Reduced toxicity matched sibling bone marrow transplant results in excellent outcomes for severe congenital neutropenia.

Severe congenital neutropenia (SCN) is caused by germline mutations, most commonly in ELANE, impacting neutrophil maturation and leading to high risk of life-threatening infections. Most patients with ELANE-mutant SCN can achieve safe neutrophil counts with chronic Granulocyte-Colony Stimulating Factor (G-CSF). However, up to 10% of patients have neutropenia refractory to G-CSF and require allogeneic stem cell transplant. Traditional conditioning for these patients includes busulfan and cyclophosphamide which is associated with significant toxicities. We present five patients with SCN without myeloid malignancy transplanted using a reduced toxicity regimen of busulfan, fludarabine and thymoglobulin. 5 pediatric patients with SCN underwent matched sibling donor bone marrow transplant (MSD-BMT) between 2014-2022 on or per CHP14BT057 (NCT02928991), a prospective, single center trial testing elimination of cyclophosphamide from conditioning in pediatric patients with single lineage inherited BMF syndromes. All patients had MSDs and no evidence of MDS. Conditioning consisted of PK-adjusted busulfan, fludarabine, and thymoglobulin, with calcineurin inhibitor and mycophenolate mofetil GVHD prophylaxis. With median follow-up of 48.4 months, overall and event-free survival were 100%. There was no acute GVHD and one instance of chronic limited GVHD. Patients exhibited >95% donor myeloid chimerism at 5 years post-BMT. Two patients experienced CMV reactivation without end-organ disease, and no other viral reactivation or significant infections occurred. MSD-BMT with reduced toxicity myeloablation for SCN provides excellent outcomes while minimizing toxicity. These data suggest that busulfan, fludarabine, and ATG can be considered an efficacious, low-toxicity standard of care regimen for patients with SCN undergoing MSD-BMT.

Impact of different genetic mutations on granulocyte development and G-CSF responsiveness in congenital neutropenia.

ABSTRACT: Congenital neutropenia (CN) is a genetic disorder characterized by persistent or intermittent low peripheral neutrophil counts, thus increasing susceptibility to bacterial and fungal infections. Various forms of CN, caused by distinct genetic mutations, exhibit differential responses to granulocyte colony-stimulating factor (G-CSF) therapy, with the underlying mechanisms not fully understood. This study presents an in-depth comparative analysis of clinical and immunological features in 5 CN patient groups (severe congenital neutropenia [SCN]1, SCN3, cyclic neutropenia [CyN], warts, hypogammaglobulinaemia, infections and myelokathexis [WHIM], and Shwachman-Bodian-Diamond Syndrome [SBDS]) associated with mutations in ELANE, HAX1, CXCR4, and SBDS genes. Our analysis led to the identification of 11 novel mutations in ELANE and 1 each in HAX1, CXCR4, and G6PC3 genes. Investigating bone marrow (BM) granulopoiesis and blood absolute neutrophil count after G-CSF treatment, we found that SCN1 and SCN3 presented with severe early-stage disruption between the promyelocyte and myelocyte, leading to a poor response to G-CSF. In contrast, CyN, affected at the late polymorphonuclear stage of neutrophil development, showed a strong G-CSF response. WHIM, displaying normal neutrophil development, responded robustly to G-CSF, whereas SBDS, with moderate disruption from the early myeloblast stage, exhibited a moderate response. Notably, SCN1 uniquely impeded neutrophil development, whereas SCN3, CyN, WHIM, and SBDS also affected eosinophils and basophils. In addition, SCN1, SCN3, and CyN presented with elevated serum immunoglobulins, increased BM plasma cells, and higher A Proliferation-Inducing Ligand levels. Our study reveals a strong correlation between the stage and severity of granulocyte development disruption and the efficacy of G-CSF therapy.

Coexistence of Bloom Syndrome and Kostmann Disease and a Novel Mutation.

