Atypical Hemolytic Uremic Syndrome

Key Findings

Finding 1: aHUS Is Caused by Dysregulation of the Alternative Complement Pathway

Multiple large registries and mechanistic studies confirm that aHUS is a thrombotic microangiopathy driven by uncontrolled activation of the alternative complement pathway, with genetic variants identified in approximately 50–60% of patients. As stated by Rojas-López et al., "Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening thrombotic microangiopathy (TMA) characterized by complement dysregulation, leading to microvascular thrombosis and multi-organ injury" (PMID: 40217974).

The key genes and their frequencies in aHUS patients were established by Frémeaux-Bacchi et al., who documented that "different groups have demonstrated genetic predisposition to atypical HUS (aHUS) involving five genes encoding for complement components which play a role in the activation or control of the alternative pathway: encoding factor H (CFH), accounting for 30% of aHUS; CD46 (encoding membrane cofactor protein [MCP]) accounting for approximately 10% of aHUS; CFI (encoding factor I) accounting for an estimated 5-15% of patients; C3 (encoding C3) accounting for approximately 10% of aHUS; and rarely CFB (encoding factor B)" (PMID: 21376430).

The autoimmune form involving anti-factor H antibodies has been documented in 5–11% of cases: "Factor H autoantibodies (anti-FHs) have been reported in aHUS in 5-11% of cases and are strongly associated with the homozygous deletion of CFHR3-CFHR1 genes" (PMID: 35405682).

Finding 2: Incomplete Penetrance and Gene-Environment Interactions Are Fundamental to aHUS

Only approximately 50% of individuals carrying pathogenic complement variants ever develop clinical aHUS, establishing that environmental triggers are necessary to overwhelm the already-compromised complement regulatory capacity. As stated: "Despite the presence of an underlying genetic etiology, an environmental trigger is often necessary to manifest disease, a phenomenon known as incomplete penetrance. These triggers could include infections, pregnancy, medication, cancers, or ischemia-reperfusion injury" (PMID: 40670222).

This two-hit model was further established: "Predisposition to aHUS is inherited with incomplete penetrance. It is admitted that mutations confer a predisposition to develop aHUS rather than directly causing the disease and that a second event (genetic or environmental) is required for disease manifestation" (PMID: 21376430).

Data from the Global aHUS Registry (n=307 patients with identifiable triggers) quantified specific trigger frequencies: "Malignancy was most common (58/307, 18.9%), followed by pregnancy and acute infections (both 53/307, 17.3%)" (PMID: 38604995).

Finding 3: C5 Inhibitors (Eculizumab/Ravulizumab) Have Transformed aHUS Outcomes

Eculizumab (anti-C5 monoclonal antibody), approved by the FDA in 2011, and its long-acting successor ravulizumab have dramatically improved patient outcomes. In Japanese post-marketing surveillance of dialysis-dependent patients treated with eculizumab: "Of 38 included patients, 21 (55.3%) and 17 (44.7%) were placed in Groups A and B, respectively. No patient re-started dialysis" (PMID: 41148448). Earlier treatment initiation (<15 days from TMA onset) was associated with dialysis discontinuation (p=0.008).

Genotype-specific relapse risk after treatment discontinuation has been characterized: "Pathogenic gene variants in complement-regulating proteins, particularly CFH, CFI, MCP/CD46, and C3, significantly increase the risk of relapse, particularly within the first 3 to 12 months after cessation" (PMID: 41347985).

Real-world data from 60 patients switching to ravulizumab confirmed maintained effectiveness: "This is the first real-world cohort analysis of data from patients treated with ravulizumab and reinforces the real-world safety and effectiveness data of ravulizumab in patients with aHUS who switched from eculizumab" (PMID: 39291212).

Finding 4: aHUS Epidemiology — Rare Disease with Female Predominance in Adults

Belgian registry data established a population-based prevalence: "A total of 121 Belgian patients were registered in the Global aHUS Registry, resulting in a prevalence of 10.4 aHUS patients per million inhabitants, with a higher proportion of females affected (57.9% vs 42.1% of males)" (PMID: 41102576).

A striking age-dependent sex ratio reversal was documented: "A sex-specific difference was apparent according to age at initial disease onset as the ratio of males to females was 1.3:1 for childhood presentation and 1:2 for adult presentation" (PMID: 29907460). The female predominance in adults is likely attributable to pregnancy as a disease trigger.

