Four different NCF2 mutations in six families from Turkey and an overview of NCF2 gene mutations

Clinical and molecular significance of flow cytometric analysis for reactive oxygen species production and residual p67phox expression in p67phox-deficient chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease caused by molecular defects in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. p67phox-CGD is an autosomal recessive CGD, which is caused by a defect in the cytosolic components of NADPH oxidase, p67phox, encoded by NCF2. We previously established a flow cytometric analysis for p67phox expression, which allows accurate assessment of residual protein expression in p67phox-CGD. We evaluated the correlation between oxidase function and p67phox expression, and assessed the relevancy to genotypes and clinical phenotypes in 11 patients with p67phox-CGD. Reactive oxygen species (ROS) production by granulocytes was evaluated using dihydrorhodamine-1,2,3 (DHR) assays. p67phox expression was evaluated in the monocyte population. DHR activity and p67phox expression were significantly correlated (r = 0.718, p < 0.0162). Additionally, DHR activity and p67phox expression were significantly higher in patients carrying one missense variant in combination with one nonsense or frameshift variant in the NCF2 gene than in patients with only null variants. The available clinical parameters of our patients (i.e., age at disease onset, number of infectious episodes, and each infection complication) were not linked with DHR activity or p67phox expression levels. In summary, our flow cytometric analysis revealed a significant correlation between residual ROS production and p67phox expression. More deleterious NCF2 genotypes were associated with lower levels of DHR activity and p67phox expression. DHR assays and protein expression analysis by using flow cytometry may be relevant strategies for predicting the genotypes of p67phox-CGD.

Phenomic Analysis of Chronic Granulomatous Disease Reveals More Severe Integumentary Infections in X-Linked Compared With Autosomal Recessive Chronic Granulomatous Disease

Background

Chronic granulomatous disease (CGD) is an inborn error of immunity (IEI), characterised by recurrent bacterial and fungal infections. It is inherited either in an X-linked (XL) or autosomal recessive (AR) mode. Phenome refers to the entire set of phenotypes expressed, and its study allows us to generate new knowledge of the disease. The objective of the study is to reveal the phenomic differences between XL and AR-CGD by using Human Phenotype Ontology (HPO) terms.

Methods

We collected data on 117 patients with genetically diagnosed CGD from Asia and Africa referred to the Asian Primary Immunodeficiency Network (APID network). Only 90 patients with sufficient clinical information were included for phenomic analysis. We used HPO terms to describe all phenotypes manifested in the patients.

Results

XL-CGD patients had a lower age of onset, referral, clinical diagnosis, and genetic diagnosis compared with AR-CGD patients. The integument and central nervous system were more frequently affected in XL-CGD patients. Regarding HPO terms, perianal abscess, cutaneous abscess, and elevated hepatic transaminase were correlated with XL-CGD. A higher percentage of XL-CGD patients presented with BCGitis/BCGosis as their first manifestation. Among our CGD patients, lung was the most frequently infected organ, with gastrointestinal system and skin ranking second and third, respectively. Aspergillus species, Mycobacterium bovis, and Mycobacteirum tuberculosis were the most frequent pathogens to be found.

Conclusion

Phenomic analysis confirmed that XL-CGD patients have more recurrent and aggressive infections compared with AR-CGD patients. Various phenotypic differences listed out can be used as clinical handles to distinguish XL or AR-CGD based on clinical features.

Transcriptomic analysis using dual RNA sequencing revealed a Pathogen-Host interaction after Edwardsiella anguillarum infection in European eel (Anguilla anguilla)

Many studies have explored differentially expressed genes (DEGs) between some pathogens and hosts, but no study has focused on the interaction of DEGs between Edwardsiella anguillarum (Ea) and Anguilla anguilla (Aa). In this study, we examined the interactions of DEGs during Ea infection and Aa anti-infection processes by dual RNA sequencing. Total RNA from in vitro and in vivo (Aa liver) Ea culture was extracted. Using high-throughput transcriptomics, significant DEGs that were expressed between Ea cultured in vitro versus in vivo and those in the liver of the infected group versus control group were identified. Protein-protein interactions between the pathogen and host were explored using Cytoscape according to the HPIDB 3.0 interaction transcription database. The results showed that the liver in the infection group presented with severe bleeding and a large number of thrombi in the hepatic vessels. We found 490 upregulated and 398 downregulated DEGs of Ea in vivo versus Ea cultured in vitro, and 2177 upregulated and 970 downregulated genes in the liver of the infected eels. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the pathogen DEGs revealed that the upregulated genes were mainly enriched in migration, colonization, biofilm formation, and significantly enriched in ABC transport and quorum sensing; the downregulated genes were mainly involved in metabolism, information transduction, organelle formation, enzyme catalysis, molecular transport, and binding. GO of the host DEGs showed that metabolic process, catalytic activity, single organism metabolic process, small molecule binding, nucleotide binding, nucleotide phosphate binding, and anion binding were markedly enriched. Finally, we found that 79 Ea and 148 Aa proteins encoded by these DEGs were involved in an interaction network, and some pathogen (DegP, gcvP, infC, carB, rpoC, trpD, sthA, and FhuB) and host proteins (MANBA, STAT1, ETS2, ZEP1, TKT1, NMI and RBPMS) appear to play crucial roles in infection. Thus, determining the interaction networks revealed crucial molecular mechanisms underlying the process of pathogenic infection and host anti-infection.