Bloom syndrome (BS) is a rare autosomal recessive inherited disorder. Patients with BS have photosensitivity, telangiectatic facial erythema, and stunted growth. They usually have mild microcephaly, and distinctive facial features such as a narrow, slender face, micrognathism, and a prominent nose. Kostmann disease (KD) is a subgroup of severe congenital neutropenias. The diagnosis of severe congenital neutropenia is based on clinical symptoms, bone marrow findings, and genetic mutation. Here, we report a female patient with a triangular face, nasal prominence, and protruding ears presenting with recurrent infections and severe neutropenia. Molecular genetic testing revealed a compound heterozygous variant in the HCLS-1-associated protein X-1 gene [(c.130_131insA) p.(trp44*), c.430 dup(p.Val144fs)] and a new homozygous variant in Bloom Syndrome RecQ like helicase gene [c.2074+2T>C p.(?)]. She was diagnosed with both BS and KD. To the best of our knowledge, this is the first case of coexisting BS and KD in a patient ever reported.

Screening for ELANE, HAX1 and GFI1 gene mutations in children with neutropenia and clinical characterization of two novel mutations in ELANE gene.

BACKGROUND: Congenital neutropenia is a rare disease. Recurrent infections since young age are the presentation. The most common mutation causing severe congenital neutropenia (SCN) and cyclic neutropenia (CyN) is the ELANE gene. The objectives of this study were to screen the three common genetic mutations of ELANE, HAX1 and GFI1 in children with chronic neutropenia and to describe the clinical characteristics of children who had the mutations. METHODS: Infants having ANC < 1,000/cu mm or children aged > 1 year having ANC < 1,500/cu mm at least 3 times in 3 months were enrolled in the study. Patients who had acquired neutropenia due to infection, immune deficiency, or drugs were excluded. The ELANE gene was first studied; and if mutations were not identified, the HAX1 and GFI1 genes were further examined. RESULTS: A total of 60 patients were enrolled in the study. The median (range) age, ratio of female to male, ANC, and last follow-up age were 9.2 (0.5-45.2) months, 1:1.2, 248 (0-1,101) /cu mm, and 19.9 (3.5-202.3) months, respectively. Infections were noted in 67.3% of all patients. ELANE gene mutation was found in only four patients (6.7%), and the rest (56 patients) showed no mutations in the HAX1 and GFI1 genes. In patients without mutations, 66.0% had normal ANC during the follow-up, with a median (range) age for normal ANC of 19.8 (4.0-60.0) months. Two novel mutations p. Ala79del (c.234_236del) and p. Val197GlufsTer18 (c.589_590insAGGCCGGC) were identified, and they respectively cause SCN and CyN. Patients with the two novel mutations presented with several episodes of infection, including pneumonia, sepsis, abscess, otitis media, and gum infection. CONCLUSION: The genetic screening for ELANE, HAX1, and GFI1 gene mutations in 60 patients with chronic neutropenia could identify four patients (6.7%) with ELANE gene mutation and two novel mutations, p. Ala79del in exon 3 and p. Val197GlufsTer18 in exon 4 causing SCN; and CyN, respectively.

Case Report: Characterization of known (c.607G>C) and novel (c.416C>G) ELANE mutations in two Mexican families with congenital neutropenia.

The most common causes of congenital neutropenia are mutations in the ELANE (Elastase, Neutrophil Expressed) gene (19p13.3), mostly in exon 5 and the distal portion of exon 4, which result in different clinical phenotypes of neutropenia. Here, we report two pathogenic mutations in ELANE, namely, c.607G>C (p.Gly203Arg) and a novel variant c.416C>G (p.Pro139Arg), found in two Mexican families ascertained via patients with congenital neutropenia who responded positively to the granulocyte colony-stimulating factor (G-CSF) treatment. These findings highlight the usefulness of identifying variants in patients with inborn errors of immunity for early clinical management and the need to rule out mosaicism in noncarrier parents with more than one case in the family.

HAX1-related congenital neutropenia: Long-term observation in paediatric and adult patients enrolled in the European branch of the Severe Chronic Neutropenia International Registry (SCNIR).