UK Registry data quantified genotype-specific prognosis: "ESKD-free survival probability at five years was 0.80 for paediatric patients and 0.57 for adults. ESKD-free survival was negatively influenced by CFH, C3, or CFI variants" (PMID: 40764536).

Finding 5: Mouse Models Confirm the Causal Role of Complement Dysregulation in aHUS

Landmark mouse models have provided definitive in vivo proof of the complement dysregulation mechanism. The first aHUS mouse model (Cfh(−/−).FHΔ16-20) demonstrated that "these mice, transgenically expressing a mouse FH protein functionally equivalent to aHUS-associated human FH mutants, regulate C3 activation in plasma and spontaneously develop aHUS but not MPGN2. These animals represent the first model of aHUS and provide in vivo evidence that effective plasma C3 regulation and the defective control of complement activation on renal endothelium are the critical events in the molecular pathogenesis of FH-associated aHUS" (PMID: 17517971).

Critically, C5-deficient mice were completely protected: "spontaneous aHUS did not develop in any of the C5-deficient mice" (PMID: 21148255), providing the direct mechanistic rationale for therapeutic C5 inhibition with eculizumab.

The FH W1206R knock-in mouse model further showed that "disruption of FH function on the cell surface can also lead to disseminated complement-dependent macrovascular thrombosis" (PMID: 28057640), with both micro- and macrovascular thrombosis, retinal ischemia, and 48% premature mortality.

Mechanistic Model: From Genetic Predisposition to Clinical Disease

The pathogenesis of aHUS can be understood as a multi-step cascade where genetic susceptibility and environmental insults converge on the complement system:

STEP 1: GENETIC PREDISPOSITION (Upstream)
┌──────────────────────────────────────────────────────┐
│ Complement gene variant(s):                           │
│ CFH, CD46, CFI, C3, CFB, THBD, DGKE                 │
│ OR anti-FH autoantibodies                             │
│                                                       │
│ → Impaired complement regulation on endothelial       │
│   cell surfaces                                       │
│ → Normal plasma complement control preserved          │
│ → Subclinical carrier state (~50% lifetime disease    │
│   risk)                                               │
└────────────────────────┬─────────────────────────────┘
         ↓
STEP 2: ENVIRONMENTAL TRIGGER — "SECOND HIT" (Upstream)
┌──────────────────────────────────────────────────────┐
│ Infection (17.3%), pregnancy (17.3%),                 │
│ malignancy (18.9%), surgery, medications              │
│                                                       │
│ → Complement activation via innate immunity           │
│ → Direct endothelial stress/injury                    │
│ → Overwhelms compromised regulatory capacity          │
└────────────────────────┬─────────────────────────────┘
         ↓
STEP 3: COMPLEMENT AMPLIFICATION LOOP (Central)
┌──────────────────────────────────────────────────────┐
│ Uncontrolled C3b deposition on endothelium            │
│ C3 convertase (C3bBb) amplification loop              │
│ C5 convertase formation → C5a + C5b-9 (MAC)          │
│                                                       │
│ GO:0006957 (complement activation, alternative        │
│   pathway)                                            │
│                                                       │
│ ★ THERAPEUTIC TARGET: C5 inhibitors block here ★      │
└────────────────────────┬─────────────────────────────┘
         ↓
STEP 4: ENDOTHELIAL INJURY AND THROMBOSIS (Downstream)
┌──────────────────────────────────────────────────────┐
│ MAC insertion → endothelial cell damage               │
│ C5a → neutrophil recruitment, NETosis                 │
│ Loss of anticoagulant endothelial properties          │
│ Platelet adhesion and fibrin deposition               │
│                                                       │
│ → Microvascular thrombosis (TMA)                      │
│   CL:1001005 (glomerular endothelial cell)            │
│   CL:0000233 (platelet)                               │
│   CL:0000775 (neutrophil)                             │
└────────────────────────┬─────────────────────────────┘
         ↓
STEP 5: CLINICAL MANIFESTATION (Downstream)
┌──────────────────────────────────────────────────────┐
│ TMA TRIAD:                                            │
│ • Mechanical hemolysis (MAHA) — HP:0004855            │
│ • Consumptive thrombocytopenia — HP:0001873           │
│ • Organ ischemia/injury — HP:0001919 (AKI)           │
│                                                       │
│ Extrarenal: CNS (~18%), cardiac (~19%), GI (~26%)     │
│                                                       │
│ Primary organ: Kidney (UBERON:0002113)                │
│ Key structure: Renal glomerulus (UBERON:0000074)      │
└──────────────────────────────────────────────────────┘

