Vitamin deficiency (e.g., iron, vitamin B12, or folate deficiency): This is a common cause of cytopenia in young adults, particularly due to dietary deficiencies or increased demand during periods of growth.

Anemia of chronic disease: Conditions like chronic infections, autoimmune diseases, or chronic kidney disease can lead to cytopenia.
Bone marrow suppression due to medication: Certain medications, such as chemotherapy agents, can suppress bone marrow function, leading to cytopenia.
Hypersplenism: Enlargement of the spleen can lead to sequestration and destruction of blood cells, resulting in cytopenia.
Chronic liver disease: Liver disease can affect the production of thrombopoietin, leading to thrombocytopenia, and can also contribute to anemia and leukopenia.

Aplastic anemia: A rare but potentially life-threatening condition where the bone marrow fails to produce blood cells.
Leukemia or lymphoma: Malignancies that can cause cytopenia due to bone marrow infiltration.
Severe combined immunodeficiency (SCID): A group of rare disorders caused by mutations in different genes involved in the development and function of infection-fighting immune cells.
Paroxysmal nocturnal hemoglobinuria (PNH): A rare, acquired, life-threatening disease of the blood characterized by the destruction of red blood cells, bone marrow failure, and the potential for blood clot formation.

Congenital bone marrow failure syndromes (e.g., Fanconi anemia, Diamond-Blackfan anemia): These are rare genetic disorders that affect the bone marrow's ability to produce blood cells.
Myelodysplastic syndromes (MDS): A group of disorders caused by poorly formed or dysfunctional blood cells, which can progress to leukemia.
Gaucher disease: A genetic disorder that can lead to cytopenia due to bone marrow infiltration by lipid-laden macrophages.
Other rare genetic disorders (e.g., Shwachman-Diamond syndrome, dyskeratosis congenita): These conditions can affect the bone marrow and lead to cytopenia.