🩸 When Should You Suspect and Screen for PNH? — The CATCH Mnemonic 🎤 Highlights from the 15th Annual Conference of the Saudi Society of Blood and Marrow Transplantation (#SSBMT2026) ⸻ 🔑 CATCH = High-Yield Screening Tool for PNH 🅲 — Cytopenias Unexplained: Anemia Neutropenia Thrombocytopenia Pancytopenia Especially if associated with: Aplastic anemia Hypocellular MDS Refractory cytopenias ⸻ 🅰 — Aplastic Anemia / MDS Screen all patients with: Acquired aplastic anemia Hypocellular MDS Selected low-risk MDS Up to 70% of AA patients harbor a detectable PNH clone. ⸻ 🆃 — Thrombosis (Unprovoked or Unusual Site) Any unexplained thrombosis: Hepatic veins (Budd–Chiari) Portal vein Mesenteric veins Cerebral venous sinus Renal veins PNH should be excluded in every unusual-site thrombosis. ⸻ 🅲 — Coombs-Negative Hemolysis Evidence of hemolysis: ↑ LDH ↓ Haptoglobin ↑ Reticulocytes ↑ Indirect bilirubin Negative DAT ⸻ 🅷 — Hemoglobinuria Dark urine, especially in the morning Hemosiderinuria Chronic iron deficiency ⸻ 🩺 Core Symptoms Suggestive of PNH 😴 Fatigue 🌬️ Dyspnea 🌑 Dark urine 🍽️ Dysphagia 🤕 Abdominal pain ❤️ Chest pain 🔞 Erectile dysfunction 🩸 Thrombosis ⸻ 🧪 Diagnostic Test of Choice High-Sensitivity Flow Cytometry with FLAER Assess on: Granulocytes Monocytes RBCs Detects absence of: CD55 CD59 GPI-linked proteins ⸻ ⚠️ Who Must Be Tested? Test for PNH if any one of the following is present: Unexplained cytopenia Aplastic anemia Hypocellular MDS Unusual-site thrombosis Coombs-negative hemolytic anemia Hemoglobinuria ⸻ 💎 Clinical Pearl If you see Coombs-negative hemolysis or unexplained splanchnic thrombosis, think PNH until proven otherwise. ⸻ ❓ Board-Style MCQ Which test is the gold standard for diagnosing PNH? A. Direct Coombs test B. Bone marrow biopsy C. High-sensitivity flow cytometry with FLAER D. Osmotic fragility test ✅ Answer: C. High-sensitivity flow cytometry with FLAER ⸻ 📚 Reference Röth et al. European screening algorithm for PNH International PNH Guidelines #PNH #CATCHMnemonic #Hemolysis #AplasticAnemia #Thrombosis #FlowCytometry #ComplementBiology #Hematology #KFSHRC #SSBMT2026

🩸 PNH Pathophysiology & Clinical Manifestations — High-Yield Pearls 🎤 Highlights from the 15th Annual Conference of the Saudi Society of Blood and Marrow Transplantation (#SSBMT2026) ⸻ 🧬 Complement Regulation in Normal RBCs Normal red cells express two key GPI-anchored proteins: 🛡️ CD55 (Decay-Accelerating Factor, DAF) ⛔ Inhibits formation and stability of C3 convertase. 🛡️ CD59 (Membrane Inhibitor of Reactive Lysis, MIRL) ⛔ Prevents assembly of the membrane attack complex (MAC; C5b-9). ⸻ 💥 What Happens in PNH? Acquired mutation in PIGA → loss of GPI anchor → absent CD55/CD59. Result: Uncontrolled complement activation Terminal MAC formation Intravascular hemolysis Nitric oxide depletion Platelet activation Thrombosis ⸻ ⚙️ Terminal Complement Cascade C3 → C5 cleavage → C5b C6–C9 → MAC → RBC lysis. Additional effects: ↑ LDH ↓ Haptoglobin Hemoglobinuria End-organ damage ⸻ 🧪 Nitric Oxide Scavenging Free plasma hemoglobin binds nitric oxide. Clinical consequences: Dysphagia Esophageal spasm Abdominal pain Erectile dysfunction Pulmonary hypertension Chest pain ⸻ 🩸 Why Thrombosis Occurs Multiple mechanisms: Platelet activation Complement-mediated endothelial injury NO depletion Procoagulant microparticles Common sites: Hepatic veins (Budd–Chiari) Portal vein Mesenteric veins Cerebral veins ⸻ 🩺 Common Symptoms of PNH 😴 Fatigue 🩸 Anemia 🌑 Dark urine / hemoglobinuria 😮‍💨 Dyspnea 🍽️ Dysphagia 🤕 Abdominal pain ❤️ Chest pain 🔞 Erectile dysfunction ⸻ ⚠️ Major Complications 🩸 Venous/arterial thrombosis 🫁 Pulmonary hypertension 🩺 Chronic kidney disease 🫀 Cardiac dysfunction 🧠 Neurologic events ⸻ 🔬 Key Laboratory Findings ↑ LDH (best marker of hemolysis) ↓ Haptoglobin ↑ Reticulocytes Indirect hyperbilirubinemia Negative DAT ⸻ 💊 Therapeutic Targets C5 Inhibitors Soliris® (eculizumab) Ultomiris® (ravulizumab) C3 Inhibitor Empaveli® (pegcetacoplan) Factor B Inhibitor Fabhalta® (iptacopan) Factor D Inhibitor Voydeya® (danicopan) ⸻ 💎 Clinical Pearl In PNH, thrombosis—not anemia—is the leading cause of mortality. ⸻ ❓ Board-Style MCQ Which protein directly prevents membrane attack complex formation? A. CD34 B. CD55 C. CD59 D. C3 ✅ Answer: C. CD59 Explanation: CD59 blocks C9 polymerization and MAC assembly. ⸻ 📚 References PNH Source for Physicians Frontiers in Immunology Review on PNH Pathogenesis Holt M et al. Annals of Blood. 2024. Brodsky RA. Blood. 2014. #PNH #ComplementBiology #Eculizumab #Ravulizumab #Iptacopan #BoneMarrowFailure #Thrombosis #Hematology #KFSHRC #SSBMT2026

