Severe congenital neutropenia or hyper-IgM syndrome? A novel mutation of CD40 ligand in a patient with severe neutropenia

Approach to genetic diagnosis of inborn errors of immunity through next-generation sequencing

Patients with inborn errors of immunity (IEI) present with a heterogeneous clinical and immunological phenotype, therefore a correct molecular diagnosis is crucial for the classification and subsequent therapeutic management. On the other hand, IEI are a group of rare congenital diseases with highly diverse features and, in most cases, an as yet unknown genetic etiology. Next generation sequencing has facilitated genetic examinations of rare inherited disorders during the recent years, thus allowing a suitable molecular diagnosis in the IEI patients. This review aimed to investigate the current findings about these techniques in the field of IEI, suggesting an efficient stepwise approach to molecular diagnosis of inborn errors of immunity.

CD40 Ligand Deficiency

CD40 ligand deficiency (CD40L), currently classified as an inborn error of immunity affecting cellular and humoral immunity, prevalently emerges in boys within the first two years of life. It manifests itself as a decrease in serum IgG, IgA and IgE, with normal or high IgM, defects in T cell proliferation, and decrease in soluble CD40L. These accompany sinopulmonary and/or gastrointestinal infections, and there may be infections caused by pyogenic bacteria, opportunistic infections, autoimmune diseases, and neoplasms. Mild and moderate cases of this deficiency may respond well to prophylactic antibiotic therapy or to human immunoglobulin replacement therapy, in addition to the early treatment of infections. Severe cases can be treated with hematopoietic stem cell transplantation, which allows the healing of such patients, rather than sequelae and a poor progression. Thus, its differential diagnosis with other inborn errors of immunity is essential, especially CD40 deficiency and variable common immunodeficiency; the reason why we have proposed the present literature review.

Genetic Analysis of Patients with Two Different Types of Hyper IgM Syndrome

BACKGROUND

Hyper IgM Syndrome (HIGM) is a rare primary immunodeficiency in which impairment of class switching recombination (CSR) and somatic hyper-mutation (SHM) leads to recurrent infections.

OBJECTIVES

The aim of this study is to report the clinical and genetic features of six Iranian HIGM patients.

METHODS

Six patients, who suspected to have HIGM based on two clinical findings, including recurrent infections and low levels of IgG and IgA and normal or elevated levels of IgM, were entered this study to undergo genetic studies. Sanger sequencing was applied to detect pathogenic mutations in CD40L and AID genes causing two most common forms of HIGM, which known as HIGM type 1 and 2, respectively.

RESULTS

All patients who entered the study were males from unrelated families with a median age of 3.8 years. The most frequent clinical manifestation was recurrent pneumonia. Genetic studies of the patients revealed six different mutations, including five mutations in CD40L besides one mutation in AID. Two mutations in CD40L (p.F31fsX5 and p.C84S) were novel and three mutations (p. G219R, p.D62fsX18, and p.Q186X) have been previously reported. The mutation found in AID (p.E122X) was also previously described.

CONCLUSION

The study results may provide valuable information for prenatal diagnosis and also for genetic counseling especially for those who have a history of primary immunodeficiency in their family.

Increased serum IgM, immunodeficiency, and autoimmunity: A clinical series

BACKGROUND

Primary immunodeficiencies (PIDs) are generally characterized by recurrent infections; however they may be complicated by other clinical disorders such as allergy, autoimmunity, and lymphoproliferation. In particular, autoimmunity may be the first manifestation of the disease in patients with low serum immunoglobulins (Ig) levels. Here we describe a group of patients that share features of immunodeficiency and autoimmunity.

MATERIALS AND METHODS

All patients went through a complete T and B cell subset characterization and a B cell function analysis in the peripheral blood by flow-cytometry. B cell proliferation and plasma cell differentiation was measured, in vitro, after CpG stimulation for 7 days as previously described. Semi-quantitative PCR analysis for AID and UNG expression as well as serum levels of BAFF were carried out in order to better define the diagnosis.

RESULTS

Immunological and molecular analysis did not lead to the identification of known molecular defect typical of Hyper IgM syndrome. A comparative study of the peripheral blood B cell subsets between patients and healthy donors showed that in patients with autoimmune manifestations all circulating B cells expressed high amounts of surface IgM.

CONCLUSIONS

These results suggest that the increased IgM expression on circulating B cells, reflecting B cell activation, might identify a clinical condition characterized by hyper IgM serum levels of unknown molecular defects, associated with susceptibility to infections and autoimmunity.

