ABCA1 interactions support nerve-cell lipid homeostasis but do not prove that disrupted binding explains all neuropathy. HSPC myeloproliferation cited by OpenScientist arose in rheumatoid-arthritis models with multiple altered efflux genes and remains untested in Tangier patients. These are mechanistic leads rather than established universal clinical branches.

Show evidence (3 references)

PMID:37601634 SUPPORT Human Clinical

"we report a drastic reduction of total SL levels in plasma of a Tangier patient with compound heterozygosity for mutations in ABCA1."

One-patient plasma lipidomics supports sphingolipid depletion; S1P-specific reduction in this paper was shown in hepatic knockout mice.

PMID:31061090 SUPPORT Model Organism

"In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant."

Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.

PMID:29905812 SUPPORT Model Organism

"HSPCs expansion was associated with an increase in the cholesterol content, due to a down-regulation of cholesterol efflux genes, Apoe, Abca1, and Abcg1."

The RA model includes several downregulated efflux genes and is not direct Tangier HSPC evidence.

What links the ABCA1 defect to less-characterized hematologic and distal manifestations?

KNOWLEDGE GAP unresolved_distal_manifestations

Attached to

phenotypes#Dry skin phenotypes#Nail dystrophy phenotypes#Ectropion phenotypes#Abdominal pain phenotypes#Left ventricular hypertrophy phenotypes#Reticulocytosis phenotypes#Stomatocytosis phenotypes#Hemolytic anemia phenotypes#Anemia

Orphanet and GeneReviews record these manifestations, but the phenotype lists do not establish that tissue storage causes each one. In particular, the reported red-cell abnormalities and the association of splenomegaly with reticulocyte hyperplasia do not resolve the causal intermediates for anemia, hemolytic anemia, stomatocytosis, or reticulocytosis. Their clinical annotations are retained without assigning a storage-to-red-cell causal chain; the previously removed anemia edge lacked that support. The syringomyelia annotation is replaced with the documented syringomyelia-like peripheral neuropathy pattern; a spinal cord cavity requires separate evidence.

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Pathophysiology

13

ABCA1 Dysfunction

Disease-causing germline ABCA1 variants impair the ATP-binding cassette transporter required for apolipoprotein-mediated cellular lipid export. Human genetic studies identified ABCA1 mutations in Tangier disease kindreds, and cell-based studies show that ABCA1 promotes phospholipid and cholesterol efflux by loading apoA-I with lipids.

Schwann-cell lipid and PMP22 homeostasis

ABCA1 hgnc:29

cholesterol efflux GO:0033344 ↓ DECREASED phospholipid efflux GO:0033700 ↓ DECREASED

ATPase-coupled transmembrane transporter activity GO:0042626 apolipoprotein binding GO:0034185

Downstream

Impaired Cellular Lipid Efflux Loss of functional ABCA1 reduces apolipoprotein-mediated lipid export.

Platelet Dense-Granule Maturation Defect ABCA1 deficiency perturbs platelet granule maturation; specific intervening membrane-trafficking steps remain unresolved.

Impaired Glucose-Stimulated Insulin Secretion ABCA1 deficiency associates with impaired insulin release; beta-cell cholesterol handling is a candidate intermediary, not directly measured in the four-patient OGTT study.

Abnormal PMP22 Processing Abca1 deletion in mice changes PMP22 abundance and maturation in peripheral nerves.

Show evidence (4 references)

ORPHA:31150 SUPPORT Other

"ABCA1 | ATP binding cassette subfamily A member 1 | hgnc:29 | Disease-causing germline mutation(s) in"

Orphanet records ABCA1 as the disease-causing gene.

PMID:10431236 SUPPORT Human Clinical

"ABC1 were detected in both TD and FHA, indicating that TD and FHA are allelic."

Human genetic linkage and mutation detection support ABCA1 as the causal locus.

PMID:10431238 SUPPORT Human Clinical

"encoding a member of the ABC transporter superfamily, are the cause of TD."

Independent human kindred study identifies ABCA1 defects as the cause of Tangier disease.

+ 1 more reference

Impaired Cellular Lipid Efflux

Reduced export of cellular cholesterol and phospholipid to apolipoproteins creates parallel defects in HDL formation and local cholesterol homeostasis.

Inflammasome and membrane signaling amplify the efflux defect

cholesterol efflux GO:0033344 ↓ DECREASED

Experimental models

ABCA1 intracellular-domain variant expression screen CELL LINE

Downstream

Impaired HDL Biogenesis Impaired apoA-I lipidation limits nascent HDL formation.

Cholesteryl Ester Tissue Storage Persistent impaired cellular export permits cholesterol retention and ester storage.

Macrophage Foam Cell Atherogenesis Reduced macrophage efflux promotes cholesterol retention and foam-cell atherogenesis.

Membrane Cholesterol Enrichment Deficient macrophage efflux increases free cholesterol and lipid-raft abundance in experimental cells.

Myeloid Inflammasome Activation Myeloid cholesterol accumulation activates inflammasomes in combined Abca1/Abcg1-deficient models; patient cytokines support human relevance.

Show evidence (2 references)

PMID:10525055 SUPPORT In Vitro

"Blocking the expression or activity of ABC1 reduces apolipoprotein-mediated lipid efflux from cultured cells, and increasing expression of ABC1 enhances it."

Bidirectional expression/activity perturbations establish the proximal cellular efflux defect.

PMID:33994407 SUPPORT Human Clinical

"cellular cholesterol export is impaired due to ABCA1 deficiency in peripheral cells, including macrophages and Schwann cells."

The clinical synthesis distinguishes cell-autonomous export failure from low circulating HDL alone.

Impaired HDL Biogenesis

Impaired ABCA1-dependent apoA-I lipidation reduces nascent HDL production. Reduced circulating HDL is a systemic consequence; cellular storage is also driven directly by deficient local export and should not be attributed to low HDL concentration alone. Rapid apoA-I catabolism further contributes to the low circulating apolipoprotein concentration.

high-density lipoprotein particle assembly GO:0034380 ↓ DECREASED cholesterol efflux GO:0033344 ↓ DECREASED

Downstream

Decreased HDL cholesterol concentration HDL particle assembly failure produces very low or absent HDL-C.

Hypocholesterolemia Severe HDL deficiency and altered lipoprotein remodeling lower total cholesterol.

Hypertriglyceridemia Tangier disease commonly includes normal to high or elevated plasma triglycerides.

Show evidence (4 references)

PMID:10525055 SUPPORT In Vitro

"activity of ABC1 reduces apolipoprotein-mediated lipid efflux from cultured"

Cell-based studies support impaired apolipoprotein-mediated efflux as the proximal mechanism.

PMID:33994407 SUPPORT Human Clinical

"With functional deficiency in ABCA1, spherical HDL particles are not produced resulting in extremely low plasma HDL-C levels"

Clinical review links ABCA1 deficiency to failure of spherical HDL production and very low HDL-C.

PMID:7130397 SUPPORT Human Clinical

"cholesterol, apoA-I, and apoA-II concentrations that were 4, 2, and 11% of"

Human kinetic studies document the biochemical HDL and apolipoprotein deficiency in homozygotes.

+ 1 more reference

Cholesteryl Ester Tissue Storage

Impaired cellular cholesterol export permits cholesteryl ester accumulation in reticuloendothelial tissues, Schwann cells, skin, smooth muscle and mucosa. Storage contributes to orange tonsils, organomegaly and nerve involvement. Mechanisms underlying individual skin/nail findings remain less well characterized.

macrophage CL:0000235 Schwann cell CL:0002573

Downstream

Orange discolored tonsils Cholesteryl ester storage in tonsillar tissue produces orange tonsils.

Hepatosplenomegaly Reticuloendothelial lipid storage enlarges liver and spleen.

Chronic noninfectious lymphadenopathy Reticuloendothelial storage contributes to lymph-node enlargement.

Corneal opacity Lipid storage in ocular tissue can produce corneal opacity.

Thrombocytopenia Splenomegaly and reticuloendothelial involvement can be accompanied by thrombocytopenia.

Peripheral Nerve Dysfunction Schwann-cell lipid storage and abnormal myelin/axon function contribute to heterogeneous neuropathy; intervening injury mechanisms are not completely resolved.

Show evidence (3 references)

PMID:162820 SUPPORT Human Clinical

"cholesteryl esters were found in: reticuloendothelial cells (foam cells) in"

Histopathologic study directly demonstrates cholesteryl ester storage in patient tissues.

PMID:162820 SUPPORT Human Clinical

"Deposits of cholesteryl esters were found in: reticuloendothelial cells (foam cells) in tonsils, bone marrow, skin and jejunal submucosa; Schwann cells in peripheral nerves and myenteric plexus; and in nonvascular smooth muscle cells."

The pathology study supports Schwann-cell involvement in peripheral nerves.

PMID:33994407 SUPPORT Human Clinical

"cellular cholesterol export is impaired due to ABCA1 deficiency in peripheral cells, including macrophages and Schwann cells."

This review connects ABCA1 deficiency to impaired cholesterol export in macrophages and Schwann cells.

Macrophage Foam Cell Atherogenesis

Deficient macrophage lipid efflux promotes foam-cell accumulation and atherogenesis. Plasma apoB-lipoprotein burden, age and other risk factors modify clinical expression; systemic HDL-C concentration alone does not determine lesion burden.

cholesterol transport GO:0030301 ↓ DECREASED cholesterol metabolic process GO:0008203

Downstream

Accelerated atherosclerosis Impaired reverse cholesterol transport increases atherosclerotic risk in susceptible patients.

Coronary artery stenosis Atherosclerotic vascular involvement can include coronary artery disease.

Carotid artery stenosis Atherosclerotic vascular involvement can include carotid artery stenosis.

Show evidence (4 references)

PMID:10431238 SUPPORT Human Clinical

"Impaired cholesterol efflux from macrophages leads to the presence of foam cells throughout the body, which may explain the increased risk of coronary heart disease in some TD families."

Human genetic paper connects impaired macrophage efflux to foam-cell accumulation.

PMID:33994407 SUPPORT Human Clinical

"impairment of the initial stage of reverse cholesterol transport should be considered to be a risk for developing atherosclerotic diseases"

This review links the efflux defect to atherosclerotic risk.

PMID:27565770 SUPPORT Human Clinical

"25% had CVD, which increased to 52% in those between the ages of 40 and 65 years"

Review of reported Tangier cases supports age-dependent cardiovascular disease risk.

+ 1 more reference

Peripheral Nerve Dysfunction

Peripheral nerve injury may involve demyelination, conduction block and axonal loss, with relapsing-remitting or progressive courses.

Schwann cell CL:0002573

Downstream

Peripheral axonal neuropathy Schwann-cell and peripheral-nerve lipid storage contributes to neuropathy.

Progressive peripheral neuropathy Peripheral-nerve involvement may be chronic and progressive.

Facial diplegia Cranial nerve involvement can manifest as facial diplegia.

Impaired temperature sensation Sensory nerve involvement can impair temperature sensation.

Distal muscle weakness Motor neuropathy can produce distal weakness.

Syringomyelia-like neuropathy A dissociated sensory and motor neuropathy can resemble syringomyelia without demonstrating a spinal cord cavity.

Show evidence (1 reference)

PMID:29582519 SUPPORT Human Clinical

"Our literature review and our case showed the clinical spectrum of TD neuropathy is quite wide and that it should be considered in the differential diagnosis of non-uniform demyelinating neuropathies."

A selected literature series of 54 neuropathy cases supports heterogeneous nerve involvement, not a population prevalence estimate.

Membrane Cholesterol Enrichment

Free-cholesterol enrichment of macrophage membrane domains enhances sensitivity to inflammatory stimuli; this differs from bulk cholesteryl ester storage.

Downstream

Amplified Myeloid Inflammatory Signaling Membrane cholesterol enrichment enhances LPS/MyD88-dependent NF-κB and MAPK responses in Abca1-deficient macrophages.

Show evidence (1 reference)

PMID:18552351 SUPPORT In Vitro

"cholesterol depletion of macrophages with methyl-beta-cyclodextrin normalized FC content between the two genotypes and their response to LPS"

Depletion/repletion experiments support membrane-cholesterol-dependent inflammatory signaling in Abca1-deficient murine macrophages.

Myeloid Inflammasome Activation

Inflammasome activation increases IL-1β and IL-18 release in experimental myeloid cholesterol overload; elevated patient cytokines are supportive clinical observations.

Inflammasome and membrane signaling amplify the efflux defect

Animal models

Myeloid Abca1/Abcg1-deficient bone marrow in Ldlr-null recipients Mouse partially recapitulates

Downstream

Amplified Myeloid Inflammatory Signaling Inflammasome-dependent cytokine release amplifies systemic myeloid inflammation.

Show evidence (2 references)

PMID:29588315 SUPPORT Human Clinical

"Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1β and IL-18 levels."

Human cytokine observations support relevance but do not prove NLRP3 specificity, NETosis, or therapeutic response.

PMID:29588315 SUPPORT Model Organism

"Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice."

Genetic intervention supports an inflammasome contribution in a combined-transporter and hyperlipidemic mouse model.

Amplified Myeloid Inflammatory Signaling

Receptor and inflammasome pathways amplify inflammatory responses. The magnitude of this contribution to human Tangier disease remains undetermined.

Inflammasome and membrane signaling amplify the efflux defect

Downstream

Macrophage Foam Cell Atherogenesis Inflammasome-dependent inflammation, neutrophil recruitment and NET formation enhance lesion development in combined Abca1/Abcg1-deficient Ldlr-null mice.

Show evidence (2 references)

PMID:18552351 SUPPORT In Vitro

"cholesterol depletion of macrophages with methyl-beta-cyclodextrin normalized FC content between the two genotypes and their response to LPS"

Depletion/repletion experiments support membrane-cholesterol-dependent inflammatory signaling in Abca1-deficient murine macrophages.

PMID:29588315 SUPPORT Human Clinical

"Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1β and IL-18 levels."

Human cytokine observations support relevance but do not prove NLRP3 specificity, NETosis, or therapeutic response.

Platelet Dense-Granule Maturation Defect

Platelets can contain fewer dense bodies, giant granules and impaired dense-body release.

Downstream

Impaired Platelet Activation Defective granule release reduces activation by collagen or low-dose thrombin, while ADP responses can be preserved.

Show evidence (1 reference)

PMID:15163665 SUPPORT In Vitro

"The electron microscopy of Tangier platelets revealed reduced numbers of dense bodies and the presence of giant granules typically encountered in platelets from Chediak-Higashi syndrome."

Patient platelet ultrastructure identifies a dense-granule maturation abnormality; the detailed lipid-to-organelle mechanism is unresolved.

Impaired Platelet Activation

Reduced granule-dependent amplification can impair platelet activation separately from thrombocytopenia.

Downstream

Bleeding tendency Platelet dysfunction may contribute to bleeding in some patients; the splenic hematoma case does not isolate platelet dysfunction from structural/splenic factors.

Show evidence (1 reference)

PMID:15163665 SUPPORT In Vitro

"The impaired release of the content of dense bodies may explain the defective activation of Tangier platelets by collagen and low concentrations of thrombin, but not by ADP."

Patient platelet assays support agonist-selective secretion/activation defects; ADP responsiveness is preserved.

Impaired Glucose-Stimulated Insulin Secretion

Impaired insulin release after glucose challenge was measured in a small Tangier cohort.

Downstream

Impaired glucose tolerance Insufficient insulin response accompanies abnormal glucose tolerance in the reported four-patient series.

Show evidence (1 reference)

PMID:19556721 SUPPORT Human Clinical

"The calculated insulinogenic index was significantly lower in TD patients than in non-diabetic controls (0.055+/-0.034 vs 0.775+/-0.538, mean+/-SD, p<0.05, respectively)."

Four Japanese patients underwent OGTT; impaired insulin response is supported, but universal diabetes or prevalence cannot be inferred.

Abnormal PMP22 Processing

Abca1-null mouse nerves overproduce PMP22 and process it abnormally. This is an experimentally supported mechanistic lead, with its contribution to human nerve dysfunction unresolved.

Schwann cell CL:0002573

Animal models

Abca1-null peripheral nerve model Mouse partially recapitulates

Show evidence (1 reference)

PMID:31061090 SUPPORT Model Organism

"In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant."

Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.

