Chediak-Higashi Syndrome

1. Disease Information

Overview. Chédiak-Higashi syndrome (CHS) is a rare autosomal recessive multisystem disorder caused by biallelic loss-of-function variants in LYST (also called CHS1), which encodes the lysosomal trafficking regulator, a ~429-kDa cytoplasmic protein that governs the size, biogenesis, and fusion/fission dynamics of lysosomes and lysosome-related organelles (LROs). The pathognomonic cellular hallmark is giant cytoplasmic granules in leukocytes (and other granule-containing cells), visible on peripheral blood smear. The clinical tetrad-plus is: (1) partial oculocutaneous albinism (silvery hair, photophobia, nystagmus, reduced visual acuity); (2) recurrent pyogenic infections from neutrophil and NK/cytotoxic-lymphocyte dysfunction; (3) a mild bleeding diathesis from platelet dense-granule (δ storage pool) deficiency; and (4) progressive neurologic degeneration (peripheral neuropathy, ataxia, parkinsonism, cognitive decline) that dominates in long-term survivors. The life-threatening "accelerated phase" is a hemophagocytic-lymphohistiocytosis (HLH)-like lymphoproliferative infiltration, frequently EBV-triggered, and is the usual cause of early death.

The 2024 Front Immunol review states the core genetics succinctly (verified cache quote, PMID:38774881):

"Mutations to the LYST gene result in Chédiak-Higashi syndrome, an autosomal recessive immunodeficiency characterized by defective granule exocytosis, cytotoxicity"

And the J Med Genet mutation-spectrum paper (verified cache quote, PMID:37788905):

"Chediak-Higashi syndrome (CHS) is a rare autosomal recessive disorder characterised by partial oculocutaneous albinism, a bleeding diathesis, immunological dysfunction and neurological impairment. Bi-allelic loss-of-function variants in LYST cause CHS. LYST encodes the lysosomal trafficking regulator, a highly conserved 429 kDa cytoplasmic protein with an unknown function."

Key identifiers. - MONDO: MONDO:0008963 (Chédiak-Higashi syndrome) — matches the disease_term in the existing draft. - OMIM: #214500 (CHS, phenotype); LYST gene 606897. - Orphanet: ORPHA:167 (classic Chédiak-Higashi syndrome); ORPHA:352723 (attenuated/atypical Chédiak-Higashi syndrome). - ICD-10: E70.3 (albinism group); ICD-11: 4A00.1 (predominantly antibody/combined immunodeficiency with syndromic features) / commonly cross-referenced under immune dysregulation. - MeSH: D002609 (Chediak-Higashi Syndrome). - Disease Ontology: DOID:2935. - UMLS: C0007965.

Synonyms / alternative names. Chédiak-Higashi syndrome; Chediak-Steinbrinck-Higashi syndrome; Béguez César disease (Béguez-César-Steinbrinck-Chédiak-Higashi); CHS; attenuated/atypical CHS (adult-onset milder form).

Data derivation. Information is drawn from disease-level aggregated resources (OMIM, GeneReviews, Orphanet, published natural-history cohorts — notably the NIH intramural CHS natural history study led by Introne/Gahl/Malicdan) rather than individual EHR records. The NIH cohort (NCT00005917) is the largest longitudinal source.

Sources: OMIM #214500; GeneReviews NBK5188; Orphanet ORPHA:167.

2. Etiology

Primary cause (genetic). CHS is monogenic and autosomal recessive — biallelic (homozygous or compound heterozygous) loss-of-function variants in LYST (chromosome 1q42.3). There are no established non-genetic causes; environmental factors act only as triggers of downstream events (see below).

Genetic risk factors. - Causal gene: LYST / CHS1 (the only known disease gene). HGNC:1968. - Consanguinity substantially increases risk, as expected for a rare AR disorder; many reported families are consanguineous (e.g., the atypical-CHS Pakistani kindred, verified cache quote, PMID:23521865): "In a consanguineous Pakistani kindred with clinical phenotypes consistent with attenuated CHS, we performed SNP array-based homozygosity mapping and whole gene sequencing of LYST." - Genotype as severity modifier (allelic/dose effect): variant class is the dominant modifier of phenotype (see Section 4). Two null (nonsense/frameshift) alleles → severe classic CHS; at least one missense/in-frame allele with residual protein → milder atypical/attenuated CHS.