AICDA single nucleotide polymorphism in common variable immunodeficiency and selective IgA deficiency

BACKGROUND

Primary antibody deficiencies (PADs) are a heterogeneous group of disorders, characterised by increased susceptibility to recurrent bacterial infections. Common variable immunodeficiency (CVID) is the most important PAD from the clinical point of view and selective IgA deficiency (IgAD) is the most common PAD. However, the underlying gene defect in both is still unknown. As a recent study in Europe showed an association between a single nucleotide polymorphism (SNP) of AICDA gene with PADs, this study was performed to evaluate such an association in Iranian patients.

METHODS

Fifty-eight patients with PAD, including 39 CVID and 19 IgAD, as well as 34 healthy volunteers, were enrolled in this study. Genotyping was done in all groups for an intronic SNP in AICDA (rs2580874), using real-time PCR genotyping assay.

RESULTS

The less frequent genotype of AICDA in IgAD patients was AA, seen in 10.5% of the patients, which was much lower than the 30.8% in CVID patients and 38.2% in the controls. However, these differences were not significant. Indeed the GG genotype in the patients with PADs was seen in 20.7%, compared to 8.8% in the controls without any significant difference.

CONCLUSIONS

There was no significant association between the previously reported genetic variant of AICDA gene and the development of CVID or IgAD, but further multi-center studies are also needed.

ICON: the early diagnosis of congenital immunodeficiencies

Primary immunodeficiencies are intrinsic defects in the immune system that result in a predisposition to infection and are frequently accompanied by a propensity to autoimmunity and/or immunedysregulation. Primary immunodeficiencies can be divided into innate immunodeficiencies, phagocytic deficiencies, complement deficiencies, disorders of T cells and B cells (combined immunodeficiencies), antibody deficiencies and immunodeficiencies associated with syndromes. Diseases of immune dysregulation and autoinflammatory disorder are many times also included although the immunodeficiency in these disorders are often secondary to the autoimmunity or immune dysregulation and/or secondary immunosuppression used to control these disorders. Congenital primary immunodeficiencies typically manifest early in life although delayed onset are increasingly recognized. The early diagnosis of congenital immunodeficiencies is essential for optimal management and improved outcomes. In this International Consensus (ICON) document, we provide the salient features of the most common congenital immunodeficiencies.

Spectrum of bone marrow failures of myeloid series: new report of neutropenic patients from a referral pediatric center in Iran

Neutropenia is a reduction of the absolute neutrophil count (ANC), which could be seen in different conditions, while its association with a number of primary immunodeficiency diseases has been reported. This study was performed in all neutropenic patients who were admitted in a referral pediatric hospital during a 6-year period (2006-2011). One hundred and forty patients with ANC of below 1500/mm(3) were investigated in this study. The most common causes of neutropenia were severe congenital neutropenia (41%), aplastic anemia (19%), cyclic neutropenia (11%), hyperimmunoglobulin M syndrome (9%), and fanconi anemia (7%). The patients experienced their first manifestation at a median age of 1 year, while the median diagnostic age was 21 months. Parental consanguinity was present in about half of the cases. The most common clinical manifestations of the patients were sinusitis (62 cases), periodontitis (51 cases), acute diarrhea (39 cases), pneumonia (38 cases), abscess (36 cases), skin rashes (35 cases), and otitis media (31 cases). Twenty two patients (16%) died during the study period. Considering the differential diagnosis of neutropenia, making the diagnosis and appropriate treatments are the keys in management of patients with neutropenia to avoid further complications.

Novel mutation of the activation-induced cytidine deaminase gene in a Tajik family: special review on hyper-immunoglobulin M syndrome

The hyper-immunoglobulin M (HIGM) syndrome comprises a group of primary immunodeficiency disorders characterized by normal or elevated serum levels of IgM and low levels of other immunoglobulin classes. Patients with HIGM usually suffer from a variety of recurrent infections. Herein, we report two siblings of a Tajik family with a HIGM phenotype in which a novel missense mutation in the activation-induced cytidine deaminase (AICDA) gene was detected. Mutations in this gene are responsible for an autosomal recessive form of HIGM. We have also reviewed and summarized all published cases with HIGM due to defects in AICDA.

X-linked hyper IgM syndrome: a novel sequence variant associated with an atypical mild phenotype

X-linked hyper IgM syndrome is associated with abnormalities in the gene encoding CD40 ligand (CD40LG). A typical phenotype evolves during infancy in affected males. This phenotype includes neutropenia, dysgammaglobulinemia, bacterial sinopulmonary infections, and opportunistic infections. In the absence of the typical phenotypic features, clinicians must maintain a high level of suspicion for X-linked hyper IgM syndrome. We describe a unique hemizygous CD40LG mutation which was discovered in a 12-year-old boy with chronic severe neutropenia, a normal IgG level, and absence of sinopulmonary or opportunistic infections. The clinical implications of this mutation and associated atypical phenotype are discussed.

