Hematologically important mutations: The autosomal forms of chronic granulomatous disease (third update).

Chronic granulomatous disease (CGD) is an immunodeficiency disorder affecting about 1 in 250,000 individuals. CGD patients suffer from severe, recurrent bacterial and fungal infections. The disease is caused by mutations in the genes encoding the components of the leukocyte NADPH oxidase. This enzyme produces superoxide, which is subsequently metabolized to hydrogen peroxide and other reactive oxygen species (ROS). These products are essential for intracellular killing of pathogens by phagocytic leukocytes (neutrophils, eosinophils, monocytes and macrophages). The leukocyte NADPH oxidase is composed of five subunits, four of which are encoded by autosomal genes. These are CYBA, encoding p22phox, NCF1, encoding p47phox, NCF2, encoding p67phox and NCF4, encoding p40phox. This article lists all mutations identified in these genes in CGD patients. In addition, cytochrome b558 chaperone-1 (CYBC1), recently recognized as an essential chaperone protein for the expression of the X-linked NADPH oxidase component gp91phox (also called Nox2), is encoded by the autosomal gene CYBC1. Mutations in this gene also lead to CGD. Finally, RAC2, a small GTPase of the Rho family, is needed for activation of the NADPH oxidase, and mutations in the RAC2 gene therefore also induce CGD-like symptoms. Mutations in these last two genes are also listed in this article.

Hematologically important mutations: X-linked chronic granulomatous disease (fourth update).

Chronic granulomatous disease (CGD) is an immunodeficiency disorder affecting about 1 in 250,000 individuals. CGD patients suffer from severe bacterial and fungal infections. The disease is caused by a lack of superoxide production by the leukocyte enzyme NADPH oxidase. Superoxide and subsequently formed other reactive oxygen species (ROS) are instrumental in killing phagocytosed micro-organisms in neutrophils, eosinophils, monocytes and macrophages. The leukocyte NADPH oxidase is composed of five subunits, of which the enzymatic component is gp91phox, also called Nox2. This protein is encoded by the CYBB gene on the X chromosome. Mutations in this gene are found in about 70% of all CGD patients in Europe and in about 20% in countries with a high ratio of parental consanguinity. This article lists all mutations identified in CYBB and should therefore help in genetic counseling of X-CGD patients' families. Moreover, apparently benign polymorphisms in CYBB are also given, which should facilitate the recognition of disease-causing mutations. In addition, we also include some mutations in G6PD, the gene on the X chromosome that encodes glucose-6-phosphate dehydrogenase, because inactivity of this enzyme may lead to shortage of NADPH and thus to insufficient activity of NADPH oxidase. Severe G6PD deficiency can induce CGD-like symptoms.

Clinical, Immunological, and Molecular Profile of Chronic Granulomatous Disease: A Multi-Centric Study of 236 Patients From India.

Background: Chronic granulomatous disease (CGD) is an inherited defect in phagocytic respiratory burst that results in severe and life-threatening infections in affected children. Single center studies from India have shown that proportion of autosomal recessive (AR) CGD is more than that reported from the West. Further, affected patients have high mortality rates due to late referrals and difficulties in accessing appropriate treatment. However, there is lack of multicentric collaborative data on CGD from India. Objective: To describe infection patterns, immunological, and molecular features of CGD from multiple centers in India. Methods: A detailed proforma that included clinical and laboratory details was prepared and sent to multiple centers in India that are involved in the care and management of patients with inborn errors of immunity. Twelve centers have provided data which were later pooled together and analyzed. Results: Of the 236 patients analyzed in our study, X-linked and AR-CGD was seen in 77 and 97, respectively. Male female ratio was 172:64. Median age at onset of symptoms and diagnosis was 8 and 24 months, respectively. Common infections documented include pneumonia (71.6%), lymphadenitis (31.6%), skin and subcutaneous abscess (23.7%), blood-stream infection (13.6%), osteomyelitis (8.6%), liver abscess (7.2%), lung abscess (2.9%), meningoencephalitis (2.5%), splenic abscess (1.7%), and brain abscess (0.9%). Forty-four patients (18.6%) had evidence of mycobacterial infection. Results of molecular assay were available for 141 patients (59.7%)-CYBB (44.7%) gene defect was most common, followed by NCF1 (31.9%), NCF2 (14.9%), and CYBA (8.5%). While CYBA variants were documented only in Southern and Western parts of India, a common dinucleotide deletion in NCF2 (c.835_836delAC) was noted only in North Indian population. Of the 174 patients with available outcome data, 67 (38.5%) had expired. Hematopoietic stem cell transplantation was carried out in 23 patients, and 12 are doing well on follow-up. Conclusions: In India, proportion of patients with AR-CGD is higher as compared to Western cohorts, though regional differences in types of AR-CGD exist. Clinical profile and mortality rates are similar in both X-linked and AR-CGD. However, this may be a reflection of the fact that milder forms of AR-CGD are probably being missed.