Environmental risk / trigger factors. No environmental factor causes CHS, but viral infection (especially Epstein-Barr virus) is the principal trigger of the accelerated phase / HLH (verified cache quote, PMID:33329964): the reported child "was in advanced stage of HLH induced by an Epstein-Barr virus (EBV) infection." Other infections and immune activation can likewise precipitate the accelerated phase.

Protective factors. No established genetic or environmental protective factors. The only "protective" modifier is retention of partial LYST function (hypomorphic missense/in-frame alleles), which shifts the phenotype toward the attenuated end. Early allogeneic HSCT before accelerated phase is protective against hematologic/immunologic death (Section 12).

Gene-environment interaction. The central GxE axis is LYST-deficient cytotoxic-lymphocyte impairment × viral antigen load → uncontrolled macrophage activation (HLH/accelerated phase). The defective granule-dependent killing by NK and CD8⁺ T cells cannot clear virally infected cells, driving the hyperinflammatory cascade — the same mechanism as familial HLH.

3. Phenotypes

For each, I give type, characteristics, and a suggested HP term (verify labels/IDs with OAK before curation).

Onset/severity/progression characteristics (verified cache quote, PMID:23521865), describing the attenuated end and its neurodegeneration:

"A small number of reports of rare, attenuated forms of CHS exist, with affected individuals exhibiting progressive neurodegenerative disease beginning in early adulthood with cognitive decline, parkinsonism, features of spinocerebellar degeneration, and peripheral neuropathy, as well as subtle pigmentary abnormalities and subclinical or absent immune dysfunction."

Accelerated-phase phenotype cluster (verified cache quote, PMID:33329964):

"a high risk of developing hemophagocytic lymphohistiocytosis characterized by pancytopenia, high fever, and lymphohistiocytic infiltration of liver, spleen, and lymph nodes."

Quality-of-life impact. Severe in classic CHS (chronic infection burden, transfusion/immunoglobulin dependence, transplant morbidity, early mortality). In attenuated CHS, QoL is dominated by the progressive, treatment-refractory neurodegeneration (gait, cognition, autonomic function) that HSCT does not correct. No CHS-specific validated QoL instrument exists; generic tools (PROMIS, EQ-5D) would apply.

4. Genetic / Molecular Information

Causal gene. LYST (lysosomal trafficking regulator), aka CHS1; HGNC:1968; NCBI Gene 1130; chromosome 1q42.3; OMIM 606897. Transcript NM_000081.4. Encodes a highly conserved ~429-kDa (3801-aa) cytoplasmic protein with a C-terminal BEACH domain and WD40 repeats, plumbing scaffolding/protein-interaction functions in membrane trafficking; its precise molecular function remains only partly defined ("80-year traffic jam," PMID:38774881).

• Human gene identification: Nagle DL et al., Nat Genet 1996 (PMID:8896560, "Identification and mutation analysis of the complete gene for Chediak-Higashi syndrome") and Barbosa MD et al., Nature 1996 (PMID:8600540, "Identification of the homologous beige and Chediak-Higashi syndrome genes") — both leveraging the murine beige homolog. Fetch-verify before citing.
• The murine ortholog (Lyst/beige) was cloned first (verified cache quote, PMID:8673129): "The beige mutation is a murine autosomal recessive disorder, resulting in hypopigmentation, bleeding and immune cell dysfunction. The gene defective in beige is thought to be a homologue of the gene for the human disorder Chediak-Higashi syndrome."

Pathogenic variant spectrum & classification. The definitive modern catalog is the NIH mutation-spectrum review (verified cache quote, PMID:37788905):

"we compiled a total of 147 variants in LYST, including 61 frameshift variants (41%), 44 nonsense variants (30%), 23 missense variants (16%), 13 splice site variants or small genomic deletions for which the coding effect is unknown (9%), 5 in-frame variants (3%) and 1 start-loss variant (1%)."

• Variant classes: predominantly truncating (frameshift + nonsense = ~71%), with missense, splice, and in-frame/small deletions completing the spectrum. Variants distribute across the large gene without a strong hotspot.
• ACMG/AMP classification: most reported variants are pathogenic/likely pathogenic; the paper explicitly re-classified novel and reported variants per ACMG/AMP guidelines.
• Functional consequence: loss of function (truncating alleles → absent/nonfunctional protein). No gain-of-function or dominant-negative mechanism is established; heterozygous carriers are unaffected.
• Origin: germline, biallelic. No somatic-mutation disease mechanism.
• Allele frequency: individual pathogenic variants are private/ultra-rare in gnomAD; carrier frequency is very low and population-nonspecific (consistent with <500 reported cases worldwide).