Second Report of Chronic Granulomatous Disease in Jordan: Clinical and Genetic Description of 31 Patients From 21 Different Families, Including Families From Lybia and Iraq

Chronic granulomatous Disease (CGD) is a rare innate immunodeficiency disorder caused by mutations in one of the six genes (CYBA, CYBB, NCF1, NCF2, NCF4, and CYBC1/EROS) encoding the superoxide-producing nicotinamide adenine dinucleotide phosphate (NADPH)—oxidase complex in phagocytes. In the Western population, the most prevalent form of CGD (about two-thirds of all cases) is the X-linked form (X-CGD) caused by mutations in CYBB. The autosomal recessive forms (AR-CGD), due to mutations in the other genes, collectively account for the remaining one-third of CGD cases. We investigated the clinical and molecular features of 22 Jordanian, 7 Libyan, and 2 Iraqi CGD patients from 21 different families. In addition, 11 sibling patients from these families were suspected to have been died from CGD as suggested by their familial and clinical history. All patients except 9 were children of consanguineous parents. Most of the patients suffered from AR-CGD, with mutations in CYBA, NCF1, and NCF2, encoding p22^phox, p47^phox, and p67^phox proteins, respectively. AR-CGD was the most frequent form, in Jordan probably because consanguineous marriages are common in this country. Only one patient from non-consanguineous parents suffered from an X91⁰ CGD subtype (0 indicates no protein expression). AR67⁰ CGD and AR22⁰ CGD appeared to be the most frequently found sub-types but also the most severe clinical forms compared to AR47⁰ CGD. As a geographical clustering of 11 patients from eight Jordanian families exhibited the c.1171_1175delAAGCT mutation in NCF2, segregation analysis with nine polymorphic markers overlapping NCF2 indicates that a common ancestor has arisen ~1,075 years ago.

TREC and KREC profiling as a representative of thymus and bone marrow output in patients with various inborn errors of immunity

Primary immune deficiency (PID) disorders are clinically and molecularly heterogeneous diseases. T cell receptor excision circles (TRECs) and κ (kappa)-deleting excision circles (KRECs) are markers of T and B cell development, respectively. They are useful tools to assess T and B cell function and immune reconstitution and have been used for newborn screening for severe combined immunodeficiency disease (SCID) and agammaglobulinemia, respectively. Their profiles in several genetically confirmed PIDs are still lacking. The objective of this study was to determine TREC and KREC genomic profiling among various molecularly confirmed PIDs. We used real-time-quantitative polymerase chain reaction (RT-qPCR)-based triplex analysis of TRECs, KRECs and β-actin (ACTB) in whole blood genomic DNA isolated from 108 patients with molecularly confirmed PIDs. All agammaglobulinemia patients had low KREC counts. All SCIDs and Omenn syndrome patients secondary to mutations in RAG1, RAG2, DCLRE1C and NHEJ1 had low TREC and KREC counts. JAK3-deficient patients had normal KREC and the TREC count was influenced by the type of mutation. Early-onset ADA patients had low TREC and KREC counts. Four patients with zeta-chain-associated protein kinase 70 (ZAP70) had low TREC. All purine nucleoside phosphorylase (PNP) patients had low TREC. Combined immunodeficiency (CID) patients secondary to AK2, PTPRC, CD247, DCLREC1 and STAT1 had normal TREC and KREC counts. Most patients with ataxia-telangiectasia (AT) patients had low TREC and KREC, while most DOCK8-deficient patients had low TRECs only. Two of five patients with Wiskott-Aldrich syndrome (WAS) had low TREC counts as well as one patient each with bare lymphocyte syndrome (BLS) and chronic granulomatous disease. All patients with Griscelli disease, Chediak-Higashi syndrome, hyper-immunoglobulin (Ig)M syndrome and IFNGR2 had normal TREC and KREC counts. These data suggest that, in addition to classical SCID and agammaglobulinemia, TREC/KREC assay may identify ZAP70 patients and secondary target PIDs, including dedicator of cytokinesis 8 (DOCK8) deficiency, AT and some individuals with WAS and BLS.

