[Polysaccharide specific humoral immunodeficiency in ectodermal dysplasia. Case report of a boy with two affected brothers]

Frequent somatic mosaicism of NEMO in T cells of patients with X-linked anhidrotic ectodermal dysplasia with immunodeficiency

Somatic mosaicism has been described in several primary immunodeficiency diseases and causes modified phenotypes in affected patients. X-linked anhidrotic ectodermal dysplasia with immunodeficiency (XL-EDA-ID) is caused by hypomorphic mutations in the NF-κB essential modulator (NEMO) gene and manifests clinically in various ways. We have previously reported a case of XL-EDA-ID with somatic mosaicism caused by a duplication mutation of the NEMO gene, but the frequency of somatic mosaicism of NEMO and its clinical impact on XL-EDA-ID is not fully understood. In this study, somatic mosaicism of NEMO was evaluated in XL-EDA-ID patients in Japan. Cells expressing wild-type NEMO, most of which were derived from the T-cell lineage, were detected in 9 of 10 XL-EDA-ID patients. These data indicate that the frequency of somatic mosaicism of NEMO is high in XL-ED-ID patients and that the presence of somatic mosaicism of NEMO could have an impact on the diagnosis and treatment of XL-ED-ID patients.

Congenital alterations of NEMO glutamic acid 223 result in hypohidrotic ectodermal dysplasia and immunodeficiency with normal serum IgG levels

BACKGROUND

Hypomorphic mutations in the nuclear factor-κB (NF-κB) essential modulator (NEMO) gene result in a variable syndrome of somatic and immunologic abnormalities. Clinically relevant genotype-phenotype associations are essential to understanding this complex disease.

OBJECTIVE

To study 2 unrelated boys with novel NEMO mutations altering codon 223 for similarity in phenotype in consideration of potential genotype-phenotype associations.

METHODS

Clinical and laboratory features, including cell counts, immunoglobulin quantity and quality, natural killer cell cytotoxicity, and Toll-like and tumor necrosis factor receptor signaling, were evaluated. Because both mutations affected NEMO codon 223 and were novel, consideration was given to new potential genotype-phenotype associations.

RESULTS

Both patients were diagnosed as having hypohidrotic ectodermal dysplasia and had severe or recurrent infections. One had recurrent sinopulmonary infections and the other necrotizing soft tissue methicillin-resistant Staphylococcus aureus infection and Streptococcus anginosus subdural empyema with bacteremia. NEMO gene sequence demonstrated a 3-nucleotide deletion (c.667_669delGAG) in one patient and a substitution (667G>A) in the other. These findings predict either the deletion of NEMO glutamic acid 223 or it being replaced with lysine, respectively. Both patients had normal serum IgG levels but poor specific antibodies. Natural killer cell cytotoxicity and Toll-like and tumor necrosis factor receptor signaling were also impaired. Serious bacterial infection did not occur in both patients after immunoglobulin replacement therapy.

CONCLUSIONS

Two different novel mutations affecting NEMO glutamic acid 223 resulted in clinically relevant similar phenotypes, providing further evidence to support genotype-phenotype correlations in this disease. They suggest NEMO residue 223 is required for ectodermal development and immunity and is apparently dispensable for quantitative IgG production but may be required for specific antibody production.

Septicemia without sepsis: inherited disorders of nuclear factor-kappa B-mediated inflammation

Septicemia is a life-threatening condition that may lead to sepsis and even septic shock. This cascade is usually accompanied by a pronounced inflammatory response, leading to high body temperature and elevated levels of laboratory markers of inflammation. However, this response can be significantly diminished in children with inherited disorders of nuclear factor (NF)-kappa B-mediated immunity. Three disease-causing genes involved in NF-kappa B activation have been identified: NEMO, IKBA, and IRAK4. Patients with anhidrotic ectodermal dysplasia and immunodeficiency, which is caused by mutations in NEMO and IKBA, have sparse hair, dry skin, and conical teeth and are at increased risk of severe infections caused by pyogenic bacteria and atypical mycobacteria. Patients with interleukin-1 receptor-associated kinase-4 deficiency are at increased risk of invasive disease due to pyogenic bacteria. An underlying defect in NF- kappa B activation should be suspected in children with bacterial septicemia accompanied by mild signs of inflammation.