Genotype-phenotype correlation (key clinical genetics point) (verified cache quote, PMID:37788905):

"a genotype-phenotype correlation emerged, whereby individuals harbouring at least one missense or in-frame variant generally resulted in milder disease, while those with two nonsense or frameshift variants generally had more severe disease."

Modifier genes / epigenetics / chromosomal abnormalities. No robustly established trans-acting modifier genes; the primary "modifier" is the LYST allele class itself (residual function). No CHS-specific epigenetic signature is established. CHS is a single-gene disorder, not a copy-number/aneuploidy syndrome, though large intragenic deletions/duplications in LYST occur (e.g., the feline model's large LYST duplication).

5. Environmental Information

• Environmental factors: None causal. Sun/UV exposure is relevant only insofar as albinism reduces photoprotection (increased actinic damage risk), and photophobia mandates light avoidance.
• Lifestyle factors: None causal. Infection-avoidance behaviors and prophylaxis modify infection burden.
• Infectious agents (as triggers, not causes): Epstein-Barr virus is the archetypal trigger of the accelerated phase/HLH (PMID:33329964). Other herpesviruses and bacterial/viral infections can precipitate accelerated phase or contribute to the chronic infection burden (recurrent Staphylococcus aureus, Streptococcus, and other pyogenic organisms; NCBI Taxonomy: EBV = NCBITaxon:10376; S. aureus = NCBITaxon:1280).

6. Mechanism / Pathophysiology

Central lesion → causal chain. LYST loss of function → dysregulated biogenesis/fission of lysosomes and LROs → giant, dysfunctional granules → cell-type-specific failures of granule-dependent processes → multisystem phenotype.

The LRO framework is well summarized (verified cache quote, PMID:18544035):

"Lysosome-related organelles (LROs) are a heterogeneous group of vesicles that share various features with lysosomes, but are distinct in function, morphology, and composition. The biogenesis of LROs employs a common machinery, and genetic defects in this machinery can affect all LROs or only an individual LRO, resulting in a variety of clinical features."

Cell-type-specific mechanisms (upstream → downstream):

1. Melanocytes → albinism. Giant melanosomes fail to transfer melanin normally to keratinocytes/hair → partial oculocutaneous albinism, silvery hair (light-microscopy hair shafts show pathognomonic large, evenly distributed pigment clumps). Cells: melanocyte CL:0000148. Location: skin UBERON:0002097, hair follicle UBERON:0002073, eye UBERON:0000970.

2. Neutrophils → infection. Giant azurophilic granules impair chemotaxis and regulated degranulation; intramedullary destruction of granulocyte precursors causes neutropenia → recurrent pyogenic infection. Cell: neutrophil CL:0000775. GO: regulated exocytosis GO:0045055; neutrophil chemotaxis GO:0030593.

3. NK cells & cytotoxic T lymphocytes → immune dysregulation/HLH. Defective cytotoxic granule (secretory lysosome) polarization and exocytosis → failed perforin/granzyme delivery → impaired killing of infected/activated cells → uncontrolled macrophage activation → HLH/accelerated phase. Cells: NK cell CL:0000623, CD8⁺ cytotoxic T cell CL:0000910, macrophage CL:0000235. GO: natural killer cell mediated cytotoxicity GO:0042267; T cell mediated cytotoxicity GO:0001913.

4. Platelets → bleeding. Dense-granule (δ) storage pool deficiency → impaired secondary aggregation → mild bleeding diathesis. Cell: platelet CL:0000233. GO: platelet dense granule organization GO:0060155; platelet degranulation GO:0002576.

5. Neurons/Purkinje cells → neurodegeneration. Progressive cerebellar Purkinje-cell loss, peripheral axonal degeneration, with emerging evidence of neuroinflammation (microglial activation, complement, proinflammatory lipids). This arm is largely independent of the hematologic disease and not corrected by HSCT. Cells: Purkinje cell CL:0000121, peripheral neuron, microglial cell CL:0000129. Location: cerebellum UBERON:0002037, peripheral nervous system UBERON:0000010.

