Expanding spectrum, intrafamilial diversity, and therapeutic challenges from 15 patients with heterozygous CARD11-associated diseases: A single center experience.

CARD11-associated diseases are monogenic inborn errors of immunity involving immunodeficiency, predisposition to malignancy and immune dysregulation such as lymphoproliferation, inflammation, atopic and autoimmune manifestations. Defects in CARD11 can present as mutations that confer a complete or a partial loss of function (LOF) or contrarily, a gain of function (GOF) of the affected gene product. We report clinical characteristics, immunophenotypes and genotypes of 15 patients from our center presenting with CARD11-associated diseases. Index cases are pediatric patients followed in our immunology division who had access to next generation sequencing studies. Variant significance was defined by functional analysis in cultured cells transfected with a wild type and/or with mutated hCARD11 constructs. Cytoplasmic aggregation of CARD11 products was evaluated by immunofluorescence. Nine index patients with 9 unique heterozygous CARD11 variants were identified. At the time of the identification, 7 variants previously unreported required functional validation. Altogether, four variants showed a GOF effect as well a spontaneous aggregation in the cytoplasm, leading to B cell expansion with NF-κB and T cell anergy (BENTA) diagnosis. Additional four variants showing a LOF activity were considered as causative of CARD11-associated atopy with dominant interference of NF-kB signaling (CADINS). The remaining variant exhibited a neutral functional assay excluding its carrier from further analysis. Family segregation studies expanded to 15 individuals the number of patients presenting CARD11-associated disease. A thorough clinical, immunophenotypical, and therapeutic management evaluation was performed on these patients (5 BENTA and 10 CADINS). A remarkable variability of disease expression was clearly noted among BENTA as well as in CADINS patients, even within multiplex families. Identification of novel CARD11 variants required functional studies to validate their pathogenic activity. In our cohort BENTA phenotype exhibited a more severe and expanded clinical spectrum than previously reported, e.g., severe hematological and extra hematological autoimmunity and 3 fatal outcomes. The growing number of patients with dysmorphic facial features strengthen the inclusion of extra-immune characteristics as part of the CADINS spectrum. CARD11-associated diseases represent a challenging group of disorders from the diagnostic and therapeutic standpoint, especially BENTA cases that can undergo a more severe progression than previously described.

Pulmonary Alveolar Proteinosis and Multiple Infectious Diseases in a Child with Autosomal Recessive Complete IRF8 Deficiency.

BACKGROUND: Autosomal recessive (AR) complete IRF8 deficiency is a rare severe inborn error of immunity underlying an absence of blood myeloid mononuclear cells, intracerebral calcifications, and multiple infections. Only three unrelated patients have been reported. MATERIALS AND METHODS: We studied an Argentinian child with multiple infectious diseases and severe pulmonary alveolar proteinosis (PAP). We performed whole-exome sequencing (WES) and characterized his condition by genetic, immunological, and clinical means. RESULTS: The patient was born and lived in Argentina. He had a history of viral pulmonary diseases, disseminated disease due to bacillus Calmette-Guérin (BCG), PAP, and cerebral calcifications. He died at the age of 10 months from refractory PAP. WES identified two compound heterozygous variants in IRF8: c.55del and p.R111*. In an overexpression system, the p.R111* cDNA was loss-of-expression, whereas the c.55del cDNA yielded a protein with a slightly lower molecular weight than the wild-type protein. The mutagenesis of methionine residues downstream from c.55del revealed a re-initiation of translation. However, both variants were loss-of-function in a luciferase assay, suggesting that the patient had AR complete IRF8 deficiency. The patient had no blood monocytes or dendritic cells, associated with neutrophilia, and normal counts of NK and other lymphoid cell subsets. CONCLUSION: We describe the fourth patient with AR complete IRF8 deficiency. This diagnosis should be considered in children with PAP, which is probably due to the defective development or function of alveolar macrophages.

Identification of Germline Non-coding Deletions in XIAP Gene Causing XIAP Deficiency Reveals a Key Promoter Sequence.