Clinical and Immunological Characteristics of 63 Patients with Chronic Granulomatous Disease: Hacettepe Experience.

BACKGROUND: Chronic granulomatous disease (CGD), one of the phagocytic system defects, is the primary immunodeficiency caused by dysfunction of the NADPH oxidase complex which generates reactive oxygen species (ROS), which are essential for killing pathogenic microorganisms, especially catalase-positive bacteria and fungi. OBJECTIVE: The objective of our study was to assess the clinical and laboratory characteristics, treatment modalities, and prognosis of patients with CGD. METHODS: We retrospectively reviewed 63 patients with CGD who have been diagnosed, treated, and/or followed-up between 1984 and 2018 in Hacettepe University, Ankara, in Turkey, as a developing country. RESULTS: The number of female and male patients was 26/37. The median age at diagnosis was 3.8 (IQR: 1.0-9.6) years. The rate of consanguinity was 63.5%. The most common physical examination finding was lymphadenopathy (44/63), growth retardation (33/63), and hepatomegaly (27/63). One adult patient had squamous cell carcinoma of the lung. The most common infections were lung infection (53/63), skin abscess (43/63), and lymphadenitis (19/63). Of the 63 patients with CGD, 6 patients had inflammatory bowel disease (IBD). Twelve of the 63 patients died during follow-up. CYBA, NCF1, CYBB, and NCF2 mutations were detected in 35%, 27.5%, 25%, and 12.5% of the patients, respectively. CONCLUSION: We identified 63 patients with CGD from a single center in Turkey. Unlike other cohort studies in Turkey, due to the high consanguineous marriage rate in our study group, AR form of CGD was more frequent, and gastrointestinal involvement were found at relatively lower rates. The rate of patients who treated with HSCT was lower in our research than in the literature. A majority of the patients in this study received conventional prophylactic therapies, which highlight on the outcome of individuals who have not undergone HSCT.

Genetic Characteristics, Infectious, and Noninfectious Manifestations of 32 Patients with Chronic Granulomatous Disease.

BACKGROUND: Chronic granulomatous disease (CGD) is a rare genetic disorder characterized by failure of phagocytic leukocytes to destroy certain microbes. We present a study on CGD patients enrolled at a single medical center concerning the infectious and noninfectious complications and genetic properties of the disease. METHODS: Icotinamide adenine dinucleotide phosphate oxidase activity and the expression of flavocytochrome b558 were measured by flow cytometry, and clinical outcomes of the patients were listed in relation to the genetic results. RESULTS: The clinical and genetic findings of 32 pediatric cases with CGD from 23 families were enrolled. Pneumonia and anemia were the most common infectious and noninfectious symptoms. Genetic analysis showed that 10 families (43.5%) carried CYBB variants and 13 families (56.5%) have autosomal recessive (AR) CGD, in which 6 families (26%) carried NCF1 variants, 4 (17.4%) carried CYBA variants, and 3 (13%) carried NCF2 variants. The median age of clinical onset was 3.3 and 48 months for patients with X-linked CGD (X-CGD) and AR-CGD, respectively. The onset of symptoms before age 1 year was 94% in X-CGD, 28.5% in AR-CGD, and 12.5% in patients with oxidase residual activity. Moreover, a de novo germline mutation at c.1415delG in CYBB (OMIM#300481) and a novel c.251_263del13bp in CYBA (OMIM#608508) were also investigated. CONCLUSIONS: Ihydrorhodamine-1,2,3 assay could not detect carrier mother in de novo case with CYBB variant. Most X-CGD patients have the onset of symptoms before age 1 year. Additionally, residual oxidase activity in AR-CGD causes a delay in onset, diagnosis, and prophylaxis. The protective role of residual activity is limited while the infection is ongoing and becoming serious.

