This is a mechanism module, not a specific disease. It is a functional-failure module rather than a pathological structure-formation ("Xogenesis") module: its terminal outputs are a failure of microbial killing and a loss of an immunoregulatory signal, not the formation of a pathological anatomical entity. Where a conformer goes on to form granulomas, that structure-formation process belongs to the granuloma_formation module, which carries the Xogenesis anchor; this module's conditional immunoregulatory branch hands off to it rather than duplicating it. Disorder entries reference individual nodes via conforms_to (for example, "phagocyte_oxidative_burst_failure#Failed Respiratory Burst and Phagosomal ROS Deficiency"). Operational conformance boundary: a branch is in scope when a stimulated phagocyte demonstrably fails to generate superoxide or downstream reactive oxygen species through the NOX2 oxidase. That failure is necessary and sufficient for branch-level qualification, but each conforms_to assertion remains local to the stage actually modeled. This is a curation boundary, not a formal Grouping criteria assertion. Key disorder-specific substitutions at the trigger node, which is where the distinct lesion classes differ: the catalytic complex cannot be assembled (chronic granulomatous disease, from variants in CYBB, CYBA, NCF1, NCF2, NCF4 or CYBC1); the catalytic subunit is mis-matured rather than absent (G6PC3 deficiency, through hypoglycosylation of gp91phox); an intact complex cannot be switched on because its GTPase activator is missing (RAC2 dominant-negative neutrophil immunodeficiency syndrome). A fourth class, failure to supply the NADPH the oxidase consumes, is mechanistically predicted for severe class I G6PD deficiency, but the dismech G6PD entry currently curates only the haemolysis arm and has no burst node, so it is named here as a candidate rather than asserted as a conformer. Because conformers were curated before this module existed, their process placement is not uniform, and conformance should be read node-by-node rather than assumed term-for-term. Chronic_Granulomatous_Disease and Neutrophil_Immunodeficiency_Syndrome carry GO:0042554 superoxide anion generation on the lesion-level node that conforms to the trigger, whereas this module places the enzyme-level claim as the molecular function GO:0016175 on the trigger and keeps the process view on the rate-limiting node. G6PC3 deficiency and RAC2 disease each carry an additional neutrophil chemotaxis or actin-assembly defect on a conforming node; that migration arm is outside this module and is not claimed by conformance. Out of scope. (1) Entries in which a respiratory burst is INCREASED rather than decreased - Microscopic_Polyangiitis (GO:0045730 INCREASED), Paraquat_Poisoning and Heart_Failure (GO:0042554 INCREASED). Excess oxidant production is a different mechanism, not a direction of this one. (2) Non-NOX2 members of the NADPH oxidase family. NOX1, NOX3, NOX4, NOX5, DUOX1 and DUOX2 are not the phagocyte oxidase, and DUOX2-related thyroid dyshormonogenesis is explicitly not a conformer despite involving the same enzyme family. (3) Neutropenia. A defect of phagocyte number is not a defect of phagocyte oxidative function; G6PC3 deficiency is both, and conforms on its function arm only. Its severe-congenital-neutropenia arm must not be claimed as conforming. Deferred, not excluded: myeloperoxidase deficiency. MPO acts downstream of superoxide, consuming hydrogen peroxide to generate hypochlorous acid, and MPO-deficient neutrophils are generally reported to have a normal or increased respiratory burst precisely because that peroxide is no longer consumed. If that holds, MPO deficiency fails a different node than the one this module is built around and would be NOT_SATISFIED against the rate-limiting node. Settling it needs a fetched primary source and its own scoped task; stubs/Myeloperoxidase_Deficiency.yaml is already in the curation queue. The module's treatment is a mechanistic target pattern, not an inherited treatment recommendation; agent selection, conditioning regimen, and contraindications remain disease-specific. Pathophysiology nodes bind GO processes, molecular functions, cellular components and protein complexes, plus CL cell types; they do not bind CHEBI chemicals or MONDO diseases. The treatments block may bind a therapeutic agent per the treatment schema.