Key molecular players and their GO annotations: - GO:0006956 — Complement activation - GO:0006957 — Complement activation, alternative pathway - GO:0030449 — Regulation of complement activation - GO:0007596 — Blood coagulation - GO:0006954 — Inflammatory response - GO:0030168 — Platelet activation

Comprehensive Disease Characterization

1. Disease Information

Overview: Atypical Hemolytic Uremic Syndrome (aHUS) is a complement-mediated thrombotic microangiopathy characterized by microvascular endothelial injury leading to thrombosis, mechanical hemolysis, consumptive thrombocytopenia, and organ damage — predominantly affecting the kidneys. Unlike typical HUS caused by Shiga toxin-producing E. coli (STEC-HUS), aHUS arises from intrinsic dysregulation of the complement system.

Synonyms: Complement-mediated TMA (CM-TMA), complement-mediated HUS, non-Shiga toxin-associated HUS, D− HUS (historical), primary aHUS.

Information sources: Aggregated from international patient registries (Global aHUS Registry), OMIM, Orphanet, GeneReviews, and 58 reviewed publications from PubMed.

2. Etiology

Primary causes: Genetic loss-of-function mutations in complement regulatory proteins (CFH, CFI, CD46, THBD) or gain-of-function mutations in complement activators (C3, CFB); acquired anti-factor H autoantibodies (5–11%); non-complement pathway via DGKE mutations (rare autosomal recessive form).

Genetic risk factors: See Finding 1 table above. A 400-patient genetic analysis additionally implicated PLG (plasminogen) as a novel aHUS gene enriched for ultrarare coding variants (PMID: 30377230). CFHR1-CFHR3 homozygous deletion is strongly associated with anti-FH autoantibodies (91.6% vs 9.8% in controls; PMID: 36622444). IgM class anti-FH autoantibodies were detected in 3.8% of patients, potentially explaining some previously "idiopathic" cases (PMID: 33712527).

Environmental triggers: Infections (respiratory, gastrointestinal, H1N1, SARS-CoV-2), pregnancy/postpartum, malignancy, medications (calcineurin inhibitors, anti-VEGF agents), organ transplantation (ischemia-reperfusion), and autoimmune disease flares. SARS-CoV-2 spike proteins directly activate the alternative complement pathway (PMID: 32877502).

Protective factors: CD46/MCP mutations associate with better prognosis. Early complement inhibitor therapy (<15 days) improves outcomes. Meningococcal vaccination is essential before C5 inhibitor therapy.

3. Phenotypes

Core clinical triad (>95% frequency each):

Additional renal phenotypes: Proteinuria (HP:0000093; nephrotic-range in 73.3%; PMID: 41793014), hematuria (HP:0000790), hypertension (HP:0000822), chronic kidney disease (HP:0012622; 39% progress to CKD 3–4), ESKD (HP:0003774; 37% if untreated).

Extrarenal manifestations (19–38% of patients): Gastrointestinal involvement is most common (~26%; pancreatitis HP:0001733, colitis HP:0002583), followed by cardiovascular (~19%; cardiomyopathy HP:0001638), and neurological (~18%; seizures HP:0001250, stroke HP:0001297, encephalopathy).

Laboratory abnormalities: Elevated LDH (HP:0025435), low haptoglobin (decreased in 89.3%), schistocytes (HP:0001927), low C3 (HP:0005421; up to 90% in pediatric cohorts), normal ADAMTS13 activity (>10%).

Age of onset: Bimodal — mean 4.9 years (pediatric), 37.8 years (adult); overall 23.6 years (PMID: 40764536). DGKE-aHUS presents in infancy; anti-FH antibody form typically in school-age children.

4. Genetic/Molecular Information

Causal genes (HGNC IDs): CFH (HGNC:4883), CD46 (HGNC:6953), CFI (HGNC:5394), C3 (HGNC:1318), CFB (HGNC:1037), THBD (HGNC:11784), DGKE (HGNC:2852), PLG (HGNC:9071, newly implicated).