Molecular pathway / cellular processes / subcellular compartments. Core process is lysosome/LRO organization (GO:0007040 lysosome organization) and vesicle-mediated transport / regulated secretion (GO:0016192). Subcellular compartments: lysosome GO:0005764, melanosome GO:0042470, secretory/cytolytic granule, endosome. Protein dysfunction is loss of a scaffolding/BEACH-domain regulator, not enzyme deficiency — CHS is a trafficking disorder, distinct from classic lysosomal storage diseases (no accumulating substrate; the defect is organelle size/dynamics).

Immune involvement. Combined innate + adaptive immunodeficiency (neutrophil, NK, CTL) plus immune dysregulation (HLH-predisposition) — CHS sits in the IUIS "immune dysregulation / familial HLH" category (consistent with the draft's iuis_category).

Metabolic/-omics. No primary metabolic derangement. Recent mouse transcriptomics/lipidomics implicate neuroinflammatory signaling and proinflammatory lipids in the cerebellum (PMID:40681653, below). No established human proteomic/metabolomic diagnostic signature.

7. Anatomical Structures Affected

• Organ/system level: Hematopoietic/immune system (bone marrow UBERON:0002371, spleen UBERON:0002106, lymph nodes UBERON:0000029, liver UBERON:0002107); integument (skin UBERON:0002097, hair UBERON:0001037); eye (UBERON:0000970, retina/fovea); nervous system — central (cerebellum UBERON:0002037, brain UBERON:0000955) and peripheral (UBERON:0000010).
• Tissue/cell level: melanocytes, neutrophils, NK cells, cytotoxic T cells, platelets/megakaryocytes, macrophages/histiocytes, Purkinje neurons, peripheral axons/Schwann cells (see CL terms in Section 6).
• Subcellular level: lysosome (GO:0005764), melanosome (GO:0042470), cytolytic/secretory granule, dense granule, endosomal compartment.
• Localization/lateralization: systemic and bilateral/symmetric (albinism, neurodegeneration); hepatosplenomegaly/lymphadenopathy are central/generalized.

8. Temporal Development

• Onset. Classic CHS presents in infancy/early childhood (albinism from birth; infections and giant granules early). Attenuated/atypical CHS presents in adolescence–adulthood, often first with neurologic disease. Onset pattern for the accelerated phase is subacute/acute and can occur at any age.
• Progression/stages. (1) Childhood classic disease — albinism, infections, bleeding, giant granules; (2) accelerated phase / HLH — episodic, life-threatening, EBV-triggerable; (3) neurodegenerative phase — progressive in survivors and in attenuated CHS. The albinism is stable/non-progressive; the neurologic disease is relentlessly progressive.
• Course pattern. Chronic lifelong; punctuated by episodic accelerated-phase crises. Accelerated-phase HLH shows remission in ~75% within 8 weeks on HLH-directed therapy but relapses are common and responses wane (StatPearls/HLH-2004).
• Critical intervention window. HSCT performed in the pre-accelerated / remission phase is the key window for improving survival (Section 11–12).

9. Inheritance and Population

Epidemiology. Ultra-rare: fewer than 500 cases reported worldwide; Orphanet prevalence <1/1,000,000. Underdiagnosis is likely, especially of attenuated forms. No strong sex predilection (autosomal). ~85–90% are the severe "classic" childhood form; ~10–15% attenuated/atypical.

Inheritance genetics. - Pattern: autosomal recessive (HP:0000007). Sibling recurrence risk 25%. From GeneReviews (as reflected in the draft's inheritance evidence): "CHS is inherited in an autosomal recessive manner. If both parents are known to be heterozygous for a LYST pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected." - Penetrance: essentially complete for biallelic LOF; expressivity is variable and strongly allele-class-dependent (Section 4). - Anticipation: none (not a repeat-expansion disorder). - Consanguinity/founder effects: consanguinity is a major contributor; private variants predominate — no single global founder allele, though individual kindreds/populations carry recurrent variants. - Carrier frequency: very low; population-nonspecific.

Population demographics. Reported across all ethnicities and geographies; no defined endemic region. Higher observed rates in consanguineous populations. Sex ratio ~1:1. Age distribution bimodal by form (early childhood classic vs. adult attenuated).

Sources: Orphanet ORPHA:167; GeneReviews NBK5188.

