High-Performance Liquid Chromatography Under Partially Denaturing Conditions (dHPLC) is a Fast and Cost-Effective Method for Screening Molecular Defects: Four Novel Mutations Found in X-Linked Chronic Granulomatous Disease

Variant Type X91+ Chronic Granulomatous Disease: Clinical and Molecular Characterization in a Chinese Cohort

PURPOSE

We aimed to report the clinical and immunological characteristics of variant type X91⁺ chronic granulomatous disease (CGD) in a Chinese cohort.

METHODS

The clinical manifestations and immunological phenotypes of patients with X91⁺ CGD were collected. A dihydrorhodamine (DHR) analysis was performed to evaluate neutrophil function. Gp91^phox protein expression was determined using extracellular staining with the monoclonal antibody (mAb) 7D5 and flow cytometry.

RESULTS

Patients with X91⁺ CGD accounted for 8% (7/85) of all patients with CGD. The median age of onset in the seven patients with X91⁺ CGD was 4 months. Six patients received the BCG vaccine, and 50% (3/6) had probable BCG infections. Mycobacterium tuberculosis infection was prominent. The most common sites of infection were the lung (6/7), lymph nodes (5/7), and soft tissue (3/7). Two patients experienced recurrent oral ulcers. The stimulation index (SI) of the patients with X91⁺ CGD ranged widely from 1.9 to 67.3. The difference in the SI among the three groups of patients (X91⁺ CGD, X91^- CGD, and X91⁰ CGD) was statistically significant (P = 0.0071). The three groups showed no significant differences in onset age, diagnosis age, or severe infection frequency. CYBB mutations associated with X91⁺ CGD were commonly located in the second transmembrane or intracellular regions. Three novel X91⁺ CGD-related mutations (c.1462-2 A > T, c.1243C > T, and c.925G > A) were identified.

CONCLUSIONS

Variant type X91⁺ CGD may result in varied clinical manifestations. Moreover, the laboratory findings might indicate a moderate neutrophil SI. We should deepen our understanding of variant X91⁺ CGD to prevent missed diagnoses.

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 gp91^phox, 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.

Mycobacterial disease in patients with chronic granulomatous disease: A retrospective analysis of 71 cases

BACKGROUND

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by inborn errors of the phagocyte nicotinamide adenine dinucleotide phosphate oxidase complex. From the first year of life onward, most affected patients display multiple, severe, and recurrent infections caused by bacteria and fungi. Mycobacterial infections have also been reported in some patients.

OBJECTIVE

Our objective was to assess the effect of mycobacterial disease in patients with CGD.

METHODS

We analyzed retrospectively the clinical features of mycobacterial disease in 71 patients with CGD. Tuberculosis and BCG disease were diagnosed on the basis of microbiological, pathological, and/or clinical criteria.

RESULTS

Thirty-one (44%) patients had tuberculosis, and 53 (75%) presented with adverse effects of BCG vaccination; 13 (18%) had both tuberculosis and BCG infections. None of these patients displayed clinical disease caused by environmental mycobacteria, Mycobacterium leprae, or Mycobacterium ulcerans. Most patients (76%) also had other pyogenic and fungal infections, but 24% presented solely with mycobacterial disease. Most patients presented a single localized episode of mycobacterial disease (37%), but recurrence (18%), disseminated disease (27%), and even death (18%) were also observed. One common feature in these patients was an early age at presentation for BCG disease. Mycobacterial disease was the first clinical manifestation of CGD in 60% of these patients.

CONCLUSION

Mycobacterial disease is relatively common in patients with CGD living in countries in which tuberculosis is endemic, BCG vaccine is mandatory, or both. Adverse reactions to BCG and severe forms of tuberculosis should lead to a suspicion of CGD. BCG vaccine is contraindicated in patients with CGD.

Clinical and Genotypic Spectrum of Chronic Granulomatous Disease in 71 Latin American Patients: First Report from the LASID Registry

AIM

We analyzed data from 71 patients with chronic granulomatous disease (CGD) with a confirmed genetic diagnosis, registered in the online Latin American Society of Primary Immunodeficiencies (LASID) database.