MKL1 deficiency results in a severe neutrophil motility defect due to impaired actin polymerization.

Megakaryoblastic leukemia 1 (MKL1) promotes the regulation of essential cell processes, including actin cytoskeletal dynamics, by coactivating serum response factor. Recently, the first human with MKL1 deficiency, leading to a novel primary immunodeficiency, was identified. We report a second family with 2 siblings with a homozygous frameshift mutation in MKL1. The index case died as an infant from progressive and severe pneumonia caused by Pseudomonas aeruginosa and poor wound healing. The younger sibling was preemptively transplanted shortly after birth. The immunodeficiency was marked by a pronounced actin polymerization defect and a strongly reduced motility and chemotactic response by MKL1-deficient neutrophils. In addition to the lack of MKL1, subsequent proteomic and transcriptomic analyses of patient neutrophils revealed actin and several actin-related proteins to be downregulated, confirming a role for MKL1 as a transcriptional coregulator. Degranulation was enhanced upon suboptimal neutrophil activation, whereas production of reactive oxygen species was normal. Neutrophil adhesion was intact but without proper spreading. The latter could explain the observed failure in firm adherence and transendothelial migration under flow conditions. No apparent defect in phagocytosis or bacterial killing was found. Also, monocyte-derived macrophages showed intact phagocytosis, and lymphocyte counts and proliferative capacity were normal. Nonhematopoietic primary fibroblasts demonstrated defective differentiation into myofibroblasts but normal migration and F-actin content, most likely as a result of compensatory mechanisms of MKL2, which is not expressed in neutrophils. Our findings extend current insight into the severe immune dysfunction in MKL1 deficiency, with cytoskeletal dysfunction and defective extravasation of neutrophils as the most prominent features.

Activation of cryptic splice sites in three patients with chronic granulomatous disease.

BACKGROUND: Chronic granulomatous disease (CGD) is a primary immune deficiency caused by mutations in the genes encoding the structural components of the phagocyte NADPH oxidase. As a result, the patients cannot generate sufficient amounts of reactive oxygen species required for killing pathogenic microorganisms. METHODS: We analyzed NADPH oxidase activity and component expression in neutrophils, performed genomic DNA and cDNA analysis, and used mRNA splicing prediction tools to evaluate the impact of mutations. RESULTS: In two patients with CGD, we had previously found mutations that cause aberrant pre-mRNA splicing. In one patient an exonic mutation in a cryptic donor splice site caused the deletion of the 3' part of exon 6 from the mRNA of CYBB. This patient suffers from X-linked CGD. The second patient, with autosomal CGD, has a mutation in the donor splice site of intron 1 of CYBA that activates a cryptic donor splice site downstream in intron 1, causing the insertion of intronic sequences in the mRNA. The third patient, recently analyzed, also with autosomal CGD, has a mutation in intron 4 of CYBA, 15 bp from the acceptor splice site. This mutation weakens a branch site and activates a cryptic acceptor splice site, causing the insertion of 14 intronic nucleotides into the mRNA. CONCLUSION: We found three different mutations, one exonic, one in a donor splice site and one intronic, that all caused missplicing of pre-mRNA. We analyzed these mutations with four different splice prediction programs and found that predictions of splice site strength, splice enhancer and splice silencer protein binding and branch site strength are all essential for correct prediction of pre-mRNA splicing.

