Novel hypomorphic mutation in IKBKG impairs NEMO-ubiquitylation causing ectodermal dysplasia, immunodeficiency, incontinentia pigmenti, and immune thrombocytopenic purpura.

NF-κB essential modulator (NEMO) is a component of the IKK complex, which participates in the activation of the NF-κB pathway. Hypomorphic mutations in the IKBKG gene result in different forms of anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) in males without affecting carrier females. Here, we describe a hypomorphic and missense mutation, designated c.916G>A (p.D306N), which affects our patient, his mother, and his sister. This mutation did not affect NEMO expression; however, an immunoprecipitation assay revealed reduced ubiquitylation upon CD40-stimulation in the patient's cells. Functional studies have demonstrated reduced phosphorylation and degradation of IκBα, affecting NF-κB recruitment into the nucleus. The patient presented with clinical features of ectodermal dysplasia, immunodeficiency, and immune thrombocytopenic purpura, the latter of which has not been previously reported in a patient with NEMO deficiency. His mother and sister displayed incontinentia pigmenti indicating that, in addition to amorphic mutations, hypomorphic mutations in NEMO can affect females.

Incontinentia pigmenti underlies thymic dysplasia, autoantibodies to type I IFNs, and viral diseases.

Human inborn errors of thymic T cell tolerance underlie the production of autoantibodies (auto-Abs) neutralizing type I IFNs, which predispose to severe viral diseases. We analyze 131 female patients with X-linked dominant incontinentia pigmenti (IP), heterozygous for loss-of-function (LOF) NEMO variants, from 99 kindreds in 10 countries. Forty-seven of these patients (36%) have auto-Abs neutralizing IFN-α and/or IFN-ω, a proportion 23 times higher than that for age-matched female controls. This proportion remains stable from the age of 6 years onward. On imaging, female patients with IP have a small, abnormally structured thymus. Auto-Abs against type I IFNs confer a predisposition to life-threatening viral diseases. By contrast, patients with IP lacking auto-Abs against type I IFNs are at no particular risk of viral disease. These results suggest that IP accelerates thymic involution, thereby underlying the production of auto-Abs neutralizing type I IFNs in at least a third of female patients with IP, predisposing them to life-threatening viral diseases.

Vaccination as a probable cause of incontinentia pigmenti reactivation.

We report a female infant with recurrent biopsy-proven vesicobullous incontinentia pigmenti occurring after her 12-month and 18-month immunizations. To our knowledge, incontinentia pigmenti vesicobullous recurrence following immunizations has not been reported. We propose that vaccinations may serve as triggers for incontinentia pigmenti reactivation.

Recurrent encephalomyelitis associated with incontinentia pigmenti.

A 4-year-old girl developed progressive obtundation following an upper respiratory tract illness. Physical, cerebrospinal fluid, computed tomographic, electroencephalographic, and evoked response findings were compatible with disseminated encephalomyelitis. Skin lesions indicative of incontinentia pigmenti were confirmed by biopsy. Transient loss of suppressor T cells was observed. Prior history revealed that at 6 months of age a similar episode of acute central nervous system deterioration had occurred. Recurrent encephalomyelitis does occur with incontinentia pigmenti. Transient loss of suppressor T cells suggests that this is an immune-mediated process.

Eosinophilic and neutrophilic spongiosis: clues to the diagnosis of immunobullous diseases and other inflammatory disorders.

When eosinophils or neutrophils are found within the epidermis in concert with edema, the pattern is known as eosinophilic or neutrophilic spongiosis. Although eosinophilic spongiosis has been accepted as a clue to the diagnosis of blistering disorders for some time, the fact that either pattern can serve as a clue to the diagnosis of a variety of disorders, including immunobullous diseases, is less widely known. Herein, we review the types of inflammatory skin diseases, including spongiotic dermatitides, subepidermal vesicular dermatitides, intraepidermal vesicular dermatitides, and perivascular or diffuse dermatitides, that display intraepidermal eosinophils and neutrophils. We also review the known mechanisms that explain in part why intraepidermal granulocytes are commonly found in this diverse group of skin diseases.

Serial cytokine expressions in infants with incontinentia pigmenti.