PURPOSE: X-linked inhibitor of apoptosis protein (XIAP) deficiency, also known as the X-linked lymphoproliferative syndrome of type 2 (XLP-2), is a rare immunodeficiency characterized by recurrent hemophagocytic lymphohistiocytosis, splenomegaly, and inflammatory bowel disease. Variants in XIAP including missense, non-sense, frameshift, and deletions of coding exons have been reported to cause XIAP deficiency. We studied three young boys with immunodeficiency displaying XLP-2-like clinical features. No genetic variation in the coding exons of XIAP was identified by whole-exome sequencing (WES), although the patients exhibited a complete loss of XIAP expression. METHODS: Targeted next-generation sequencing (NGS) of the entire locus of XIAP was performed on DNA samples from the three patients. Molecular investigations were assessed by gene reporter expression assays in HEK cells and CRISPR-Cas9 genome editing in primary T cells. RESULTS: NGS of XIAP identified three distinct non-coding deletions in the patients that were predicted to be driven by repetitive DNA sequences. These deletions share a common region of 839 bp that encompassed the first non-coding exon of XIAP and contained regulatory elements and marks specific of an active promoter. Moreover, we showed that among the 839 bp, the exon was transcriptionally active. Finally, deletion of the exon by CRISPR-Cas9 in primary cells reduced XIAP protein expression. CONCLUSIONS: These results identify a key promoter sequence contained in the first non-coding exon of XIAP. Importantly, this study highlights that sequencing of the non-coding exons that are not currently captured by WES should be considered in the genetic diagnosis when no variation is found in coding exons.

[Late diagnosis of WHIM sydrome]. / Diagnóstico tardío de síndrome WHIM.

WHIM syndrome is a primary autosomal dominant immuno deficiency due to CXCR4 mutations characterized by mucocutaneous warts, hypogammaglobulinemia, recurrent bacterial infections and myelokathesis. Treatment consists in prophylactic antibiotics, immunoglobulin replacement and granulocyte or granulocyte/monocyte colony stimulating factors. We present the case of a 21 year old woman who showed leukopenia at 10 months of age and one year later multiple infections with hypogammaglobulinemia requiring intravenous immunoglobulin. During follow up she developed chronic neutropenia. A bone marrow aspiration showed increased myeloid series with predominance of immature elements. On the basis of infections, low levels of IgG, IgA, IgM and lymphopenia with absent memory B cells, a diagnosis of common variable immunodeficiency was made. She started intravenous immunoglobulin replacement and prophylactic antibiotics. At age 20, small warts in hands that progressed to forearms, knees, abdomen and face were recorded. CXCR4 gene sequencing was done detecting a heterozygous p.Arg334STOP mutation, confirming WHIM syndrome. This disease is infrequent and difficult to diagnose.

Diagnóstico tardío de síndrome WHIM / Late diagnosis of WHIM sydrome

El síndrome WHIM es una inmunodeficiencia primaria de herencia autosómica dominante, debida a mutaciones en el gen CXCR4, que se caracteriza por verrugas cutáneo-mucosas, hipogammaglobulinemia, infecciones bacterianas recurrentes y mielocatesis. El tratamiento se basa en el uso de antibióticos profilácticos, gammaglobulina en dosis sustitutiva y factores estimulantes de colonias de granulocitos o de granulocitos y macrófagos, en forma crónica. Presentamos el caso de una mujer de 21 años que comenzó a los 10 meses de edad con leucopenia y al siguiente año múltiples infecciones con hipogammaglobulinemia requiriendo gammaglobulina endovenosa durante los episodios. Evolucionó con neutropenia crónica. Una punción aspiración de médula ósea mostró la serie mieloide aumentada con ligero predominio de elementos inmaduros. El cuadro fue interpretado como inmunodeficiencia común variable debido a la asociación de múltiples cuadros infecciosos, niveles disminuidos de IgG, IgM e IgA y linfopenia con disminución de linfocitos B de memoria, por lo que comenzó tratamiento sustitutivo con gammaglobulina endovenosa más antibióticos profilácticos. A los 20 años se registraron pequeñas verrugas en manos que progresaron hacia antebrazos, abdomen, cara y rodillas. Se realizaron estudios moleculares para la búsqueda de mutaciones en el gen CXCR4 donde se detectó la mutación p.Arg334STOP en estado heterocigota confirmando el diagnóstico de síndrome WHIM, que es una inmunodeficiencia infrecuente y de difícil diagnóstico.

