Leiner's disease (erythroderma desquamativum): A review and approach to therapy.

Leiner's disease (LD) is a rare and serious syndrome of infantile erythroderma of severe and progressive generalized seborrheic-like dermatitis, recalcitrant diarrhea, malabsorption and wasting, and recurrent local and systemic infections. The purpose of this study is to provide an updated review on management with a summarized review of available peer-reviewed articles on LD. The mechanisms underlying this disease process remain unclear. The diagnosis includes demonstration of deficient opsonic activity along with the clinical tetrad of erythroderma, persistent gastrointestinal disturbance, superimposed bacterial or candidal infection, and marked wasting. An important correlation between LD and defective yeast and Staphylococcus aureus opsonization has been established. For the familial form of LD, an association of either complement three deficiency or complement five dysfunction has been made. LD should be distinguished from other types of infantile erythroderma, including Omenn syndrome. Treatment includes fluid and nutrition replacement, antibiotics to control infection, and fresh-frozen plasma therapy. The prognosis is unclear; it depends on treatment. LD is a life-threatening condition that requires prompt identification and hospitalization. Affected infants who receive vigorous treatment not only have the prospect of surviving, but also generally lead a normal life after infancy.

Clinical implications of C6 complement component deficiency.

Background: Terminal complement component deficiencies are risk factors for neisserial infections. Objective: To review the clinical characteristics, the diagnosis and the management of patients with a terminal complement component deficiency. Methods: Pertinent articles were selected and reviewed in relation to a case presentation of C6 deficiency. Results: A case of a 56-year old patient with a history of meningitis, chronic rash, and C6 deficiency was presented, followed by discussion of clinical characteristics, diagnosis, and management of terminal complement component deficiencies. Clinical pearls and pitfalls were reviewed for the practicing allergist/immunologist and fellow-in-training. Conclusion: C6 deficiency is the most common terminal complement component deficiency and can present later in age with N. meningitidis infections. Patients can be screened for terminal complement component deficiency by checking CH50.

Genetic and Protein Structural Evaluation of Atypical Hemolytic Uremic Syndrome and C3 Glomerulopathy.

Atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy (C3G) are associated with loss of regulation of the alternative pathway of complement and its resulting overactivation. As rare diseases, genetic variants leading to aHUS and C3G were previously analysed in relatively low patient numbers. To improve this analysis, data were pooled from six centres. Totals of 610 rare variants for aHUS and 82 for C3G were presented in an interactive database for 13 genes. Using allele frequency comparisons with the Exome Aggregation Consortium as a reference genome, the patients with aHUS showed significantly more protein-altering ultrarare variants (allele frequency <0.01%) in five genes CFH, CFI, CD46, C3, and DGKE. In patients with C3G, the corresponding association was only found for C3 and CFH. Protein structure analyses of these five proteins showed distinct differences in the positioning of these variants in C3 and FH. For aHUS, variants were clustered at the C-terminus of FH and implicated changes in the binding of FH to host cell surfaces. For C3G, variants were clustered at the N-terminal C3b binding site of FH and implicated changes in the fluid-phase regulation of C3b. We discuss the utility of the Web database as a patient resource for clinicians.

Recurrent macroscopic hematuria in a pediatric patient: is it early to diagnose as having type I hereditary C2 deficiency?

Hereditary C2 deficiency is the most common early complement deficiency and characterized by recurrent infections and autoimmunity despite most patients are also asymptomatic. Type I hereditary C2 deficiency is caused by a heterozygous deletion in C2 gene resulting in early stop codon and lack of C2 production. Clinical spectrum may vary and pure nephrological involvement without the presence of recurrent infections is scarce in hereditary C2 deficiency.We report here a previously healthy 14-year-old boy presenting recurrent self-limited macroscopic hematuria and persistently low serum C4 levels, diagnosed as having type I hereditary C2 deficiency with confirming a novel heterozygote deletion (c.1567 + 22_1567 + 43del) in C2 gene. He has been remained asymptomatic for the next 18 months. Since the diagnosis of C2 deficiency was made in the absence of organ-threatening involvement such as immune complex-mediated glomerulonephritis, we think that early diagnosis and optimal follow-up may improve life-span of the patients with hereditary early complement deficiencies.

Newborn Screening for Presymptomatic Diagnosis of Complement and Phagocyte Deficiencies.