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Pathograph

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Phenotypes

28

Blood 5

Thrombocytopenia OCCASIONAL HP:0001873

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0001873 | Thrombocytopenia | Occasional (29-5%)"

Orphanet records thrombocytopenia as occasional.

Anemia OCCASIONAL HP:0001903

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0001903 | Anemia | Occasional (29-5%)"

Orphanet records anemia as occasional.

Bleeding tendency Abnormal bleeding HP:0001892

Show evidence (1 reference)

PMID:19723515 SUPPORT Human Clinical

"a case of Tangier disease in association with an unrecognised bleeding tendency"

A single spontaneous splenic hematoma case supports a bleeding complication without estimating population penetrance.

Reticulocytosis HP:0001923

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"mild thrombocytopenia, reticulocytosis, stomatocytosis, or hemolytic anemia."

GeneReviews describes the mild hematologic spectrum.

Hemolytic anemia HP:0001878

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"mild thrombocytopenia, reticulocytosis, stomatocytosis, or hemolytic anemia."

GeneReviews describes the mild hematologic spectrum.

Cardiovascular 3

Hepatosplenomegaly FREQUENT HP:0001433

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0001433 | Hepatosplenomegaly | Frequent (79-30%)"

Orphanet records hepatosplenomegaly as frequent.

Coronary artery stenosis FREQUENT HP:0005145

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0005145 | Coronary artery stenosis | Frequent (79-30%)"

Orphanet records coronary artery stenosis as frequent.

Left ventricular hypertrophy OCCASIONAL HP:0001712

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0001712 | Left ventricular hypertrophy | Occasional (29-5%)"

Orphanet records left ventricular hypertrophy as occasional.

Eye 1

Corneal opacity OCCASIONAL HP:0007957

Usually mild and not vision-limiting; rare severe presentations require separate clinical assessment.

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0007957 | Corneal opacity | Occasional (29-5%)"

Orphanet records corneal opacity as occasional.

Integument 2

Dry skin FREQUENT HP:0000958

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0000958 | Dry skin | Frequent (79-30%)"

Orphanet records dry skin as frequent.

Nail dystrophy FREQUENT HP:0008404

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0008404 | Nail dystrophy | Frequent (79-30%)"

Orphanet records nail dystrophy as frequent.

Metabolism 3

Decreased HDL cholesterol concentration HP:0003233

Show evidence (2 references)

PMID:22913675 SUPPORT Human Clinical

"plasma HDL concentrations less than 5 mg/dL"

The review describes the severe HDL-C depletion characteristic of Tangier disease.

PMID:33994407 SUPPORT Human Clinical

"Plasma HDL-C is mostly low, at 5 mg/dL or less"

The management review provides a concrete HDL-C diagnostic range.

Hypertriglyceridemia VERY_FREQUENT HP:0002155

Show evidence (2 references)

ORPHA:31150 SUPPORT Other

"HP:0002155 | Hypertriglyceridemia | Very frequent (99-80%)"

Orphanet records hypertriglyceridemia as very frequent.

PMID:22913675 SUPPORT Human Clinical

"normal or high plasma triglycerides"

This review supports the triglyceride abnormality.

Impaired glucose tolerance Glucose intolerance HP:0001952

Show evidence (1 reference)

PMID:19556721 SUPPORT Human Clinical

"The calculated insulinogenic index was significantly lower in TD patients than in non-diabetic controls (0.055+/-0.034 vs 0.775+/-0.538, mean+/-SD, p<0.05, respectively)."

Four Japanese patients underwent OGTT; impaired insulin response is supported, but universal diabetes or prevalence cannot be inferred.

Musculoskeletal 1

Distal muscle weakness FREQUENT HP:0002460

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0002460 | Distal muscle weakness | Frequent (79-30%)"

Orphanet records distal muscle weakness as frequent.

Constitutional 1

Abdominal pain FREQUENT HP:0002027

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0002027 | Abdominal pain | Frequent (79-30%)"

Orphanet records abdominal pain as frequent.

Other 12

Hypocholesterolemia VERY_FREQUENT HP:0003146

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0003146 | Hypocholesterolemia | Very frequent (99-80%)"

Orphanet records hypocholesterolemia as very frequent.

Orange discolored tonsils FREQUENT HP:0030814

Show evidence (2 references)

ORPHA:31150 SUPPORT Other

"HP:0030814 | Orange discoloured tonsils | Frequent (79-30%)"

Orphanet records orange discolored tonsils as frequent.

PMID:7130397 SUPPORT Human Clinical

"Tangier disease is a rare familial disorder characterized by enlarged orange tonsils, transient peripheral neuropathy, hepatosplenomegaly, and lymphadenopathy"

Classic human study supports orange enlarged tonsils as a hallmark finding.

Chronic noninfectious lymphadenopathy FREQUENT HP:0002730

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0002730 | Chronic noninfectious lymphadenopathy | Frequent (79-30%)"

Orphanet records chronic noninfectious lymphadenopathy as frequent.

Peripheral axonal neuropathy FREQUENT HP:0003477

Show evidence (2 references)

ORPHA:31150 SUPPORT Other

"HP:0003477 | Peripheral axonal neuropathy | Frequent (79-30%)"

Orphanet records peripheral axonal neuropathy as frequent.

PMID:33994407 SUPPORT Human Clinical

"Various peripheral neuropathies, ranging from mild to severe, have been reported."

Clinical review supports peripheral neuropathy as part of Tangier disease.

Progressive peripheral neuropathy FREQUENT HP:0007133

Neuropathy may instead be relapsing-remitting; progression is not universal.

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0007133 | Progressive peripheral neuropathy | Frequent (79-30%)"

Orphanet records progressive peripheral neuropathy as frequent.

Facial diplegia OCCASIONAL HP:0001349

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0001349 | Facial diplegia | Occasional (29-5%)"

Orphanet records facial diplegia as occasional.

Impaired temperature sensation OCCASIONAL HP:0010829

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0010829 | Impaired temperature sensition | Occasional (29-5%)"

Orphanet records impaired temperature sensation as occasional; the ORPHA row contains a spelling variant.

Syringomyelia-like neuropathy

Show evidence (1 reference)

PMID:29582519 SUPPORT Human Clinical

"Our literature review and our case showed the clinical spectrum of TD neuropathy is quite wide and that it should be considered in the differential diagnosis of non-uniform demyelinating neuropathies."

A selected literature series of 54 neuropathy cases supports heterogeneous nerve involvement, not a population prevalence estimate.

Ectropion FREQUENT HP:0000656

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0000656 | Ectropion | Frequent (79-30%)"

Orphanet records ectropion as frequent.

Accelerated atherosclerosis FREQUENT HP:0004943

Clinical penetrance is variable. GeneReviews describes most recognized coronary disease in the 50s–60s and usually after age 40; isolated earlier cases exist.

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0004943 | Accelerated atherosclerosis | Frequent (79-30%)"

Orphanet records accelerated atherosclerosis as frequent.

Carotid artery stenosis OCCASIONAL HP:0100546

Show evidence (1 reference)

ORPHA:31150 SUPPORT Other

"HP:0100546 | Carotid artery stenosis | Occasional (29-5%)"

Orphanet records carotid artery stenosis as occasional.

Stomatocytosis HP:0004446

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"mild thrombocytopenia, reticulocytosis, stomatocytosis, or hemolytic anemia."

GeneReviews describes the mild hematologic spectrum.

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Genetic Associations

1

Biallelic ABCA1 Pathogenic Variants (Causative)

Gene: ABCA1 hgnc:29

Autosomal recessive

Show evidence (3 references)

ORPHA:31150 SUPPORT Other

"ABCA1 | ATP binding cassette subfamily A member 1 | hgnc:29 | Disease-causing germline mutation(s) in"

Orphanet records ABCA1 as a disease-causing germline gene.

PMID:31751110 SUPPORT Human Clinical

"pathogenic variants in ABCA1 identified by molecular genetic testing."

GeneReviews identifies ABCA1 molecular testing as diagnostic.

PMID:31751110 SUPPORT Human Clinical

"The clinical expression of Tangier disease is variable, with some affected individuals only showing biochemical perturbations."

GeneReviews supports variable clinical expression despite the biochemical defect.

Variants (1)

Biallelic ABCA1 pathogenic variants

Affected individuals typically have homozygous or compound heterozygous ABCA1 pathogenic variants. Reported pathogenic alleles include deletions, insertion-deletions, and missense variants that reduce ABCA1 lipid-efflux function. A functional assay can clarify selected missense variants, but functional impairment does not alone define clinical penetrance.

Show evidence (3 references)

PMID:31751110 SUPPORT Human Clinical

"pathogenic variants in ABCA1 identified by molecular genetic testing."

GeneReviews defines diagnosis by biallelic pathogenic variants in ABCA1.

PMID:10431237 SUPPORT Human Clinical

"We have analysed five kindreds with TD and identified seven different mutations, including three that are expected to impair the function of the gene product."

Human kindred study documents multiple ABCA1 pathogenic variants.

PMID:10431238 SUPPORT Human Clinical

"In the first pedigree, a 1-bp deletion in exon 13, resulting in truncation of the predicted protein to approximately one-fourth of its normal size, co-segregated with the disease phenotype."

Human kindred study reports a truncating ABCA1 deletion allele.

💊

Medical Actions

8

Statin-Based Cardiovascular Risk Management

Action: Pharmacotherapy NCIT:C15986

Agent: statin CHEBI:87631

There is no curative Tangier-specific therapy. Management emphasizes prevention of atherosclerosis and optimization of non-HDL cardiovascular risk factors; if LDL-C is not already low, reviews recommend statin therapy or other LDL-lowering approaches.

Mechanism Target:

MODULATES Macrophage Foam Cell Atherogenesis — Statin therapy is used to reduce modifiable LDL-C and non-HDL cardiovascular risk when present.

Show evidence (1 reference)

PMID:33994407 SUPPORT Human Clinical

"Plasma LDL-C levels are generally low in patients with Tangier disease but if this is not the case, they should be reduced through administration of statins or other means."

The management review recommends LDL-lowering therapy with statins when LDL-C is not low.

Show evidence (2 references)

PMID:33994407 SUPPORT Human Clinical

"No specific curative treatment is currently available, so early identification of patients and preventing atherosclerosis development are crucial."

This supports framing statins as risk management rather than curative disease therapy.

PMID:27565770 SUPPORT Human Clinical

"Optimizing the LDL-C levels in Tangier patients with normal LDL-C levels using statin therapy is clearly warranted in our view."

HDL-deficiency treatment review recommends statin-based LDL-C optimization in at-risk Tangier patients.

Low-Fat Diet and Lipid Risk Reduction

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

Platform: Behavioral / lifestyle

Low-fat diet is recommended as part of cardiovascular risk-factor mitigation, alongside lipid-profile optimization and surveillance for atherosclerotic disease.

Mechanism Target:

MODULATES Macrophage Foam Cell Atherogenesis — Diet is used to mitigate modifiable cardiovascular risk rather than restore ABCA1 function.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"using statin therapy and a low-fat diet."

GeneReviews lists low-fat diet with statin therapy as risk mitigation.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"cardiovascular risk factors, including improvement of plasma lipid profiles"

GeneReviews supports risk-factor mitigation as prevention of primary manifestations.

Peripheral Neuropathy Rehabilitation

Action: physical therapy Ontology label: Physical Therapy NCIT:C15302

Platform: Behavioral / lifestyle

Supportive management for peripheral neuropathy includes bracing and exercise when weakness or gait impairment is present.

Mechanism Target:

MODULATES Peripheral axonal neuropathy — Bracing and exercise target functional impairment from neuropathy.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"transient bracing (such as ankle-foot orthosis) and exercise for those with peripheral neuropathy"

GeneReviews recommends exercise for neuropathy manifestations.

MODULATES Distal muscle weakness — Orthotic support can mitigate motor weakness from peripheral neuropathy.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"transient bracing (such as ankle-foot orthosis)"

GeneReviews lists bracing for peripheral neuropathy-related weakness.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"transient bracing (such as ankle-foot orthosis) and exercise for those with peripheral neuropathy"

GeneReviews supports supportive rehabilitation for neuropathy.

Tonsillectomy for Obstructive Tonsillar Disease

Action: surgical procedure Ontology label: Surgical Procedure NCIT:C15329

Platform: Surgery

Tonsillectomy is used when enlarged orange tonsils cause airway obstruction or mass symptoms; it is symptomatic management and does not address the ABCA1 lipid-efflux defect.

Mechanism Target:

MODULATES Orange discolored tonsils — Surgery addresses obstructive or mass-effect symptoms from enlarged tonsils.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"Tonsillectomy in those with airway obstruction or mass symptoms"

GeneReviews recommends tonsillectomy when airway obstruction or mass symptoms are present.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"Tonsillectomy in those with airway obstruction or mass symptoms"

GeneReviews supports tonsillectomy as treatment of tonsillar manifestations.

Corneal Transplantation for Vision-Limiting Corneal Opacity

Action: corneal transplantation Ontology label: Corneal Transplantation NCIT:C210959

Corneal transplantation is used for corneal opacities that interfere with daily living; it is symptomatic management of ocular lipid-storage complications rather than restoration of ABCA1 function.

Mechanism Target:

MODULATES Corneal opacity — Corneal transplantation addresses vision-limiting corneal opacity.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"corneal transplantation for corneal opacities that interfere with daily living"

GeneReviews recommends corneal transplantation when corneal opacities interfere with daily living.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"corneal transplantation for corneal opacities that interfere with daily living"

GeneReviews supports corneal transplantation as treatment for vision-limiting corneal opacity in Tangier disease.

Genetic Counseling and Family Screening

Action: genetic counseling Ontology label: Genetic Counseling NCIT:C15240

Genetic counseling, lipid-profile screening, apoA-I testing, and targeted familial variant testing can identify at-risk relatives and support reproductive counseling.

Show evidence (2 references)

PMID:31751110 SUPPORT Human Clinical

"Carrier testing for at-risk relatives and prenatal testing"

GeneReviews supports genetic counseling and familial testing when variants are known.

PMID:39817629 SUPPORT Human Clinical

"Family screening should be recommended to patients with consanguineous marriages after diagnosis of TD."

Pediatric cohort review recommends family screening after diagnosis.

Surveillance and complication prevention

Assess hepatosplenomegaly at visits, obtain annual neurologic/ophthalmologic evaluation and adult cardiovascular assessment, and check blood counts as indicated. Avoid contact sports with hepatosplenomegaly and medications that worsen peripheral neuropathy.

Show evidence (2 references)

PMID:31751110 SUPPORT Human Clinical

"neurology and ophthalmology evaluations annually; cardiovascular risk assessment of atherosclerotic plaque burden annually beginning in adulthood; complete blood count with differential as clinically indicated."

GeneReviews supplies multisystem surveillance.

PMID:31751110 SUPPORT Human Clinical

"medications that are toxic or potentially toxic to those who are predisposed to the development of peripheral neuropathy; contact sports in those with hepatosplenomegaly."

GeneReviews identifies condition-specific precautions.

Miglustat investigation

Action: Pharmacotherapy NCIT:C15986

Agent: miglustat CHEBI:50381

Platform: Small molecule

A 2014 withdrawal/rechallenge case and the MUSTANG nonrandomized n-of-1 ABAB study suggest possible neuropathy benefit. MUSTANG did not meet prespecified clinical-difference thresholds during the crossover phase; 21-month continuation improvement and blood-cell biomarker changes remain uncontrolled. The disease-specific therapeutic mechanism and general efficacy are unresolved.

Show evidence (2 references)

PMID:41212481 SUPPORT Human Clinical

"None of the co-primary endpoint differences reached our pre-determined level of clinical difference."

MUSTANG found small clinical signals and later extension improvement, but failed prespecified clinical-difference thresholds; one unblinded nonrandomized ABAB patient cannot establish general efficacy.

PMID:25227739 SUPPORT Human Clinical

"The mechanisms by which miglustat ameliorates at least some clinical manifestations of TD needs to be further investigated."

The initial case generated a treatment hypothesis without establishing mechanism or population efficacy.

🔬

Biochemical Markers

5

Low HDL cholesterol (DECREASED)

Context: Plasma HDL-C is absent or extremely low and is a core diagnostic readout of failed ABCA1-dependent HDL biogenesis.