RESULTS

Latin American CGD patients presented with recurrent and severe infections caused by several organisms. The mean age at disease onset was 23.9 months, and the mean age at CGD diagnosis was 52.7 months. Recurrent pneumonia was the most frequent clinical condition (76.8%), followed by lymphadenopathy (59.4%), granulomata (49.3%), skin infections (42%), chronic diarrhea (41.9%), otitis (29%), sepsis (23.2%), abscesses (21.7%), recurrent urinary tract infection (20.3%), and osteomyelitis (15.9%). Adverse reactions to bacillus Calmette-Guérin (BCG) vaccination were identified in 30% of the studied Latin American CGD cases. The genetic diagnoses of the 71 patients revealed 53 patients from 47 families with heterogeneous mutations in the CYBB gene (five novel mutations: p.W361G, p.C282X, p.W483R, p.R226X, and p.Q93X), 16 patients with the common deletion c.75_76 del.GT in exon 2 of NCF1 gene, and two patients with mutations in the CYBA gene.

CONCLUSION

The majority of Latin American CGD patients carry a hemizygous mutation in the CYBB gene. They also presented a wide range of clinical manifestations most frequently bacterial and fungal infections of the respiratory tract, skin, and lymph nodes. Thirty percent of the Latin American CGD patients presented adverse reactions to BCG, indicating that this vaccine should be avoided in these patients.

Chronic granulomatous disease: why an inflammatory disease?

Chronic granulomatous disease is a primary immunodeficiency caused by mutations in the genes encoding subunits of the phagocytic NADPH oxidase system. Patients can present with severe, recurrent infections and noninfectious conditions. Among the latter, inflammatory manifestations are predominant, especially granulomas and colitis. In this article, we systematically review the possible mechanisms of hyperinflammation in this rare primary immunodeficiency condition and their correlations with clinical aspects.

Pediatric allergy and immunology in Brazil

The subspecialty of pediatric allergy and immunology in Brazil is in its early years and progressing steadily. This review highlights the research developed in the past years aiming to show the characteristics of allergic and immunologic diseases in this vast country. Epidemiologic studies demonstrated the high prevalence of asthma in infants, children, and adolescents. Mortality rates and average annual variation of asthma hospitalization have reduced in all pediatric age groups. Indoor aeroallergen exposure is excessively high and contributes to the high rates of allergy sensitization. Prevalence of food allergy has increased to epidemic levels. Foods (35%), insect stings (30%), and drugs (23%) are the main etiological agents of anaphylaxis in children and adolescents. Molecular diagnosis of primary immunodeficiencies (PID) showed a high incidence of fungal infections including paracoccidioidomycosis in X-linked hyper-IgM syndrome, and the occurrence of BCG adverse reactions or other mycobacterial infections in patients with chronic granulomatous disease. Education in pediatric allergy and immunology is deficient for medical students, but residency programs are effective in training internists and pediatricians for the practice of allergy. The field of PID requires further training. Last, this review is a tribute to Prof. Dr. Charles Naspitz, one of the pioneers of our specialty in Brazil.

Efficient IDUA Gene Mutation Detection with Combined Use of dHPLC and Dried Blood Samples

Objectives. Development of a simple mutation directed method in order to allow lowering the cost of mutation testing using an easily obtainable biological material. Assessment of the feasibility of such method was tested using a GC-rich amplicon. Design and Methods. A method of denaturing high-performance liquid chromatography (dHPLC) was improved and implemented as a technique for the detection of variants in exon 9 of the IDUA gene. The optimized method was tested in 500 genomic DNA samples obtained from dried blood spots (DBS). Results. With this dHPLC approach it was possible to detect different variants, including the common p.Trp402Ter mutation in the IDUA gene. The high GC content did not interfere with the resolution and reliability of this technique, and discrimination of G-C transversions was also achieved. Conclusion. This PCR-based dHPLC method is proved to be a rapid, a sensitive, and an excellent option for screening numerous samples obtained from DBS. Furthermore, it resulted in the consistent detection of clearly distinguishable profiles of the common p.Trp402Ter IDUA mutation with an advantageous balance of cost and technical requirements.