Genetic Analysis of 13 Iranian Families With Leukocyte Adhesion Deficiency Type 1.

BACKGROUND AND AIM: Leukocyte adhesion deficiency type 1 is a rare, autosomal recessive disorder that results from mutations in the ITGB2 gene. This gene encodes the CD18 subunit of ß2 integrin leukocyte adhesion cell molecules. Leukocyte adhesion deficiency type 1 is characterized by recurrent bacterial infections, impaired wound healing, inadequate pus formation, and delayed separation of the umbilical cord. MATERIALS AND METHODS: Blood samples were taken from 13 patients after written consent had been obtained. Genomic DNA was extracted, and ITGB2 exons and exon-intron boundaries were amplified by polymerase chain reaction. The products were examined by Sanger sequencing. RESULTS: In this study, 8 different previously reported mutations (intron7+1G>A, c.715G>A, c.1777 C>T, c.843del C, c.1768T>C, c.1821C>A, Intron7+1G>A, c.1885G>A) and 2 novel mutations (c.1821C>A; p.Tyr607Ter and c.1822C>T; p.Gln608Ter) were found. CONCLUSIONS: c.1821C>A (p.Tyr607Ter) and c.1822C>T (p.Gln608Ter) mutations should be included in the panel of carrier detection and prenatal diagnosis.

Approach to Molecular Diagnosis of Chronic Granulomatous Disease (CGD): an Experience from a Large Cohort of 90 Indian Patients.

BACKGROUND: Chronic granulomatous disease (CGD) is characterized by mutation in any one of the five genes coding NADPH oxidase components that leads to functional abnormality preventing the killing of phagocytosed microbes by affecting the progression of a respiratory burst. CGD patients have an increased susceptibility to infections by opportunistic and pathogenic organisms. Though initial diagnosis of CGD using a nitroblue tetrazolium (NBT) test or dihydrorhodamine (DHR) test is relatively easy, molecular diagnosis is challenging due to involvement of multiple genes, presence of pseudogenes, large deletions, and GC-rich regions, among other factors. The strategies for molecular diagnosis vary depending on the affected gene and the mutation pattern prevalent in the target population. There is a paucity of molecular data related to CGD for Indian population. METHOD: This report includes data for a large cohort of CGD patients (n = 90) from India, describing the diagnostic approach, mutation spectrum, and novel mutations identified. We have used mosaicism in mothers and the expression pattern of different NADPH components by flow cytometry as a screening tool to identify the underlying affected gene. The techniques like Sanger sequencing, next-generation sequencing (NGS), and Genescan analysis were used for further molecular analysis. RESULT: Of the total molecularly characterized patients (n = 90), 56% of the patients had a mutation in the NCF1 gene, 30% had mutation in the CYBB gene, and 7% each had mutation in the CYBA and NCF2 genes. Among the patients with NCF1 gene mutation, 82% of the patients had 2-bp deletion (DelGT) mutations in the NCF1 gene. In our cohort, 41 different mutations including 9 novel mutations in the CYBB gene and 2 novel mutations each in the NCF2, CYBA, and NCF1 genes were identified. CONCLUSION: Substantial number of the patients lack NCF1 gene on both the alleles. This is often missed by advanced molecular techniques like Sanger sequencing and NGS due to the presence of pseudogenes and requires a simple Genescan method for confirmation. Thus, the diagnostic approach may depend on the prevalence of affected genes in respective population. This study identifies potential gene targets with the help of flow cytometric analysis of NADPH oxidase components to design an algorithm for diagnosis of CGD in India. In Indian population, the Genescan method should be preferred as the primary molecular test to rule out NCF1 gene mutations prior to Sanger sequencing and NGS.

Inherited p40phox deficiency differs from classic chronic granulomatous disease.