Pathograph Readouts

Readout Of Impaired HDL Biogenesis Negative Diagnostic

Lower HDL-C reports impaired ABCA1-dependent HDL particle generation.

Show evidence (1 reference)

PMID:33994407 SUPPORT Human Clinical

"Plasma HDL-C is mostly low, at 5 mg/dL or less"

The management review supports HDL-C as a diagnostic readout of Tangier disease.

Show evidence (1 reference)

PMID:33994407 SUPPORT Human Clinical

"Plasma HDL-C is mostly low, at 5 mg/dL or less"

The review provides the typical severe HDL-C depletion range in Tangier disease.

Low apolipoprotein A-I (DECREASED)

Context: ApoA-I is absent or extremely low because ABCA1-dependent lipidation and HDL particle formation fail.

Pathograph Readouts

Readout Of Impaired HDL Biogenesis Negative Diagnostic

Lower apoA-I reports failed HDL particle generation and rapid loss of apoA-I-containing HDL.

Show evidence (1 reference)

PMID:31751110 SUPPORT Human Clinical

"with absent or extremely low HDL-cholesterol and apo A-I levels and biallelic"

GeneReviews supports apoA-I depletion as a diagnostic readout in Tangier disease.

Show evidence (1 reference)

PMID:33994407 SUPPORT Human Clinical

"apoA-I concentration is 10 mg/dL or less"

The management review reports markedly low apoA-I concentrations in Tangier disease.

Low total cholesterol (DECREASED)

Context: Total plasma cholesterol is low, largely reflecting the profound HDL-C deficit and altered lipoprotein cholesterol distribution.

Pathograph Readouts

Correlates With Impaired HDL Biogenesis Negative Diagnostic

Low total cholesterol accompanies the severe HDL-C deficit in Tangier disease.

Show evidence (1 reference)

PMID:22913675 SUPPORT Human Clinical

"low total plasma cholesterol (below 150 mg/dL)"

The epidemiology review supports low total cholesterol as part of the diagnostic biochemical profile.

Show evidence (1 reference)

PMID:22913675 SUPPORT Human Clinical

"low total plasma cholesterol (below 150 mg/dL)"

The review supports low total plasma cholesterol in Tangier disease.

Elevated plasma triglycerides (INCREASED)

Context: Plasma triglycerides may be normal to high or elevated in the Tangier lipoprotein profile.

Pathograph Readouts

Correlates With Impaired HDL Biogenesis Positive Diagnostic

Higher triglycerides are part of the altered lipoprotein profile accompanying severe HDL biogenesis failure.

Show evidence (1 reference)

PMID:22913675 SUPPORT Human Clinical

"normal or high plasma triglycerides"

The review supports normal-to-high triglycerides in the Tangier biochemical profile.

Show evidence (1 reference)

PMID:22913675 SUPPORT Human Clinical

"normal or high plasma triglycerides"

The review supports triglyceride elevation or high-normal triglycerides in Tangier disease.

Plasma sphingolipids (DECREASED)

Context: One-patient finding. Parallel hepatic knockout experiments demonstrated reduced apoM/S1P, but the human S1P-specific clinical mechanism remains unresolved.

Pathograph Readouts

Correlates With Impaired HDL Biogenesis

Reduced HDL-associated lipid carriage is a candidate explanation; no validated clinical surrogate is implied.

Show evidence (1 reference)

PMID:37601634 SUPPORT Human Clinical

"we report a drastic reduction of total SL levels in plasma of a Tangier patient with compound heterozygosity for mutations in ABCA1."

One-patient plasma lipidomics supports sphingolipid depletion; S1P-specific reduction in this paper was shown in hepatic knockout mice.

Show evidence (1 reference)

PMID:37601634 SUPPORT Human Clinical

"we report a drastic reduction of total SL levels in plasma of a Tangier patient with compound heterozygosity for mutations in ABCA1."

One-patient plasma lipidomics supports sphingolipid depletion; S1P-specific reduction in this paper was shown in hepatic knockout mice.

🔬

Diagnosis

1

HDL-C, ApoA-I, and ABCA1 Genetic Testing

Absent or extremely low HDL-C and apoA-I prompt evaluation for Tangier disease. Exclude alternative genetic and acquired causes, then confirm biallelic pathogenic ABCA1 variants; variants of uncertain significance alone do not establish molecular diagnosis. Japanese clinical criteria use broader screening thresholds than the typical HDL-C below 5 mg/dL phenotype.

molecular genetic testing NCIT:C19770

Show evidence (4 references)

PMID:31751110 SUPPORT Human Clinical

"with absent or extremely low HDL-cholesterol and apo A-I levels and biallelic"

GeneReviews states the core biochemical and genetic diagnostic criteria.

PMID:33994407 SUPPORT Human Clinical

"Plasma (serum) HDL-cholesterol less than 25 mg/dL"

The Japanese diagnostic criteria include very low HDL-C.

PMID:33994407 SUPPORT Human Clinical

"The diagnosis can be definite if pathogenic mutations in the ABCA1 gene are identified."

The diagnostic criteria require ABCA1 mutation confirmation for definite diagnosis.

+ 1 more reference

📈

Progression

1

Onset

Age: Neonatal to adult

Orphanet lists neonatal, infancy, childhood, adolescent, and adult onset, reflecting broad ascertainment from childhood tonsillar findings through adult neuropathy or cardiovascular presentations.

Show evidence (4 references)

ORPHA:31150 SUPPORT Other

"Age of onset: Neonatal"

Orphanet includes neonatal onset among natural-history categories.

ORPHA:31150 SUPPORT Other

"Age of onset: Adult"

Orphanet includes adult onset among natural-history categories.

PMID:22913675 SUPPORT Human Clinical

"Nearly all the children affected by Tangier disease were identified on the basis of large, yellow-orange tonsils, while half of the adult patients affected by Tangier disease came to medical attention because of symptoms of neuropathy."

Children are frequently identified through orange tonsils.

+ 1 more reference

📊

Prevalence

1

Worldwide

Point Prevalence ≤0.1 per 100,000 <1 in 1,000,000

Orphanet records a worldwide point-prevalence estimate below 1 per 1,000,000; published reviews describe roughly 100 to 150 reported cases.

Show evidence (2 references)

ORPHA:31150 SUPPORT Other

"<1 / 1 000 000 | Worldwide | Point prevalence | PMID:22913675"

Orphanet provides the worldwide point-prevalence estimate.

PMID:33994407 SUPPORT Human Clinical

"35 cases have been reported in Japan and 109 cases"

This review supports the ultra-rare reported-case count.

🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Tangier_Disease:

LCAT deficiency and fish-eye disease

Overlapping Features Inherited severe HDL deficiency with prominent corneal disease; complete LCAT deficiency can include renal disease.

Distinguishing Features

ABCA1 testing, the orange-tonsil/neuropathy pattern and assessment of LCAT deficiency help distinguish these conditions.

Show evidence (1 reference)

PMID:33994407 SUPPORT Human Clinical

"LCAT deficiency, apoA-I deficiency and secondary hypo-HDL-cholesterolemia"

The diagnostic criteria require exclusion of alternative causes of severe HDL deficiency.

Apolipoprotein A-I deficiency

Overlapping Features APOA1-related severe HDL/apoA-I deficiency is an alternative inherited cause of low HDL.

Distinguishing Features

Evaluate APOA1 and the clinical pattern rather than diagnosing Tangier disease from HDL concentration alone.

Show evidence (1 reference)

PMID:33994407 SUPPORT Human Clinical

"LCAT deficiency, apoA-I deficiency and secondary hypo-HDL-cholesterolemia"

The diagnostic criteria require exclusion of alternative causes of severe HDL deficiency.

Secondary severe HDL deficiency

Overlapping Features Severe liver disease and drug effects can produce marked HDL reduction.

Distinguishing Features

Review liver disease and medication history before attributing low HDL to ABCA1 deficiency.

Show evidence (1 reference)

PMID:33994407 SUPPORT Human Clinical

"Care should be taken to exclude secondary hypo-HDL-cholesterolemia, such as in severe liver diseases, especially liver cirrhosis, and drug-induced hypo-HDL-cholesterolemia"

The management review describes acquired biochemical phenocopies.

🔬

Clinical Trials

2

ISRCTN17945917 NOT_APPLICABLE COMPLETED

MUSTANG: a nonrandomized, n-of-1 ABAB on/off miglustat study over two years, followed by 21 months of compassionate treatment. Registered with ISRCTN; the publication incorrectly calls the ISRCTN identifier a ClinicalTrials.gov identifier.

Show evidence (3 references)

ICTRP:ISRCTN17945917 SUPPORT Other

"This is a n-of-1 trial of ABAB design."

WHO ICTRP/ISRCTN confirms the trial registration and single-case design.

PMID:41212481 SUPPORT Human Clinical

"None of the co-primary endpoint differences reached our pre-determined level of clinical difference."

MUSTANG found small clinical signals and later extension improvement, but failed prespecified clinical-difference thresholds; one unblinded nonrandomized ABAB patient cannot establish general efficacy.

PMID:41212481 SUPPORT Human Clinical

"An n-of-1 ABAB study, alternating on and off treatment for 6-month periods, total study duration of 2 years with an additional compassionate-access period of 21 months."

The primary publication describes the completed experiment; registration was also checked at ISRCTN17945917.

NCT01782027 NOT_APPLICABLE TERMINATED

Mendelian reverse-cholesterol-transport tracer-method study including Tangier disease and other monogenic HDL disorders; terminated for lack of funding, with 17 total participants. This was not a therapeutic efficacy trial. Registry checked 2026-09-04.

Show evidence (1 reference)

clinicaltrials:NCT01782027 SUPPORT Other

"The purpose of this study is to investigate the use of radiolabeled particulate cholesterol administered intravenously in association with albumin, as a method to study reverse cholesterol transport (RCT) in people carrying mutations in genes known to affect high density lipoprotein (HDL) metabolism"

Registry summary establishes a tracer-method intervention rather than a Tangier-specific treatment.

🧫

Experimental Models

1

ABCA1 intracellular-domain variant expression screen CELL_LINE

Cell-based cholesterol-efflux and surface-localization assays for 74 ABCA1 variants.

Pathograph links

Impaired Cellular Lipid Efflux partially recapitulates fidelity: moderate

Limitations: Tests intracellular-domain variants in an expression system; clinical penetrance and tissue phenotypes require separate evidence.

Show evidence (1 reference)

PMID:40617357 SUPPORT In Vitro

"we have characterized 74 variants affecting the intracellular domains of ABCA1 by assessing cholesterol efflux activity and cell surface localization of the protein"

The expression assay quantifies allele-specific efflux/localization, not organ-level clinical severity.

🐁

Animal Models

2

Myeloid Abca1/Abcg1-deficient bone marrow in Ldlr-null recipients

Hyperlipidemic bone-marrow transplantation model used for Nlrp3/Caspase-1/11 perturbation.

Species

Mouse

Genotype

Myeloid Abca1/Abcg1 deficiency with Ldlr-null recipients

Publication

PMID:29588315

Pathograph links

Myeloid Inflammasome Activation partially recapitulates fidelity: moderate

Limitations: Combined Abca1/Abcg1 deficiency, Ldlr-null background and Western diet do not reproduce isolated human ABCA1 deficiency.

Show evidence (1 reference)

PMID:36537208 SUPPORT Model Organism

"Macrophage, but not neutrophil Abca1/g1 deficiency activated inflammasomes in macrophages and neutrophils, reflected by caspase-1 cleavage, and induced NETosis in plaques."

Conditional deletions identify macrophage-driven crosstalk in a combined-transporter Ldlr-null mouse system.

Abca1-null peripheral nerve model

Peripheral nerve protein processing studied alongside reciprocal Pmp22-null Schwann-cell experiments.

Species

Mouse

Genotype

Abca1 knockout

Publication

PMID:31061090

Pathograph links

Abnormal PMP22 Processing partially recapitulates fidelity: moderate

Limitations: Mouse nerve protein/trafficking phenotype; not evidence that all human variants disrupt the same interaction or have the same neuropathy course.

Show evidence (1 reference)

PMID:31061090 SUPPORT Model Organism

"In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant."

Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.