Successful allogeneic hemopoietic stem cell transplantation in a child who had anhidrotic ectodermal dysplasia with immunodeficiency

Anhidrotic ectodermal dysplasia with immunodeficiency is associated with multiple infections and a poor clinical outcome. Hypomorphic mutations in nuclear factor kappaB essential modulator (NEMO)/IkappaB kinase complex and a hypermorphic mutation in inhibitor alpha of nuclear factor kappaB (IkappaBalpha) both result in impaired nuclear factor kappaB activation and are associated with X-recessive and autosomal-dominant forms of anhidrotic ectodermal dysplasia with immunodeficiency, respectively. Autosomal-dominant anhidrotic ectodermal dysplasia with immunodeficiency is also associated with a severe T-cell phenotype. It is not known whether hematopoietic stem cell transplantation can cure immune deficiency in children with anhidrotic ectodermal dysplasia with immunodeficiency. A boy with autosomal-dominant anhidrotic ectodermal dysplasia with immunodeficiency and a severe T-cell immunodeficiency underwent transplantation at 1 year of age with haploidentical T-cell-depleted bone marrow after myeloablative conditioning. Engraftment occurred, with full hematopoietic chimerism. Seven years after transplantation, clinical outcome is favorable, with normal T-cell development. As expected, the developmental features of the anhidrotic ectodermal dysplasia syndrome have appeared and persisted. This is the first report of successful hematopoietic stem cell transplantation in a child with anhidrotic ectodermal dysplasia with immunodeficiency. Hematopoietic stem cell transplantation is well tolerated and efficiently cures the profound immunodeficiency associated with autosomal-dominant anhidrotic ectodermal dysplasia with immunodeficiency.

Transient hemophagocytosis with deficient cellular cytotoxicity, monoclonal immunoglobulin M gammopathy, increased T-cell numbers, and hypomorphic NEMO mutation

X-linked osteopetrosis, anhydrotic ectodermal dysplasia, and immunodeficiency (XL-O-EDA-ID) is a disorder that is caused by hypomorphic mutations in the nuclear factor kappaB essential modulator (NEMO). These mutations lead to an impaired NF-kappaB activation. In vitro analyses and studies in animal models show that inhibition of NF-kappaB leads to a decrease of cytokine production and T-cell proliferation. Patients classically display poor or delayed inflammatory response to infections. We describe a boy with XL-O-EDA-ID, 1167-1168insC NEMO mutation, and recurrent infections. In early infancy, he experienced hemophagocytosis with transient deficiency of natural killer activity. Increased immunoglobulin M levels in blood resulted from a monoclonal immunoglobulin M gammopathy. Blood T-cell numbers were constantly increased, most probably resulting from a peripheral T-cell expansion. Our observations suggest that patients with hypomorphic NEMO mutations and repeated infections may experience inflammatory dysregulation.

NF-κB-related genetic diseases

The recent identification of genetic diseases (incontinentia pigmenti, anhidrotic ectodermal dysplasia with immunodeficiency and cylindromatosis) resulting from mutations affecting components of the nuclear factor-kappaB (NF-kappaB) signaling pathway provides a unique opportunity to understand the function of NF-kappaB in vivo. Besides confirming the importance of NF-kappaB in innate and acquired immunity or bone mass control, analysis of these diseases has uncovered new critical roles played by this transcription factor in the development and homeostasis of the epidermis and the proper function of lymphatic vessels. In addition, the identified mutations will help understanding at the molecular level how NF-kappaB is activated in response to cell stimulation.

Human disease resulting from gene mutations that interfere with appropriate nuclear factor-kappaB activation

The nuclear factor (NF)-kappaB family of transcription factors serves vital roles in a wide array of cell functions. An increasing number of human genetic lesions that result in defined disease entities are linked to inappropriate activation of NF-kappaB. The resulting aberrant NF-kappaB function can lead to cellular defects that ultimately impair normal developmental processes, host immune defenses, or both. Molecular defects that lie upstream in cell-signaling pathways and rely upon NF-kappaB activation tend to give a more specific phenotype, whereas those closer to the actual NF-kappaB proteins have broader defects. A detailed study of these diseases can provide insight into the biochemistry of NF-kappaB activation as well as the role of NF-kappaB in human health.

X-linked immunodeficiencies

Recent advances in molecular genetics have allowed identification of at least seven genes involved in X-linked immunodeficiencies. This has resulted not only in improved diagnostic possibilities but also in a better understanding of the pathophysiology of these disorders. In some cases, mutations in the same gene have been shown to cause distinct clinical and immunologic phenotypes, demonstrating a strong genotype-phenotype correlation. Identification of the molecular basis of these diseases has permitted creation of disease-specific registries, with a better characterization of the clinical and immunologic features associated with the various forms of X-linked immunodeficiencies. Additionally, gene therapy has been attempted in X-linked severe combined immune deficiency (XSCID), with clear evidence of successful correction of the pathology, and the appearance of severe adverse effects.