Biallelic loss-of-function (LOF) mutations of the NCF4 gene, encoding the p40phox subunit of the phagocyte NADPH oxidase, have been described in only 1 patient. We report on 24 p40phox-deficient patients from 12 additional families in 8 countries. These patients display 8 different in-frame or out-of-frame mutations of NCF4 that are homozygous in 11 of the families and compound heterozygous in another. When overexpressed in NB4 neutrophil-like cells and EBV-transformed B cells in vitro, the mutant alleles were found to be LOF, with the exception of the p.R58C and c.120_134del alleles, which were hypomorphic. Particle-induced NADPH oxidase activity was severely impaired in the patients' neutrophils, whereas PMA-induced dihydrorhodamine-1,2,3 (DHR) oxidation, which is widely used as a diagnostic test for chronic granulomatous disease (CGD), was normal or mildly impaired in the patients. Moreover, the NADPH oxidase activity of EBV-transformed B cells was also severely impaired, whereas that of mononuclear phagocytes was normal. Finally, the killing of Candida albicans and Aspergillus fumigatus hyphae by neutrophils was conserved in these patients, unlike in patients with CGD. The patients suffer from hyperinflammation and peripheral infections, but they do not have any of the invasive bacterial or fungal infections seen in CGD. Inherited p40phox deficiency underlies a distinctive condition, resembling a mild, atypical form of CGD.

Retrotransposable genetic elements causing neutrophil defects.

BACKGROUND: Retrotransposable elements are stretches of DNA that encode proteins with the inherent ability to insert their own RNA or another RNA by reverse transcriptase as DNA into a new genomic location. In humans, the only autonomous retrotransposable elements are members of the Long INterspersed Element-1 (LINE-1) family. LINE-1s may cause gene inactivation and human disease. DESIGN: We present a brief summary of the published knowledge about LINE-1s in humans and the RNAs that these elements can transpose, and we focus on the effect of LINE-1-mediated retrotransposition on human neutrophil function. RESULTS: Retrotransposons can cause genetic disease by two primary mechanisms: (1) insertional mutagenesis and (2) nonallelic homologous recombination. The only known neutrophil function affected by retrotransposition is that of NADPH oxidase activity. Four patients with chronic granulomatous disease (CGD) are known with LINE-1-mediated insertional inactivation of CYBB, the gene that encodes the gp91phox component of the phagocyte NADPH oxidase. In addition, 5 CGD patients had a large deletion in the NCF2 gene, encoding the p67phox component, and 2 CGD patients had a similar deletion in NCF1, encoding p47phox . These deletions were caused by nonallelic homologous recombination between 2 Alu elements at the borders of each deletion. Alu elements have spread throughout the human genome by LINE-1 retrotransposition. CONCLUSIONS: Probably, the occurrence of LINE-1-mediated insertions causing autosomal CGD has been underestimated. It might be worthwhile to reinvestigate the DNA from autosomal CGD patients with missplice mutations and large deletions for indications of LINE-1-mediated insertions.

Characterization of 4 New Mutations in the CYBB Gene in 10 Iranian Families With X-linked Chronic Granulomatous Disease.

Chronic granulomatous disease (CGD) is an inherited disease of the innate immune system that results from defects in 1 of the 5 subunits of nicotinamide adenine dinucleotide phosphate oxidase complex and leads to life-threatening infections with granuloma formation. During 3 years of study, we recognized 10 male patients with X-linked CGD from a tertiary referral center for immune deficiencies in Iran. The CGD patients were diagnosed according to clinical features and biochemical tests, including nitroblue tetrazolium and dihydrorhodamine-1, 2, 3 tests, performed on patients and their mothers. In all patients, Western blot analysis showed a gp91 phenotype. Mutation screening by single strand conformation polymorphism and multiplex ligation-dependent probe amplification analysis of the CYBB gene encoding gp91, followed by sequencing, showed 9 different mutations, 4 of them novel as far as we know.

Analysis of Chronic Granulomatous Disease in the Kavkazi Population in Israel Reveals Phenotypic Heterogeneity in Patients with the Same NCF1 mutation (c.579G>A).

