Paroxysmal nocturnal hemoglobinuria

PNH begins in a blood-forming stem cell. Its descendants lack certain protective surface proteins, leaving red cells vulnerable to complement-mediated destruction, called hemolysis.

The name refers to dark urine, but not everyone has this symptom and hemolysis is not confined to nighttime. PNH can occur with aplastic anemia or other marrow disorders, but these diagnoses are not identical.

PNH usually involves an acquired change in PIGA, a gene required to attach protective proteins to blood-cell surfaces. The change occurs in a blood-forming cell rather than being present throughout the body and is generally not inherited by children.

A population of these altered cells is called a clone. Why a clinically important clone expands differs between people and can involve immune-mediated marrow injury. A small clone alone does not mean that someone has symptomatic classical PNH.

Hemolysis can cause fatigue, breathlessness, jaundice, abdominal pain and dark urine. Blood clots may occur in usual or unusual locations and can be life-threatening.

Some people also have low blood counts because the marrow is not producing enough cells. Tests of hemolysis, blood counts, clone size, symptoms and clotting history help distinguish the problems that need treatment.

Complement inhibitors reduce the immune attack on red cells and can reduce hemolysis and clotting complications. Several medicines act at different points in the complement pathway; eligibility, route of administration and access vary by country.

These medicines do not eliminate the PNH clone or directly correct severe marrow failure. Persistent anemia may have more than one cause and needs reassessment rather than an automatic assumption that the medicine has failed.

Complement blockade increases susceptibility to serious infections, including meningococcal infection. Vaccination, possible antibiotic protection and a plan for urgent symptoms are coordinated by the treating team. Vaccination does not remove all risk.

Allogeneic transplantation can replace the affected blood-forming cells but carries substantial risks. It is mainly considered for selected patients with severe marrow failure, myelodysplastic or leukemic disease, or exceptional circumstances involving uncontrolled PNH.

Ongoing care may involve regular medicine, blood tests, assessment of breakthrough symptoms and monitoring for complications. Some medicines are infused; others are injected or taken orally. Treatment schedules differ.

The team should explain which symptoms require immediate help and how treatment will be managed during infection, surgery or pregnancy. People with overlapping marrow failure may need transfusions or additional treatment alongside complement inhibition.

A donor transplant is generally not the usual treatment for classical PNH that is controlled with complement inhibitors. An unrelated donor may matter when transplantation is appropriate for a particular person’s marrow failure or other serious complications.

It is inaccurate to assume that all people with PNH need a match, or that someone who does need transplantation is being treated for exactly the same problem as every other person with PNH.

What is the exact diagnosis or subtype? What is the goal of each treatment option? If transplant is being considered, why does it fit this situation, which cells would be used and what are the alternatives?