Novel NCF2 Mutation Causing Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disorder caused by defects in the NADPH oxidase complex. Mutations in NCF2 encoding the cytosolic factor p67^phox result in autosomal recessive CGD. We describe three patients with a novel c.855G>C NCF2 mutation presenting with diverse clinical phenotype. Two siblings were heterozygous for the novel mutation and for a previously described exon 8-9 duplication, while a third unrelated patient was homozygous for the novel mutation. Mutation pathogenicity was confirmed by abnormal DHR123 assay and absent p67^phox production and by sequencing of cDNA which showed abnormal RNA splicing. Clinically, the homozygous patient presented with suspected early onset interstitial lung disease and NCF2 mutation was found on genetic testing performed in search for surfactant-related defects. The two siblings also had variable presentation with one having history of severe pneumonia, lymphadenitis, and recurrent skin abscesses and the other presenting in his 30s with discoid lupus erythematosus and without significant infectious history. We therefore identified a novel pathogenic NCF2 mutation causing diverse and unusual clinical phenotype.

Neutrophils acquire antigen-presenting cell features after phagocytosis of IgG-opsonized erythrocytes

Neutrophils are particularly well known for their antimicrobial function. Although historically they are regarded as strictly a phagocyte of the innate immune system, over time it has become clear that neutrophils are versatile cells with numerous functions including innate and adaptive immune regulation. We have previously described a role for human neutrophils in antibody-mediated red blood cell (RBC) clearance. Under homeostatic conditions, neutrophils do not take up RBCs. Yet, when RBCs are immunoglobulin G (IgG) opsonized, which can occur in alloimmunization or autoimmunization reactions, neutrophils can effectively phagocytose RBCs. In the present study, we show that human neutrophils acquire an antigen-presenting cell (APC) phenotype following RBC phagocytosis. Subsequent to RBC phagocytosis, neutrophils expressed major histocompatibility complex class II (MHC-II) and costimulatory molecules such as CD40 and CD80. Moreover, in classical APCs, the respiratory burst is known to regulate antigen presentation. We found that the respiratory burst in neutrophils is reduced after IgG-mediated RBC phagocytosis. Additionally, following RBC phagocytosis, neutrophils were demonstrated to elicit an antigen-specific T-cell response, using tetanus toxoid (TT) as an antigen to elicit an autologous TT-specific CD4⁺ T-cell response. Lastly, although the "don't eat me" signal CD47 is known to have a powerful restrictive role in the activation of immunity against RBCs in dendritic cells, CD47 does not seem to have a significant effect on the antigen-presenting function of neutrophils in this context. Overall, these findings reveal that besides their classical antimicrobial role, neutrophils show plasticity in their phenotype.

A novel variant in the neutrophil cytosolic factor 2 (NCF2) gene results in severe disseminated BCG infectious disease: A clinical report and literature review

Background

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disorder (PID) affecting NADPH oxidase activity. The rarest form of the disease is considered to be caused by NCF2 gene bi‐allelic variant. Here, we report the clinical and molecular characterization of a patient presenting with early‐onset severe disease due to bi‐allelic NCF2 variant.

Methods

Gene mutational analysis was performed by whole‐exome and Sanger sequencing.

Results

The patient presented with a history of fever and rash since the age of 1 month, followed by destructive osteomyelitis and necrotizing lymphadenopathy. The patient received the Bacillus Calmette‐Guérin (BCG) vaccine at birth; she was subsequently diagnosed with disseminated BCG infection. Whole‐exome sequencing identified a private (unreported) homozygous variant in NCF2 (c.290C > A) that results in a nonconservative change, p.Ala97Asp, in the p67^phox protein. The variant is located in the third helix of the TRP domain, which is crucial for the binding of GTPase RAC2 to the NADPH oxidase complex.

Conclusion

We identified a novel NCF2 variant located in the region interacting with RAC2 that is linked to a severe and early CGD phenotype in the setting of disseminated BCG infection. Our findings support postponing BCG vaccination until 6–12 months of age and after PID assessment.

