Chronic Granulomatous Disease is the most commonly encountered immunodeficiency involving the phagocyte, and is characterized by repeated infections with bacterial and fungal pathogens, as well as the formation of granulomas in tissue. The disease is the result of a disorder of the NADPH oxidase system, culminating in an inability of the phagocyte to generate superoxide, leading to the defective killing of pathogenic organisms. This can lead to infections with Staphylococcus aureus, Psedomonas species, Nocardia species, and fungi (such as Aspergillus species and Candida albicans). Involvement of vital or large organs can contribute to morbidity and/or mortality in the affected patients. Major advances have occurred in the diagnosis and treatment of this disease, with the potential for gene therapy or stem cell transplantation looming on the horizon.
Chronic Granulomatous Disease (CGD), a disorder of the NADPH oxidase system, results in phagocyte functional defects and subsequent infections with bacterial and fungal pathogens (such as Aspergillus species and Candida albicans). Deletions and missense, frameshift, or nonsense mutations in the gp91phox gene (also termed CYBB), located in the Xp21.1 region of the X chromosome, are associated with the most common form of CGD. When larger X-chromosomal deletions occur, including the XK gene deletion, a so-called "Contiguous Gene Deletion Syndrome" may result. The contiguous gene deletion syndrome is known to associate the Kell phenotype/McLeod syndrome with diseases such as X-linked chronic granulomatous disease, Duchenne muscular dystrophy, and X-linked retinitis pigmentosa. These patients are often complicated and management requires special attention to the various facets of the syndrome.
Advances in technology have lowered the limits of viability in premature births to 24 weeks of gestation. This brought forth a new population of children, who are born 3-4 months early and spent considerable amounts of time in neonatal intensive care unit (NICU), instead of sterile environment of mother's womb. Besides, other problems associated with prematurity, these children often undergo invasive procedures resulting in mucosal inflammation and/ or injury by feeding tubes, endotracheal tubes, and prolonged IV catheter. To test whether "ex-preemie-infants" were different than "term-infants" with regard to their immunity, preterm infants (< 32 weeks) and term infants (control) at the corrected age of 9-12 months were analyzed for their resting and stimulated immune responses. Preterm infants had a significant Th1 skewed response, higher number of activated and functionally competent T cells compared to term infants. The critical role of neonatal environmental exposure on immune system development is imminent; nevertheless detailed mechanistic studies on pathways are warranted.
Chronic granulomatous disease (CGD) is associated with defective function of the NADPH-oxidase system in conjunction with phagocytic defects which leads to granuloma formation and serious infectious complications. This is often associated with significant morbidity and mortality. The association of defective phagocyte function with other coincidental immune defects is unknown. Defects in innate pathways seen with CGD, including complement systems, and toll-like and dectin receptor pathways, have not been described before. We present the case of a 2-year old male patient hospitalized with recurrent pneumonia, a non-healing skin ulcer, necrotizing lung granulomas, and epididymo-orchitis. Defective neutrophil chemiluminescence was detected by dihydrorhodamine (DHR) testing. Further evaluation demonstrated characteristic molecular mutations of CYBB consistent with CGD. Immune evaluation demonstrated polyclonal hyperglobulinemia, but a greatly reduced mannose binding lectin (MBL) level. Six biallelic polymorphisms in MBL gene and its promoter were analyzed using Light CyclerTM Real-time PCR assay. The LXPA/LYPB haplotype of MBL was detected in our patient; the latter is the defective haplotype associated with low MBL levels. Due to the implications for innate immunity and the protection against bacterial, viral, and fungal infections provided by MBL, a deficiency of this protein may have disastrous consequences on the long term outcomes of CGD. MBL deficiency can also complicate other disorders affecting the immune system, significantly increasing the risk of infection in such patients. Further studies looking at the frequency and implications of MBL deficiency in CGD are needed.
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