PURPOSE: Chronic granulomatous disease (CGD) is an innate immune deficiency disorder of phagocytes, resulting from mutations in the components of the NADPH oxidase complex that impair the synthesis of oxygen radicals, thus rendering patients susceptible to recurrent infections and excessive hyperinflammatory responses. The most common autosomal recessive form of CGD is p47phox deficiency, which is often clinically milder than the more common X-linked recessive form. Here, we report data on genetics, clinical and biochemical findings in 17 CGD patients of Kavkazi origin with the nonsense mutation c.579G>A in the NCF1 gene, leading to p47phox deficiency. METHODS: Diagnosis was based on detailed clinical evaluation, respiratory burst activity by cytochrome c reduction and dihydrorhodamine-1,2,3 (DHR) assay by flow cytometry, expression of p47phox by immunoblotting and molecular confirmation by DNA sequence analysis. RESULTS: Twelve male and five female patients with median age at onset of 2.5 years (range 1 day to 9 years) were included in the study. The present cohort displays an encouraging 88% overall long-term survival, with median follow-up of 17 years. Clinical manifestations varied from mild to severe expression of the disease. Correlation between genotype and phenotype is unpredictable, although the Kavkazi patients were more severely affected than other patients with p47phox deficiency. CONCLUSIONS: Kavkazi CGD patients harbor a common genetic mutation that is associated with a heterogeneous clinical phenotype. Early diagnosis and proper clinical management in an experienced phagocytic leukocyte center is imperative to ensure favorable patient outcome. New treatment strategies are ongoing, but results are not yet conclusive.

A false-carrier state for the c.579G>A mutation in the NCF1 gene in Ashkenazi Jews.

BACKGROUND: Mutations in the NCF1 gene that encodes p47phox, a subunit of the NADPH oxidase complex, cause chronic granulomatous disease (CGD). In Kavkazi Jews, a c.579G>A (p.Trp193Ter) mutation in NCF1 is frequently found, leading to CGD. The same mutation is found in about 1% of Ashkenazi Jews, although Ashkenazi CGD patients with this mutation have never been described. METHODS: We used Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), gene scan analysis and Ion Torrent Next Generation Sequencing for genetic analysis, and measured NADPH oxidase activity and p47phox expression. RESULTS: In an Ashkenazi couple expecting a baby, both parents were found to be heterozygotes for this mutation, as was the fetus. However, segregation analysis in the extended family was consistent with the fetus inheriting both carrier alleles from the parents. MLPA indicated four complete NCF1 genes in the fetus and three in each parent. Gene sequencing confirmed these results. Analysis of fetal leucocytes obtained by cordocentesis revealed substantial oxidase activity with three different assays, which was confirmed after birth. In six additional Ashkenazi carriers of the NCF1 c.579G>A mutation, we found five individuals with three complete NCF1 genes of which one was mutated (like the parents), and one individual with in addition a fusion gene of NCF1 with a pseudogene. CONCLUSION: These results point to the existence of a 'false-carrier' state in Ashkenazi Jews and have wide implications regarding pre-pregnancy screening in this and other population groups.

Diagnostic Challenges in the Early Onset of Inflammatory Bowel Disease: A Case Report.

Inflammatory bowel disease (IBD) with very early onset manifestations (younger than six years of age) is an essential pediatric gastrointestinal disease that encompasses a group of diverse and rare genetic defects. It may be associated with chronicity, premalignant nature, and high morbidity and mortality during childhood. Because of overlapping phenotypes, the definitive diagnosis based on conventional strategies is frequently a challenge. However, many patients with different molecular pathologies are treated with the same therapeutic strategy. In this context, it is essential to define a more reliable method to provide an opportunity for a rapid and accurate diagnosis. Here we report a novel homozygous exonic variant in a patient with an IBD-like lesion in the colon during the infancy period. A 7 months old boy who was born of a consanguineous marriage developed gastrointestinal disorders early in life. After complete diagnostic workups, this case underwent conventional therapy of IBD for five months; but clinical remission was not achieved. We identified a novel homozygous mutation (c.684C>T p(=)) in exon 7 of IL-12RB1 gene that in silico studies indicated its significance in the splicing process. At the 14th month of age, this case died. Our finding reveals the importance of genetic screening as an early diagnostic tool in the identification of the underlying causes of IBD with very early onset manifestations, particularly infantile (< 2 years of age) IBD. This strategy makes an opportunity in prompt diagnosis and targeted therapy.

