Clinical Manifestations in Carriers of X-Linked Chronic Granulomatous Disease in Mexico

X-linked chronic granulomatous disease secondary to skewed X-chromosome inactivation in female patients

BACKGROUND

Chronic granulomatous disease (CGD) is a heterogeneous primary immunodeficiency. X-linked (XL) CGD caused by gene defects of CYBB is the most prevalent type of CGD.

OBJECTIVE

We aim to understand the clinical and molecule features of XL-CGD secondary to skewed X-chromosome inactivation (XCI) in female.

METHODS

We retrospectively reviewed the medical records of a female patient diagnosed with XL-CGD. Flow cytometry was used to detect the respiratory burst function. After restriction enzyme digestion of DNA, XCI was calculated by detecting fluorescent PCR products with capillary electrophoresis. The previously published female XL-CGD cases secondary to skewed XCI was summarized.

RESULTS

Clinical data were available for 15 female subjects. The median age of diagnosis was 16 years. Consistent with XL-CGD in males, infection was the most frequent manifestation in the female patients. Catalase-positive pathogens including Serratia marcescens and Staphylococcus aureus infections were the most common pathogens. Autoimmune/autoinflammation manifestations were observed in five patients. Dihydrorhodamine (DHR) assay showed that median %DHR+ values were 6.5% and the values varying with age were observed in 2 patients. All patients had a skewing XCI and there was no consistency between the daughter and carrier mother. Anti-infective treatment was effective in majority and there was no mortality reported in XL-CGD female patients to date.

CONCLUSION

XL-CGD should not be neglected in female patients manifested as CGD phenotype and it is necessary to make periodic clinical evaluation of CGD female carriers as the neutrophil oxidative function may decline with aging and increase the risk for infection.

Allogeneic HSCT for Symptomatic Female X-linked Chronic Granulomatous Disease Carriers

X-linked chronic granulomatous disease (XL-CGD) is an inherited disorder of superoxide production, causing failure to generate the oxidative burst in phagocytes. It is characterized by invasive bacterial and fungal infections, inflammation, and chronic autoimmune disease. While XL-CGD carriers were previously assumed to be healthy, a range of clinical manifestations with significant morbidity have recently been described in a subgroup of carriers with impaired neutrophil oxidative burst due to skewed lyonization. Allogeneic hematopoietic stem cell transplantation (HSCT) is the standard curative treatment for CGD but has rarely been reported in individual symptomatic carriers to date. We undertook a retrospective international survey of outcome of HSCT for symptomatic XL-CGD carriers. Seven symptomatic female XL-CGD carriers aged 1-56 years underwent HSCT in four centers, indicated for severe and recurrent infection, colitis, and autoimmunity. Two patients died from transplant-related complications, following donor engraftment and restoration of oxidative burst. All surviving patients demonstrated resolution of their neutrophil oxidative burst defect with concordant reduction in infection and inflammatory symptoms and freedom from further immunosuppressive therapy. In conclusion, allogeneic HSCT may cure the phagocyte defect in symptomatic XL-CGD carriers and improve their recurrent and disabling infective and inflammatory symptoms but risks transplant-related complications.

Unlocking the power of NOX2: A comprehensive review on its role in immune regulation

Reactive oxygen species (ROS) are a family of highly reactive molecules with numerous, often pleiotropic functions within the cell and the organism. Due to their potential to destroy biological structures such as membranes, enzymes and organelles, ROS have long been recognized as harmful yet unavoidable by-products of cellular metabolism leading to "oxidative stress" unless counterbalanced by cellular anti-oxidative defense mechanisms. Phagocytes utilize this destructive potential of ROS released in high amounts to defend against invading pathogens. In contrast, a regulated and fine-tuned release of "signaling ROS" (sROS) provides essential intracellular second messengers to modulate central aspects of immunity, including antigen presentation, activation of antigen presenting cells (APC) as well as the APC:T cell interaction during T cell activation. This regulated release of sROS is foremost attributed to the specialized enzyme NADPH-oxidase (NOX) 2 expressed mainly in myeloid cells such as neutrophils, macrophages and dendritic cells (DC). NOX-2-derived sROS are primarily involved in immune regulation and mediate protection against autoimmunity as well as maintenance of self-tolerance. Consequently, deficiencies in NOX2 not only result in primary immune-deficiencies such as Chronic Granulomatous Disease (CGD) but also lead to auto-inflammatory diseases and autoimmunity. A comprehensive understanding of NOX2 activation and regulation will be key for successful pharmaceutical interventions of such ROS-related diseases in the future. In this review, we summarize recent progress regarding immune regulation by NOX2-derived ROS and the consequences of its deregulation on the development of immune disorders.

Clinical Features of Female Taiwanese Carriers with X-linked Chronic Granulomatous Disease from 2004 to 2019

PURPOSE

Female carriers with X-linked chronic granulomatous disease (XL-CGD) who have < 10% reactive oxygen species (ROS) production due to profound X-chromosome inactivation (XCI or lyonization) are more susceptible to infections. We assessed ROS production in Taiwanese female carriers with XL-CGD to investigate whether the level of ROS correlated to their clinical features of infection, autoimmunity, and autoinflammation.

METHODS

Clinical course, ROS production, flavocytochrome b558 (Cyto b558) expression, and genetic analysis in carriers were investigated after identifying their index cases between 2004 and 2019.

RESULTS

A total of 19 mothers (median 27 years; range 25-60 years) and three of four girls (range 4-6 years) relative to 22 male index XL-CGD cases from 19 unrelated families were enrolled. Approximately half (8/19, 42%) of the mothers had novel one-allele mutations. Twenty-two of the 23 females were carriers. One carrier with de novo [Arg290X]CYBB who suffered from refractory salmonella sepsis and chorioretinitis as an XL-CGD phenotype had extreme XCI, absent Cyto b558 expression, and only 8% ROS production. The remaining carriers had bimodal patterns of Cyto b558 expressions (median 40.2%, 26.8-52.4%) and ROS production (38.3%, range 28.2-54.2%) sufficient to prevent significant infections, although neck lymphadenitis recurred in one mother and sister who had ROS expressions of 28.2% and 38.0%, respectively. However, none of the carriers had manifestations of autoimmunity or autoinflammation (e.g., photosensitivity, aphthous stomatitis, or joint disorders), of which each was seen in approximately one-third of XL-CGD carriers from the Western world.

CONCLUSION

One carrier had undetectable Cyto b558 expression and an extremely low ROS production, and consequently presented with an XL-CGD phenotype. One mother and her daughter experienced recurrent neck lymphadenitis despite having sufficient ROS production. Significant autoimmunity/autoinflammation did not develop in any of the carriers. Studies with a longer follow-up period are needed to validate our findings.