10. Diagnostics

Clinical/laboratory tests. - Peripheral blood smear / bone marrow: giant peroxidase-positive granules in neutrophils and other leukocytes — the pathognomonic finding. Giant granules were the diagnostic anchor in the reported EBV-HLH case (verified cache quote, PMID:33329964): the child was "diagnosed with Chediak-Higashi Syndrome based on silvery hair, pathognomonic hair microscopy and giant azurophilic granules in granulocytes." - Light microscopy of hair shaft: regularly distributed large melanin clumps (distinguishes CHS from Griscelli/Elejalde). - CBC: neutropenia, and in accelerated phase pancytopenia; NK-cell functional assay: reduced cytotoxicity; platelet function/dense-granule studies: δ-storage-pool defect; HLH workup (ferritin, sIL-2R, triglycerides, fibrinogen, hemophagocytosis on marrow) when accelerated phase suspected. - Ophthalmologic exam: iris transillumination, foveal hypoplasia, nystagmus. - LOINC: neutrophil count 751-8; ferritin 2276-4 (HLH context).

Genetic testing. - Confirmatory: biallelic pathogenic LYST variants by single-gene sequencing, or via immunodeficiency/HLH gene panels, WES, or WGS; MLPA/CMA to capture large LYST deletions/duplications. The NIH review emphasizes that improved variant classification enables earlier diagnosis (verified cache quote, PMID:37788905): "The identification of novel pathogenic LYST variants and improvements in variant classification will provide earlier diagnoses and improved care to individuals with CHS." - Carrier/prenatal/PGT: possible once familial variants are known.

Differential diagnosis. Griscelli syndrome type 2 (RAB27A), Hermansky-Pudlak syndrome (HPS genes — same LRO-biogenesis family, PMID:18544035), Elejalde syndrome, familial HLH (PRF1, UNC13D, STX11, STXBP2), other primary immunodeficiencies with silvery hair. Distinguishing feature: giant leukocyte granules + evenly clumped hair melanin are unique to CHS.

Omics-based diagnostics. Not routine; research-stage transcriptomic/lipidomic signatures only.

Screening. Not part of standard newborn screening. Suspicion is clinical (silvery hair + infections/bleeding) → smear → LYST sequencing. Cascade carrier testing in families.

11. Outcome / Prognosis

• Survival/mortality. Without HSCT, classic CHS is usually fatal in the first decade, most often from the accelerated phase/HLH or overwhelming infection. The EBV-HLH case illustrates the grim accelerated-phase prognosis (verified cache quote, PMID:33329964): "Treatment of accelerated-phase CHS is difficult with poor prognosis" — the child "did not survive."
• HSCT outcomes. In the landmark international cohort of 35 children (Eapen et al., Bone Marrow Transplant 2007, PMID:17293882 — fetch-verify), the 5-year overall survival was ~62%, best with HLA-matched sibling donors and when transplanted in remission/pre-accelerated phase; outcomes were worst with active accelerated-phase disease at transplant.
• The neurologic caveat. HSCT corrects the immunologic/hematologic disease but does not prevent or reverse the progressive neurodegeneration, which becomes the dominant long-term morbidity in survivors and attenuated CHS (PMID:23521865). Recovery of neurologic function is not expected.
• Prognostic factors. Genotype (two null alleles → severe; ≥1 missense/in-frame → attenuated, PMID:37788905); presence/absence of accelerated phase; timing of HSCT; donor type. No validated molecular prognostic biomarker beyond genotype.

12. Treatment

Curative / disease-modifying. - Allogeneic hematopoietic stem cell transplantation (HSCT) — the only treatment that corrects the immune/hematologic disease and prevents/treats the accelerated phase; ideally performed early, in remission, before organ damage. (MAXO: hematopoietic stem cell transplantation — verify term, e.g. MAXO:0010039 organ/cell transplantation.) Note this parallels HSCT experience in other inborn errors of immunity (the XLA transplant survey, PMID:37454339, is an analogous IEI-HSCT reference but is not about CHS — do not cite it as CHS evidence).

Accelerated-phase / HLH therapy. - HLH-2004 protocol: etoposide + dexamethasone + cyclosporine A, bridging to HSCT once remission achieved. Remission in ~75% within 8 weeks; relapses common. - CHEBI: etoposide CHEBI:4911; dexamethasone CHEBI:41879; ciclosporin CHEBI:4031. (MAXO: chemotherapy MAXO:0000647.)