Genetic variation of human neutrophil Fcγ receptors and SIRPα in antibody-dependent cellular cytotoxicity towards cancer cells.

The efficacy of cancer therapeutic antibodies varies considerably among patients. Anti-cancer antibodies act through different mechanisms, including antibody-dependent cellular cytotoxicity (ADCC) triggered via Fcγ receptors (FcγR). This phagocyte ADCC can be promoted by interference with CD47-SIRPα interactions, but the magnitude of this enhancement also varies among individuals. Both FcγR and SIRPα display considerable genetic variation, and we investigated whether this explains some of the variability in ADCC. Because of linkage disequilibrium between FcγR variants the interpretation of previous reports suggesting a potential link between FcγR polymorphisms and ADCC has been troublesome. We performed an integrated genetic analysis that enables stratification. ADCC by activated human neutrophils towards Trastuzumab-coated breast cancer cells was predominantly dependent on FcγRIIa. Neutrophils from individuals with the FcγRIIa-131H polymorphic variant displayed significantly higher killing capacity relative to those with FcγRIIa-131R. Furthermore, ADCC was consistently enhanced by targeting CD47-SIRPα interactions, and there were no significant functional differences between the two most prevalent SIRPα polymorphic variants. Thus, neutrophil ADCC capacity is directly related to the FcγRIIa polymorphism, and targeting CD47-SIRPα interactions enhances ADCC independently of FcγR and SIRPα genotype, thereby further suggesting that CD47-SIRPα interference might be a generic strategy for potentiating the efficacy of antibody therapy in cancer.

Mutation in an exonic splicing enhancer site causing chronic granulomatous disease.

In a male patient suffering from X-linked chronic granulomatous disease (CGD) we found a c.389G>T mutation in exon 5 of the CYBB gene. We have analyzed why 95% of the transcripts of this gene lacked exon 5, leading to a frameshift and premature termination codon. The mutation was located in a region comprising three putative exonic splicing enhancer binding sites, for SRSF1, SRFS2 and SRFS6, according to the ESEfinder Tool (http://rulai.cshl.edu/cgi-bin/tools/ESE3/esefinder.cgi). With the Analyser Splice Tool we calculated the probability of skipping of exon 5 in CYBB mRNA, and by means of Sroogle the number of putative binding motifs for splicing enhancer and splicing silencer proteins (http://astlab.tau.ac.il/index.php). These analyses clarify why this exon was skipped in the majority of the mRNA. The normally spliced transcript contains an amino acid change p.Arg130Leu. This poorly expressed transcript gives rise to a protein with low expression but presumably normal activity, leading to a respiratory burst activity in the patient's neutrophils of about 15% of normal.

Diagnosis of Interstitial Lung Disease Caused by Possible Hypersensitivity Pneumonitis in a Child: Think CGD.

Interstitial lung disease (ILD) is a rare and heterogeneous group of disorder affecting the lung parenchyma and has a detrimental effect on gas exchange. Chronic granulomatous disease (CGD), when it affects primarily lungs, may cause ILD. We report a 16-year-old patient with CGD caused by homozygous deletion of NCF1 who atypically presented with ILD. The patient had many pigeons and was a pigeon breeder. Exacerbated clinical symptoms were linked to hypersensitivity pneumonitis (HP), and the patient was suggested to keep away from pigeons. In addition to allergen avoidance and prophylactic antibacterial therapy, treatment with corticosteroids and hydroxychloroquine was started for mainly obstructive and persistant symptoms of ILD. CGD is known to cause a hyperinflammatory state and the patients present with excessive granuloma formation and HP. Control of inflammation either by avoidance of allergen exposure and by anti-inflammatory drugs is necessary for the relief of symptoms.