{ }

Source YAML

click to show

name: Tangier_Disease
creation_date: '2026-05-04T06:39:03Z'
category: Mendelian
description: >
  Tangier disease is an autosomal recessive ABCA1 deficiency disorder of HDL
  biogenesis and cellular cholesterol efflux. Biallelic ABCA1 pathogenic
  variants impair apolipoprotein-mediated cholesterol and phospholipid export,
  producing extremely low or absent HDL cholesterol and apoA-I, reduced
  cholesterol removal from peripheral cells, and cholesteryl ester accumulation
  in tissues. The clinical phenotype includes orange tonsils, hepatosplenomegaly,
  lymphadenopathy, peripheral neuropathy, ocular and skin/nail findings, and
  variable premature atherosclerotic cardiovascular disease.
disease_term:
  preferred_term: Tangier disease
  term:
    id: MONDO:0008783
    label: Tangier disease
synonyms:
- ATP-binding cassette transporter A1 deficiency
- Analphalipoproteinemia
- HDL lipoprotein deficiency disease
- High density lipoprotein deficiency, Tangier type
parents:
- Hypoalphalipoproteinemia
- Hypolipoproteinemia
- Neurometabolic Disorder
notes: >-
  ORPHA:31150 maps Tangier disease exactly to MONDO:0008783 and also lists
  MeSH:D013631, MedDRA:10051875, OMIM:205400, UMLS:C0039292, ICD-10:E78.6,
  and ICD-11:5C81.0.
inheritance:
- name: Autosomal Recessive
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Autosomal recessive"
    explanation: Orphanet records autosomal recessive inheritance for Tangier disease.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Tangier disease is an autosomal recessive disease"
    explanation: This clinical management review states the autosomal recessive inheritance pattern.
  - reference: PMID:31751110
    reference_title: Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Tangier disease is inherited in an autosomal recessive manner.
    explanation: >-
      Autosomal recessive segregation supports conditional Mendelian recurrence; the GeneReviews detailed genetic-counseling section gives the affected/carrier/noncarrier probabilities.
  description: >-
    When both parents carry a pathogenic ABCA1 allele, each pregnancy has a 25% affected, 50% carrier and 25% noncarrier probability. Carrier biochemical HDL reduction is distinguishable from the biallelic clinical disorder; recurrence changes if a parent is affected.
prevalence:
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: BELOW_1_IN_1000000
  rate_high: 0.1
  percentage: <1 per 1,000,000
  notes: >-
    Orphanet records a worldwide point-prevalence estimate below 1 per
    1,000,000; published reviews describe roughly 100 to 150 reported cases.
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "<1 / 1 000 000 | Worldwide | Point prevalence | PMID:22913675"
    explanation: Orphanet provides the worldwide point-prevalence estimate.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "35 cases have been reported in Japan and 109 cases"
    explanation: This review supports the ultra-rare reported-case count.
progression:
- phase: Onset
  age_range: Neonatal to adult
  notes: >-
    Orphanet lists neonatal, infancy, childhood, adolescent, and adult onset,
    reflecting broad ascertainment from childhood tonsillar findings through
    adult neuropathy or cardiovascular presentations.
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Neonatal"
    explanation: Orphanet includes neonatal onset among natural-history categories.
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Adult"
    explanation: Orphanet includes adult onset among natural-history categories.
  - reference: PMID:22913675
    reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nearly all the children affected by Tangier disease were identified on the basis of large, yellow-orange tonsils, while half of the adult patients affected by Tangier disease came to medical attention because of symptoms of neuropathy."
    explanation: Children are frequently identified through orange tonsils.
  - reference: PMID:22913675
    reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nearly all the children affected by Tangier disease were identified on the basis of large, yellow-orange tonsils, while half of the adult patients affected by Tangier disease came to medical attention because of symptoms of neuropathy."
    explanation: Adult presentations often involve neuropathic symptoms.
mechanistic_hypotheses:
- hypothesis_group_id: canonical_abca1_hdl_efflux_model
  hypothesis_label: Canonical ABCA1 HDL Efflux Model
  status: CANONICAL
  description: >
    Biallelic ABCA1 pathogenic variants impair apolipoprotein-mediated
    phospholipid and cholesterol efflux, blocking nascent HDL formation.
    Cellular cholesterol export falls in macrophages, Schwann cells, and other
    peripheral cells, leading to cholesteryl ester storage in tissues and a
    combination of reticuloendothelial, neurologic, biochemical, and vascular
    manifestations.
  notes: >-
    Retain CANONICAL for ABCA1 loss and impaired lipid efflux. The OpenScientist report is assessed in assessments/openscientist-assessment-by-codex.yaml beside the report. Human inflammasome-associated cytokines, experimental membrane signaling, sphingolipid depletion, platelet defects, and impaired insulin secretion extend the model with different evidence strengths. NLRP3/NETosis causality primarily comes from combined Abca1/Abcg1-deficient mice; plasma S1P loss was demonstrated in hepatic knockout mice, while one Tangier patient had low total sphingolipids. Neither establishes the quantitative clinical contribution. PMP22 interaction and HSPC expansion require disease/context qualifications. The report missed an existing miglustat n-of-1 trial and GenCC assertions.
  evidence:
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is caused by a dysfunctional mutation of the ATP-binding cassette transporter A1 (ABCA1) gene, the mandatory gene for generation of HDL particles from cellular cholesterol and phospholipids, and it appears in an autosomal recessive hereditary profile."
    explanation: This review links ABCA1 to HDL particle generation from cellular lipid export.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Cholesterol therefore accumulates in these cells, causing orange-colored pharyngeal tonsillar swelling, corneal opacity, hepatosplenomegaly, lymphadenopathy and peripheral neuropathy."
    explanation: This review summarizes the downstream tissue-storage phenotype.
  - reference: PMID:28602350
    reference_title: "Structure of the Human Lipid Exporter ABCA1."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Mutations of human ABCA1 are associated with Tangier disease and familial HDL deficiency."
    explanation: >
      Cryo-EM structural biology directly connects ABCA1 to Tangier disease
      and provides an atomic-resolution framework for interpreting the
      diverse mutations that cause loss of cholesterol/phospholipid efflux.
  - reference: PMID:40617357
    reference_title: "Functional characterization of genetic variants affecting the intracellular domains of ATP-binding cassette transporter A1 (ABCA1)."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we have characterized 74 variants affecting the intracellular domains of ABCA1 by assessing cholesterol efflux activity"
    explanation: >
      Large-scale in vitro variant characterization shows that cholesterol
      efflux activity stratifies ABCA1 variants by pathogenicity, providing
      functional support for efflux failure as the canonical mechanism.
  - reference: PMID:20418488
    reference_title: "A functional ABCA1 gene variant is associated with low HDL-cholesterol levels and shows evidence of positive selection in Native Americans."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Cells expressing the C230 allele showed a 27% cholesterol efflux reduction (P< 0.001)"
    explanation: >-
      Common R230C variation supports an efflux/HDL relationship in populations; it is not proof that this allele causes recessive Tangier disease.
  - reference: PMID:12771001
    reference_title: "Restoration of endothelial function by increasing high-density lipoprotein in subjects with isolated low high-density lipoprotein."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Infusion of apoA-I/PC disks increased plasma HDL to 1.3+/-0.4 mmol/L in ABCA1 heterozygotes, which resulted in"
    explanation: >-
      Acute infusion improved endothelial responses in nine ABCA1 heterozygotes. This is physiological evidence in carriers, not demonstrated treatment efficacy for biallelic Tangier disease or long-term clinical events.
  - reference: PMID:29588315
    reference_title: "Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with Tangier disease, who have increased myeloid cholesterol content, showed markers of inflammasome activation"
    explanation: >-
      Tangier plasma IL-1β and IL-18 elevations support inflammasome relevance. NLRP3-specific perturbation and plaque NETosis evidence came from combined myeloid Abca1/Abcg1-deficient mice, not a human intervention.
  - reference: PMID:37601634
    reference_title: "Hepatocyte ABCA1 deficiency is associated with reduced HDL sphingolipids."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "drastic reduction of total SL levels in plasma of a Tangier patient with compound heterozygosity for mutations in ABCA1"
    explanation: >-
      One Tangier patient had reduced total plasma sphingolipids. ApoM/S1P reduction was measured in hepatic Abca1 knockout mice; human S1P-specific depletion and clinical mediation are not established by this observation.
  - reference: PMID:38979632
    reference_title: "Roles for PMP22 in Schwann cell cholesterol homeostasis in health and disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "PMP22 and ABCA1 in cholesterol efflux"
    explanation: >-
      This review motivates a Schwann-cell mechanism. Primary mouse/Schwann-cell experiments demonstrate reciprocal PMP22/ABCA1 trafficking abnormalities; their contribution to human neuropathy remains unquantified.
  - reference: PMID:11950702
    reference_title: "Increased atherosclerosis in hyperlipidemic mice with inactivation of ABCA1 in macrophages."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "the selective inactivation of ABCA1 in macrophages markedly increased atherosclerosis and foam cell accumulation"
    explanation: >
      Qualifies the cardiovascular component of the canonical model by
      dissecting macrophage-specific from total-body ABCA1 loss; total ABCA1
      knockout did not accelerate atherosclerosis owing to concurrent LDL
      reduction, whereas macrophage-specific loss did.
  - reference: PMID:29582519
    reference_title: "Peripheral neuropathy in Tangier disease: A literature review and assessment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Syringomyelia-like neuropathy subtype (52.4%) was more frequent than multifocal sensorial and motor neuropathy subtype (26.2%)"
    explanation: >-
      A selected review of 54 patients with neuropathy supports four patterns; subtype percentages cannot be generalized to all Tangier patients.
- hypothesis_group_id: inflammatory_amplification
  hypothesis_label: Inflammasome and membrane signaling amplify the efflux defect
  status: EMERGING
  description: >-
    Macrophage free-cholesterol accumulation enhances inflammatory signaling. NLRP3/NETosis intervention evidence comes mainly from combined Abca1/Abcg1-deficient hyperlipidemic mice; Tangier patient plasma cytokines provide clinical relevance without proving the whole chain.
  evidence:
  - reference: PMID:29588315
    reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1β and IL-18 levels.
    explanation: >-
      Human cytokine observations support relevance but do not prove NLRP3 specificity, NETosis, or therapeutic response.
  - reference: PMID:29588315
    reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice.
    explanation: >-
      Genetic intervention supports an inflammasome contribution in a combined-transporter and hyperlipidemic mouse model.
- hypothesis_group_id: schwann_lipid_protein_homeostasis
  hypothesis_label: Schwann-cell lipid and PMP22 homeostasis
  status: EMERGING
  description: >-
    Reciprocal ABCA1/PMP22 interactions couple lipid trafficking to peripheral myelin protein processing. Mouse and Schwann-cell experiments support this extension, while human clinical severity and allele-specific mediation remain unresolved.
  evidence:
  - reference: PMID:31061090
    reference_title: PMP22 Regulates Cholesterol Trafficking and ABCA1-Mediated Cholesterol Efflux.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant.
    explanation: >-
      Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.
pathophysiology:
- name: ABCA1 Dysfunction
  description: >
    Disease-causing germline ABCA1 variants impair the ATP-binding cassette
    transporter required for apolipoprotein-mediated cellular lipid export.
    Human genetic studies identified ABCA1 mutations in Tangier disease kindreds,
    and cell-based studies show that ABCA1 promotes phospholipid and cholesterol
    efflux by loading apoA-I with lipids.
  gene:
    preferred_term: ABCA1
    term:
      id: hgnc:29
      label: ABCA1
  molecular_functions:
  - preferred_term: ATPase-coupled transmembrane transporter activity
    term:
      id: GO:0042626
      label: ATPase-coupled transmembrane transporter activity
  - preferred_term: apolipoprotein binding
    term:
      id: GO:0034185
      label: apolipoprotein binding
  biological_processes:
  - preferred_term: cholesterol efflux
    term:
      id: GO:0033344
      label: cholesterol efflux
    modifier: DECREASED
  - preferred_term: phospholipid efflux
    term:
      id: GO:0033700
      label: phospholipid efflux
    modifier: DECREASED
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "ABCA1 | ATP binding cassette subfamily A member 1 | hgnc:29 | Disease-causing germline mutation(s) in"
    explanation: Orphanet records ABCA1 as the disease-causing gene.
  - reference: PMID:10431236
    reference_title: "Mutations in ABC1 in Tangier disease and familial high-density lipoprotein deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ABC1 were detected in both TD and FHA, indicating that TD and FHA are allelic."
    explanation: Human genetic linkage and mutation detection support ABCA1 as the causal locus.
  - reference: PMID:10431238
    reference_title: "Tangier disease is caused by mutations in the gene encoding ATP-binding cassette transporter 1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "encoding a member of the ABC transporter superfamily, are the cause of TD."
    explanation: Independent human kindred study identifies ABCA1 defects as the cause of Tangier disease.
  - reference: PMID:11309399
    reference_title: "ATP-binding cassette transporter A1 (ABCA1) functions as a cholesterol efflux regulatory protein."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "cellular phospholipid and cholesterol efflux by loading free apoA-I with these"
    explanation: In vitro evidence supports ABCA1 as a transporter involved in apoA-I lipid loading.
  downstream:
  - target: Impaired Cellular Lipid Efflux
    description: >-
      Loss of functional ABCA1 reduces apolipoprotein-mediated lipid export.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:10525055
      reference_title: The Tangier disease gene product ABC1 controls the cellular apolipoprotein-mediated lipid removal pathway.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Blocking the expression or activity of ABC1 reduces apolipoprotein-mediated lipid efflux from cultured cells, and increasing expression of ABC1 enhances it.
      explanation: >-
        Bidirectional expression/activity perturbations establish the proximal cellular efflux defect.
  - target: Platelet Dense-Granule Maturation Defect
    description: >-
      ABCA1 deficiency perturbs platelet granule maturation; specific intervening membrane-trafficking steps remain unresolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:15163665
      reference_title: Impaired platelet activation in familial high density lipoprotein deficiency (Tangier disease).
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The electron microscopy of Tangier platelets revealed reduced numbers of dense bodies and the presence of giant granules typically encountered in platelets from Chediak-Higashi syndrome.
      explanation: >-
        Patient platelet ultrastructure identifies a dense-granule maturation abnormality; the detailed lipid-to-organelle mechanism is unresolved.
  - target: Impaired Glucose-Stimulated Insulin Secretion
    description: >-
      ABCA1 deficiency associates with impaired insulin release; beta-cell cholesterol handling is a candidate intermediary, not directly measured in the four-patient OGTT study.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:19556721
      reference_title: Impaired insulin secretion in four Tangier disease patients with ABCA1 mutations.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The calculated insulinogenic index was significantly lower in TD patients than in non-diabetic controls (0.055+/-0.034 vs 0.775+/-0.538, mean+/-SD, p<0.05, respectively).
      explanation: >-
        Four Japanese patients underwent OGTT; impaired insulin response is supported, but universal diabetes or prevalence cannot be inferred.
  - target: Abnormal PMP22 Processing
    description: >-
      Abca1 deletion in mice changes PMP22 abundance and maturation in peripheral nerves.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:31061090
      reference_title: PMP22 Regulates Cholesterol Trafficking and ABCA1-Mediated Cholesterol Efflux.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant.
      explanation: >-
        Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.
    hypothesis_groups:
    - schwann_lipid_protein_homeostasis
- name: Impaired Cellular Lipid Efflux
  description: >-
    Reduced export of cellular cholesterol and phospholipid to apolipoproteins creates parallel defects in HDL formation and local cholesterol homeostasis.
  evidence:
  - reference: PMID:10525055
    reference_title: The Tangier disease gene product ABC1 controls the cellular apolipoprotein-mediated lipid removal pathway.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: Blocking the expression or activity of ABC1 reduces apolipoprotein-mediated lipid efflux from cultured cells, and increasing expression of ABC1 enhances it.
    explanation: >-
      Bidirectional expression/activity perturbations establish the proximal cellular efflux defect.
  - reference: PMID:33994407
    reference_title: Current Diagnosis and Management of Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: cellular cholesterol export is impaired due to ABCA1 deficiency in peripheral cells, including macrophages and Schwann cells.
    explanation: >-
      The clinical synthesis distinguishes cell-autonomous export failure from low circulating HDL alone.
  biological_processes:
  - preferred_term: cholesterol efflux
    term:
      id: GO:0033344
      label: cholesterol efflux
    modifier: DECREASED
  downstream:
  - target: Impaired HDL Biogenesis
    description: >-
      Impaired apoA-I lipidation limits nascent HDL formation.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:10525055
      reference_title: The Tangier disease gene product ABC1 controls the cellular apolipoprotein-mediated lipid removal pathway.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: Blocking the expression or activity of ABC1 reduces apolipoprotein-mediated lipid efflux from cultured cells, and increasing expression of ABC1 enhances it.
      explanation: >-
        Bidirectional expression/activity perturbations establish the proximal cellular efflux defect.
  - target: Cholesteryl Ester Tissue Storage
    description: >-
      Persistent impaired cellular export permits cholesterol retention and ester storage.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:33994407
      reference_title: Current Diagnosis and Management of Tangier Disease.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: cellular cholesterol export is impaired due to ABCA1 deficiency in peripheral cells, including macrophages and Schwann cells.
      explanation: >-
        The clinical synthesis distinguishes cell-autonomous export failure from low circulating HDL alone.
    intermediate_mechanisms:
    - retention and esterification of cellular cholesterol
  - target: Macrophage Foam Cell Atherogenesis
    description: >-
      Reduced macrophage efflux promotes cholesterol retention and foam-cell atherogenesis.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:11950702
      reference_title: Increased atherosclerosis in hyperlipidemic mice with inactivation of ABCA1 in macrophages.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: the selective inactivation of ABCA1 in macrophages markedly increased atherosclerosis and foam cell accumulation
      explanation: >-
        Bone-marrow transplantation in hyperlipidemic mice isolates a macrophage contribution independently of plasma HDL; concomitant Apoe/Ldlr backgrounds limit direct extrapolation.
    intermediate_mechanisms:
    - macrophage cholesterol retention
    - foam-cell accumulation
  - target: Membrane Cholesterol Enrichment
    description: >-
      Deficient macrophage efflux increases free cholesterol and lipid-raft abundance in experimental cells.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:18552351
      reference_title: Increased cellular free cholesterol in macrophage-specific Abca1 knock-out mice enhances pro-inflammatory response of macrophages.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: cholesterol depletion of macrophages with methyl-beta-cyclodextrin normalized FC content between the two genotypes and their response to LPS
      explanation: >-
        Depletion/repletion experiments support membrane-cholesterol-dependent inflammatory signaling in Abca1-deficient murine macrophages.
  - target: Myeloid Inflammasome Activation
    description: >-
      Myeloid cholesterol accumulation activates inflammasomes in combined Abca1/Abcg1-deficient models; patient cytokines support human relevance.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29588315
      reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1β and IL-18 levels.
      explanation: >-
        Human cytokine observations support relevance but do not prove NLRP3 specificity, NETosis, or therapeutic response.
    - reference: PMID:29588315
      reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice.
      explanation: >-
        Genetic intervention supports an inflammasome contribution in a combined-transporter and hyperlipidemic mouse model.
    hypothesis_groups:
    - inflammatory_amplification
- name: Impaired HDL Biogenesis
  description: >-
    Impaired ABCA1-dependent apoA-I lipidation reduces nascent HDL production. Reduced circulating HDL is a systemic consequence; cellular storage is also driven directly by deficient local export and should not be attributed to low HDL concentration alone. Rapid apoA-I catabolism further contributes to the low circulating apolipoprotein concentration.
  biological_processes:
  - preferred_term: high-density lipoprotein particle assembly
    term:
      id: GO:0034380
      label: high-density lipoprotein particle assembly
    modifier: DECREASED
  - preferred_term: cholesterol efflux
    term:
      id: GO:0033344
      label: cholesterol efflux
    modifier: DECREASED
  chemical_entities:
  - preferred_term: high-density lipoprotein
    term:
      id: CHEBI:39025
      label: high-density lipoprotein
    modifier: DECREASED
  - preferred_term: high-density lipoprotein cholesterol
    term:
      id: CHEBI:47775
      label: high-density lipoprotein cholesterol
    modifier: DECREASED
  evidence:
  - reference: PMID:10525055
    reference_title: "The Tangier disease gene product ABC1 controls the cellular apolipoprotein-mediated lipid removal pathway."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "activity of ABC1 reduces apolipoprotein-mediated lipid efflux from cultured"
    explanation: Cell-based studies support impaired apolipoprotein-mediated efflux as the proximal mechanism.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "With functional deficiency in ABCA1, spherical HDL particles are not produced resulting in extremely low plasma HDL-C levels"