Inherited disorders of NF-kappaB-mediated immunity in man

The transcription factors of the NF-kappaB family play an important role in immunity to infection in animal models. Three human primary immunodeficiencies associated with impaired NF-kappaB signaling were recently described. X-linked recessive anhidrotic ectodermal dysplasia with immunodeficiency (XL-EDA-ID) is caused by hypomorphic mutations in the gene encoding NEMO/IKKgamma, the regulatory subunit of the IkappaB-kinase (IKK) complex. Autosomal dominant EDA-ID (AD-EDA-ID) is caused by a hypermorphic mutation in the gene encoding the inhibitory protein IkappaBalpha. Autosomal recessive immunodeficiency without EDA is caused by mutations in the gene encoding IRAK-4, a kinase acting upstream from the IKK complex in the TIR signaling pathway. The description of the infectious phenotypes associated with these genetic defects has initiated the forward genetic dissection of NF-kappaB-mediated immunity in man.

The presentation and natural history of immunodeficiency caused by nuclear factor kappaB essential modulator mutation

BACKGROUND

An increasing number of rare genetic defects are associated with immunodeficiency and impaired ability to activate gene transcription through nuclear factor (NF) kappaB. Hypomorphic mutations in the NFkappaB essential modulator (NEMO) impair NFkappaB function and are linked to both immunodeficiency and ectodermal dysplasia (ED), as well as susceptibility to atypical mycobacterial infections.

OBJECTIVE

We sought to investigate the clinical and immunologic natural history of patients with NEMO mutation with immunodeficiency (NEMO-ID).

METHODS

Patients with severe bacterial infection and ED or unexplained mycobacterial sensitivity were evaluated for NEMO mutation. Laboratory investigations and clinical data were retrospectively and prospectively accumulated and reviewed.

RESULTS

We have given a diagnosis of NEMO-ID to 7 boys; 6 had ED, and 5 had gene mutations in the 10th exon of NEMO. Our resulting estimated incidence of NEMO-ID is 1:250,000 live male births. All patients had serious pyogenic bacterial illnesses early in life, and the median age of first infection was 8.1 months. Most boys had mycobacterial disease (median age, 84 months), and a minority had herpesviral infections. Initial immunologic assessments showed hypogammaglobulinemia (median IgG, 170 mg/dL) with variable IgM (median, 41 mg/dL) and IgA (median, 143 mg/dL) levels. Two patients had increased IgM levels, and 5 had increased IgA levels. All patients evaluated had normal lymphocyte subsets with impaired proliferative responses, specific antibody production, and natural killer cell function. Two patients died from complications of mycobacterial disease (ages 21 and 33 months).

CONCLUSION

NEMO-ID is a combined immunodeficiency with early susceptibility to pyogenic bacteria and later susceptibility to mycobacterial infection. Specific features of particular NEMO mutations in these patients provide insight into the role of this gene in immune function.

X-linked ectodermal dysplasia and immunodeficiency caused by reversion mosaicism of NEMO reveals a critical role for NEMO in human T-cell development and/or survival

X-linked ectodermal dysplasia and immunodeficiency (XL-EDA-ID) is an X-linked recessive disease caused by a mutation in the nuclear factor-kappaB (NF-kappaB) essential modulator (NEMO). Here we report an XL-EDA-ID patient with atypical features of very few naive-phenotype T cells and defective mitogen-induced proliferation of peripheral blood mononuclear cells (PBMCs). The patient's NEMO defect was diagnosed by flow cytometric analysis of intracellular NEMO staining. Specific cell lineages (monocytes and neutrophils) expressed reduced levels of NEMO, but 2 populations of T, B, and NK cells were detected with normal and reduced expression of NEMO. Genomic analysis revealed that duplication of a 4.4-kb sequence ranging from intron 3 to exon 6 caused the reduced expression of NEMO. Polymorphism analysis showed that the patient's B- and T-cell lines with reduced and normal expression of NEMO had the same X chromosome, indicating that the somatic mosaicism was not due to fetomaternal transfusion but was most likely due to postzygotic reversion. This XLEDA-ID case adds to our understanding of NEMO biology, indicating that NEMO is critical for T-cell development and/or survival in humans as well as in mice.