Supportive / preventive. - Infection management: prophylactic antibiotics, aggressive treatment of infections, immunoglobulin support as needed; vaccination (MAXO:0001017). - Bleeding: platelet support/desmopressin peri-procedure for the δ-storage-pool defect. - Ophthalmologic/dermatologic: photoprotection, tinted lenses, refractive correction, sun protection. - Neurologic: symptomatic/rehabilitative care (physical, occupational therapy; MAXO:0000011 physical therapy); no disease-modifying neuro-therapy exists. - Supportive care MAXO:0000950; genetic counseling MAXO:0000079.

Experimental / investigational. - High-dose ascorbate and the tyrosine-kinase inhibitor context: the "Towards the targeted management of Chediak-Higashi syndrome" review (Orphanet J Rare Dis 2014, ~PMID:24618333 — fetch-verify) discusses emerging targeted concepts. Preclinical work has explored agents that modulate LYST-dependent granule size. - Gene therapy / next-gen models: the new complete-knockout mouse (PMID:40681653) is positioned as "a robust platform for therapeutic development," including for the neurologic disease that HSCT cannot address. - Clinical study: NIH natural history study NCT00005917.

13. Prevention

• Primary prevention: not possible (monogenic). Genetic counseling for at-risk consanguineous families; carrier screening and prenatal / preimplantation genetic testing once familial LYST variants are known.
• Secondary prevention: early diagnosis (smear + sequencing) and pre-emptive HSCT before accelerated phase; vigilant infection prophylaxis; EBV monitoring to catch accelerated-phase onset early.
• Tertiary prevention: HLH-directed therapy to prevent accelerated-phase mortality; photoprotection to prevent actinic skin damage; rehabilitation to mitigate neuro-disability.
• Counseling: cornerstone — recurrence risk 25%, reproductive options, and expectation-setting about persistent neurodegeneration post-HSCT.

14. Other Species / Natural Disease

CHS is a classic comparative-genetics disorder — naturally occurring LYST/beige-orthologue mutants exist across mammals and beyond, all showing hypopigmentation + giant granules + bleeding/immune defects, underscoring LYST's conserved trafficking role.

• Beige mouse (Mus musculus, NCBITaxon:10090) — the foundational model; Lyst/beige gene cloned first and used to find the human gene (verified cache quote, PMID:8673129): "The beige mutation is a murine autosomal recessive disorder, resulting in hypopigmentation, bleeding and immune cell dysfunction."
• Other natural models: Japanese Black cattle (Bos taurus), Persian cats (Felis catus — a large LYST duplication; feline model "resurrected" via assisted reproduction, Sci Rep 2019), Aleutian mink, blue/silver foxes, rat, corn snake, and a reported killer whale. (OMIA has CHS entries across species; VBO for specific breeds.)
• Orthologous genes: mouse Lyst (NCBI Gene 17864), and conserved BEACH-domain orthologs in C. elegans and yeast (per PMID:8673129).
• Comparative pathology / conservation. All models share partial oculocutaneous albinism, infection susceptibility, hemorrhagic tendency, and enlarged membrane-bound granules — but natural animal models incompletely recapitulate the human neurodegeneration, motivating engineered models (Section 15).
• Zoonosis: not applicable (genetic disorder).

15. Model Organisms

• Natural mutants: beige mouse, Persian cat, cattle, mink, etc. (Section 14) — good for pigment, hematologic, and immune phenotypes; limited for neurologic disease.
• Engineered mouse (state of the art): a CRISPR-Cas9 complete-knockout Lyst mouse (ΔLYST-B6) — Greene et al., Communications Biology 2025 (PMID:40681653 — fetch-verify) — is reported to recapitulate CHS with an earlier-onset neurodegenerative phenotype: partial oculocutaneous albinism, enlarged neutrophil granules/lysosomes, platelet dense-granule reduction with prolonged bleeding, and progressive cerebellar Purkinje-cell loss + peripheral axonal degeneration with significant neurological impairment by ~6 months, alongside cerebellar neuroinflammation (microglial/complement activation, proinflammatory lipids). Positioned as "a robust platform for therapeutic development." This is the best current model for the neurologic arm HSCT cannot treat.
• Model types available: knockout/null alleles (engineered), spontaneous hypomorph/null alleles (natural), plus patient-derived cell lines (fibroblasts, EBV-LCLs, iPSC potential) for cell-biological study of granule dynamics and cytotoxic-granule exocytosis.
• Applications: dissecting LYST's trafficking function, HLH/cytotoxicity mechanisms, and — with the new mouse — neurodegeneration mechanisms and preclinical therapeutics (gene therapy, small molecules).
• Limitations: natural models under-represent neurodegeneration; LYST's biochemical function remains incompletely defined ("80-year traffic jam," PMID:38774881).
• Resources: MGI (mouse Lyst/beige), OMIA (cross-species CHS), IMSR/JAX for beige strains.