    explanation: Clinical review links ABCA1 deficiency to failure of spherical HDL production and very low HDL-C.
  - reference: PMID:7130397
    reference_title: "Tangier disease. High density lipoprotein deficiency due to defective metabolism of an abnormal apolipoprotein A-i (ApoA-ITangier)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "cholesterol, apoA-I, and apoA-II concentrations that were 4, 2, and 11% of"
    explanation: Human kinetic studies document the biochemical HDL and apolipoprotein deficiency in homozygotes.
  - reference: PMID:33994407
    reference_title: Current Diagnosis and Management of Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: found that that apoA-I was catabolized at a much greater fractional rate in patients
    explanation: >-
      The clinical review reinterprets early labeled-HDL kinetic findings in the context of ABCA1 deficiency.
  downstream:
  - target: Decreased HDL cholesterol concentration
    description: HDL particle assembly failure produces very low or absent HDL-C.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "With functional deficiency in ABCA1, spherical HDL particles are not produced resulting in extremely low plasma HDL-C levels"
      explanation: The clinical review directly links ABCA1 deficiency and failed HDL production to extremely low HDL-C.
  - target: Hypocholesterolemia
    description: Severe HDL deficiency and altered lipoprotein remodeling lower total cholesterol.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - severe HDL-C depletion and altered HDL-to-VLDL/LDL cholesterol transfer
    evidence:
    - reference: PMID:22913675
      reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "low total plasma\ncholesterol (below 150 mg/dL)"
      explanation: The epidemiology review supports low total cholesterol as part of the biochemical Tangier phenotype.
  - target: Hypertriglyceridemia
    description: Tangier disease commonly includes normal to high or elevated plasma triglycerides.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:22913675
      reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "normal or high plasma triglycerides"
      explanation: The review supports normal-to-high plasma triglycerides as part of the Tangier biochemical pattern.
- name: Cholesteryl Ester Tissue Storage
  description: >-
    Impaired cellular cholesterol export permits cholesteryl ester accumulation in reticuloendothelial tissues, Schwann cells, skin, smooth muscle and mucosa. Storage contributes to orange tonsils, organomegaly and nerve involvement. Mechanisms underlying individual skin/nail findings remain less well characterized.
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: Schwann cell
    term:
      id: CL:0002573
      label: Schwann cell
  chemical_entities:
  - preferred_term: cholesteryl ester
    term:
      id: CHEBI:17002
      label: cholesteryl ester
    modifier: INCREASED
  evidence:
  - reference: PMID:162820
    reference_title: "The pathology of Tangier disease. A light and electron microscopic study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "cholesteryl esters were found in: reticuloendothelial cells (foam cells) in"
    explanation: Histopathologic study directly demonstrates cholesteryl ester storage in patient tissues.
  - reference: PMID:162820
    reference_title: "The pathology of Tangier disease. A light and electron microscopic study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Deposits of cholesteryl esters were found in: reticuloendothelial cells (foam cells) in tonsils, bone marrow, skin and jejunal submucosa; Schwann cells in peripheral nerves and myenteric plexus; and in nonvascular smooth muscle cells."
    explanation: The pathology study supports Schwann-cell involvement in peripheral nerves.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "cellular cholesterol export is impaired due to ABCA1 deficiency in peripheral cells, including macrophages and Schwann cells."
    explanation: This review connects ABCA1 deficiency to impaired cholesterol export in macrophages and Schwann cells.
  downstream:
  - target: Orange discolored tonsils
    description: Cholesteryl ester storage in tonsillar tissue produces orange tonsils.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Cholesterol therefore accumulates in these cells, causing orange-colored pharyngeal tonsillar swelling, corneal opacity, hepatosplenomegaly, lymphadenopathy and peripheral neuropathy."
      explanation: The review directly links cellular cholesterol accumulation to orange pharyngeal tonsillar swelling.
  - target: Hepatosplenomegaly
    description: Reticuloendothelial lipid storage enlarges liver and spleen.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Cholesterol therefore accumulates in these cells, causing orange-colored pharyngeal tonsillar swelling, corneal opacity, hepatosplenomegaly, lymphadenopathy and peripheral neuropathy."
      explanation: The review directly links cellular cholesterol accumulation to hepatosplenomegaly.
  - target: Chronic noninfectious lymphadenopathy
    description: Reticuloendothelial storage contributes to lymph-node enlargement.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Cholesterol therefore accumulates in these cells, causing orange-colored pharyngeal tonsillar swelling, corneal opacity, hepatosplenomegaly, lymphadenopathy and peripheral neuropathy."
      explanation: The review directly links cellular cholesterol accumulation to lymphadenopathy.
  - target: Corneal opacity
    description: Lipid storage in ocular tissue can produce corneal opacity.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Cholesterol therefore accumulates in these cells, causing orange-colored pharyngeal tonsillar swelling, corneal opacity, hepatosplenomegaly, lymphadenopathy and peripheral neuropathy."
      explanation: The review directly links cellular cholesterol accumulation to corneal opacity.
  - target: Thrombocytopenia
    description: Splenomegaly and reticuloendothelial involvement can be accompanied by thrombocytopenia.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - splenomegaly-associated platelet sequestration or reticuloendothelial involvement
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In addition, splenomegaly and associated thrombocytopenia and/or reticulocyte hyperplasia may be present"
      explanation: The management review links splenomegaly with associated thrombocytopenia.
  - target: Peripheral Nerve Dysfunction
    description: >-
      Schwann-cell lipid storage and abnormal myelin/axon function contribute to heterogeneous neuropathy; intervening injury mechanisms are not completely resolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:33994407
      reference_title: Current Diagnosis and Management of Tangier Disease.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: cellular cholesterol export is impaired due to ABCA1 deficiency in peripheral cells, including macrophages and Schwann cells.
      explanation: >-
        The clinical synthesis distinguishes cell-autonomous export failure from low circulating HDL alone.
    - reference: PMID:29582519
      reference_title: 'Peripheral neuropathy in Tangier disease: A literature review and assessment.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Our literature review and our case showed the clinical spectrum of TD neuropathy is quite wide and that it should be considered in the differential diagnosis of non-uniform demyelinating neuropathies.
      explanation: >-
        A selected literature series of 54 neuropathy cases supports heterogeneous nerve involvement, not a population prevalence estimate.
- name: Macrophage Foam Cell Atherogenesis
  description: >-
    Deficient macrophage lipid efflux promotes foam-cell accumulation and atherogenesis. Plasma apoB-lipoprotein burden, age and other risk factors modify clinical expression; systemic HDL-C concentration alone does not determine lesion burden.
  biological_processes:
  - preferred_term: cholesterol transport
    term:
      id: GO:0030301
      label: cholesterol transport
    modifier: DECREASED
  - preferred_term: cholesterol metabolic process
    term:
      id: GO:0008203
      label: cholesterol metabolic process
  chemical_entities:
  - preferred_term: cholesterol
    term:
      id: CHEBI:16113
      label: cholesterol
  evidence:
  - reference: PMID:10431238
    reference_title: "Tangier disease is caused by mutations in the gene encoding ATP-binding cassette transporter 1."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Impaired cholesterol efflux from macrophages leads to the presence of foam cells throughout the body, which may explain the increased risk of coronary heart disease in some TD families."
    explanation: Human genetic paper connects impaired macrophage efflux to foam-cell accumulation.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "impairment of the initial stage of reverse cholesterol transport should be considered to be a risk for developing atherosclerotic diseases"
    explanation: This review links the efflux defect to atherosclerotic risk.
  - reference: PMID:27565770
    reference_title: "Diagnosis and treatment of high density lipoprotein deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "25% had CVD, which increased to 52% in those between the ages of 40 and 65 years"
    explanation: Review of reported Tangier cases supports age-dependent cardiovascular disease risk.
  - reference: PMID:11950702
    reference_title: Increased atherosclerosis in hyperlipidemic mice with inactivation of ABCA1 in macrophages.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: the selective inactivation of ABCA1 in macrophages markedly increased atherosclerosis and foam cell accumulation
    explanation: >-
      Bone-marrow transplantation in hyperlipidemic mice isolates a macrophage contribution independently of plasma HDL; concomitant Apoe/Ldlr backgrounds limit direct extrapolation.
  downstream:
  - target: Accelerated atherosclerosis
    description: Impaired reverse cholesterol transport increases atherosclerotic risk in susceptible patients.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "impairment of the initial stage of reverse cholesterol transport should be considered to be a risk for developing atherosclerotic diseases"
      explanation: The review directly supports impaired reverse cholesterol transport as a risk for atherosclerotic disease.
  - target: Coronary artery stenosis
    description: Atherosclerotic vascular involvement can include coronary artery disease.
    causal_link_type: DIRECT
    evidence:
    - reference: ORPHA:31150
      reference_title: "Tangier disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0005145 | Coronary artery stenosis | Frequent (79-30%)"
      explanation: Orphanet records coronary artery stenosis as a frequent cardiovascular phenotype in Tangier disease.
  - target: Carotid artery stenosis
    description: Atherosclerotic vascular involvement can include carotid artery stenosis.
    causal_link_type: DIRECT
    evidence:
    - reference: ORPHA:31150
      reference_title: "Tangier disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0100546 | Carotid artery stenosis | Occasional (29-5%)"
      explanation: Orphanet records carotid artery stenosis as an occasional cardiovascular phenotype in Tangier disease.
- name: Peripheral Nerve Dysfunction
  description: >-
    Peripheral nerve injury may involve demyelination, conduction block and axonal loss, with relapsing-remitting or progressive courses.
  evidence:
  - reference: PMID:29582519
    reference_title: 'Peripheral neuropathy in Tangier disease: A literature review and assessment.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our literature review and our case showed the clinical spectrum of TD neuropathy is quite wide and that it should be considered in the differential diagnosis of non-uniform demyelinating neuropathies.
    explanation: >-
      A selected literature series of 54 neuropathy cases supports heterogeneous nerve involvement, not a population prevalence estimate.
  cell_types:
  - preferred_term: Schwann cell
    term:
      id: CL:0002573
      label: Schwann cell
  downstream:
  - target: Peripheral axonal neuropathy
    description: Schwann-cell and peripheral-nerve lipid storage contributes to neuropathy.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "cellular cholesterol export is impaired due to ABCA1 deficiency in peripheral cells, including macrophages and Schwann cells."
      explanation: The review supports impaired cholesterol export in Schwann cells as a cellular basis for peripheral neuropathy.
  - target: Progressive peripheral neuropathy
    description: Peripheral-nerve involvement may be chronic and progressive.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Various peripheral neuropathies, ranging from mild to severe, have been reported."
      explanation: The clinical review supports the peripheral neuropathy spectrum downstream of Tangier tissue storage.
  - target: Facial diplegia
    description: Cranial nerve involvement can manifest as facial diplegia.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: ORPHA:31150
      reference_title: "Tangier disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0001349 | Facial diplegia | Occasional (29-5%)"
      explanation: Orphanet records facial diplegia as an occasional neurologic phenotype in Tangier disease.
  - target: Impaired temperature sensation
    description: Sensory nerve involvement can impair temperature sensation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: ORPHA:31150
      reference_title: "Tangier disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0010829 | Impaired temperature sensition | Occasional (29-5%)"
      explanation: Orphanet records impaired temperature sensation as an occasional neurologic phenotype in Tangier disease.
  - target: Distal muscle weakness
    description: Motor neuropathy can produce distal weakness.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: ORPHA:31150
      reference_title: "Tangier disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "HP:0002460 | Distal muscle weakness | Frequent (79-30%)"
      explanation: Orphanet records distal muscle weakness as a frequent neuromuscular phenotype in Tangier disease.
  - target: Syringomyelia-like neuropathy
    description: >-
      A dissociated sensory and motor neuropathy can resemble syringomyelia without demonstrating a spinal cord cavity.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29582519
      reference_title: 'Peripheral neuropathy in Tangier disease: A literature review and assessment.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Our literature review and our case showed the clinical spectrum of TD neuropathy is quite wide and that it should be considered in the differential diagnosis of non-uniform demyelinating neuropathies.
      explanation: >-
        A selected literature series of 54 neuropathy cases supports heterogeneous nerve involvement, not a population prevalence estimate.
- name: Membrane Cholesterol Enrichment
  description: >-
    Free-cholesterol enrichment of macrophage membrane domains enhances sensitivity to inflammatory stimuli; this differs from bulk cholesteryl ester storage.
  evidence:
  - reference: PMID:18552351
    reference_title: Increased cellular free cholesterol in macrophage-specific Abca1 knock-out mice enhances pro-inflammatory response of macrophages.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: cholesterol depletion of macrophages with methyl-beta-cyclodextrin normalized FC content between the two genotypes and their response to LPS
    explanation: >-
      Depletion/repletion experiments support membrane-cholesterol-dependent inflammatory signaling in Abca1-deficient murine macrophages.
  downstream:
  - target: Amplified Myeloid Inflammatory Signaling
    description: >-
      Membrane cholesterol enrichment enhances LPS/MyD88-dependent NF-κB and MAPK responses in Abca1-deficient macrophages.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:18552351
      reference_title: Increased cellular free cholesterol in macrophage-specific Abca1 knock-out mice enhances pro-inflammatory response of macrophages.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: cholesterol depletion of macrophages with methyl-beta-cyclodextrin normalized FC content between the two genotypes and their response to LPS
      explanation: >-
        Depletion/repletion experiments support membrane-cholesterol-dependent inflammatory signaling in Abca1-deficient murine macrophages.
    intermediate_mechanisms:
    - MyD88-dependent receptor signaling
- name: Myeloid Inflammasome Activation
  mechanism_confidence: PROVISIONAL
  description: >-
    Inflammasome activation increases IL-1β and IL-18 release in experimental myeloid cholesterol overload; elevated patient cytokines are supportive clinical observations.
  evidence:
  - reference: PMID:29588315
    reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1β and IL-18 levels.
    explanation: >-
      Human cytokine observations support relevance but do not prove NLRP3 specificity, NETosis, or therapeutic response.
  - reference: PMID:29588315
    reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice.
    explanation: >-
      Genetic intervention supports an inflammasome contribution in a combined-transporter and hyperlipidemic mouse model.
  downstream:
  - target: Amplified Myeloid Inflammatory Signaling
    description: >-
      Inflammasome-dependent cytokine release amplifies systemic myeloid inflammation.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29588315
      reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice.
      explanation: >-
        Genetic intervention supports an inflammasome contribution in a combined-transporter and hyperlipidemic mouse model.
    intermediate_mechanisms:
    - IL-1β and IL-18 release
    hypothesis_groups:
    - inflammatory_amplification
- name: Amplified Myeloid Inflammatory Signaling
  mechanism_confidence: PROVISIONAL
  description: >-
    Receptor and inflammasome pathways amplify inflammatory responses. The magnitude of this contribution to human Tangier disease remains undetermined.
  evidence:
  - reference: PMID:18552351
    reference_title: Increased cellular free cholesterol in macrophage-specific Abca1 knock-out mice enhances pro-inflammatory response of macrophages.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: cholesterol depletion of macrophages with methyl-beta-cyclodextrin normalized FC content between the two genotypes and their response to LPS
    explanation: >-
      Depletion/repletion experiments support membrane-cholesterol-dependent inflammatory signaling in Abca1-deficient murine macrophages.
  - reference: PMID:29588315
    reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1β and IL-18 levels.
    explanation: >-
      Human cytokine observations support relevance but do not prove NLRP3 specificity, NETosis, or therapeutic response.
  downstream:
  - target: Macrophage Foam Cell Atherogenesis
    description: >-
      Inflammasome-dependent inflammation, neutrophil recruitment and NET formation enhance lesion development in combined Abca1/Abcg1-deficient Ldlr-null mice.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:29588315
      reference_title: Cholesterol Efflux Pathways Suppress Inflammasome Activation, NETosis, and Atherogenesis.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice.
      explanation: >-
        Genetic intervention supports an inflammasome contribution in a combined-transporter and hyperlipidemic mouse model.
    - reference: PMID:36537208
      reference_title: Cholesterol accumulation in macrophages drives NETosis in atherosclerotic plaques via IL-1β secretion.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Macrophage, but not neutrophil Abca1/g1 deficiency activated inflammasomes in macrophages and neutrophils, reflected by caspase-1 cleavage, and induced NETosis in plaques.
      explanation: >-
        Conditional deletions identify macrophage-driven crosstalk in a combined-transporter Ldlr-null mouse system.
    intermediate_mechanisms:
    - neutrophil recruitment and plaque NET formation
    hypothesis_groups:
    - inflammatory_amplification
- name: Platelet Dense-Granule Maturation Defect
  description: >-
    Platelets can contain fewer dense bodies, giant granules and impaired dense-body release.
  evidence:
  - reference: PMID:15163665
    reference_title: Impaired platelet activation in familial high density lipoprotein deficiency (Tangier disease).
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The electron microscopy of Tangier platelets revealed reduced numbers of dense bodies and the presence of giant granules typically encountered in platelets from Chediak-Higashi syndrome.
    explanation: >-
      Patient platelet ultrastructure identifies a dense-granule maturation abnormality; the detailed lipid-to-organelle mechanism is unresolved.
  downstream:
  - target: Impaired Platelet Activation
    description: >-
      Defective granule release reduces activation by collagen or low-dose thrombin, while ADP responses can be preserved.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:15163665
      reference_title: Impaired platelet activation in familial high density lipoprotein deficiency (Tangier disease).
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The impaired release of the content of dense bodies may explain the defective activation of Tangier platelets by collagen and low concentrations of thrombin, but not by ADP.
      explanation: >-
        Patient platelet assays support agonist-selective secretion/activation defects; ADP responsiveness is preserved.
    intermediate_mechanisms:
    - impaired dense-body secretion
- name: Impaired Platelet Activation
  description: >-
    Reduced granule-dependent amplification can impair platelet activation separately from thrombocytopenia.
  evidence:
  - reference: PMID:15163665
    reference_title: Impaired platelet activation in familial high density lipoprotein deficiency (Tangier disease).
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: The impaired release of the content of dense bodies may explain the defective activation of Tangier platelets by collagen and low concentrations of thrombin, but not by ADP.
    explanation: >-
      Patient platelet assays support agonist-selective secretion/activation defects; ADP responsiveness is preserved.
  downstream:
  - target: Bleeding tendency
    description: >-
      Platelet dysfunction may contribute to bleeding in some patients; the splenic hematoma case does not isolate platelet dysfunction from structural/splenic factors.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:19723515
      reference_title: A novel ABCA1 nonsense mutation, R1270X, in Tangier disease associated with an unrecognised bleeding tendency.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: a case of Tangier disease in association with an unrecognised bleeding tendency
      explanation: >-
        A single spontaneous splenic hematoma case supports a bleeding complication without estimating population penetrance.
    - reference: PMID:15163665
      reference_title: Impaired platelet activation in familial high density lipoprotein deficiency (Tangier disease).
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: The impaired release of the content of dense bodies may explain the defective activation of Tangier platelets by collagen and low concentrations of thrombin, but not by ADP.
      explanation: >-
        Patient platelet assays support agonist-selective secretion/activation defects; ADP responsiveness is preserved.
- name: Impaired Glucose-Stimulated Insulin Secretion
  description: >-
    Impaired insulin release after glucose challenge was measured in a small Tangier cohort.
  evidence:
  - reference: PMID:19556721
    reference_title: Impaired insulin secretion in four Tangier disease patients with ABCA1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The calculated insulinogenic index was significantly lower in TD patients than in non-diabetic controls (0.055+/-0.034 vs 0.775+/-0.538, mean+/-SD, p<0.05, respectively).
    explanation: >-