Interferon gamma prophylaxis is standard care in many chronic granulomatous disease centres, but does it act by restoring the respiratory burst? If not, which node does it act on, and can it be given a target_mechanisms edge at all?
KNOWLEDGE GAP
OPEN
ifn_gamma_mechanism_not_burst_restoration
Attached to:
Failed Respiratory Burst and Phagosomal ROS Deficiency
This gap is recorded deliberately rather than resolved, because the tempting shortcut is wrong. Interferon gamma is widely used prophylactically and its clinical benefit is well attested, so it is easy to curate it as an agent acting on the oxidase - but in most patients the burst is not measurably restored, and the mechanism of benefit is not established. Curating it as a burst-restoring agent would attach a mechanism claim to this module that the evidence does not support, and would then propagate to every conformer. Until the mechanism is pinned down, interferon gamma belongs here as an open question and not in the treatments block.
Phagocyte NADPH Oxidase Assembly or Activation Failure
trigger
The phagocyte NADPH oxidase cannot deliver electrons from cytosolic NADPH to molecular oxygen. This is the lesion-class node, and it is where conforming disorders differ from one another: the complex may be unbuildable because a structural subunit is absent, mis-matured because a subunit is hypoglycosylated, or unactivatable because its small-GTPase activator is missing while every catalytic component is present and quantitatively normal. The node asserts loss of oxidase activity, not a particular lesion; the specific defect is substituted by the conforming entry.
Downstream
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Failed Respiratory Burst and Phagosomal ROS Deficiency
Loss of oxidase activity is, by definition of the enzyme's function, loss of the stimulated superoxide burst.
Show evidence (4 references)
"Chronic granulomatous disease is a defect in phagocytosis due to deficiency of gp91phox, p22phox, p47phox, p40phox, and p67phox (classic form of the disease)."
Enumerates the subunit-deficiency lesion class - the oxidase complex cannot be assembled - which is the substitution chronic granulomatous disease makes at this node.
"Neutrophils from this patient exhibited decreased chemotaxis, polarization, azurophilic granule secretion, and superoxide anion (O(2)(-)) production but had normal expression and up-regulation of CD11b."
Establishes in patient neutrophils that the activation lesion class produces a real burst defect, with CD11b expression and up-regulation normal - so the failure is not a loss of the phagocyte itself.
"Rac2(D57N) binds GDP but not GTP and inhibits oxidase activation and O(2)(-) production in vitro."
Establishes the second, distinct lesion class asserted by this node: an activation failure rather than an assembly failure. The reconstitution result in the same study - adding recombinant Rac to patient neutrophil extracts restores superoxide production - is what shows the catalytic machinery itself is intact.
+ 1 more reference
Failed Respiratory Burst and Phagosomal ROS Deficiency
central effector
The rate-limiting node and the key conformance target. On stimulation the phagocyte fails to mount a respiratory burst, so superoxide and the reactive oxygen species derived from it do not accumulate in the phagosome. This step is disorder-agnostic: every conforming entry funnels through it regardless of which upstream lesion it carries, and it is the step clinical diagnostics actually measure. Operationally it is read out by dihydrorhodamine oxidation or ferricytochrome c reduction in stimulated neutrophils, which is why a conformer can be checked against this node rather than argued about.
Downstream
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Impaired Oxidant-Dependent Microbial Killing
The obligate arm. Oxidant-dependent killing has no substrate once the burst fails.
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Loss of ROS-Dependent Immunoregulation
The conditional arm. Reactive oxygen species also serve as signals that restrain and terminate inflammatory responses; losing them dysregulates inflammation through intermediates that are not the killing pathway. Conformers opt into this arm rather than inheriting it.
Show evidence (2 references)
"Superoxide anion generation was <25% of control values, but phox proteins appeared quantitatively normal."
Measures the burst deficit directly in patient neutrophils and, because the oxidase subunits were quantitatively normal, shows this node is separable from the assembly lesion upstream of it. That separability is what makes it usable as a shared conformance target rather than a restatement of the trigger.