Primary Immunodeficiency Diseases and Bacillus Calmette-Guérin (BCG)-Vaccine-Derived Complications: A Systematic Review

BACKGROUND

Bacillus Calmette-Guérin (BCG) vaccine is a live attenuated bacterial vaccine derived from Mycobacterium bovis, which is mostly administered to neonates in regions where tuberculosis is endemic. Adverse reactions after BCG vaccination are rare; however, immunocompromised individuals and in particular patients with primary immunodeficiencies (PIDs) are prone to develop vaccine-derived complications.

OBJECTIVE

To systematically review demographic, clinical, immunologic, and genetic data of PIDs that present with BCG vaccine complications. Moreover, we performed a meta-analysis aiming to determine the BCG-vaccine complications rate for patients with PID.

METHODS

We conducted electronic searches on Embase, Web of Science, PubMed, and Scopus (1966 to September 2018) introducing terms related to PIDs, BCG vaccination, and BCG vaccine complications. Studies with human subjects with confirmed PID, BCG vaccination history, and vaccine-associated complications (VACs) were included.

RESULTS

A total of 46 PIDs associated with BCG-VAC were identified. Severe combined immunodeficiency was the most common (466 cases) and also showed the highest BCG-related mortality. Most BCG infection cases in patients with PID were reported from Iran (n = 219 [18.8%]). The overall frequency of BCG-VAC in the included 1691 PID cases was 41.5% (95% CI, 29.9-53.2; I² = 98.3%), based on the results of the random-effect method used in this meta-analysis. Patients with Mendelian susceptibility to mycobacterial diseases had the highest frequency of BCG-VACs with a pooled frequency of 90.6% (95% CI, 79.7-1.0; I² = 81.1%).

CONCLUSIONS

Several PID entities are susceptible to BCG-VACs. Systemic neonatal PID screening programs may help to prevent a substantial amount of BCG vaccination complications.

NCF1 (p47phox)-deficient chronic granulomatous disease: comprehensive genetic and flow cytometric analysis

Mutations in NCF1 (p47phox) cause autosomal recessive chronic granulomatous disease (CGD) with abnormal dihydrorhodamine (DHR) assay and absent p47phox protein. Genetic identification of NCF1 mutations is complicated by adjacent highly conserved (>98%) pseudogenes (NCF1B and NCF1C). NCF1 has GTGT at the start of exon 2, whereas the pseudogenes each delete 1 GT (ΔGT). In p47phox CGD, the most common mutation is ΔGT in NCF1 (c.75_76delGT; p.Tyr26fsX26). Sequence homology between NCF1 and its pseudogenes precludes reliable use of standard Sanger sequencing for NCF1 mutations and for confirming carrier status. We first established by flow cytometry that neutrophils from p47phox CGD patients had negligible p47phox expression, whereas those from p47phox CGD carriers had ∼60% of normal p47phox expression, independent of the specific mutation in NCF1 We developed a droplet digital polymerase chain reaction (ddPCR) with 2 distinct probes, recognizing either the wild-type GTGT sequence or the ΔGT sequence. A second ddPCR established copy number by comparison with the single-copy telomerase reverse transcriptase gene, TERT We showed that 84% of p47phox CGD patients were homozygous for ΔGT NCF1 The ddPCR assay also enabled determination of carrier status of relatives. Furthermore, only 79.2% of normal volunteers had 2 copies of GTGT per 6 total (NCF1/NCF1B/NCF1C) copies, designated 2/6; 14.7% had 3/6, and 1.6% had 4/6 GTGT copies. In summary, flow cytometry for p47phox expression quickly identifies patients and carriers of p47phox CGD, and genomic ddPCR identifies patients and carriers of ΔGT NCF1, the most common mutation in p47phox CGD.

Three variants in the nicotinamide adenine dinucleotide phosphate oxidase complex are associated with HCV-related liver damage