      Four Japanese patients underwent OGTT; impaired insulin response is supported, but universal diabetes or prevalence cannot be inferred.
  downstream:
  - target: Impaired glucose tolerance
    description: >-
      Insufficient insulin response accompanies abnormal glucose tolerance in the reported four-patient series.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:19556721
      reference_title: Impaired insulin secretion in four Tangier disease patients with ABCA1 mutations.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The calculated insulinogenic index was significantly lower in TD patients than in non-diabetic controls (0.055+/-0.034 vs 0.775+/-0.538, mean+/-SD, p<0.05, respectively).
      explanation: >-
        Four Japanese patients underwent OGTT; impaired insulin response is supported, but universal diabetes or prevalence cannot be inferred.
- name: Abnormal PMP22 Processing
  mechanism_confidence: PROVISIONAL
  description: >-
    Abca1-null mouse nerves overproduce PMP22 and process it abnormally. This is an experimentally supported mechanistic lead, with its contribution to human nerve dysfunction unresolved.
  evidence:
  - reference: PMID:31061090
    reference_title: PMP22 Regulates Cholesterol Trafficking and ABCA1-Mediated Cholesterol Efflux.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant.
    explanation: >-
      Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.
  cell_types:
  - preferred_term: Schwann cell
    term:
      id: CL:0002573
      label: Schwann cell
phenotypes:
- name: Decreased HDL cholesterol concentration
  category: Biochemical
  description: HDL cholesterol is absent or extremely low.
  phenotype_term:
    preferred_term: Decreased HDL cholesterol concentration
    term:
      id: HP:0003233
      label: Decreased HDL cholesterol concentration
  evidence:
  - reference: PMID:22913675
    reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "plasma HDL concentrations less than 5 mg/dL"
    explanation: The review describes the severe HDL-C depletion characteristic of Tangier disease.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Plasma HDL-C is mostly low, at 5 mg/dL or less"
    explanation: The management review provides a concrete HDL-C diagnostic range.
- name: Hypertriglyceridemia
  category: Biochemical
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Hypertriglyceridemia
    term:
      id: HP:0002155
      label: Hypertriglyceridemia
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002155 | Hypertriglyceridemia | Very frequent (99-80%)"
    explanation: Orphanet records hypertriglyceridemia as very frequent.
  - reference: PMID:22913675
    reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "normal or high plasma triglycerides"
    explanation: This review supports the triglyceride abnormality.
- name: Hypocholesterolemia
  category: Biochemical
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Hypocholesterolemia
    term:
      id: HP:0003146
      label: Hypocholesterolemia
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003146 | Hypocholesterolemia | Very frequent (99-80%)"
    explanation: Orphanet records hypocholesterolemia as very frequent.
- name: Orange discolored tonsils
  category: Head and Neck
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Orange discolored tonsils
    term:
      id: HP:0030814
      label: Orange discolored tonsils
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0030814 | Orange discoloured tonsils | Frequent (79-30%)"
    explanation: Orphanet records orange discolored tonsils as frequent.
  - reference: PMID:7130397
    reference_title: "Tangier disease. High density lipoprotein deficiency due to defective metabolism of an abnormal apolipoprotein A-i (ApoA-ITangier)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Tangier disease is a rare familial disorder characterized by enlarged orange tonsils, transient peripheral neuropathy, hepatosplenomegaly, and lymphadenopathy"
    explanation: Classic human study supports orange enlarged tonsils as a hallmark finding.
- name: Hepatosplenomegaly
  category: Hepatic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001433 | Hepatosplenomegaly | Frequent (79-30%)"
    explanation: Orphanet records hepatosplenomegaly as frequent.
- name: Chronic noninfectious lymphadenopathy
  category: Lymphatic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Chronic noninfectious lymphadenopathy
    term:
      id: HP:0002730
      label: Chronic noninfectious lymphadenopathy
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002730 | Chronic noninfectious lymphadenopathy | Frequent (79-30%)"
    explanation: Orphanet records chronic noninfectious lymphadenopathy as frequent.
- name: Peripheral axonal neuropathy
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Peripheral axonal neuropathy
    term:
      id: HP:0003477
      label: Peripheral axonal neuropathy
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0003477 | Peripheral axonal neuropathy | Frequent (79-30%)"
    explanation: Orphanet records peripheral axonal neuropathy as frequent.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Various peripheral neuropathies, ranging from mild to severe, have been reported."
    explanation: Clinical review supports peripheral neuropathy as part of Tangier disease.
- name: Progressive peripheral neuropathy
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Progressive peripheral neuropathy
    term:
      id: HP:0007133
      label: Progressive peripheral neuropathy
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0007133 | Progressive peripheral neuropathy | Frequent (79-30%)"
    explanation: Orphanet records progressive peripheral neuropathy as frequent.
  notes: >-
    Neuropathy may instead be relapsing-remitting; progression is not universal.
- name: Distal muscle weakness
  category: Neuromuscular
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Distal muscle weakness
    term:
      id: HP:0002460
      label: Distal muscle weakness
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002460 | Distal muscle weakness | Frequent (79-30%)"
    explanation: Orphanet records distal muscle weakness as frequent.
- name: Facial diplegia
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Facial diplegia
    term:
      id: HP:0001349
      label: Facial diplegia
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001349 | Facial diplegia | Occasional (29-5%)"
    explanation: Orphanet records facial diplegia as occasional.
- name: Impaired temperature sensation
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Impaired temperature sensation
    term:
      id: HP:0010829
      label: Impaired temperature sensation
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0010829 | Impaired temperature sensition | Occasional (29-5%)"
    explanation: Orphanet records impaired temperature sensation as occasional; the ORPHA row contains a spelling variant.
- name: Syringomyelia-like neuropathy
  category: Neurologic
  phenotype_term:
    preferred_term: Syringomyelia-like peripheral neuropathy
  evidence:
  - reference: PMID:29582519
    reference_title: 'Peripheral neuropathy in Tangier disease: A literature review and assessment.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Our literature review and our case showed the clinical spectrum of TD neuropathy is quite wide and that it should be considered in the differential diagnosis of non-uniform demyelinating neuropathies.
    explanation: >-
      A selected literature series of 54 neuropathy cases supports heterogeneous nerve involvement, not a population prevalence estimate.
  description: >-
    Peripheral neuropathy with dissociated pain/temperature loss and weakness resembling syringomyelia; this does not establish anatomical syringomyelia. The literature-derived 52.4% applies to classified neuropathy cases, not all Tangier disease.
- name: Corneal opacity
  category: Ophthalmologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Corneal opacity
    term:
      id: HP:0007957
      label: Corneal opacity
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0007957 | Corneal opacity | Occasional (29-5%)"
    explanation: Orphanet records corneal opacity as occasional.
  notes: >-
    Usually mild and not vision-limiting; rare severe presentations require separate clinical assessment.
- name: Dry skin
  category: Dermatologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Dry skin
    term:
      id: HP:0000958
      label: Dry skin
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000958 | Dry skin | Frequent (79-30%)"
    explanation: Orphanet records dry skin as frequent.
- name: Nail dystrophy
  category: Dermatologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Nail dystrophy
    term:
      id: HP:0008404
      label: Nail dystrophy
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0008404 | Nail dystrophy | Frequent (79-30%)"
    explanation: Orphanet records nail dystrophy as frequent.
- name: Ectropion
  category: Ophthalmologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Ectropion
    term:
      id: HP:0000656
      label: Ectropion
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000656 | Ectropion | Frequent (79-30%)"
    explanation: Orphanet records ectropion as frequent.
- name: Abdominal pain
  category: Gastrointestinal
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abdominal pain
    term:
      id: HP:0002027
      label: Abdominal pain
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002027 | Abdominal pain | Frequent (79-30%)"
    explanation: Orphanet records abdominal pain as frequent.
- name: Thrombocytopenia
  category: Hematologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Thrombocytopenia
    term:
      id: HP:0001873
      label: Thrombocytopenia
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001873 | Thrombocytopenia | Occasional (29-5%)"
    explanation: Orphanet records thrombocytopenia as occasional.
- name: Anemia
  category: Hematologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001903 | Anemia | Occasional (29-5%)"
    explanation: Orphanet records anemia as occasional.
- name: Accelerated atherosclerosis
  category: Cardiovascular
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Accelerated atherosclerosis
    term:
      id: HP:0004943
      label: Accelerated atherosclerosis
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0004943 | Accelerated atherosclerosis | Frequent (79-30%)"
    explanation: Orphanet records accelerated atherosclerosis as frequent.
  notes: >-
    Clinical penetrance is variable. GeneReviews describes most recognized coronary disease in the 50s–60s and usually after age 40; isolated earlier cases exist.
- name: Coronary artery stenosis
  category: Cardiovascular
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Coronary artery stenosis
    term:
      id: HP:0005145
      label: Coronary artery stenosis
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0005145 | Coronary artery stenosis | Frequent (79-30%)"
    explanation: Orphanet records coronary artery stenosis as frequent.
- name: Carotid artery stenosis
  category: Cardiovascular
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Carotid artery stenosis
    term:
      id: HP:0100546
      label: Carotid artery stenosis
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0100546 | Carotid artery stenosis | Occasional (29-5%)"
    explanation: Orphanet records carotid artery stenosis as occasional.
- name: Left ventricular hypertrophy
  category: Cardiovascular
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Left ventricular hypertrophy
    term:
      id: HP:0001712
      label: Left ventricular hypertrophy
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001712 | Left ventricular hypertrophy | Occasional (29-5%)"
    explanation: Orphanet records left ventricular hypertrophy as occasional.
- name: Bleeding tendency
  category: Hematologic
  description: >-
    Bleeding has been reported, including a spontaneous splenic hematoma; population frequency is unknown.
  phenotype_term:
    preferred_term: Abnormal bleeding
    term:
      id: HP:0001892
      label: Abnormal bleeding
  evidence:
  - reference: PMID:19723515
    reference_title: A novel ABCA1 nonsense mutation, R1270X, in Tangier disease associated with an unrecognised bleeding tendency.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: a case of Tangier disease in association with an unrecognised bleeding tendency
    explanation: >-
      A single spontaneous splenic hematoma case supports a bleeding complication without estimating population penetrance.
- name: Impaired glucose tolerance
  category: Metabolic
  description: >-
    Observed in four Japanese patients; a selected small study does not establish penetrance.
  phenotype_term:
    preferred_term: Abnormal glucose tolerance
    term:
      id: HP:0001952
      label: Glucose intolerance
  evidence:
  - reference: PMID:19556721
    reference_title: Impaired insulin secretion in four Tangier disease patients with ABCA1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The calculated insulinogenic index was significantly lower in TD patients than in non-diabetic controls (0.055+/-0.034 vs 0.775+/-0.538, mean+/-SD, p<0.05, respectively).
    explanation: >-
      Four Japanese patients underwent OGTT; impaired insulin response is supported, but universal diabetes or prevalence cannot be inferred.
- name: Reticulocytosis
  category: Hematologic
  description: >-
    Reported hematologic manifestation; frequency is not established by this clinical summary.
  phenotype_term:
    preferred_term: Reticulocytosis
    term:
      id: HP:0001923
      label: Reticulocytosis
  evidence:
  - reference: PMID:31751110
    reference_title: Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: mild thrombocytopenia, reticulocytosis, stomatocytosis, or hemolytic anemia.
    explanation: >-
      GeneReviews describes the mild hematologic spectrum.
- name: Stomatocytosis
  category: Hematologic
  description: >-
    Reported hematologic manifestation; frequency is not established by this clinical summary.
  phenotype_term:
    preferred_term: Stomatocytosis
    term:
      id: HP:0004446
      label: Stomatocytosis
  evidence:
  - reference: PMID:31751110
    reference_title: Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: mild thrombocytopenia, reticulocytosis, stomatocytosis, or hemolytic anemia.
    explanation: >-
      GeneReviews describes the mild hematologic spectrum.
- name: Hemolytic anemia
  category: Hematologic
  description: >-
    Reported hematologic manifestation; frequency is not established by this clinical summary.
  phenotype_term:
    preferred_term: Hemolytic anemia
    term:
      id: HP:0001878
      label: Hemolytic anemia
  evidence:
  - reference: PMID:31751110
    reference_title: Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: mild thrombocytopenia, reticulocytosis, stomatocytosis, or hemolytic anemia.
    explanation: >-
      GeneReviews describes the mild hematologic spectrum.
biochemical:
- name: Low HDL cholesterol
  presence: DECREASED
  context: >
    Plasma HDL-C is absent or extremely low and is a core diagnostic readout of
    failed ABCA1-dependent HDL biogenesis.
  biomarker_term:
    preferred_term: high-density lipoprotein cholesterol
    term:
      id: CHEBI:47775
      label: high-density lipoprotein cholesterol
  readouts:
  - target: Impaired HDL Biogenesis
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Lower HDL-C reports impaired ABCA1-dependent HDL particle generation.
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Plasma HDL-C is mostly low, at 5 mg/dL or less"
      explanation: The management review supports HDL-C as a diagnostic readout of Tangier disease.
  evidence:
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Plasma HDL-C is mostly low, at 5 mg/dL or less"
    explanation: The review provides the typical severe HDL-C depletion range in Tangier disease.
- name: Low apolipoprotein A-I
  presence: DECREASED
  context: >
    ApoA-I is absent or extremely low because ABCA1-dependent lipidation and HDL
    particle formation fail.
  biomarker_term:
    preferred_term: apolipoprotein A-I
    term:
      id: CHEBI:39015
      label: apolipoprotein
  readouts:
  - target: Impaired HDL Biogenesis
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Lower apoA-I reports failed HDL particle generation and rapid loss of apoA-I-containing HDL.
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "with absent or extremely low HDL-cholesterol and apo A-I levels and biallelic"
      explanation: GeneReviews supports apoA-I depletion as a diagnostic readout in Tangier disease.
  evidence:
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "apoA-I concentration is 10 mg/dL or less"
    explanation: The management review reports markedly low apoA-I concentrations in Tangier disease.
- name: Low total cholesterol
  presence: DECREASED
  context: >
    Total plasma cholesterol is low, largely reflecting the profound HDL-C
    deficit and altered lipoprotein cholesterol distribution.
  biomarker_term:
    preferred_term: cholesterol
    term:
      id: CHEBI:16113
      label: cholesterol
  readouts:
  - target: Impaired HDL Biogenesis
    relationship: CORRELATES_WITH
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Low total cholesterol accompanies the severe HDL-C deficit in Tangier disease.
    evidence:
    - reference: PMID:22913675
      reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "low total plasma\ncholesterol (below 150 mg/dL)"
      explanation: The epidemiology review supports low total cholesterol as part of the diagnostic biochemical profile.
  evidence:
  - reference: PMID:22913675
    reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "low total plasma\ncholesterol (below 150 mg/dL)"
    explanation: The review supports low total plasma cholesterol in Tangier disease.
- name: Elevated plasma triglycerides
  presence: INCREASED
  context: >
    Plasma triglycerides may be normal to high or elevated in the Tangier
    lipoprotein profile.
  biomarker_term:
    preferred_term: triglyceride
    term:
      id: CHEBI:17855
      label: triglyceride
  readouts:
  - target: Impaired HDL Biogenesis
    relationship: CORRELATES_WITH
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Higher triglycerides are part of the altered lipoprotein profile accompanying severe HDL biogenesis failure.
    evidence:
    - reference: PMID:22913675
      reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "normal or high plasma triglycerides"
      explanation: The review supports normal-to-high triglycerides in the Tangier biochemical profile.
  evidence:
  - reference: PMID:22913675
    reference_title: "Tangier disease: epidemiology, pathophysiology, and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "normal or high plasma triglycerides"
    explanation: The review supports triglyceride elevation or high-normal triglycerides in Tangier disease.
- name: Plasma sphingolipids
  presence: DECREASED
  context: >-
    One-patient finding. Parallel hepatic knockout experiments demonstrated reduced apoM/S1P, but the human S1P-specific clinical mechanism remains unresolved.
  evidence:
  - reference: PMID:37601634
    reference_title: Hepatocyte ABCA1 deficiency is associated with reduced HDL sphingolipids.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: we report a drastic reduction of total SL levels in plasma of a Tangier patient with compound heterozygosity for mutations in ABCA1.
    explanation: >-
      One-patient plasma lipidomics supports sphingolipid depletion; S1P-specific reduction in this paper was shown in hepatic knockout mice.
  readouts:
  - target: Impaired HDL Biogenesis
    relationship: CORRELATES_WITH
    description: Reduced HDL-associated lipid carriage is a candidate explanation; no validated clinical surrogate is implied.
    evidence:
    - reference: PMID:37601634
      reference_title: Hepatocyte ABCA1 deficiency is associated with reduced HDL sphingolipids.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: we report a drastic reduction of total SL levels in plasma of a Tangier patient with compound heterozygosity for mutations in ABCA1.
      explanation: >-
        One-patient plasma lipidomics supports sphingolipid depletion; S1P-specific reduction in this paper was shown in hepatic knockout mice.
genetic:
- name: Biallelic ABCA1 Pathogenic Variants
  association: Causative
  gene_term:
    preferred_term: ABCA1
    term:
      id: hgnc:29
      label: ABCA1
  inheritance:
  - name: Autosomal recessive
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Tangier disease is inherited in an autosomal recessive"
      explanation: GeneReviews supports autosomal recessive inheritance.
  variants:
  - name: Biallelic ABCA1 pathogenic variants
    description: >-
      Affected individuals typically have homozygous or compound heterozygous ABCA1 pathogenic variants. Reported pathogenic alleles include deletions, insertion-deletions, and missense variants that reduce ABCA1 lipid-efflux function. A functional assay can clarify selected missense variants, but functional impairment does not alone define clinical penetrance.
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "pathogenic variants in ABCA1 identified by molecular genetic testing."
      explanation: GeneReviews defines diagnosis by biallelic pathogenic variants in ABCA1.
    - reference: PMID:10431237
      reference_title: "The gene encoding ATP-binding cassette transporter 1 is mutated in Tangier disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We have analysed five kindreds with TD and identified seven different mutations, including three that are expected to impair the function of the gene product."
      explanation: Human kindred study documents multiple ABCA1 pathogenic variants.
    - reference: PMID:10431238
      reference_title: "Tangier disease is caused by mutations in the gene encoding ATP-binding cassette transporter 1."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In the first pedigree, a 1-bp deletion in exon 13, resulting in truncation of the predicted protein to approximately one-fourth of its normal size, co-segregated with the disease phenotype."
      explanation: Human kindred study reports a truncating ABCA1 deletion allele.
  features: >
    ABCA1 encodes ATP-binding cassette subfamily A member 1, a membrane
    transporter required for cellular phospholipid and cholesterol efflux to
    lipid-poor apolipoproteins. Biallelic pathogenic variants cause Tangier
    disease; heterozygotes can have partially reduced HDL-C without the full
    clinical phenotype.
  evidence:
  - reference: ORPHA:31150
    reference_title: "Tangier disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "ABCA1 | ATP binding cassette subfamily A member 1 | hgnc:29 | Disease-causing germline mutation(s) in"
    explanation: Orphanet records ABCA1 as a disease-causing germline gene.
  - reference: PMID:31751110
    reference_title: "Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "pathogenic variants in ABCA1 identified by molecular genetic testing."
    explanation: GeneReviews identifies ABCA1 molecular testing as diagnostic.
  - reference: PMID:31751110
    reference_title: Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The clinical expression of Tangier disease is variable, with some affected individuals only showing biochemical perturbations.
    explanation: >-
      GeneReviews supports variable clinical expression despite the biochemical defect.
diagnosis:
- name: HDL-C, ApoA-I, and ABCA1 Genetic Testing
  description: >-
    Absent or extremely low HDL-C and apoA-I prompt evaluation for Tangier disease. Exclude alternative genetic and acquired causes, then confirm biallelic pathogenic ABCA1 variants; variants of uncertain significance alone do not establish molecular diagnosis. Japanese clinical criteria use broader screening thresholds than the typical HDL-C below 5 mg/dL phenotype.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
  evidence:
  - reference: PMID:31751110
    reference_title: "Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with absent or extremely low HDL-cholesterol and apo A-I levels and biallelic"
    explanation: GeneReviews states the core biochemical and genetic diagnostic criteria.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Plasma (serum) HDL-cholesterol less than 25 mg/dL"
