Recurrent episodes of abnormally low levels of neutrophils in the body (neutropenia). [https://rarediseases.info.nih.gov/diseases/6229/cyclic-neutropenia]

Cyclic neutropenia (CyN) is a rare hematologic disorder and form of congenital neutropenia that tends to occur approximately every three weeks and lasting for few days at a time due to changing rates of neutrophil production by the bone marrow. It causes a temporary condition with a low absolute neutrophil count and because the neutrophils make up the majority of circulating white blood cells it places the body at severe risk of inflammation and infection...