<s>[INST] context: Kostmann's syndrome (severe congenital neutropenia)

Kostmann's syndrome, an autosomal recessive disorder, is an inherited disorder of the bone marrow in which there is the arrest of maturation of neutrophils at promyelocyte stage.
There is congenital neutropenia and neutrophils are often completely absent in the blood at the time of diagnosis.
Because of neutropenia, these patients suffer from severe infections e.g., omphalitis (infection of the navel), Pneumonia, Skin abscesses, otitis media.
Kostmann's syndrome is believed to be caused due to defect in the receptor of granulocyte colony stimulating factor (GCSF) on neutrophils (granulocytes). The purpose of this receptor is the binding of the granulocyte to the cytokine (GCSF) in order to give the signal to the cell to mature and multiply.
Patients with Kostamann's syndrome produce GCSF but because of the defect in GCSF receptor the response of neutrophils to normal amounts of GCSF in the blood is reduced: However, they can respond if the amount of GCSF is increased → These patients will respond to a higher dose of GCSE [/INST] question: Kostmann's syndrome–treatment is – | options: A: Anti–thymocyte globulin + cyclosporin B: Anti–thymocyte globulin + cyclosporin + GM–CSF C: G–CSF D: GM–CSF | answer: C </s>