HAX1-related congenital neutropenia (HAX1-CN) is a rare autosomal recessive disorder caused by pathogenic variants in the HAX1 gene. HAX1-CN patients suffer from bone marrow failure as assessed by a maturation arrest of the myelopoiesis revealing persistent severe neutropenia from birth. The disorder is strongly associated with severe bacterial infections and a high risk of developing myelodysplastic syndrome or acute myeloid leukaemia. This study aimed to describe the long-term course of the disease, the treatment, outcome and quality of life in patients with homozygous HAX1 mutations reported to the European branch of the Severe Chronic Neutropenia International Registry. We have analysed a total of 72 patients with different types of homozygous (n = 68), compound heterozygous (n = 3), and digenic (n = 1) HAX1 mutations. The cohort includes 56 paediatric (<18 years) and 16 adult patients. All patients were initially treated with G-CSF with a sufficient increase in absolute neutrophil counts. Twelve patients required haematopoietic stem cell transplantation for leukaemia (n = 8) and non-leukaemic indications (n = 4). While previous genotype-phenotype reports documented a striking correlation between two main transcript variants and clinical neurological phenotypes, our current analysis reveals novel mutation subtypes and clinical overlaps between all genotypes including severe secondary manifestations, e.g., high incidence of secondary ovarian insufficiency.

JAGN1 mutation with distinct clinical features; two case reports and literature review.

Jagunal homolog 1 (JAGN1) has been recognized as an essential protein in neutrophil function. The mutated JAGN1 is responsible for immunodeficiency related to innate and humoral defense mechanisms. This deficiency impairs neutrophil development and function, leading to recurrent infections and facial dysmorphism as phenotypic consequences of severe congenital neutropenia (SCN). We report two siblings having the reported JAGN1 mutation with different clinical manifestations. Recurrent abscess formation unresponsive to antibiotic therapy, a history of delayed umbilical separation, frequent bacterial or fungal infection, dysmorphic face, failure to thrive, and other coexisting organ abnormalities should prompt physicians to syndromic immunodeficiencies involving neutrophils. Genetic investigations to elucidate the responsible mutation is critical as clinical management varies. Once the diagnosis is confirmed, a multi-disciplinary team should perform further workups to investigate other coexisting malformations and neurodevelopmental evaluation.

Historical Cohort of Severe Congenital Neutropenia in Iran: Clinical Course, Laboratory Evaluation, Treatment, and Survival.

INTRODUCTION: Severe congenital neutropenia (SCN) is one of the primary immunodeficiency diseases developed by genetic alterations. Mutations in several genes including HAX-1 , G6PC3 , jagunal , and VPS45 account for autosomal recessive SCN. PATIENTS AND METHODS: Patients with SCN registered in the Iranian Primary Immunodeficiency Registry and referred to our clinic at the Children's Medical Center were reviewed. RESULTS: Thirty-seven eligible patients with a mean age of 28.51 ± 24.38 months at the time of diagnosis were included. Nineteen cases had consanguineous parents and 10 cases had confirmed or unconfirmed positive family history. The most prevalent infectious symptoms were oral infections followed by respiratory infections. We identified HAX-1 mutation in 4, ELANE mutation in 4 cases, G6PC3 mutation in 1, and WHIM syndrome in 1 case. Other patients remained genetically unclassified. After the median follow-up of 36 months from the time of diagnosis, the overall survival was 88.88%. The mean event-free survival was 185.84 months (95% CI: 161.02, 210.66). DISCUSSION: Autosomal recessive SCN is more common in countries with high rates of consanguinity like Iran. The genetic classification was possible only for a few patients in our study. This might suggest that there are other autosomal recessive genes causative of neutropenia that have yet to be described.

Family Knowledge, Attitudes, and Practices Toward Severe Congenital Neutropenia.

Severe congenital neutropenia is a rare disorder. The survival and quality of life of patients radically improved through infection prevention, use of granulocyte colony-stimulating factor, and the appropriate use of antibiotics during infections. The aim of this study was to evaluate the precautions taken by families to prevent infections, the level of knowledge regarding the disease, and the impact of external factors such as education and economic status on behavior and compliance in patients and caregivers in terms of the following treatment protocols. Questionnaires were designed with the aim of determining how the social, cultural, and economic conditions of the families of children with severe congenital neutropenia affected their behavior and knowledge levels. They were completed using one-on-one video interviews with the caregivers. Thirty-one patients from 25 families were enrolled into the study. No correlations between family disease knowledge, parent education levels, working status of the mother, sibling numbers, economic status, ease of hospital access, and/or residential location were found. An increase in disease knowledge of patients and caregivers, as well as proven approaches to living with the disease, would directly correlate to increased life quality and long-term survival rates of patients.

Diagnostic guidance for hereditary neutropenia in children: Narrative literature review.