Gene immunotherapy of chronic lymphocytic leukemia: a phase I study of intranodally injected adenovirus expressing a chimeric CD154 molecule

New therapies for chronic lymphocytic leukemia (CLL) are needed, particularly those that can eradicate residual disease and elicit anti-CLL immune responses. CD40 ligation on CLL cells, which can be achieved using adenovirus encoding chimeric CD154 (Ad-ISF35), enhances their ability to function as antigen-presenting cells and increases their sensitivity to clearance by immune-effector mechanisms. In this study, we report the results of a first-in-man phase I trial of intranodal direct injection (IDI) of Ad-ISF35 in patients with CLL to evaluate toxicity, safety, and tolerability. Fifteen patients received a single IDI of 1 × 10(10) to 33 × 10(10) Ad-ISF35 viral particles (vp), with a defined maximum tolerated dose as 1 × 10(11) vp. Although the most common adverse events were transient grade 1 to 2 pain at the injection site and flu-like symptoms following IDI, some patients receiving the highest dose had transient, asymptomatic grade 3 to 4 hypophosphatemia, neutropenia, or transaminitis. Increased expression of death receptor, immune costimulatory molecules, and Ad-ISF35 vector DNA was detected in circulating CLL cells. Notably, we also observed preliminary clinical responses, including reductions in leukemia cell counts, lymphadenopathy, and splenomegaly. Six patients did not require additional therapy for more than 6 months, and three achieved a partial remission. In conclusion, Ad-ISF35 IDI was safely delivered in patients with CLLs and induced systemic biologic and clinical responses. These results provide the rationale for phase II studies in CLLs, lymphomas, and CD40-expressing solid tumors.

Hyper-IgM, Neutropenia, Mild Infections and Low Response to Polyclonal Stimulation: Hyper-IgM Syndrome or Common Variable Immunodeficiency?

A young woman presenting respiratory infections, polyarthritis, severe neutropenia, and increased serum IgM was treated with Intravenous Immunoglobulin (IVIG) with good clinical and laboratory outcome followed by a loss of efficacy. The increased serum IgM associated to recurrent infections and autoimmune manifestations suggested the diagnosis of a hyper–IgM syndrome (HIGMs). The frequency of peripheral T cells, the expression of CD40 on the patients' B cells and CD40L on T cells and the Activation-Induced cytidine Deaminase (AID) and Uracyl-DNA glycosylase (UNG) at mRNA level was comparable to controls. In contrast, the frequency of B cells was one half of the healthy control and all cells showed an atypical phenotype. Although AID and UNG were normal, class-switch recombination was not very efficient because circulating switched memory were reduced and, once stimulated with CpG, generated less antibody-secreting cells than controls. An increase in serum B Lymphocytes stimulator (BLyS) was also found. The patient presented a peculiar clinical and immunological phenotype fitting for many aspects of both HIGM4 and Common Variable Immunodeficiency (CVID). These findings underline the need to better explore the complex link between these two diseases.

Genetic and molecular diagnosis of severe congenital neutropenia

PURPOSE OF REVIEW

Severe congenital neutropenia has been a well known hematological condition for over 50 years. Over this long period of time, the variable genetic causes and associated sequelae of the disease have been ascertained, and successful treatment strategies developed. Over the past 2 years, however, new studies have added greatly to our understanding of the molecular basis of the disease, details of which are presented in this review.

RECENT FINDINGS

Recent studies have elucidated a role for the unfolded protein response in mediating the pathogenic effects of ELA2 mutations, the most common mutation in severe congenital neutropenia (SCN) as well as cyclic neutropenia. Genetic lesions in HAX1 have also been identified in the original Kostmann pedigree representing the autosomal recessive form of SCN. An emerging theme is the convergence of these and other genetic lesions underlying SCN in enhancing neutrophil apoptosis. Other studies have revealed the importance of multiple independent mutations in these and other genes in SCN. Finally, the key role for signal transducer and activator of transcription 5 in mediating the effects of granulocyte colony-stimulating factor receptor truncation mutations in the development of myelodysplastic syndrome/acute myeloid leukemia following SCN has been elucidated.

SUMMARY

As the full spectrum of molecular mutations causing neutropenia emerges, it is becoming possible to differentiate patients into subtypes with different prognoses, for whom tailored therapies are indicated.