Approximately 71 million people are chronically infected with the hepatitis C virus (HCV), a potentially lethal pathogen. HCV generates oxidative stress correlating with disease severity. HCV proteins increase reactive oxygen species production by stimulating nicotinamide adenine dinucleotide phosphate oxidase (NOX) activity. Reactive oxygen species are necessary for host defense and cell signaling; however, elevated NOX activity contributes to cancer, and NOX overexpression is associated with hepatic fibrosis. Our aim was to investigate whether single nucleotide polymorphisms (SNPs) in NOX family members are associated with HCV-related liver damage. Three hundred and thirty-one individuals of European ancestry and 90 individuals of African ancestry, all diagnosed with HCV, were genotyped for 243 tagSNPs in NOX enzymes and their regulatory factors. Pathology scores were available for 288 Caucasians and 71 Africans, and mortality status was determined for all subjects. SNPs were tested for association with pathology scores and as predictors of mortality. In Africans, homozygosity for the A allele of rs12753665 (neutrophil cytosolic factor 2) and homozygosity for the T allele of rs760519 (neutrophil cytosolic factor 4) were associated with and predictive of higher rates of advanced fibrosis and cirrhosis compared to other genotypes after controlling for age and sex. In Caucasians, homozygosity for the T allele of rs2292464 (dual oxidase 1) was associated with and predictive of decreased periportal inflammation after controlling for age and sex. No SNPs were significant predictors of mortality. Conclusion: In this exploratory study, three NOX-related polymorphisms in two ethnic groups were significantly associated with hepatic inflammation and fibrosis. Future studies investigating these SNPs in larger cohorts of patients with HCV are warranted. (Hepatology Communications 2017;1:973-982).

Advances in the diagnosis and treatment of chronic granulomatous disease

PURPOSE OF REVIEW

Chronic granulomatous disease (CGD), characterized 50 years ago as a primary immunodeficiency disorder of phagocytic cells (resulting in failure to kill a defined spectrum of bacteria and fungi and in concomitant chronic granulomatous inflammation) now comprises five genetic defects impairing one of the five subunits of phagocyte NADPH oxidase (Phox). Phox normally generates reactive oxygen species (ROS) engaged in intracellular and extracellular host defence and resolving accompanying inflammatory processes. 'Fatal' granulomatous disease has now changed into a chronic inflammatory condition with a median survival of 35 years and is now of interest to both paediatricians and internists. Clinical vigilance and expert knowledge are needed for early recognition and tailored treatment of this relatively rare genetic disorder.

RECENT FINDINGS

Infections by unanticipated pathogens and noncirrhotic portal hypertension need to be recognized as new CGD manifestations. Adult-onset CGD too is increasingly observed even in the elderly. Conservative treatment of fungal infections needs close monitoring due to the spread of azole resistance following extensive use of azoles in agriculture. Curative haematopoietic stem cell transplantation (HSCT) in early childhood has expanded with impressive results following use of matched, unrelated or cord blood donors and of a reduced intensity conditioning (RIC) regimen. Gene therapy, however, still has major limitations, remaining experimental.

SUMMARY

CGD is more prevalent than initially believed with a birth prevalence of 1: 120 000. As patients are increasingly diagnosed around the world and grow older, further manifestations of CGD are expected. While fungal infections have lost some threat, therapeutic research focuses on two other important aims: pharmacologic cure of chronic inflammation and long-term cure of CGD by gene therapy.

Molecular diagnosis of chronic granulomatous disease

Patients with chronic granulomatous disease (CGD) suffer from recurrent, life-threatening bacterial and fungal infections of the skin, the airways, the lymph nodes, liver, brain and bones. Frequently found pathogens are Staphylococcus aureus, Aspergillus species, Klebsiella species, Burkholderia cepacia and Salmonella species. CGD is a rare (∼1:250 000 births) disease caused by mutations in any one of the five components of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in phagocytes. This enzyme generates superoxide and is essential for intracellular killing of pathogens by phagocytes. Molecular diagnosis of CGD involves measuring NADPH oxidase activity in phagocytes, measuring protein expression of NADPH oxidase components and mutation analysis of genes encoding these components. Residual oxidase activity is important to know for estimation of the clinical course and the chance of survival of the patient. Mutation analysis is mandatory for genetic counselling and prenatal diagnosis. This review summarizes the different assays available for the diagnosis of CGD, the precautions to be taken for correct measurements, the flow diagram to be followed, the assays for confirmation of the diagnosis and the determinations for carrier detection and prenatal diagnosis.

Clinical, functional, and genetic characterization of chronic granulomatous disease in 89 Turkish patients

BACKGROUND

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disorder of phagocytes resulting in impaired killing of bacteria and fungi. A mutation in one of the 4 genes encoding the components p22(phox), p47(phox), p67(phox), and p40(phox) of the leukocyte nicotinamide dinucleotide phosphate reduced (NADPH) oxidase leads to autosomal recessive (AR) CGD. A mutation in the CYBB gene encoding gp91(phox) leads to X-linked recessive CGD.