In the era of genomics, orientation in the face of hereditary neutropenia still requires, first and foremost, a good clinical and cytological analysis. The thirty responsible genes now explain 60% of congenital neutropenia. These are rare since they are only found in 1‰ of all congenital neutropenia, estimated at 1% of the population. The clinical examination looks for phenotypes associated with syndromic hereditary neutropenia and cytology will guide this etiological research thanks to the data collected from blood count and bone marrow analysis. The objective of this narrative literature review is to provide an overview of the most recent literature regarding acquired and congenital chronic neutropenia and will provide a decision tree to guide towards aetiology. This will allow a better discussion with geneticists even if the genotype-phenotype correlation is not very strong.

Severe Congenital Neutropenia Type 4: A Rare Disease Harboring a G6pc3 Gene Pathogenic Variant Particular to the Mexican Population.

Background: Severe congenital neutropenia type 4 (SCN4) is a rare autosomal recessive granulopoiesis disorder caused by G6PC3 gene pathogenic variants. The estimated prevalence is 1/10,000,000 people. Over 90% of patients present a syndromic form with variable multisystemic involvement, including congenital heart defects, increased visibility of superficial veins (IVSV), inflammatory bowel disease, and congenital urogenital defects as prominent symptoms. Objectives: The objective of the study was to study non-hematological phenotypic findings that suggest a clinical diagnosis of SCN4. Methods: We examined medical records of patients diagnosed with neutropenia from January 2000 to December 2020, selecting cases with non-hematologic manifestations for phenotypic description and G6PC3 gene sequencing. Results: We found 11 cases with non-hematologic features: congenital heart defects in 8, IVSV in 6, inflammatory bowel disease in 4, urogenital defects in 4, and similar facial appearance. In addition, Sanger sequencing confirmed 3 homozygous cases for the c.210delC variant, a compound heterozygous harboring this variant, and a c.199_218+1 deletion. Conclusions: Our findings of the c.210delC variant in very close geographical settings, to date, have only been reported among Mexicans, and a mutual uncommon surname in two families strongly supports a founder effect for the variant in the studied population. Furthermore, the described non-hematologic symptoms in patients with severe primary neutropenia should be explored, confirming SCN4 by investigating G6PC3 gene mutations.

Genetics of severe congenital neutropenia as a gateway to personalized therapy.

Severe congenital neutropenias (SCNs) are rare diseases, and to date about 30 subtypes have been described according to their genetic causes. Standard care aims to prevent infections and limit the risk of leukemic transformation; however, several subtypes may have additional organ dysfunction(s), requiring specialized care. Granulocyte colony-stimulating factor and hematopoietic stem cell transplantation are now the bedrock of standard care. Better understanding of SCN mechanisms now offers the possibility of adapted therapy for some entities. An inhibitor of sodium glucose cotransporter, an antidiabetic drug, may attenuate glycogen storage disease type Ib and glucose-6-phosphatase catalytic subunit 3 neutropenias by clearing 1,5-anhydroglucitol, the precursor of the phosphate ester responsible for these SCNs. Chemokine receptor CXCR4 inhibitors contribute to reversing the leukocyte defect in warts, hypoglobulinemia, infections, and myelokathexis syndrome. All these new approaches use oral drugs, which notably improve quality of life. Additionally, improved research into clonal evolution has highlighted some ways to potentially prevent leukemia, such as stimulating somatic genetic rescue, a physiological process that might limit the risk of leukemic transformation.

[Congenital neutropenia type IV: case report]. / Neutropenia congénita de tipo IV: reporte de un caso.

Severe congenital neutropenia (SCN) is a heterogeneous disease whose more common feature is an absolute neutrophil count less than 0.5 x 109/l. It presents great genetic heterogeneity. Autosomal dominant inherited mutations of the elastase 2 gene (ELA2) represent the most common etiology. The first choice treatment is the administration of granulocyte colony stimulating factor. Patients with SCN develop severe infections early in life. We present a patient who associated SCN to a peculiar phenotype, characterized by triangular facies, retromicrognathia, prominent venous pattern in the lower limbs, atrial septal defect and poor weight progress, in whom a deficiency of the enzyme glucose 6 phosphate dehydrogenase, Neutropenia congénita de tipo IV: reporte de un caso Congenital neutropenia type IV: case report a catalytic subunit 3 (G6PC3), was diagnosed. Despite the infrequency of this mutation as the origin of SCN (2%), its knowledge becomes important because the coexistence of the characteristic phenotype and SCN guides the request for the genetic study that allows reaching the diagnosis.

