Cancer chemotherapy is probably the most common cause of neutropenia. People with chemotherapy-related neutropenia are prone to infections while they wait for their cell counts to recover. Neutrophils are manufactured in bone marrow — the spongy tissue inside some of your larger bones. Anything that disrupts neutrophil production can result in neutropenia. Specific causes include: Kostmann's syndrome — a congenital disorder involving low production of neutrophils.