The clinical outcomes of primary immunodeficiencies (PIDs) are greatly improved by accurate diagnosis early in life. However, it is not common to consider PIDs before the manifestation of severe clinical symptoms. Including PIDs in the nation-wide newborn screening programs will potentially improve survival and provide better disease management and preventive care in PID patients. This calls for the detection of disease biomarkers in blood and the use of dried blood spot samples, which is a part of routine newborn screening programs worldwide. Here, we developed a newborn screening method based on multiplex protein profiling for parallel diagnosis of 22 innate immunodeficiencies affecting the complement system and respiratory burst function in phagocytosis. The proposed method uses a small fraction of eluted blood from dried blood spots and is applicable for population-scale performance. The diagnosis method is validated through a retrospective screening of immunodeficient patient samples. This diagnostic approach can pave the way for an earlier, more comprehensive and accurate diagnosis of complement and phagocytic disorders, which ultimately lead to a healthy and active life for the PID patients.

Complement factor I deficiency: A potentially treatable cause of fulminant cerebral inflammation.

OBJECTIVE: To raise awareness of complement factor I (CFI) deficiency as a potentially treatable cause of severe cerebral inflammation. METHODS: Case report with neuroradiology, neuropathology, and functional data describing the mutation with review of literature. RESULTS: We present a case of acute, fulminant, destructive cerebral edema in a previously well 11-year-old, demonstrating massive activation of complement pathways on neuropathology and compound heterozygote status for 2 pathogenic mutations in CFI which result in normal levels but completely abrogate function. CONCLUSIONS: Our case adds to a very small number of extant reports of this phenomenon associated with a spectrum of inflammatory histopathologies including hemorrhagic leukoencephalopathy and clinical presentations resembling severe acute disseminated encephalomyelitis. CFI deficiency can result in uncontrolled activation of the complement pathways in the brain resulting in devastating cerebral inflammation. The deficit is latent, but the catastrophic dysregulation of the complement system may be the result of a C3 acute phase response. Diagnoses to date have been retrospective. Diagnosis requires a high index of suspicion and clinician awareness of the limitations of first-line clinical tests of complement activity and activation. Simple measurement of circulating CFI levels, as here, may fail to diagnose functional deficiency with absent CFI activity. These diagnostic challenges may mean that the CFI deficiency is being systematically under-recognized as a cause of fulminant cerebral inflammation. Complement inhibitory therapies (such as eculizumab) offer new potential treatment, underlining the importance of prompt recognition, and real-time whole exome sequencing may play an important future role.

Development of hypocomplementemic urticarial vasculitis during certolizumab pegol treatment for rheumatoid arthritis: A case report.

WHAT IS KNOWN AND OBJECTIVE: Tumour necrosis factor-α-blocking agents potentially cause vasculitis. However, no study has reported on the association between hypocomplementemic urticarial vasculitis (HUV) and certolizumab pegol (CZP) usage. CASE DESCRIPTION: We present the first case of HUV development during CZP treatment for rheumatoid arthritis. Hypocomplementemic urticarial vasculitis improved after CZP was discontinued and the dose of oral prednisolone was increased. WHAT IS NEW AND CONCLUSION: Clinicians should be aware about the potential development of HUV during CZP treatment, which is presumed to be safe considering its unique structural characteristics that differ from those of other tumour necrosis factor-α-blocking agents.

Analysis of the Complement System in the Clinical Immunology Laboratory.

The complement system is a critical component of both the innate and adaptive immune systems that augments the function of antibodies and phagocytes. Antigen-antibody immune complexes, lectin binding, and accelerated C3 tick-over can activate this well-coordinated and carefully regulated process. The importance of this system is highlighted by the disorders that arise when complement components or regulators are deficient or dysregulated. This article describes the pathways involved in complement activation and function, the regulation of these various pathways, and the interpretation of laboratory testing performed for the diagnosis of diseases of complement deficiency, exuberant complement activation, and complement dysregulation.

Classical and Non-classical Presentations of Complement Factor I Deficiency: Two Contrasting Cases Diagnosed via Genetic and Genomic Methods.

Deficiency of complement factor I is a rare immunodeficiency that typically presents with increased susceptibility to encapsulated bacterial infections. However, non-infectious presentations including rheumatological, dermatological and neurological disease are increasingly recognized and require a high-index of suspicion to reach a timely diagnosis. Herein, we present two contrasting cases of complement factor I deficiency: one presenting in childhood with invasive pneumococcal disease, diagnosed using conventional immunoassays and genetics and the second presenting in adolescence with recurrent sterile neuroinflammation, diagnosed via a genomic approach. Our report and review of the literature highlight the wide spectrum of clinical presentations associated with CFI deficiency and the power of genomic medicine to inform rare disease diagnoses.