OBJECTIVE

The aim of this study is to show the correlation between clinical, functional, and genetic data of patients with CGD from Turkey.

METHODS

We report here the results of 89 patients with CGD from 73 Turkish families in a multicenter study.

RESULTS

Most of the families (55%) have an AR genotype, and 38% have an X-linked genotype; patients from 5 families with a suspected AR genotype (7%) were not fully characterized. We compared patients with CGD according to the severity of NADPH oxidase deficiency of neutrophils. Patients with A22(0), A67(0) or X91(0) phenotypes with a stimulation index of 1.5 or less have early clinical presentation and younger age at diagnosis (mean, 3.2 years). However, in p47(phox)-deficient cases and in 5 other AR cases with high residual oxidase activity (stimulation index ≥ 3), later and less severe clinical presentation and older age at diagnosis (mean, 7.1 years) were found. Pulmonary involvement was the most common clinical feature, followed by lymphadenitis and abscesses.

CONCLUSION

Later and less severe clinical presentation and older age at diagnosis are related to the residual NADPH oxidase activity of neutrophils and not to the mode of inheritance. CGD caused by A22(0) and A67(0) subtypes manifests as severe as the X91(0) subtype.

Thirty years of primary immunodeficiencies in Turkey

Turkey, with its population of some 75 million, has a high rate of consanguineous marriages. Because the majority of the primary immunodeficiencies (PIDs) are inherited as autosomal recessive (AR) forms, the high consanguinity rate leads to a high prevalence of PID diseases in Turkey. The first pediatric immunology division was established in 1972, since then over 10 other immunology divisions have been established in different cities. Approximately 4,000 patients with possible PID are referred to these centers annually. The percentages of some of the major immunodeficiency groups and individual disease numbers among these patients differ somewhat in comparison with Western countries, likely because the relative incidences of PIDs with AR inheritance and of rare diseases are higher. These characteristics of the patient population, and our determination of differences in disease presentation and unusual features, have led us to undertake studies in collaboration with various centers in Western countries. These collaborations have contributed to the identification of the genes responsible for some rare immunodeficiencies, to the resolution of the genetic heterogeneity underlying conventional phenotypes, and to the description of new clinical phenotypes.

Molecular basis of autosomal recessive chronic granulomatous disease in iran

INTRODUCTION

Chronic granulomatous disease (CGD) is a rare inherited condition resulting from mutations in the genes that encode the proteins of the NADPH oxidase enzyme in phagocytes, rendering these cells incapable of killing invading pathogens.

MATERIALS AND METHODS

Patients subtypes are determined by neutrophil functional assays and immunoblotting. Although defects in the X-chromosome-linked gp91-phox component account for the majority of CGD patients in the world, in Iran, there are many CGD patients suffering from the autosomal recessive forms of the disease. Most of these patients show impairment in the synthesis of the 47-kDa cytosolic component p47-phox of the oxidase. The second causative factor of autosomal recessive CGD is deficiency of the 22-kDa component (p22-phox) of the oxidase. Another rare form of the disease is due to mutations in the NCF2 gene encoding the 67-kDa component (p67-phox) of the oxidase.

RESULTS

Mutation analysis showed a novel homozygous splice site mutation, c.intron4+1G>T, in CYBA. A novel mutation in NCF2: a gross homozygous deletion of exon 1 and 2, causing p.Met1_Lys58 deletion in p67-phox. We also found a previously published homozygous nonsense mutation, c.196C>T, causing p.Arg66X.33 in p67-phox.

DISCUSSION

Our data show that CGD in Iran is predominantly due to mutations in p47-phox, while the number of mutations in p22-phox is roughly equal to that in gp91-phox. These data indicate that the genetics of CGD are ethnically variable, and this should be considered in approaching families with CGD.

Hematologically important mutations: the autosomal recessive forms of chronic granulomatous disease (second update)

Chronic granulomatous Disease (CGD) is an immunodeficiency disorder affecting about 1 in 250,000 individuals. The disease is caused by mutations in the genes encoding the components of the leukocyte NADPH oxidase. This enzyme produces superoxide, which is essential in the process of intracellular pathogen killing by phagocytic leukocytes. Four of the five genes involved in CGD are autosomal; these are CYBA, encoding p22-phox, NCF2, encoding p67-phox, NCF1, encoding p47-phox, and NCF4, encoding p40-phox. This article lists all mutations identified in these genes in the autosomal forms of CGD. Moreover, polymorphisms in these genes are also given, which should facilitate the recognition of future disease-causing mutations.