    explanation: The Japanese diagnostic criteria include very low HDL-C.
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis can be definite if pathogenic mutations in the ABCA1 gene are identified."
    explanation: The diagnostic criteria require ABCA1 mutation confirmation for definite diagnosis.
  - reference: PMID:39817629
    reference_title: "The clinical presentation and genetic diagnosis of Tangier disease in the pediatric age group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genetic analysis should be carried out if necessary. Family screening should be recommended to patients with consanguineous marriages after diagnosis of TD."
    explanation: Pediatric cohort review supports genetic testing when clinical and HDL findings suggest Tangier disease.
treatments:
- name: Statin-Based Cardiovascular Risk Management
  description: >
    There is no curative Tangier-specific therapy. Management emphasizes
    prevention of atherosclerosis and optimization of non-HDL cardiovascular
    risk factors; if LDL-C is not already low, reviews recommend statin therapy
    or other LDL-lowering approaches.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: statin
      term:
        id: CHEBI:87631
        label: statin
  target_mechanisms:
  - target: Macrophage Foam Cell Atherogenesis
    treatment_effect: MODULATES
    description: Statin therapy is used to reduce modifiable LDL-C and non-HDL cardiovascular risk when present.
    evidence:
    - reference: PMID:33994407
      reference_title: "Current Diagnosis and Management of Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Plasma LDL-C levels are generally low in patients with Tangier disease but if this is not the case, they should be reduced through administration of statins or other means."
      explanation: The management review recommends LDL-lowering therapy with statins when LDL-C is not low.
  evidence:
  - reference: PMID:33994407
    reference_title: "Current Diagnosis and Management of Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "No specific curative treatment is currently available, so early identification of patients and preventing atherosclerosis development are crucial."
    explanation: This supports framing statins as risk management rather than curative disease therapy.
  - reference: PMID:27565770
    reference_title: "Diagnosis and treatment of high density lipoprotein deficiency."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Optimizing the LDL-C levels in Tangier patients with normal LDL-C levels using statin therapy is clearly warranted in our view."
    explanation: HDL-deficiency treatment review recommends statin-based LDL-C optimization in at-risk Tangier patients.
- name: Low-Fat Diet and Lipid Risk Reduction
  description: >
    Low-fat diet is recommended as part of cardiovascular risk-factor mitigation,
    alongside lipid-profile optimization and surveillance for atherosclerotic
    disease.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: dietary intervention
    term:
      id: NCIT:C15447
      label: Dietary Intervention
  target_mechanisms:
  - target: Macrophage Foam Cell Atherogenesis
    treatment_effect: MODULATES
    description: Diet is used to mitigate modifiable cardiovascular risk rather than restore ABCA1 function.
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "using statin therapy and a low-fat diet."
      explanation: GeneReviews lists low-fat diet with statin therapy as risk mitigation.
  evidence:
  - reference: PMID:31751110
    reference_title: "Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "cardiovascular risk factors, including improvement of plasma lipid profiles"
    explanation: GeneReviews supports risk-factor mitigation as prevention of primary manifestations.
- name: Peripheral Neuropathy Rehabilitation
  description: >
    Supportive management for peripheral neuropathy includes bracing and exercise
    when weakness or gait impairment is present.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: physical therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  target_mechanisms:
  - target: Peripheral axonal neuropathy
    treatment_effect: MODULATES
    description: Bracing and exercise target functional impairment from neuropathy.
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "transient bracing (such as ankle-foot orthosis) and exercise for those with peripheral neuropathy"
      explanation: GeneReviews recommends exercise for neuropathy manifestations.
  - target: Distal muscle weakness
    treatment_effect: MODULATES
    description: Orthotic support can mitigate motor weakness from peripheral neuropathy.
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "transient bracing (such as ankle-foot orthosis)"
      explanation: GeneReviews lists bracing for peripheral neuropathy-related weakness.
  evidence:
  - reference: PMID:31751110
    reference_title: "Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "transient bracing (such as ankle-foot orthosis) and exercise for those with peripheral neuropathy"
    explanation: GeneReviews supports supportive rehabilitation for neuropathy.
- name: Tonsillectomy for Obstructive Tonsillar Disease
  description: >
    Tonsillectomy is used when enlarged orange tonsils cause airway obstruction
    or mass symptoms; it is symptomatic management and does not address the
    ABCA1 lipid-efflux defect.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: surgical procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Orange discolored tonsils
    treatment_effect: MODULATES
    description: Surgery addresses obstructive or mass-effect symptoms from enlarged tonsils.
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Tonsillectomy in those with airway obstruction or mass symptoms"
      explanation: GeneReviews recommends tonsillectomy when airway obstruction or mass symptoms are present.
  evidence:
  - reference: PMID:31751110
    reference_title: "Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Tonsillectomy in those with airway obstruction or mass symptoms"
    explanation: GeneReviews supports tonsillectomy as treatment of tonsillar manifestations.
- name: Corneal Transplantation for Vision-Limiting Corneal Opacity
  description: >
    Corneal transplantation is used for corneal opacities that interfere with
    daily living; it is symptomatic management of ocular lipid-storage
    complications rather than restoration of ABCA1 function.
  treatment_term:
    preferred_term: corneal transplantation
    term:
      id: NCIT:C210959
      label: Corneal Transplantation
  target_mechanisms:
  - target: Corneal opacity
    treatment_effect: MODULATES
    description: Corneal transplantation addresses vision-limiting corneal opacity.
    evidence:
    - reference: PMID:31751110
      reference_title: "Tangier Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "corneal transplantation for\ncorneal opacities that interfere with daily living"
      explanation: GeneReviews recommends corneal transplantation when corneal opacities interfere with daily living.
  evidence:
  - reference: PMID:31751110
    reference_title: "Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "corneal transplantation for\ncorneal opacities that interfere with daily living"
    explanation: GeneReviews supports corneal transplantation as treatment for vision-limiting corneal opacity in Tangier disease.
- name: Genetic Counseling and Family Screening
  description: >
    Genetic counseling, lipid-profile screening, apoA-I testing, and targeted
    familial variant testing can identify at-risk relatives and support
    reproductive counseling.
  treatment_term:
    preferred_term: genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:31751110
    reference_title: "Tangier Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Carrier testing for at-risk relatives and prenatal testing"
    explanation: GeneReviews supports genetic counseling and familial testing when variants are known.
  - reference: PMID:39817629
    reference_title: "The clinical presentation and genetic diagnosis of Tangier disease in the pediatric age group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Family screening should be recommended to patients with consanguineous marriages after diagnosis of TD."
    explanation: Pediatric cohort review recommends family screening after diagnosis.
- name: Surveillance and complication prevention
  notes: >-
    NCIT was searched through OAK/OLS on 2026-09-05. Surveillance (C15719) denotes systematic health-data collection, Patient Observation (C15722) implies withholding treatment, and Disease Screening (C15419) concerns detection of usually asymptomatic disease. No single precise action term was selected for this combination of established-disease follow-up and complication precautions.
  description: >-
    Assess hepatosplenomegaly at visits, obtain annual neurologic/ophthalmologic evaluation and adult cardiovascular assessment, and check blood counts as indicated. Avoid contact sports with hepatosplenomegaly and medications that worsen peripheral neuropathy.
  treatment_term:
    preferred_term: Clinical surveillance
  evidence:
  - reference: PMID:31751110
    reference_title: Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: neurology and ophthalmology evaluations annually; cardiovascular risk assessment of atherosclerotic plaque burden annually beginning in adulthood; complete blood count with differential as clinically indicated.
    explanation: >-
      GeneReviews supplies multisystem surveillance.
  - reference: PMID:31751110
    reference_title: Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: medications that are toxic or potentially toxic to those who are predisposed to the development of peripheral neuropathy; contact sports in those with hepatosplenomegaly.
    explanation: >-
      GeneReviews identifies condition-specific precautions.
- name: Miglustat investigation
  description: >-
    A 2014 withdrawal/rechallenge case and the MUSTANG nonrandomized n-of-1 ABAB study suggest possible neuropathy benefit. MUSTANG did not meet prespecified clinical-difference thresholds during the crossover phase; 21-month continuation improvement and blood-cell biomarker changes remain uncontrolled. The disease-specific therapeutic mechanism and general efficacy are unresolved.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: miglustat
      term:
        id: CHEBI:50381
        label: miglustat
  evidence:
  - reference: PMID:41212481
    reference_title: 'Miglustat as a Treatment for Adults with Tangier Disease Neuropathy: The MUSTANG N-of-1 Trial with 21 months Clinical Observation.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: None of the co-primary endpoint differences reached our pre-determined level of clinical difference.
    explanation: >-
      MUSTANG found small clinical signals and later extension improvement, but failed prespecified clinical-difference thresholds; one unblinded nonrandomized ABAB patient cannot establish general efficacy.
  - reference: PMID:25227739
    reference_title: Effects of miglustat treatment in a patient affected by an atypical form of Tangier disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The mechanisms by which miglustat ameliorates at least some clinical manifestations of TD needs to be further investigated.
    explanation: >-
      The initial case generated a treatment hypothesis without establishing mechanism or population efficacy.
  therapeutic_modality: SMALL_MOLECULE
references:
- reference: ORPHA:31150
  title: Tangier disease
- reference: PMID:22913675
  title: "Tangier disease: epidemiology, pathophysiology, and management."
- reference: PMID:31751110
  title: "Tangier Disease."
  tags:
  - GeneReviews
- reference: PMID:33994407
  title: "Current Diagnosis and Management of Tangier Disease."
- reference: PMID:10431236
  title: "Mutations in ABC1 in Tangier disease and familial high-density lipoprotein deficiency."
- reference: PMID:10431237
  title: "The gene encoding ATP-binding cassette transporter 1 is mutated in Tangier disease."
- reference: PMID:10431238
  title: "Tangier disease is caused by mutations in the gene encoding ATP-binding cassette transporter 1."
- reference: PMID:10525055
  title: "The Tangier disease gene product ABC1 controls the cellular apolipoprotein-mediated lipid removal pathway."
- reference: PMID:7130397
  title: "Tangier disease. High density lipoprotein deficiency due to defective metabolism of an abnormal apolipoprotein A-i (ApoA-ITangier)."
- reference: PMID:162820
  title: "The pathology of Tangier disease. A light and electron microscopic study."
- reference: PMID:11309399
  title: "ATP-binding cassette transporter A1 (ABCA1) functions as a cholesterol efflux regulatory protein."
- reference: PMID:27565770
  title: "Diagnosis and treatment of high density lipoprotein deficiency."
- reference: PMID:39817629
  title: "The clinical presentation and genetic diagnosis of Tangier disease in the pediatric age group."
discussions:
- discussion_id: context_limits
  kind: KNOWLEDGE_GAP
  prompt: Which experimental extensions of ABCA1 dysfunction determine human clinical severity?
  attaches_to:
  - pathophysiology#Impaired Cellular Lipid Efflux
  - pathophysiology#Myeloid Inflammasome Activation
  - pathophysiology#Peripheral Nerve Dysfunction
  - pathophysiology#Abnormal PMP22 Processing
  rationale: >-
    Human S1P signaling effects remain unquantified; one Tangier plasma sample established low total sphingolipids, while apoM/S1P results came from hepatic knockout mice. PMP22/ABCA1 interactions support nerve-cell lipid homeostasis but do not prove that disrupted binding explains all neuropathy. HSPC myeloproliferation cited by OpenScientist arose in rheumatoid-arthritis models with multiple altered efflux genes and remains untested in Tangier patients. These are mechanistic leads rather than established universal clinical branches.
  evidence:
  - reference: PMID:37601634
    reference_title: Hepatocyte ABCA1 deficiency is associated with reduced HDL sphingolipids.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: we report a drastic reduction of total SL levels in plasma of a Tangier patient with compound heterozygosity for mutations in ABCA1.
    explanation: >-
      One-patient plasma lipidomics supports sphingolipid depletion; S1P-specific reduction in this paper was shown in hepatic knockout mice.
  - reference: PMID:31061090
    reference_title: PMP22 Regulates Cholesterol Trafficking and ABCA1-Mediated Cholesterol Efflux.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant.
    explanation: >-
      Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.
  - reference: PMID:29905812
    reference_title: Defective cholesterol metabolism in haematopoietic stem cells promotes monocyte-driven atherosclerosis in rheumatoid arthritis.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: HSPCs expansion was associated with an increase in the cholesterol content, due to a down-regulation of cholesterol efflux genes, Apoe, Abca1, and Abcg1.
    explanation: >-
      The RA model includes several downregulated efflux genes and is not direct Tangier HSPC evidence.
- discussion_id: unresolved_distal_manifestations
  kind: KNOWLEDGE_GAP
  prompt: What links the ABCA1 defect to less-characterized hematologic and distal manifestations?
  attaches_to:
  - phenotypes#Dry skin
  - phenotypes#Nail dystrophy
  - phenotypes#Ectropion
  - phenotypes#Abdominal pain
  - phenotypes#Left ventricular hypertrophy
  - phenotypes#Reticulocytosis
  - phenotypes#Stomatocytosis
  - phenotypes#Hemolytic anemia
  - phenotypes#Anemia
  rationale: >-
    Orphanet and GeneReviews record these manifestations, but the phenotype lists do not establish that tissue storage causes each one. In particular, the reported red-cell abnormalities and the association of splenomegaly with reticulocyte hyperplasia do not resolve the causal intermediates for anemia, hemolytic anemia, stomatocytosis, or reticulocytosis. Their clinical annotations are retained without assigning a storage-to-red-cell causal chain; the previously removed anemia edge lacked that support. The syringomyelia annotation is replaced with the documented syringomyelia-like peripheral neuropathy pattern; a spinal cord cavity requires separate evidence.
clinical_trials:
- name: ISRCTN17945917
  phase: NOT_APPLICABLE
  status: COMPLETED
  description: >-
    MUSTANG: a nonrandomized, n-of-1 ABAB on/off miglustat study over two years, followed by 21 months of compassionate treatment. Registered with ISRCTN; the publication incorrectly calls the ISRCTN identifier a ClinicalTrials.gov identifier.
  evidence:
  - reference: ICTRP:ISRCTN17945917
    reference_title: Investigating the role of miglustat in the management of a patient with Tangier Disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: This is a n-of-1 trial of ABAB design.
    explanation: >-
      WHO ICTRP/ISRCTN confirms the trial registration and single-case design.
  - reference: PMID:41212481
    reference_title: 'Miglustat as a Treatment for Adults with Tangier Disease Neuropathy: The MUSTANG N-of-1 Trial with 21 months Clinical Observation.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: None of the co-primary endpoint differences reached our pre-determined level of clinical difference.
    explanation: >-
      MUSTANG found small clinical signals and later extension improvement, but failed prespecified clinical-difference thresholds; one unblinded nonrandomized ABAB patient cannot establish general efficacy.
  - reference: PMID:41212481
    reference_title: 'Miglustat as a Treatment for Adults with Tangier Disease Neuropathy: The MUSTANG N-of-1 Trial with 21 months Clinical Observation.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: An n-of-1 ABAB study, alternating on and off treatment for 6-month periods, total study duration of 2 years with an additional compassionate-access period of 21 months.
    explanation: >-
      The primary publication describes the completed experiment; registration was also checked at ISRCTN17945917.
- name: NCT01782027
  phase: NOT_APPLICABLE
  status: TERMINATED
  description: >-
    Mendelian reverse-cholesterol-transport tracer-method study including Tangier disease and other monogenic HDL disorders; terminated for lack of funding, with 17 total participants. This was not a therapeutic efficacy trial. Registry checked 2026-09-04.
  evidence:
  - reference: clinicaltrials:NCT01782027
    reference_title: A Validation Study Evaluating the Use of 3H-Cholesterol Bound to Albumin as a Method to Assess Reverse Cholesterol Transport in Subjects With Monogenic Diseases Affecting HDL Metabolism
    supports: SUPPORT
    evidence_source: OTHER
    snippet: The purpose of this study is to investigate the use of radiolabeled particulate cholesterol administered intravenously in association with albumin, as a method to study reverse cholesterol transport (RCT) in people carrying mutations in genes known to affect high density lipoprotein (HDL) metabolism
    explanation: >-
      Registry summary establishes a tracer-method intervention rather than a Tangier-specific treatment.
animal_models:
- name: Myeloid Abca1/Abcg1-deficient bone marrow in Ldlr-null recipients
  species: Mouse
  genotype: Myeloid Abca1/Abcg1 deficiency with Ldlr-null recipients
  publication: PMID:29588315
  description: Hyperlipidemic bone-marrow transplantation model used for Nlrp3/Caspase-1/11 perturbation.
  modeled_mechanisms:
  - target: Myeloid Inflammasome Activation
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    limitations: Combined Abca1/Abcg1 deficiency, Ldlr-null background and Western diet do not reproduce isolated human ABCA1 deficiency.
    evidence:
    - reference: PMID:36537208
      reference_title: Cholesterol accumulation in macrophages drives NETosis in atherosclerotic plaques via IL-1β secretion.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: Macrophage, but not neutrophil Abca1/g1 deficiency activated inflammasomes in macrophages and neutrophils, reflected by caspase-1 cleavage, and induced NETosis in plaques.
      explanation: >-
        Conditional deletions identify macrophage-driven crosstalk in a combined-transporter Ldlr-null mouse system.
- name: Abca1-null peripheral nerve model
  species: Mouse
  genotype: Abca1 knockout
  publication: PMID:31061090
  description: Peripheral nerve protein processing studied alongside reciprocal Pmp22-null Schwann-cell experiments.
  modeled_mechanisms:
  - target: Abnormal PMP22 Processing
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: TISSUE
    limitations: Mouse nerve protein/trafficking phenotype; not evidence that all human variants disrupt the same interaction or have the same neuropathy course.
    evidence:
    - reference: PMID:31061090
      reference_title: PMP22 Regulates Cholesterol Trafficking and ABCA1-Mediated Cholesterol Efflux.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: In nerves from ABCA1 KO mice, the expression of PMP22 was significantly elevated and the subcellular processing of the overproduced protein was aberrant.
      explanation: >-
        Primary Abca1-null nerve experiments support altered PMP22 processing; human variant-specific clinical causation remains unresolved.
experimental_models:
- name: ABCA1 intracellular-domain variant expression screen
  experimental_model_type: CELL_LINE
  description: Cell-based cholesterol-efflux and surface-localization assays for 74 ABCA1 variants.
  modeled_mechanisms:
  - target: Impaired Cellular Lipid Efflux
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: CELLULAR
    limitations: Tests intracellular-domain variants in an expression system; clinical penetrance and tissue phenotypes require separate evidence.
    evidence:
    - reference: PMID:40617357
      reference_title: Functional characterization of genetic variants affecting the intracellular domains of ATP-binding cassette transporter A1 (ABCA1).
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: we have characterized 74 variants affecting the intracellular domains of ABCA1 by assessing cholesterol efflux activity and cell surface localization of the protein
      explanation: >-
        The expression assay quantifies allele-specific efflux/localization, not organ-level clinical severity.
differential_diagnoses:
- name: LCAT deficiency and fish-eye disease
  description: Inherited severe HDL deficiency with prominent corneal disease; complete LCAT deficiency can include renal disease.
  distinguishing_features:
  - ABCA1 testing, the orange-tonsil/neuropathy pattern and assessment of LCAT deficiency help distinguish these conditions.
  evidence:
  - reference: PMID:33994407
    reference_title: Current Diagnosis and Management of Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: LCAT deficiency, apoA-I deficiency and secondary hypo-HDL-cholesterolemia
    explanation: >-
      The diagnostic criteria require exclusion of alternative causes of severe HDL deficiency.
- name: Apolipoprotein A-I deficiency
  description: APOA1-related severe HDL/apoA-I deficiency is an alternative inherited cause of low HDL.
  distinguishing_features:
  - Evaluate APOA1 and the clinical pattern rather than diagnosing Tangier disease from HDL concentration alone.
  evidence:
  - reference: PMID:33994407
    reference_title: Current Diagnosis and Management of Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: LCAT deficiency, apoA-I deficiency and secondary hypo-HDL-cholesterolemia
    explanation: >-
      The diagnostic criteria require exclusion of alternative causes of severe HDL deficiency.
- name: Secondary severe HDL deficiency
  description: Severe liver disease and drug effects can produce marked HDL reduction.
  distinguishing_features:
  - Review liver disease and medication history before attributing low HDL to ABCA1 deficiency.
  evidence:
  - reference: PMID:33994407
    reference_title: Current Diagnosis and Management of Tangier Disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Care should be taken to exclude secondary hypo-HDL-cholesterolemia, such as in severe liver diseases, especially liver cirrhosis, and drug-induced hypo-HDL-cholesterolemia
    explanation: >-
      The management review describes acquired biochemical phenocopies.

