Kostmann syndrome, also known as severe congenital neutropenia, is a congenital disorder characterized by genetic mutations that prevent the progression of myeloid differentiation in the bone marrow. Most cases are associated with specific genetic mutations, including those in HAX1 and ELANE. Treatment with antibiotics and granulocyte colony-stimulating factor (G-CSF) is primarily prophylactic. We report a pediatric case of severe congenital neutropenia present since birth, with negative whole-exome sequencing (WES), complicated by multiple hospital admissions for recurrent infections and subsequent progression to myelodysplastic syndrome with excess blasts associated with monosomy 7, for which the patient ultimately underwent hematopoietic stem cell transplantation (HSCT). This case highlights that many patients with Kostmann syndrome can present with negative genetic testing and draws attention to the importance of surveillance for malignant transformation.

Kostmann syndrome is an autosomal recessive disorder caused by a mutation of the hematopoietic cell-specific Lyn substrate 1 associated protein X-1 (HAX1) gene, and characterized by low number of neutrophils and increased susceptibility to infections. Additionally, Kostmann syndrome is known to be complicated by periodontitis, though the etiological molecular basis remains unclear. We previously reported findings showing that junctional adhesion molecule 1 (JAM1), a tight junction-associated protein, has an important role to maintain epithelial barrier function in gingival tissues, which prevents penetration of bacterial virulence factors, such as lipopolysaccharide (LPS) and peptidoglycan (PGN). In the present study, the effects of HAX1 on gingival barrier function were investigated. Examinations of immortalized human gingival epithelial (IHGE) cells showed HAX1 localization in mitochondria. In HAX1-knockdown IHGE cells, significantly decreased levels of JAM1 were found. Additionally, cisplatin, a chemotherapeutic agent reported to inhibit HAX1, also led to decreased expression of both HAX1 and JAM1. Furthermore, JAM1 was scarcely detected in HAX1-knockout cells, while administration of bafilomycin A1, a lysosomal inhibitor, restored JAM1 expression in those cells. Finally, using a three-dimensional multilayered gingival epithelial tissue model, HAX1 knockout along with cisplatin administration was also found to increase permeability to LPS and PGN, which was dependent on JAM1 expression. These results indicate that periodontal diseases complicated with Kostmann syndrome are induced by reduced JAM1 expression, caused by JAM1 being missorted into lysosomes by HAX1 dysfunction.

Severe congenital neutropenia (SCN), commonly known as the Kostmann syndrome, is a rare and complex set of disorders defined by a lack of neutrophil maturation in the bone marrow, leading to life-threatening complications. This case report discusses a young adult patient scheduled for elective laparoscopic cholecystectomy. The patient presented with skin lesions which are a common scenario of Kostmann syndrome, but along with that, our patient posed challenges of short neck, limited neck extension, and gynecomastia. These additional conditions dramatically increased the challenges for anesthesiologists to address the anticipated difficult airway. The anticipated difficult airway challenges were handled by following the protocols of difficult airway guidelines 2022.

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.

Gaucher Disease (GD) is the most common lysosomal storage disorder has traditionally been classified into three clinical phenotypes. Type 3 GD is characterized by neurological involvement but neurological symptoms generally appear later in life than in type 2 disease. Neutropenia is much rarer than other hematological manifestations in GD and has not been scrutinized adequately. Severe congenital neutropenia (SCN) is a rare disease entity which is characterized by a paucity of peripherally circulating neutrophils with arrest of neutrophil maturation at the promyelocyte stage and consequent increased susceptibility to severe and recurrent infections. We report a patient who presented in the first year of life with visceral involvement and severe neutropenia in whom the propositus had a unique coexistence of Gaucher Disease and severe congenital neutropenia associated with a mutation in HAX1. In contrast to his expired siblings he had experienced no severe infections. These clinical observations suggest that enzyme replacement therapy may display a modulating factor with respect to the clinical course of SCN. SYNOPSIS: Our patient is the only report of the combination of Gaucher Disease and Kostmann Syndrome in the literature. The clinical course of our patient is not severe when comparing with exitus siblings and other Kostmann Syndrome patients. But when considering the patient's only clinical difference is ERT, this case is very important to emphasise the role of enzyme replacement therapy in bone marrow.