Consolidated Ontology-Term Suggestions (verify with OAK before curation)

• MONDO: MONDO:0008963 (disease).
• HGNC/Gene: LYST HGNC:1968; use lowercase hgnc:1968 per repo convention.
• GO (process): lysosome organization GO:0007040; vesicle-mediated transport GO:0016192; regulated exocytosis GO:0045055; natural killer cell mediated cytotoxicity GO:0042267; platelet degranulation GO:0002576. (GO CC): lysosome GO:0005764; melanosome GO:0042470.
• CL: neutrophil CL:0000775; NK cell CL:0000623; cytotoxic T cell CL:0000910; melanocyte CL:0000148; platelet CL:0000233; macrophage CL:0000235; Purkinje cell CL:0000121; microglial cell CL:0000129.
• UBERON: skin UBERON:0002097; hair follicle UBERON:0002073; eye UBERON:0000970; bone marrow UBERON:0002371; spleen UBERON:0002106; liver UBERON:0002107; cerebellum UBERON:0002037; peripheral nervous system UBERON:0000010.
• HP: see Section 3 table (HP:0000007 AR inheritance; HP:0000613 photophobia; HP:0000639 nystagmus; HP:0002718 recurrent bacterial infections; HP:0001875 neutropenia; HP:0001892 abnormal bleeding; HP:0009830 peripheral neuropathy; HP:0001251 ataxia; HP:0001300 parkinsonism; HP:0012156 hemophagocytosis; HP:0011364/HP:0002216 pigment/silvery-hair).
• CHEBI: etoposide CHEBI:4911; dexamethasone CHEBI:41879; ciclosporin CHEBI:4031; ascorbate CHEBI:38290/29073.
• MAXO: HSCT (cell transplantation) MAXO:0010039; chemotherapy MAXO:0000647; genetic counseling MAXO:0000079; supportive care MAXO:0000950; vaccination MAXO:0001017; physical therapy MAXO:0000011.

Curation-ready evidence anchors (already cache-verified in this branch)

Sources

• OMIM #214500 — Chediak-Higashi Syndrome
• GeneReviews: Chediak-Higashi Syndrome (NBK5188)
• Orphanet ORPHA:167 — Chédiak-Higashi syndrome and ORPHA:352723 — Attenuated CHS
• StatPearls: Chediak-Higashi Syndrome (NBK507881)
• Morimoto et al. 2024, J Med Genet — LYST mutation spectrum (PMID:37788905)
• Turner et al. 2024, Front Immunol — "LYST: an 80-year traffic jam" (PMID:38774881)
• Weisfeld-Adams et al. 2013, Orphanet J Rare Dis — attenuated CHS (PMID:23521865)
• Gopaal et al. 2020, Cureus — CHS with EBV-triggered HLH (PMID:33329964)
• Huizing et al. 2008, Annu Rev Genomics Hum Genet — LRO biogenesis (PMID:18544035)
• Perou et al. 1996, Nat Genet — murine beige gene (PMID:8673129)
• Eapen et al. 2007 — HSCT for CHS (PMID:17293882)
• Greene et al. 2025, Communications Biology — Lyst-KO mouse (PMID:40681653) and PMC12274407
• Toro et al. 2014, Orphanet J Rare Dis — targeted management of CHS
• NORD — Chediak-Higashi Syndrome

One caretaker's note for the curator picking this up: the existing kb/disorders/Chediak-Higashi_Syndrome.yaml draft is already solid on the LYST/AR/HLH backbone. The two richest veins still worth mining into structured pathophysiology nodes are (a) the cell-type-resolved granule-dysfunction cascade (melanocyte / neutrophil / NK-CTL / platelet / neuron — each a clean causal edge), and (b) the HSCT-corrects-blood-but-not-brain dissociation, which is the single most clinically important nuance and is well-supported by PMID:23521865 + the 2025 mouse paper. Before committing any of the ⚠️ web-sourced PMIDs, run just fetch-reference and eyeball the snippet against the cached abstract — a couple of those (17293882, 24618333, 40681653) I inferred numbers for from secondary sources, so they need a first-hand read.