CONGENITAL NEUTROPENIA

Scientific Background

Severe congenital neutropenias (SCN) are a heterogeneous group of disorders of myelopoiesis and are characterized by absolute neutrophil numbers <200/μl blood with a normal lymphocyte count. There is an isolated block in the maturation of cells of the myeloid lineage at the promyelocyte level in the bone marrow. The first noticeable symptom in patients with SCN is delayed umbilical cord separation; recurrent episodes of fever and bacterial infections (otitis, pneumonia, gingivitis, aphthous ulcers, skin abscesses) also occur. Absent or reduced pus formation is also characteristic. Around 10-30% of patients with SCN develop myelodysplastic syndrome or acute myeloid leukemia during their lifetime. Neutropenia is also a common feature of various genetic syndromes that are associated with extrahematopoietic manifestations, such as Barth syndrome, Cohen syndrome, glycogenosis caused by glucose-6-phosphatase deficiency type b, Hermansky-Pudlak syndrome type 2, poikiloderma with neutropenia, or Shwachman-Diamond syndrome. The most frequent genetic cause of congenital neutropenia are pathogenic variants in the ELANE gene. They are found in about 40-55% of patients with permanent severe neutropenia or cyclic neutropenia. In rare cases, pathogenic variants are present in other SCN-associated genes. In up to 40% of SCN cases, the genetic cause remains unknown.

References

Spoor et al. 2019, Crit Rev Oncol Hematol 133:149 / Bousfiha et al. 2018, J Clin Immunol 38:129 / Picard et al. 2018, J Clin Immunol 38:96 / Boztug und Klein 2013, Hematol Oncol Clin North Am 27:43 / Hauck und Klein 2013, Curr Opin Allergy Clin Immunol 13:596