Study of the potential role of CASPASE-10 mutations in the development of autoimmune lymphoproliferative syndrome.

Autoimmune lymphoproliferative syndrome (ALPS) is a primary disorder of lymphocyte homeostasis, leading to chronic lymphoproliferation, autoimmune cytopenia, and increased risk of lymphoma. The genetic landscape of ALPS includes mutations in FAS, FASLG, and FADD, all associated with apoptosis deficiency, while the role of CASP10 defect in the disease remains debated. In this study, we aimed to assess the impact of CASP10 variants on ALPS pathogenesis. We benefit from thousands of genetic analysis datasets performed in our Institute's genetic platform to identify individuals carrying CASP10 variants previously suspected to be involved in ALPS outcome: p.C401LfsX15, p.V410I and p.Y446C, both at heterozygous and homozygous state. Clinical and laboratory features of the six included subjects were variable but not consistent with ALPS. Two individuals were healthy. Comprehensive analyses of CASP10 protein expression and FAS-mediated apoptosis were conducted and compared to healthy controls and ALPS patients with FAS mutations. Missense CASP10 variants (p.V410I and p.Y446C), which are common in the general population, did not disrupt CASP10 expression, nor FAS-mediated apoptosis. In contrast, homozygous p.C401LfsX15 CASP10 variant lead to a complete abolished CASP10 expression but had no impact on FAS-mediated apoptosis function. At heterozygous state, this p.C401LfsX15 variant lead to a reduced CASP10 protein levels but remained associated with a normal FAS-mediated apoptosis function. These findings demonstrate that CASPASE 10 is dispensable for FAS-mediated apoptosis. In consequences, CASP10 defect unlikely contribute to ALPS pathogenesis, since they did not result in an impairment of FAS-mediated apoptosis nor in clinical features of ALPS in human. Moreover, the absence of FAS expression up-regulation in subjects with CASP10 variants rule out any compensatory mechanisms possibly involved in the normal apoptosis function observed. In conclusion, this study challenges the notion that CASP10 variants contribute to the development of ALPS.

Recurrent bacterial infections, but not fungal infections, characterise patients with ELANE-related neutropenia: a French Severe Chronic Neutropenia Registry study.

Among 143 patients with elastase, neutrophil-expressed (ELANE)-related neutropenia enrolled in the French Severe Chronic Neutropenia Registry, 94 were classified as having severe chronic neutropenia (SCN) and 49 with cyclic neutropenia (CyN). Their infectious episodes were classified as severe, mild or oral, and analysed according to their natural occurrence without granulocyte-colony stimulating factor (G-CSF), on G-CSF, after myelodysplasia/acute leukaemia or after haematopoietic stem-cell transplantation. During the disease's natural history period (without G-CSF; 1913 person-years), 302, 957 and 754 severe, mild and oral infectious events, respectively, occurred. Among severe infections, cellulitis (48%) and pneumonia (38%) were the most common. Only 38% of episodes were microbiologically documented. The most frequent pathogens were Staphylococcus aureus (37·4%), Escherichia coli (20%) and Pseudomonas aeruginosa (16%), while fungal infections accounted for 1%. Profound neutropenia (<200/mm3 ), high lymphocyte count (>3000/mm3 ) and neutropenia subtype were associated with high risk of infection. Only the p.Gly214Arg variant (5% of the patients) was associated with infections but not the overall genotype. The first year of life was associated with the highest infection risk throughout life. G-CSF therapy achieved lower ratios of serious or oral infectious event numbers per period but was less protective for patients requiring >10 µg/kg/day. Infections had permanent consequences in 33% of patients, most frequently edentulism.

Inherited GATA2 Deficiency Is Dominant by Haploinsufficiency and Displays Incomplete Clinical Penetrance.

PURPOSE: Germline heterozygous mutations of GATA2 underlie a variety of hematological and clinical phenotypes. The genetic, immunological, and clinical features of GATA2-deficient patients with mycobacterial diseases in the familial context remain largely unknown. METHODS: We enrolled 15 GATA2 index cases referred for mycobacterial disease. We describe their genetic and clinical features including their relatives. RESULTS: We identified 12 heterozygous GATA2 mutations, two of which had not been reported. Eight of these mutations were loss-of-function, and four were hypomorphic. None was dominant-negative in vitro, and the GATA2 locus was found to be subject to purifying selection, strongly suggesting a mechanism of haploinsufficiency. Three relatives of index cases had mycobacterial disease and were also heterozygous, resulting in 18 patients in total. Mycobacterial infection was the first clinical manifestation in 11 patients, at a mean age of 22.5 years (range: 12 to 42 years). Most patients also suffered from other infections, monocytopenia, or myelodysplasia. Strikingly, the clinical penetrance was incomplete (32.9% by age 40 years), as 16 heterozygous relatives aged between 6 and 78 years, including 4 older than 60 years, were completely asymptomatic. CONCLUSION: Clinical penetrance for mycobacterial disease was found to be similar to other GATA2 deficiency-related manifestations. These observations suggest that other mechanisms contribute to the phenotypic expression of GATA2 deficiency. A diagnosis of autosomal dominant GATA2 deficiency should be considered in patients with mycobacterial infections and/or other GATA2 deficiency-related phenotypes at any age in life. Moreover, all direct relatives should be genotyped at the GATA2 locus.

Chronic Lung Suppurative Disease in a Child Related to a STAT1 Heterozygous Gain-of-Function Mutation / Enfermedad pulmonar supurativa crónica en un niño relacionada con una mutación en heterocigosis de ganancia de función del STAT1

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Lymphoma-Like Syndrome: 4 Case Reports About Atypical Presentation of Primary Cytomegalovirus Infection in Immunocompetent Children.

In immunocompetent persons, primary cytomegalovirus (CMV) infection is self-limited infection. Lymphoma-like syndromes have been sometimes described in adults but have not been described for children.Lymphoma-like syndromes (protracted fever, alteration of the general status, and clinical lymphoproliferative syndrome) were retrospectively recorded in children attending our hospital from 1999 to 2008 for primary CMV infection. Patients with immunodeficiency, coinfection (Epstein-Barr virus, toxoplasmosis, or mycobacterial), or biological criteria of mononucleosis-like syndrome were excluded.We report 4 cases of lymphoma-like syndrome. The median duration of fever was 21.5 days (range 15-27). Tonsillitis and hepatitis are most of the time missing. A probable malignant diagnosis was raised in 3 cases. Clinical outcome was protracted (15-35 days) but favorable.To our knowledge, our study is the first pediatric case series of lymphoma-like syndrome. This clinical presentation is a source of delayed diagnosis due to diagnosis pitfall.

Favorable outcome in a case of Mycoplasma pneumoniae-associated crescentic glomerulonephritis.

Mycoplasma pneumoniae-associated nephritis has been reported in children with various pathological findings. It nevertheless remains an uncommon disease and, within this clinical context, endo-and extracapillary glomerulonephritis in a child has never been described. We report here a case of a 3-year-old girl diagnosed with severe crescentic glomerulonephritis associated with M. pneumoniae infection who presented with nephrotic syndrome and impaired renal function. The serum C3 complement level was initially low but returned to normal after 1 month. Two courses of three methylprednisolone pulses were administered in association with plasmapheresis and, secondarily, mycophenolate mophetil. This treatment regimen led to disease remission and a favorable renal outcome at the 6-month follow-up. However, the treatment guidelines in this situation remain debatable.