NOCARH syndrome (neonatal onset of cytopenia, autoinflammation, rash, and episodes of hemophagocytic lymphohistiocytosis [HLH]) is an extremely rare syndrome characterized by neonatal onset pancytopenia / dyshematopoiesis, autoinflammation, rash, and HLH. It is caused by a mutation in the cell division cycle 42 (CDC42) protein, usually in p. R186C at the C-terminal. CDC42 is responsible for ensuring proper functioning of the cell cycle, as well as cellular proliferation, adhesion, and migration. Thus, mutation in this protein causes dysregulated cell functioning, including hematological cell lines in the bone marrow. Most patients diagnosed with NOCARH syndrome have no family history. A single family with a recessively inherited mutation has been reported.

This syndrome presents with fever, rash, failure to thrive, hepatosplenomegaly, diarrhea, pancytopenia, and HLH starting in infancy. NOCARH syndrome is a fatal disease if not treated promptly; many pediatric patients have not survived this disease even with treatment.