📚

References & Deep Research

References

13

ORPHA:31150

Tangier disease

No top-level findings curated for this source.

PMID:22913675

Tangier disease: epidemiology, pathophysiology, and management.

No top-level findings curated for this source.

PMID:31751110

Tangier Disease.

No top-level findings curated for this source.

PMID:33994407

Current Diagnosis and Management of Tangier Disease.

No top-level findings curated for this source.

PMID:10431236

Mutations in ABC1 in Tangier disease and familial high-density lipoprotein deficiency.

No top-level findings curated for this source.

PMID:10431237

The gene encoding ATP-binding cassette transporter 1 is mutated in Tangier disease.

No top-level findings curated for this source.

PMID:10431238

Tangier disease is caused by mutations in the gene encoding ATP-binding cassette transporter 1.

No top-level findings curated for this source.

PMID:10525055

The Tangier disease gene product ABC1 controls the cellular apolipoprotein-mediated lipid removal pathway.

No top-level findings curated for this source.

PMID:7130397

Tangier disease. High density lipoprotein deficiency due to defective metabolism of an abnormal apolipoprotein A-i (ApoA-ITangier).

No top-level findings curated for this source.

PMID:162820

The pathology of Tangier disease. A light and electron microscopic study.

No top-level findings curated for this source.

PMID:11309399

ATP-binding cassette transporter A1 (ABCA1) functions as a cholesterol efflux regulatory protein.

No top-level findings curated for this source.

PMID:27565770

Diagnosis and treatment of high density lipoprotein deficiency.

No top-level findings curated for this source.

PMID:39817629

The clinical presentation and genetic diagnosis of Tangier disease in the pediatric age group.

No top-level findings curated for this source.

Deep Research

1

Tangier Disease Deep Research Fallback ▸

Tangier Disease Deep Research Fallback

Provider attempts

timeout 120 just research-disorder falcon Tangier_Disease
Result: timed out after 120 seconds.
Terminal output ended with: Recipe research-disorder was terminated by signal 15.
No research/Tangier_Disease-deep-research-falcon.md file was produced.
timeout 120 just research-disorder openai Tangier_Disease
Result: timed out after 120 seconds.
Terminal output ended with: Recipe research-disorder was terminated by signal 15.
No research/Tangier_Disease-deep-research-openai.md file was produced.

Evidence scope used

The curation proceeded from generated Orphanet cache ORPHA:31150 plus validator-fetched PubMed caches for the core Tangier disease literature:

PMID:22913675 - epidemiology, pathophysiology, and management review.
PMID:31751110 - GeneReviews Tangier disease entry.
PMID:33994407 - current diagnosis and management review.
PMID:10431236, PMID:10431237, PMID:10431238 - independent 1999 ABCA1/Tangier disease discovery papers.
PMID:10525055 and PMID:11309399 - ABCA1 lipid-efflux functional studies.
PMID:7130397 and PMID:162820 - classic HDL/apolipoprotein kinetics and tissue pathology studies.
PMID:27565770 - HDL deficiency diagnosis and treatment review.
PMID:39817629 - pediatric clinical presentation and genetic diagnosis cohort.

Curation conclusion

The evidence consistently supports a canonical mechanism in which biallelic ABCA1 pathogenic variants impair apoA-I-mediated cholesterol and phospholipid efflux, blocking HDL particle formation and causing extremely low HDL-C/apoA-I. Reduced cellular cholesterol export leads to cholesteryl ester accumulation in reticuloendothelial tissues and Schwann cells, explaining orange tonsils, hepatosplenomegaly, lymphadenopathy, corneal/skin/nail findings, and peripheral neuropathy. Cardiovascular risk is variable but supported by reviews of reported cases; treatment remains non-curative and focuses on modifiable cardiovascular risk, supportive neuropathy care, tonsillectomy when obstructive, and genetic counseling/family screening.

Tangier_Disease

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References & Deep Research

References

Deep Research

Tangier Disease Deep Research Fallback

Provider attempts

Evidence scope used

Curation conclusion