| domain | best-supported finding | evidence type/strength | key ontology suggestions |
|---|---|---|---|
| Definition / criteria | HELLP syndrome is the severe microangiopathic form of hypertensive disease of pregnancy, defined by hemolysis, elevated liver enzymes, and low platelets; Tennessee criteria require hemolysis, AST >70 IU/L and/or LDH >600 IU/L or bilirubin >1.2 mg/dL, and platelets <100 × 10^9/L; it typically occurs after 20 weeks or immediately postpartum and improves after placental delivery (pqac-00000006, pqac-00000012) | Human clinical/trial registry + peer-reviewed review; moderate-strong for diagnostic criteria | MONDO: HELLP syndrome (MONDO:0008585); MeSH: HELLP Syndrome (D017359); HPO: Hemolytic anemia, Elevated hepatic transaminases, Thrombocytopenia, Hypertension, Proteinuria |
| Epidemiology | Global pooled prevalence was 0.39% (95% CI 0.16–0.72) across 9 studies/133,611 participants, with regional variation and higher prevalence in low-income settings; one contemporary trial record notes occurrence up to 0.9% of pregnancies and severe maternal/perinatal mortality in historical literature (pqac-00000013, pqac-00000006) | Systematic review/meta-analysis + registry background; moderate, but HELLP estimate is limited by small study pool | ICD/MeSH pregnancy-hypertension grouping; HPO: Maternal morbidity, Fetal death |
| Pathophysiology | Best-supported model: abnormal placentation/poor spiral artery remodeling → placental ischemia/hypoxia → trophoblast injury, anti-angiogenic factor excess (sFLT1), complement activation (especially terminal pathway C5a/C5b-9), endothelial injury, platelet activation/consumption, microangiopathic hemolysis, liver injury, and multiorgan dysfunction; placental C5b-9 and sFLT1 are associated, and disease improves after placental removal (pqac-00000010, pqac-00000012, pqac-00000015) | Mixed human placental, biomarker, in vitro, and animal evidence; strong for placental/angiogenic role, moderate for complement-causal contribution | GO: angiogenesis, complement activation, endothelial cell activation, platelet activation, apoptotic process, response to hypoxia; CL: trophoblast cell, monocyte, endothelial cell, platelet; UBERON: placenta, liver, kidney |
| Genetics | HELLP is not a Mendelian disorder, but complement regulatory variants are enriched in subsets: reported MCP/CD46 variants in ~8% of preeclampsia/HELLP cohorts, CFH mutations ~1.2%, CFI ~4.2%; in one small series, complement variants/CFHR deletions were found in 45% (5/11) of HELLP cases; fetal fatty-acid oxidation defects are historically discussed as overlap/association evidence rather than established common cause of HELLP (pqac-00000015, pqac-00000016, pqac-00000014) | Human association/candidate-gene evidence; moderate to weak because cohorts are small and heterogeneous | HGNC genes: CD46/MCP, CFH, CFI, CFHR1, CFHR3; GO: regulation of complement activation; note multifactorial/polygenic rather than monogenic inheritance |
| Diagnosis / differential | Diagnosis is laboratory-clinical and overlaps with severe preeclampsia, acute fatty liver of pregnancy, TTP, and atypical HUS; distinguishing features rely on hemolysis pattern, liver injury, thrombocytopenia, kidney injury severity, ADAMTS13 for TTP, and persistent postpartum TMA/complement-mediated disease for aHUS rather than resolving HELLP (pqac-00000002, pqac-00000014) | Human clinical review/trial rationale; moderate | HPO: Right upper quadrant pain, Nausea, Vomiting, Acute kidney injury, Disseminated intravascular coagulation; NCIT/MeSH differential concepts: Thrombotic Microangiopathy, Acute Fatty Liver of Pregnancy, Thrombotic Thrombocytopenic Purpura, Atypical Hemolytic Uremic Syndrome |
| Treatment | Current management remains supportive plus expedited delivery when maternal/fetal status warrants: blood-pressure control, magnesium seizure prophylaxis, corticosteroids for fetal lung maturity when preterm, transfusion support as needed, and delivery as definitive treatment; maternal dexamethasone has been studied for HELLP-I lab recovery/hospitalization but remains controversial; complement blockade with eculizumab is investigational in early preterm HELLP (pqac-00000007, pqac-00000009, pqac-00000014) | Guidelines/review-level standard care + interventional trial records; strong for delivery/supportive care, weak-emerging for eculizumab | NCIT: Delivery, Magnesium Sulfate, Antihypertensive Therapy, Dexamethasone, Platelet Transfusion, Plasma Transfusion, Eculizumab |
| Prognosis | HELLP is associated with major maternal complications including eclampsia, DIC, liver rupture, placental abruption, stroke, pulmonary and kidney failure; fetal risks include IUFD, NICU admission, low Apgar/acidemia, and iatrogenic prematurity; biologic recovery usually begins after delivery and often occurs within about 1 week postpartum in uncomplicated recovery (pqac-00000003, pqac-00000004, pqac-00000005) | Human observational/trial-registry evidence; moderate | HPO: Disseminated intravascular coagulation, Hepatic rupture, Placental abruption, Stroke, Pulmonary edema/respiratory failure, Acute kidney injury, Intrauterine fetal death |
| Research gaps | Major gaps include lack of validated HELLP-specific biomarkers, limited large genomic studies, poor separation of HELLP from adjacent pregnancy TMAs, sparse HELLP-specific multi-omics/single-cell data, uncertainty about which patients have complement-driven disease, and very small interventional studies for targeted therapy such as anti-C5 blockade (pqac-00000008, pqac-00000014, pqac-00000016) | Evidence synthesis across reviews and trial landscape; strong for existence of gaps | GO/ontology curation needs: complement dysregulation, placental cell-state atlases, disease subclassification within hypertensive disorders of pregnancy |


*Table: This compact table summarizes the best-supported findings for HELLP syndrome across clinical definition, epidemiology, mechanisms, genetics, diagnosis, treatment, prognosis, and research gaps. It is useful as a quick evidence map for building a disease knowledge-base entry.*