Differential diagnosis in ulcerative colitis in an adolescent: Chronic granulomatous disease needs extra attention

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 p22^phox, NCF1, encoding p47^phox, NCF2, encoding p67^phox and NCF4, encoding p40^phox. 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 gp91^phox (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.

New Findings of Immunodysregulation, Polyendocrinopathy, and Enteropathy X-linked Syndrome (IPEX); Granulomas in Lung and Duodenum

Immune dysregulation, polyendocrinopathy and enteropathy, X-linked (IPEX) syndrome is a rare disorder caused by loss-of-function mutations in the gene forkhead box protein 3 (FOXP3). IPEX patients frequently show chronic diarrhea (enteropathy) associated with villous atrophies in the small intestine. Our case is different from this classical information in the literature, since he presented with neonatal onset inflammatory bowel disease within the first months of life accompanied by deep ulcers throughout colonic mucosa. Moreover, he developed chronic lung disease during follow-up and histopathological examinations showed granulomas in both gastrointestinal tract and lung parenchyma. Genetic analysis revealed the diagnosis of IPEX syndrome with a germline mutation in FOXP3. Thus, our study provides an unusual presentation of IPEX syndrome with colitis and granulomas presence in histopathological examinations.

Long-term observational studies of chronic granulomatous disease

PURPOSE OF REVIEW

Chronic granulomatous disease (CGD) is a primary immunodeficiency, with a defect of phagocytes in killing specific pathogens. CGD is characterized by severe recurrent bacterial and fungal infections and dysregulated inflammatory response. Since its first description as fatal disease about 60 years ago, a significant improvement in outcome has been achieved in the last 20 years. The purpose of this review is to framework recent advances in CGD immunopathogenesis, management of disease manifestation and cure of CGD patients.

RECENT FINDINGS

For years, CGD is a known cause of life-threatening infections and excessive inflammation. The cause and the management of inflammatory reactions, however, have not been clarified, and the range of clinical presentation is growing with corresponding novel therapeutic interventions. Recent work focuses on the best outcome of hematopoietic stem cell transplantation (HSCT) and gene therapy for the cure of CGD patients, more specifically, those with X-linked and p47 mutations.

SUMMARY

The genetics and phenotype of CGD is well characterized; however, the underlying mechanisms, the treatment of its inflammatory manifestations and the cure of CGD is under further investigation.