Hemophagocytic Lymphohistiocytosis in Children with Chronic Granulomatous Disease-Single-Center Experience from North India

The paradox of autoimmunity and autoinflammation in inherited neutrophil disorders - in search of common patterns

Congenital defects of neutrophil number or function are associated with a severe infectious phenotype that may require intensive medical attention and interventions to be controlled. While the infectious complications in inherited neutrophil disorders are easily understood much less clear and explained are autoimmune and autoinflammatory phenomena. We survey the clinical burden of autoimmunity/autoinflammation in this setting, search for common patterns, discuss potential mechanisms and emerging treatments.

Microbiome and Its Dysbiosis in Inborn Errors of Immunity

Inborn errors of immunity (IEI) can present with infections, autoimmunity, lymphoproliferation, granulomas, and malignancy. IEIs are due to genetic abnormalities that disrupt normal host-immune response or immune regulation. The microbiome appears essential for maintaining host immunity, especially in patients with a defective immune system. Altered gut microbiota in patients with IEI can lead to clinical symptoms. Microbial dysbiosis is the consequence of an increase in pro-inflammatory bacteria or a reduction in anti-inflammatory bacteria. However, functional and compositional differences in microbiota are also involved. Dysbiosis and a reduced alpha-diversity are well documented, particularly in conditions like common variable immunodeficiency. Deranged microbiota is also seen in Wiskott–Aldrich syndrome, severe combined immunodeficiency, chronic granulomatous disease, selective immunoglobulin-A deficiency, Hyper IgE syndrome (HIGES), X-linked lymphoproliferative disease-2, immunodysregulation, polyendocrinopathy, enteropathy, x-linked syndrome, and defects of IL10 signalling. Distinct gastrointestinal, respiratory, and cutaneous symptoms linked to dysbiosis are seen in several IEIs, emphasizing the importance of microbiome identification. In this study, we discuss the processes that maintain immunological homeostasis between commensals and the host and the disruptions thereof in patients with IEIs. As the connection between microbiota, host immunity, and infectious illnesses is better understood, microbiota manipulation as a treatment strategy or infection prevention method would be more readily employed. Therefore, optimal prebiotics, probiotics, postbiotics, and fecal microbial transplantation can be promising strategies to restore the microbiota and decrease disease pathology in patients with IEIs.

Targeted Gene Sanger Sequencing Should Remain the First-Tier Genetic Test for Children Suspected to Have the Five Common X-Linked Inborn Errors of Immunity

To address inborn errors of immunity (IEI) which were underdiagnosed in resource-limited regions, our centre developed and offered free genetic testing for the most common IEI by Sanger sequencing (SS) since 2001. With the establishment of The Asian Primary Immunodeficiency (APID) Network in 2009, the awareness and definitive diagnosis of IEI were further improved with collaboration among centres caring for IEI patients from East and Southeast Asia. We also started to use whole exome sequencing (WES) for undiagnosed cases and further extended our collaboration with centres from South Asia and Africa. With the increased use of Next Generation Sequencing (NGS), we have shifted our diagnostic practice from SS to WES. However, SS was still one of the key diagnostic tools for IEI for the past two decades. Our centre has performed 2,024 IEI SS genetic tests, with in-house protocol designed specifically for 84 genes, in 1,376 patients with 744 identified to have disease-causing mutations (54.1%). The high diagnostic rate after just one round of targeted gene SS for each of the 5 common IEI (X-linked agammaglobulinemia (XLA) 77.4%, Wiskott–Aldrich syndrome (WAS) 69.2%, X-linked chronic granulomatous disease (XCGD) 59.5%, X-linked severe combined immunodeficiency (XSCID) 51.1%, and X-linked hyper-IgM syndrome (HIGM1) 58.1%) demonstrated targeted gene SS should remain the first-tier genetic test for the 5 common X-linked IEI.

Neonatal Manifestations of Chronic Granulomatous Disease: MAS/HLH and Necrotizing Pneumonia as Unusual Phenotypes and Review of the Literature

Chronic granulomatous disease (CGD) is a rare inborn error of immunity (IEI), characterized by a deficient phagocyte killing due to the inability of NADPH oxidase to produce reactive oxygen species in the phagosome. Patients with CGD suffer from severe and recurrent infections and chronic inflammatory disorders. Onset of CGD has been rarely reported in neonates and only as single case reports or small case series. We report here the cases of three newborns from two different kindreds, presenting with novel infectious and inflammatory phenotypes associated with CGD. A girl with CYBA deficiency presented with necrotizing pneumonia, requiring a prolonged antibiotic treatment and resulting in fibrotic pulmonary changes. From the second kindred, the first of two brothers developed a fatal Burkholderia multivorans sepsis and died at 24 days of life. His younger brother had a diagnosis of CYBB deficiency and presented with Macrophage Activation Syndrome/Hemophagocytic Lympho-Histiocytosis (MAS/HLH) without any infection, that could be controlled with steroids. We further report the findings of a review of the literature and show that the spectrum of microorganisms causing infections in neonates with CGD is similar to that of older patients, but the clinical manifestations are more diverse, especially those related to the inflammatory syndromes. Our findings extend the spectrum of the clinical presentation of CGD to include unusual neonatal phenotypes. The recognition of the very early, potentially life-threatening manifestations of CGD is crucial for a prompt diagnosis, improvement of survival and reduction of the risk of long-term sequelae.

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.

Case Report: Symptomatic Chronic Granulomatous Disease in the Newborn

Chronic granulomatous disease (CGD) is a primary immunodeficiency, which is diagnosed in most patients between one and three years of age. Here we report on a boy who presented at birth with extensive skin lesions and lymphadenopathy which were caused by CGD. An analysis of the literature revealed 24 patients with CGD who became symptomatic during the first six weeks of life. Although pulmonary complications and skin lesions due to infection were the leading symptoms, clinical features were extremely heterogenous. As follow-up was not well specified in most patients, the long-term prognosis of children with very early onset of CGD remains unknown.

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.