Pediatric Blood Disorders: Paroxysmal Nocturnal Hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a type of aplastic anemia. It is an acquired genetic disease in which a mutation occurs in a marrow stem cell, causing a blood and marrow stem cell disorder. PNH is a disease of adulthood, but has been described in children as well. Memorial Sloan Kettering investigators have published one of the world’s largest single center studies of pediatric patients with childhood PNH.(1),(2)

PNH is characterized by a number of signs and symptoms including:

  • aplastic anemia
  • destruction of red blood cells known as hemolysis, leading to the release of hemoglobin in the urine, known as hemoglobinuria
  • a high risk of developing blood clots, or thrombosis

Other symptoms of young patients with PNH include increased susceptibility to infection, fatigue, headache, esophageal spasms, abdominal pain, back pain, and male erectile dysfunction.

There are two major treatment options for this disease today. The first is a recently developed monoclonal antibody called eculizumab (Soliris®), which can slow the progression of the disease. In certain instances, an allogeneic stem cell transplant is the best treatment for this disease. Transplantation has been performed successfully at Memorial Sloan Kettering using siblings or unrelated donors who are a bone marrow match.(3),(4)

Stem Cell Transplantation

In this treatment, another person’s healthy stem cells are transplanted into your child to stimulate the production of red blood cells, white blood cells, and platelets.

The goals of the transplant are to limit the risk of graft-versus-host disease, in which the child’s immune system attacks the transplanted cells; to decrease the risk that your child will develop infections during the treatment process; and to reduce the chance that your child will reject the transplanted cells.

The transplantation process begins with a process called conditioning, in which your child’s abnormal bone marrow stem cells and immune cells are destroyed through several days of chemotherapy and/or radiation therapy. Studies in which we are participating ensure that prior to transplants we are able to use minimal amounts of total-body irradiation or chemotherapy, or avoid their use altogether.

The actual stem cell transplant typically takes place a day or two after conditioning is completed. The donor stem cells or bone marrow are given to your child through a catheter or central venous line inserted in the chest or the arm into large veins close to the heart, in a process similar to that of a blood transfusion. The procedure is painless and takes between five and 20 minutes.

After the transplant, it takes about three to six months for a child’s body – especially the immune system – to recover. We ask our patients to remain in the New York area to receive care for about six months.