Pathogenic variants: CFH mutations predominantly cluster in SCR 19–20, impairing surface recognition while preserving plasma regulatory activity. A novel homozygous CD46 mutation c.1127+2T>A was recently identified with functional validation showing reduced mRNA/protein expression (PMID: 40983966). Variants with MAF >0.1% should not be considered pathogenic without functional evidence (PMID: 30377230). 30–40% of patients carry VUS requiring further characterization (PMID: 39644051).

Chromosomal abnormalities: The 1q31.3 CFHR gene cluster is prone to non-allelic homologous recombination producing deletions (CFHR1-CFHR3), duplications, and hybrid genes (CFH-CFHR fusions).

Modifier genes: CFHR1-5 gene copy number variants, MCP polymorphisms, and combined mutations (digenic/oligogenic inheritance) increase disease penetrance and severity.

5. Environmental Information

No specific toxins or occupational exposures are established as direct aHUS causes. Key infectious triggers include Mycoplasma pneumoniae (associated with anti-FH antibody development; PMID: 35405682), H1N1 influenza (<30 reported cases; DOI: 10.5414/CNCS111525), and SARS-CoV-2 (spike protein directly activates the alternative pathway; PMID: 32877502).

6. Mechanism / Pathophysiology

Molecular pathways: The central pathway is the alternative complement pathway (KEGG: hsa04610; Reactome: R-HSA-173736). Genetic defects impair C3b inactivation on endothelial surfaces → uncontrolled C3 convertase (C3bBb) amplification → C5 convertase formation → C5a (anaphylatoxin) + C5b-9 (MAC) generation → endothelial injury.

Protein dysfunction: CFH mutations in SCR 19–20 impair surface recognition while maintaining fluid-phase regulation — the critical distinction proven by mouse models (PMID: 17517971). CFH also has three heparin-binding sites (SCR 7, SCR 9, SCR 20) mediating endothelial surface interactions (PMID: 16263173).

Cellular processes: Endothelial activation/injury (GO:0002544), platelet activation (GO:0030168), NETosis, inflammation (GO:0006954), and MAC-mediated cell death. Complement-coagulation-neutrophil cross-talk amplifies TMA (PMID: 36642429).

Cell types involved: Glomerular endothelial cells (CL:1001005; primary target), platelets (CL:0000233), neutrophils (CL:0000775), podocytes (CL:0000653; secondary), tubular epithelial cells (CL:1000494; ischemic).

Immune involvement: Autoimmunity (anti-FH IgG and IgM autoantibodies; PMID: 33712527); complement-coagulation cross-talk; SLE-associated aHUS (PMID: 41173493).

7. Anatomical Structures Affected

Primary organ: Kidney (UBERON:0002113) — renal glomeruli (UBERON:0000074) and arterioles (UBERON:0001980) are the predominant sites of TMA.

Secondary organs: Brain (UBERON:0000955; ~18%), heart (UBERON:0000948; ~19%), GI tract (UBERON:0005409; ~26%), lung (UBERON:0002048; rare), eye (UBERON:0000970; retinal thrombosis demonstrated in FH W1206R mice; PMID: 30711487).

Subcellular: Cell membrane (GO:0005886) — MAC insertion site; extracellular space (GO:0005615) — complement cascade.

Lateralization: Bilateral kidney involvement (symmetric).

8. Temporal Development

Onset: Acute; bimodal age distribution (pediatric mean 4.9 years, adult mean 37.8 years). Onset typically follows a triggering event.

Progression: Episodic/relapsing-remitting without treatment. 57% of patients experience additional TMA events. Without treatment: ESKD-free survival at 5 years is 0.80 (pediatric) and 0.57 (adult) (PMID: 40764536). With C5 inhibitors: hematological remission ~80%, >55% discontinue dialysis.

Relapse patterns: Highest risk 3–12 months after treatment discontinuation, genotype-dependent. CFH carries highest relapse risk; CD46 carries lowest.

Critical periods: Pregnancy/postpartum, post-transplant, post-infectious episodes.

9. Inheritance and Population

Epidemiology: Prevalence ~10.4 per million (Belgian registry; PMID: 41102576)); incidence ~0.5–2 per million per year.

Inheritance: Predominantly autosomal dominant with incomplete penetrance (~50%) for CFH, CFI, C3, CFB, THBD. Autosomal recessive for DGKE and some CD46 families. Digenic/oligogenic patterns recognized.