"To optimize the 1,2,3-dihydrorhodamine technique using zymosan to assess neutrophil respiratory burst and detect the non-classical chronic granulomatous disease."
Identifies the dihydrorhodamine oxidation assay as the operational readout of this node, and notes that stimulus choice determines which lesion classes it detects - relevant because a conformer's burst defect may be stimulus-dependent.
Impaired Oxidant-Dependent Microbial Killing
effector
Ingested bacteria and fungi are not killed. Phagocytosis and ingestion may be intact or only partly reduced; what fails is the oxidative killing step that follows. The organisms that survive are characteristically those a phagocyte would otherwise need the oxidative burst to clear.
Downstream
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Recurrent Bacterial and Fungal Infection
Uncleared organisms establish deep and recurrent infection at sites of phagocyte-dependent defense.
Show evidence (2 references)
"Bactericidal activity at bacteria/neutrophil ratios >1:1 was also diminished and was associated with attenuated ingestion."
Measures the killing defect itself, in patient neutrophils, as a step distinct from the superoxide measurement in the same study. The attenuated ingestion noted alongside it is why this node states that phagocytosis may be partly reduced rather than asserting it is intact.
"Chronic granulomatous disease (CGD) is a primary immunodeficiency disorder of phagocytes (neutrophils, monocytes, macrophages, and eosinophils) resulting from impaired killing of bacteria and fungi."
States impaired killing of bacteria and fungi as the defining functional consequence, and names the four phagocyte lineages the module binds. Evidence source is OTHER because this is a GeneReviews chapter, not a primary study.
Recurrent Bacterial and Fungal Infection
consequence
Recurrent, deep-seated bacterial and fungal infection at the organism level, with a pathogen spectrum characteristic of oxidative killing failure rather than of immunodeficiency in general. The specific organisms and the organ distribution are disorder- and cohort-specific and should be evidenced locally rather than inherited from this node.
Show evidence (2 references)
"Pneumonia was the most prevalent infection (79% of patients; Aspergillus most prevalent cause), followed by suppurative adenitis (53% of patients; Staphylococcus most prevalent cause)"
A 368-patient national registry quantifying the infection burden and its pathogen spectrum, which is the organism-level consequence this node represents.
"Surviving patients have had no new CGD-related infections, and six have been able to discontinue CGD-related antibiotic prophylaxis."
Reversal evidence: restoring oxidase-positive neutrophils removed the infection phenotype, which supports the causal direction from burst failure to recurrent infection rather than mere association.
Loss of ROS-Dependent Immunoregulation
effector
A conditional branch, not part of the obligate chain. Beyond killing microbes, phagocyte-derived reactive oxygen species act as signals that restrain and terminate inflammatory responses. Losing that signal permits dysregulated, often sterile inflammation - granulomatous obstruction of the gastrointestinal and genitourinary tracts, colitis, and other inflammatory disease occurring independently of active infection. Conformers vary: this arm is prominent in chronic granulomatous disease and absent in RAC2 dominant-negative neutrophil immunodeficiency syndrome, so a conforming entry must opt into it with its own evidence rather than inherit it. Where the branch does proceed to organised granuloma assembly, that structure-formation process is handed off to the granuloma_formation module and is not duplicated here.
Show evidence (2 references)
"CGD is characterized by severe recurrent bacterial and fungal infections and dysregulated inflammatory responses resulting in granuloma formation and other inflammatory disorders such as colitis."
Separates the inflammatory arm from the infection arm as two distinct consequences of the same oxidase defect, which is the branching this node represents. Evidence source is OTHER because this is a GeneReviews chapter.
"Fifteen percent of patients had gastric outlet obstruction, 10% urinary tract obstruction, and 17% colitis/enteritis."
Quantifies the inflammatory and obstructive burden in a 368-patient registry, showing this arm affects a substantial minority rather than all patients - which is the empirical basis for treating it as conditional. Support is PARTIAL because the registry counts the manifestations without establishing the ROS-signalling mechanism.