For all the early-stage PIs and young investigators out there actively pursuing research in #complementbiology and #therapeutics: Don't miss this great opportunity 👇! Just one week left to submit your work and apply for a trainee travel award! #ComplementTherapeutics

Pleased to share our paper 📄published on New Year’s Eve 🎉: “The temporal gene expression landscape of rhabdomyolysis-induced acute kidney injury reveals the timing of complement activation”, Communications Biology Read it here👇 rdcu.be/eW4t5 #complementbiology #AKI

Excited to share our latest review: Complement system in tumor growth and metastases just published in the British Journal of Cancer! #complementbiology #CancerResearch nature.com/articles/s41416-0…

A compelling keynote by Dr. Arvind Sahu @unescorcb on “Viral Teachings on Complement Regulation”—revealing how pathogens exploit immune mechanisms and what this means for host–pathogen biology. A highlight of Day 1 at the Indo–French Workshop. #ComplementBiology #InfectiousDiseases @DBTIndia @BricDbt

Excited to share our review: Complement and the hallmarks of cancer - hot off the press in Seminars in Immunology! Everything you ever wanted to know about #complementbiology and #cancer but never sared ask is here👇 sciencedirect.com/science/ar…

The infinite beauty of finely regulated biology from a neutrophil's perspective...with the helping hand of #complementbiology! The recent study by Hsu et al. sciencedirect.com/science/ar… nicely placed in context by @lai9uan and @ImmanuelKwok in this preview sciencedirect.com/science/ar…

Looking forward to joining #EULAR2025 #Barcelona to discuss the latest developments in #complementbiology and #therapeutics and their implications in health, disease and therapy. Many thanks to the organizers and session chairs for this invitation!

Interested in #complementbiology and cancer? Review#3 of our Seminars in Immunology special issue is out! Learn from @olcina_lab about the complex effects of cytotoxic therapy on complement and what can be learned to identify more effective therapy. 👇 sciencedirect.com/science/ar…

Interested in #complementbiology? Time has come to submit your abstracts for 17th Int'l Conference on #ComplementTherapeutics, Greece May 10-15 PIs -> Encourage your students to apply for our generous travel grants Students -> We have travel grants for you! Talk to your PIs! 👇

The complement system in clinical oncology: Applications, limitations and challenges A great #complementbiology review by Ruben Pio for our special issue of Seminars in Immunology to enjoy before the 🎄 holidays Check it out! 👇 sciencedirect.com/science/ar…

Very interesting paper on #complementbiology and cancer, check it out! The C5a/C5aR1 axis promotes migration of tolerogenic dendritic cells to lymph nodes, impairing the anticancer immune response aacrjournals.org/cancerimmun…

Brilliant PhD defense of Mikel Rezola Artero on Mechanisms of #Complementbiology Subversion in Infection & Cancer! Amazing, master class!!! 👏 1st double diploma PhD from @helsinkiuni and @Sorbonne_Univ_ thanks to the Corvos EU PhD program We are so proud of you! 🎊💐👏

What an inspiring #ASH2024 congress! #Complementbiology was on many presentations and posters! With Anne Grunenwald we were so happy to discuss our transcriptomic atlases of #SickleCell and hemolysis, featuring key role of complement for organ injury @palheox @CRCordeliers

Interested in #complementbiology and attending #ASH2024? Come to the Interface of Complement and Coagulation symposium this afternoon at 4 PM, room 33. Meet @DrDKavanagh, Dr Vlachaki and me to discuss this exciting subject! A teaser from my talk about #sicklecell disease 👇

Disruption of the C5a/C5aR1 axis confers protection against hookworm infection in lung Congratulations Sarah Walachowski! #complementbiology 👇 frontiersin.org/journals/imm…

Great review on #complementbiology of C3 glomerulopathy and Ig-MPGN by Julia Roquigny and @VeroniqueBacchi ! 👇 Acquired and genetic drivers of C3 and C5 convertase dysregulation in C3 glomerulopathy and immunoglobulin-associated MPGN academic.oup.com/ndt/article…

Congratulations @MSMeuleman for the brilliant PhD defense! What a pleasure to listen to the presentation and the discussion with the jury about #complementbiology of #C3 Glomerulopathy Fantastic project under the supervision of @chauvet_sophie in our team of @CRCordeliers

Huge applause to Veronique Fremeaux-Bacchi for receiving the medal for being an Outstanding Complementologist, from the European Complement Network 🏅🌹👏 It was so emotional to present a laudation to my mentor and friend. @CRCordeliers #complementbiology #EMCHD2024