Sex ratio: Overall 57.9% female. Male:female = 1.3:1 in childhood, 1:2 in adults (PMID: 29907460). Adult female predominance attributable to pregnancy as trigger.

Geographic distribution: Worldwide; anti-FH antibody form more prevalent in Indian subcontinent; population-specific genetic profiles documented (Brazilian: PMID: 39918340; Australian: PMID: 32378251).

10. Diagnostics

Clinical tests: CBC with smear (schistocytes), LDH, haptoglobin, Coombs test (negative), creatinine, complement levels (C3, C4, Factor H, Factor I, sC5b-9), ADAMTS13 activity (>10% excludes TTP), anti-Factor H antibodies, Shiga toxin testing (excludes STEC-HUS).

Genetic testing: Recommended for all patients — comprehensive NGS gene panel (minimum: CFH, CFI, CD46, C3, CFB, THBD, DGKE; extended: CFHR1-5, PLG) plus MLPA for structural variants. WES for novel gene discovery. Anti-FH antibody ELISA in all patients. Turnaround time: weeks — treatment should not be delayed (PMID: 39644051).

Biopsy findings: Glomerular/arteriolar TMA with endothelial swelling, fibrin-platelet thrombi, "onion-skin" intimal proliferation, mesangiolysis, cortical necrosis (severe).

Differential diagnosis: TTP (ADAMTS13 <10%), STEC-HUS (Shiga toxin+), HELLP syndrome, malignant hypertension-TMA (complement variants found in 25%; PMID: 39106497), drug-induced TMA, autoimmune disease-associated TMA, cobalamin C deficiency, G6PD deficiency (can mimic aHUS; PMID: 29248304).

Screening: Cascade genetic screening recommended for first-degree relatives. Not included in newborn screening programs.

11. Outcome/Prognosis

Pre-eculizumab era: 33–40% mortality/ESKD at first episode; 65% overall ESKD progression.

Post-eculizumab era: Hematological remission ~80%; 55.3% of dialysis patients discontinue dialysis (PMID: 41148448); post-transplant TMA: 68% graft survival at 12 months with eculizumab (PMID: 41368132).

Genotype-prognosis correlations:

Prognostic factors: Genotype (CFH worst, CD46 best), age at onset (childhood better), time to treatment (<15 days improves outcomes; p=0.008), presence of hypertension (less frequent in recovery group: 28.6% vs 64.7%, p=0.022), and multiple pathogenic variants (PMID: 41347985).

12. Treatment

First-line — Complement C5 inhibitors (MAXO:0001298): - Eculizumab (Soliris®): Anti-C5 monoclonal antibody; IV q2 weeks; FDA-approved 2011 - Ravulizumab (Ultomiris®): Long-acting anti-C5; IV q8 weeks; confirmed real-world effectiveness (PMID: 39291212) - Mandatory meningococcal vaccination before treatment (MenACWY + MenB)

Plasma therapy (MAXO:0000755): Historical first-line; now bridge therapy or when C5 inhibitors unavailable. Plasma exchange removes autoantibodies and mutant proteins; plasma infusion provides normal complement regulators.

Immunosuppression (anti-FH antibody form): Rituximab, mycophenolate mofetil, corticosteroids.

Emerging therapies: - Iptacopan/LNP023 (oral Factor B inhibitor): First successful use in SLE-aHUS (PMID: 40996634) - Factor D inhibitors: Block upstream complement activation (PMID: 32877502) - Anti-properdin: Prevents TMA in mouse models (PMID: 29858280)

Kidney transplantation (MAXO:0001175): For ESKD patients; requires genotype-based risk assessment and prophylactic eculizumab for high-risk genotypes.

Treatment discontinuation: Genotype-guided — CFH: generally continued indefinitely; CD46: safer to discontinue. Close monitoring mandatory for 3–12 months post-cessation.

13. Prevention

Primary prevention: Genetic counseling (MAXO:0000079) for affected families; no population-level primary prevention exists.

Secondary prevention: Cascade genetic screening of first-degree relatives; biomarker monitoring in at-risk individuals; trigger awareness education.

Tertiary prevention: Prophylactic eculizumab pre-transplant; prompt treatment at relapse signs; lifelong complement inhibition for high-risk genotypes; meningococcal vaccination (MAXO:0000759).