WHIM syndrome is a primary autosomal dominant immuno deficiency due to CXCR4 mutations characterized by mucocutaneous warts, hypogammaglobulinemia, recurrent bacterial infections and myelokathesis. Treatment consists in prophylactic antibiotics, immunoglobulin replacement and granulocyte or granulocyte/monocyte colony stimulating factors. We present the case of a 21 year old woman who showed leukopenia at 10 months of age and one year later multiple infections with hypogammaglobulinemia requiring intravenous immunoglobulin. During follow up she developed chronic neutropenia. A bone marrow aspiration showed increased myeloid series with predominance of immature elements. On the basis of infections, low levels of IgG, IgA, IgM and lymphopenia with absent memory B cells, a diagnosis of common variable immunodeficiency was made. She started intravenous immunoglobulin replacement and prophylactic antibiotics. At age 20, small warts in hands that progressed to forearms, knees, abdomen and face were recorded. CXCR4 gene sequencing was done detecting a heterozygous p.Arg334STOP mutation, confirming WHIM syndrome. This disease is infrequent and difficult to diagnose.

Corrigendum: Germline hypomorphic CARD11 mutations in severe atopic disease.

This corrects the article DOI: 10.1038/ng.3898.

Germline hypomorphic CARD11 mutations in severe atopic disease.

Few monogenic causes for severe manifestations of common allergic diseases have been identified. Through next-generation sequencing on a cohort of patients with severe atopic dermatitis with and without comorbid infections, we found eight individuals, from four families, with novel heterozygous mutations in CARD11, which encodes a scaffolding protein involved in lymphocyte receptor signaling. Disease improved over time in most patients. Transfection of mutant CARD11 expression constructs into T cell lines demonstrated both loss-of-function and dominant-interfering activity upon antigen receptor-induced activation of nuclear factor-κB and mammalian target of rapamycin complex 1 (mTORC1). Patient T cells had similar defects, as well as low production of the cytokine interferon-γ (IFN-γ). The mTORC1 and IFN-γ production defects were partially rescued by supplementation with glutamine, which requires CARD11 for import into T cells. Our findings indicate that a single hypomorphic mutation in CARD11 can cause potentially correctable cellular defects that lead to atopic dermatitis.

Novel syntaxin 11 gene (STX11) mutation in three Argentinean patients with hemophagocytic lymphohistiocytosis.

INTRODUCTION: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease with major diagnostic and therapeutic difficulties, basically comprising two different conditions: primary and secondary forms. Recent advances regarding molecular diagnosis may be useful to distinguish from one another, especially in sporadic cases starting in early infancy. MATERIALS AND METHODS: In this report, we evaluated three Argentinean patients with clinical suspicion of HLH, but without family history. We excluded mutations in the perforin gene but identified in the three patients a novel homozygous deletion (c. 581_584delTGCC; p.Leu194ProfsX2) in the gene-encoding syntaxin 11 (STX11), causing a premature termination codon. RESULTS AND CONCLUSION: Each parent from the three unrelated families resulted heterozygous for this deletion confirming the diagnosis of familial hemophagocytic lymphohistiocytosis type 4. Patients shared the same single-nucleotide polymorphism profile in STX11 gene, and genotyping at ten microsatellites surrounding this gene support the presence of a single-haplotype block carrying the novel mutation.

Clinical and molecular analysis of 49 patients with X-linked agammaglobulinemia from a single center in Argentina.

INTRODUCTION: Argentina has a large number of patients with definite diagnosis of X-linked agammaglobulinemia reported in the Latin-American registry. Forty-nine of them were seen in our referral pediatric hospital, between 1987 and 2005. RESULTS AND DISCUSSION: A retrospective study of clinical, laboratory, and molecular data showed that respiratory tract infections were the most frequent initial clinical presentation and the most common among all manifestations prior to diagnosis (69%). Up to diagnosis, we found a high frequency of severe infections (sepsis, 14% and meningitis, 16%) and a high proportion of patients with chronic lung disease. During follow-up, the development of chronic lung disease was significantly related with age at diagnosis and inappropriate treatment. CONCLUSION: Although molecular diagnosis has been available in our center for the past 10 years, there is no doubt that awareness for early recognition of immunodeficiency should be improved through broader and more comprehensive education programs emphasizing characteristics of patients with immunodeficiencies.