Kostmann Syndrome With Neurological Abnormalities: A Case Report and Literature Review

Background: Severe congenital neutropenia (SCN), also known as Kostmann syndrome, is a rare heterogeneous group of diseases characterized by arrested neutrophil maturation in the bone marrow.Case Presentation: We report a case of Kostmann syndrome and review previously reported SCN cases with neurological abnormalities. A 10-year-old boy had a history of recurrent, once a month, infection starting at 6 months of age. He had neutropenia for more than 9 years, as well as intellectual disability. He was homozygous for the exon 3 c.430dupG mutation of the HAX1 gene NM-006118. After treatment of antibiotics and G-CSF, his symtoms were relieved and was 3 months free of infection. The search revealed 29 articles related to Kostmann syndrome caused by HAX1 gene mutation; they were screened, and the main clinical features of 13 cases of Kostmann syndrome with neurological abnormalities were summarized and analyzed.Conclusions: Kostmann syndrome has three main characteristics: severe neutropenia (<0.2 × 109/L), maturation arrest of granulopoiesis at the promyelocyte stage, and death due to infections. HAX1 gene mutations affecting both isoforms A and B are associated with additional neurological symptoms. G-CSF can improve and maintain neutrophil counts, and improve prognosis and quality of life. At present, hematopoietic stem cell transplantation is the only cure.

Immunoblotting validation of research antibodies generated against HS1-associated protein X-1 in the human neutrophil model cell line PLB-985.

HS1-associated protein X-1 (Hax1) is a 35 kDa protein that is ubiquitously expressed. Hax1 is an anti-apoptotic protein with additional roles in cell motility, and autosomal recessive loss of Hax1 results in Kostmann syndrome, a form of severe congenital neutropenia. Because of the important role of Hax1 in neutrophils we demonstrate here validation of two commercially available research antibodies directed against human Hax1 in the human myeloid leukemia cell line PLB-985 cells. We show that both the mouse anti-Hax1 monoclonal IgG directed against amino acids 10-148 of Hax1 and a rabbit anti-Hax1 polyclonal IgG antibody directed against full-length Hax1 reliably and consistently detect Hax1 during immunoblotting of three different PLB-985 cell densities. Using shRNA mediated Hax1 knockdown, we demonstrate the specificity of both Hax1 antibodies. In addition, our results suggest that the rabbit anti-Hax1 polyclonal antibody provides a stronger intensity in detecting Hax1 protein, with detection in as few as 0.1 x 10 6 cells in 6 total replicates we have performed.