Osteopetrosis, lymphedema, anhidrotic ectodermal dysplasia, and immunodeficiency in a boy and incontinentia pigmenti in his mother

A child with X-linked osteopetrosis, lymphedema, anhidrotic ectodermal dysplasia, and immunodeficiency (OL-EDA-ID) was recently reported. We report the clinical features of a second boy with this novel syndrome and his mother, who presented with signs of incontinentia pigmenti (IP). The child had mild osteopetrosis without neurosensory complications, unilateral lymphedema of the left leg, and characteristic features of anhidrotic ectodermal dysplasia with sparse hair, facial dysmorphy, delayed eruption of teeth, and sweat gland abnormalities. He died at 18 months of severe immunodeficiency with multiple infections caused by Gram-negative (Salmonella enteritidis) and Gram-positive (Streptococcus pneumoniae) bacteria, nontuberculous mycobacteria (Mycobacterium kansasii), and fungi (Pneumocystis carinii). His 30-year-old mother's medical history, together with residual cutaneous lesions, was highly suggestive of IP without neurologic impairment. In this patient with OL-EDA-ID, we detected the same NF-kappaB essential modulator stop codon hypomorphic mutation identified in the previous patient. The occurrence of the same clinical features in 2 unrelated patients with the same genotype demonstrates that OL-EDA-ID is a genuine clinical syndrome. The clinical and biological descriptions of the proband and his mother further corroborate the relationship between IP and EDA. Both syndromes are allelic and are associated with mutations in NF-kappaB essential modulator, with a genotype-phenotype correlation in hemizygous males. In contrast, loss-of-function mutations and hypomorphic mutations may cause IP in females.

X-linked anhidrotic ectodermal dysplasia with immunodeficiency is caused by impaired NF-kappaB signaling

The molecular basis of X-linked recessive anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) has remained elusive. Here we report hypomorphic mutations in the gene IKBKG in 12 males with EDA-ID from 8 kindreds, and 2 patients with a related and hitherto unrecognized syndrome of EDA-ID with osteopetrosis and lymphoedema (OL-EDA-ID). Mutations in the coding region of IKBKG are associated with EDA-ID, and stop codon mutations, with OL-EDA-ID. IKBKG encodes NEMO, the regulatory subunit of the IKK (IkappaB kinase) complex, which is essential for NF-kappaB signaling. Germline loss-of-function mutations in IKBKG are lethal in male fetuses. We show that IKBKG mutations causing OL-EDA-ID and EDA-ID impair but do not abolish NF-kappaB signaling. We also show that the ectodysplasin receptor, DL, triggers NF-kappaB through the NEMO protein, indicating that EDA results from impaired NF-kappaB signaling. Finally, we show that abnormal immunity in OL-EDA-ID patients results from impaired cell responses to lipopolysaccharide, interleukin (IL)-1beta, IL-18, TNFalpha and CD154. We thus report for the first time that impaired but not abolished NF-kappaB signaling in humans results in two related syndromes that associate specific developmental and immunological defects.

A novel X-linked disorder of immune deficiency and hypohidrotic ectodermal dysplasia is allelic to incontinentia pigmenti and due to mutations in IKK-gamma (NEMO)

Hypohidrotic ectodermal dysplasia (HED), a congenital disorder of teeth, hair, and eccrine sweat glands, is usually inherited as an X-linked recessive trait, although rarer autosomal dominant and recessive forms exist. We have studied males from four families with HED and immunodeficiency (HED-ID), in which the disorder segregates as an X-linked recessive trait. Affected males manifest dysgammaglobulinemia and, despite therapy, have significant morbidity and mortality from recurrent infections. Recently, mutations in IKK-gamma (NEMO) have been shown to cause familial incontinentia pigmenti (IP). Unlike HED-ID, IP affects females and, with few exceptions, causes male prenatal lethality. IKK-gamma is required for the activation of the transcription factor known as "nuclear factor kappa B" and plays an important role in T and B cell function. We hypothesize that "milder" mutations at this locus may cause HED-ID. In all four families, sequence analysis reveals exon 10 mutations affecting the carboxy-terminal end of the IKK-gamma protein, a domain believed to connect the IKK signalsome complex to upstream activators. The findings define a new X-linked recessive immunodeficiency syndrome, distinct from other types of HED and immunodeficiency syndromes. The data provide further evidence that the development of ectodermal appendages is mediated through a tumor necrosis factor/tumor necrosis factor receptor-like signaling pathway, with the IKK signalsome complex playing a significant role.