La neutropenia congénita grave (NCG) es una entidad heterogénea cuya característica común es un recuento absoluto de neutrófilos inferior a 0,5 x 109/l. Presenta gran heterogeneidad genética, las mutaciones más frecuentes son las del gen de la elastasa 2 (ELA 2). El tratamiento de primera elección es la administración de factor estimulador de colonias de granulocitos. Los pacientes con NCG presentan infecciones graves en etapas tempranas de la vida. Se presenta una paciente con NCG asociada a fenotipo peculiar con facies triangular, retromicrognatia, patrón venoso prominente en miembros inferiores, comunicación interauricular y mal progreso ponderal, en quien se diagnosticó déficit de la enzima glucosa 6 fosfato deshidrogenasa, subunidad catalítica 3 (G6PC3). A pesar de lo infrecuente de esta mutación como causa de NCG (2 %), su conocimiento cobra importancia porque la coexistencia del fenotipo característico con una NCG orienta en la solicitud del estudio genético que permite arribar al diagnóstico.

Neutropenia congénita de tipo IV: reporte de un caso / Congenital neutropenia type IV: case report

La neutropenia congénita grave (NCG) es una entidad heterogénea cuya característica común es un recuento absoluto de neutrófilos inferior a 0,5 x 10 9/l. Presenta gran heterogeneidad genética, las mutaciones más frecuentes son las del gen de la elastasa 2 (ELA 2). El tratamiento de primera elección es la administración de factor estimulador de colonias de granulocitos. Los pacientes con NCG presentan infecciones graves en etapas tempranas de la vida. Se presenta una paciente con NCG asociada a fenotipo peculiar con facies triangular, retromicrognatia, patrón venoso prominente en miembros inferiores, comunicación interauricular y mal progreso ponderal, en quien se diagnosticó déficit de la enzima glucosa 6 fosfato deshidrogenasa, subunidad catalítica 3 (G6PC3). A pesar de lo infrecuente de esta mutación como causa de NCG (2 %), su conocimiento cobra importancia porque la coexistencia del fenotipo característico con una NCG orienta en la solicitud del estudio genético que permite arribar al diagnóstico.

Severe congenital neutropenia (SCN) is a heterogeneous disease whose more common feature is an absolute neutrophil count less than 0.5 x 10 9/l. It presents great genetic heterogeneity. Autosomal dominant inherited mutations of the elastase 2 gene (ELA2) represent the most common etiology. The first choice treatment is the administration of granulocyte colony stimulating factor. Patients with SCN develop severe infections early in life. We present a patient who associated SCN to a peculiar phenotype, characterized by triangular facies, retromicrognathia, prominent venous pattern in the lower limbs, atrial septal defect and poor weight progress, in whom a deficiency of the enzyme glucose 6 phosphate dehydrogenase, a catalytic subunit 3 (G6PC3), was diagnosed. Despite the infrequency of this mutation as the origin of SCN (2%), its knowledge becomes important because the coexistence of the characteristic phenotype and SCN guides the request for the genetic study that allows reaching the diagnosis.

Case Report: Association between cyclic neutropenia and SRP54 deficiency.

Autosomal dominant mutations in the signal recognition particle (SRP) 54 gene were recently described in patients with severe congenital neutropenia (SCN). SRP54 deficiency cause a chronic and profound neutropenia with maturation arrest at the promyelocyte stage, occurring in the first months of life. Nearly all reported patients with SRP54 mutations had neutropenia without a cyclic pattern and showed a poor or no response to granulocyte colony-stimulating factor (G-CSF) therapy. We report here an 11-year-old female patient with cyclic neutropenia and recurrent heterozygous p.T117del (c.349_351del) in-frame deletion mutation in SRP54, who showed remarkable therapeutic response to G-CSF treatment. The diagnosis of cyclic pattern of neutropenia was established by acceptable standards. ELANE gene mutation was excluded by using various genetic approaches. The patient described here also had dolichocolon which has not been described before in association with SCN.