NF-κB dysfunction resulting from NEMO (NF-kappaB essential modulator) mutation can lead to significant alterations in cytokine production. However, little is known about changes in the expression of downstream molecules in patients with incontinentia pigmenti (IP). We aim to investigate serial cytokine expressions during the first 2 years of life in young infants with IP, the period in which skin inflammation and morphological changes are most significant. Gene analysis and X-inactivation test were performed for the two neonates with IP. Peripheral mononuclear cells were obtained after birth and successively at 6-month interval up to the age of two years. Levels of TNF-α and IL-6 were analyzed with ELISA before and after stimulating with Toll-like receptor ligands. The result showed the male IP patient had normal NEMO allele. His cytokine level, although initially lower, had returned to a level comparable with those of controls at 12 months of age. The female infant had mutated NEMO gene. Her baseline TNF-α level was significantly higher than those of the control subjects at birth and remained high by 6 months of age. All cytokine responses had decreased significantly by 2 years of age, the time in which all vesicular skin lesions had resolved. Both infants had normal serum immunoglobulin level and remained infection free during the follow up period. To our knowledge, this is the first report that demonstrates serial changes of cytokine profiles in humans with IP. This study showed that in the presence of NEMO mutation, alteration of cytokine production was remarkable during the first year of life, which may account for the prominent inflammatory changes in skin morphology.

Incontinentia pigmenti in combination with decreased IgG subclass concentrations in a female newborn.

Incontinentia pigmenti (IP) is a rare neurocutaneous disorder caused by mutations in the NEMO (NF-kappaB essential modulator) gene. Skin lesions are typically the first manifestation of IP though they may be accompanied by multiple malformations. This report presents the case of a female newborn with early onset of IP lesions within the 1st day of life. After the age of 1 month she developed frequent episodes of severe gastroenteritis. Examination of the immune system revealed low concentrations of IgG subclasses. This study suggests that, contrary to previous belief, IP is associated with immune deficiency.

Immunologic investigations in eight patients with incontinentia pigmenti.

We studied eight patients with incontinentia pigmenti to investigate the possibility of immunologic abnormalities. In six patients a defect of polymorphonuclear chemotaxis was revealed; lymphocyte subpopulations, serum immunoglobulin levels, and peripheral eosinophils were within normal limits. We hope these findings will stimulate further investigations into the mechanisms involved.

Incontinentia pigmenti and Behçet's syndrome: an unusual combination.

We describe an unusual case of a child who had had incontinentia pigmenti from birth and developed the clinical picture of Behçet's syndrome at five years of age. Among the various investigations performed, chemotactic activity of the polymorphonuclear leukocyte was found to be low. We discuss the possibility that there are common immunological abnormalities in the two syndromes.

Incontinentia pigmenti and Behçet's disease: a case of impaired neutrophil chemotaxis.

We describe a patient with incontinentia pigmenti who developed the clinical picture of intestinal Behçet's disease. Diagnosis of Behçet's disease was base on a recurrent genital and oral ulcer and a positive HLA-B51. Impaired neutrophil chemotactic activity and an elevated plasma IL-6 level were found. Chromosomal study revealed no abnormality in the patient or her family. We discuss the possibility that there are common immunological abnormalities in the two syndromes.

Expression of eotaxin, an eosinophil-selective chemokine, parallels eosinophil accumulation in the vesiculobullous stage of incontinentia pigmenti.

Incontinentia pigmenti (IP) is an X-linked dominant genodermatosis primarily affecting female children. The initial vesiculobullous stage of IP is characterized clinically by inflammatory papules, blisters, and pustules, and histopathologically by acanthosis, keratinocyte necrosis, epidermal spongiosis and massive epidermal eosinophil infiltration. The cause of this multisystem disease is attributed to the mutations of an X-linked regulatory gene, termed nuclear factor-kappaB essential modulator (NEMO). The exact mechanism of epidermal eosinophil accumulation has not yet been determined. We explored the possible role of an eosinophil-selective, nuclear factor-kappaB-activated chemokine, eotaxin, in the accumulation of eosinophils in the initial stage of the disease. Monoclonal antibody (6H9) specific for human eotaxin strongly labelled the suprabasal epidermis of IP skin, paralleling the upper epidermal accumulation of eosinophils, but did not label the epidermis of normal skin or lesional skin from patients with other inflammatory skin diseases not characterized by prominent eosinophil accumulation, namely dermatitis herpetiformis and selected cases of atopic dermatitis lacking significant numbers of eosinophils. In addition, endothelial cells in lesional skin of IP also exhibited strong expression of eotaxin, which correlated with perivascular and intravascular eosinophil infiltration. We also examined the in vitro effects on epidermally derived eotaxin of several cytokines that were nuclear factor-kappaB-activated and/or known to induce eotaxin expression. In normal human keratinocytes, proinflammatory cytokines either independently (IL-1alpha) or synergistically (tumour necrosis factor-alpha (TNF-alpha)/ interferon-gamma (IFN-gamma) and TNF-alpha/IL-4) up-regulated eotaxin expression. These studies suggest that release of cytokines during the initial inflammatory stage of IP induces epidermal expression of eotaxin, which may play a role in the epidermal accumulation of eosinophils.