Overview of Severe Congenital Neutropenia

Severe congenital neutropenia describes a condition in which an individual is born with severe neutropenia (defined as a neutrophil count of less than 500 cells per microliter, and often less than 200). One specific form is called Kostmann Syndrome, a rare condition affecting an estimated 1–2 per million individuals.

Symptoms

Symptoms of congenital neutropenia generally start shortly after birth. Neutrophils are a type of white blood cell that fight bacterial infections. The severely low neutrophil count that characterizes this condition increases risk of bacterial infections. Fever is also a common symptom, but this is due to the infection, not neutropenia. 

Birth defects are generally not seen. Symptoms may include:

• Recurrent fever
• Sore throat (pharyngitis)
• Inflammation of the gums (gingivitis) 
• Inflamed and sore mouth (stomatitis)
• Infections in the skin and in other areas of the body

Diagnosis

It is likely that during one of these infections, your healthcare provider will obtain a complete blood count (CBC). In severe neutropenia (less than 500 cells/microliter), white blood cells are the only type of blood cell affected. Red blood cells and platelets should be normal. Usually, monocytes—another type of white blood cell—will also be elevated. If more than one type of blood cell is affected, other diagnoses (like Shwachman Diamond syndrome) should be considered.

Once severe neutropenia is identified, your healthcare provider may consider referring you to a hematologist, a practitioner who specializes in blood disorders. Initially, you may have a CBC drawn two to three times weekly to rule out cyclic neutropenia (a more benign condition) as the cause. 

The next step is a bone marrow biopsy. This test involves removing a small piece of bone from your hip to assess the bone marrow, the area where white blood cells are made. In severe congenital neutropenia, the cells are made normally initially but then at some point, they die before being released into circulation. 

If your bone marrow is consistent with severe congenital neutropenia, your healthjcare provider will likely order genetic testing to determine the particular mutation you have. This is important, as it will determine if or how you might pass this condition on to your children. 

Treatments

• Granulocyte colony stimulating factor (G-CSF or filgrastim): G-CSF is given as subcutaneous (under the skin) injections daily. This medication stimulates bone marrow production and maturation of neutrophils. The goal is to bring the neutrophil count to a consistently normal level to prevent infections.
• Bone marrow transplantation: Bone marrow transplantation can be curative. This is usually considered for people with poor response to G-CSF. If receiving a bone marrow transplant from a sibling, it is important to make sure they do not have a milder form of severe congenital neutropenia. 
• Antibiotics: If you have severe congenital neutropenia and develop a fever, you should seek immediate medical attention. Fever may be the only symptom of a serious infection. Blood work should be sent to identify the possible cause of infection. During this time, you will be placed on IV (through the vein) antibiotics in case you do have an infection. 

Are There Any Long-Term Concerns? 

With better treatment, life expectancy for people with severe congenital neutropenia has improved greatly. With increasing age, people with this condition are at increased risk for myelodysplastic syndrome (MDS) and leukemia (mostly acute myeloid leukemia) compared to the general population. This risk was thought to be secondary to G-CSF treatment, but now appears to be a complication of the condition. 

Treatment with G-CSF may increase the size of the spleen and cause a low platelet count (thrombocytopenia, which could require a splenectomy.