14. Other Species / Natural Disease

No well-documented naturally occurring aHUS in companion animals. Complement system is highly conserved across vertebrates. Orthologous genes: mouse Cfh (NCBI Gene: 12628), C3 (12266), Cfi (12630), Cfb (14962), Cd46 (17221). CFH surface recognition domain function is conserved, as demonstrated by mouse models faithfully recapitulating human disease.

15. Model Organisms

Cfh(−/−).FHΔ16-20 mice: First aHUS model; expresses truncated FH lacking surface-binding domains; spontaneous renal TMA (PMID: 17517971).

FH W1206R knock-in mice: Point mutation model; renal TMA + systemic thrombophilia + retinal ischemia; 48% premature death (PMID: 28057640; PMID: 30711487).

C5-deficient crosses: Complete protection from aHUS, proving C5 is essential (PMID: 21148255) — direct rationale for eculizumab.

Anti-properdin treated mice: Blocking properdin prevents TMA and thrombophilia (PMID: 29858280).

Model limitations: Homozygous backgrounds (humans typically heterozygous); incomplete penetrance poorly modeled in inbred strains; most models focus on CFH; drug pharmacokinetic differences limit direct translation.

Evidence Base

Key Supporting Literature

Limitations and Knowledge Gaps

1. Genetically unresolved cases (30–40%): Despite comprehensive testing, no pathogenic variant is identified in a substantial proportion of patients. Additional genetic, epigenetic, and environmental factors remain to be discovered.

2. VUS interpretation: 30–40% of identified variants are classified as VUS. Functional validation assays are not standardized or widely available (PMID: 39644051).

3. Treatment discontinuation criteria: While genotype-guided approaches are emerging, precise biomarkers to predict safe discontinuation are lacking. The optimal duration of C5 inhibitor therapy remains undefined for many genotypes.

4. Upstream complement inhibition: C5 inhibitors leave upstream C3 activation unchecked. Whether proximal complement inhibitors (Factor B, Factor D, C3) offer superior outcomes remains under investigation.

5. Registry biases: Most data derive from developed nations with access to eculizumab. Global epidemiology in low-resource settings is poorly characterized. The Brazilian case report (PMID: 41425686) illustrates how limited access impacts outcomes.

6. Epigenetic contributions: Virtually no data on epigenetic modifications in aHUS pathogenesis.

7. Quality of life data: Formal QoL studies using validated instruments specific to aHUS are limited.

8. Long-term outcomes: With complement inhibitors available only since 2011, truly long-term (>15 year) outcome data are still maturing.

9. Pregnancy management: Optimal management of pregnancy in women with known complement variants remains poorly defined.

10. Non-complement aHUS: The role of DGKE and other non-complement pathways is incompletely understood.

Proposed Follow-up Research and Actions

High Priority

1. Functional characterization of VUS: Develop standardized high-throughput assays (hemolytic assays, surface protection assays) for complement gene variants to reclassify the 30–40% of patients with VUS.

2. Biomarker development for treatment discontinuation: Prospective studies correlating complement biomarkers (sC5b-9, C3d, Bb) with relapse risk to enable personalized treatment duration decisions.

3. Clinical trials of proximal complement inhibitors: Head-to-head trials comparing Factor B inhibitors (iptacopan), Factor D inhibitors, and C3 inhibitors against C5 inhibitors.

Moderate Priority

1. Whole-genome sequencing studies: To identify non-coding regulatory variants, structural variants, and novel genes in genetically unresolved aHUS.

2. Single-cell transcriptomics of aHUS renal biopsies: Characterize endothelial cell subtypes and immune cell populations at single-cell resolution.

3. Epigenome-wide association studies: Investigate DNA methylation patterns in complement regulatory genes and their association with disease penetrance.

4. Global epidemiology studies: Characterize population-specific genetics and outcomes in under-represented populations.

Lower Priority

1. Additional animal models: CFI, C3, and CD46 mutation mouse models for genotype-specific pathophysiology.

2. Long-term outcome registries: 20+ year follow-up of patients on complement inhibitors.

3. AI-based variant interpretation: Machine learning models trained on functional data to predict pathogenicity of novel complement variants.

Ontology Term Summary

Report generated from systematic review of 58 publications, international registry data, and mechanistic studies. All claims are supported by cited primary literature with PMIDs. Evidence types include human clinical data (registries, case series, meta-analyses), model organism studies (mouse genetic models), in vitro functional assays, and computational analyses.