The observational CERTITUDE study follows liver transplant patients who completed the SIMCER trial. SIMCER randomized patients at month 1 after transplant to everolimus (EVR) with stepwise tacrolimus ...(TAC) withdrawal or to standard TAC, both with basiliximab induction and mycophenolic acid ± steroids. After completing SIMCER at 6 months after transplant, 65 EVR‐treated patients and 78 TAC‐treated patients entered CERTITUDE. At month 24 after transplant, 34/65 (52.3%) EVR‐treated patients remained calcineurin inhibitor (CNI) free. Mean estimated glomerular filtration rate (eGFR) was significantly higher with EVR versus TAC during months 3‐12. At month 24, eGFR values were 83.6 versus 75.3 mL/minute/1.73 m2, respectively (P = 0.90) and adjusted mean change in eGFR from randomization was −8.0 versus −13.5 mL/minute/1.73 m2 (P = 0.15). At month 24, 45.9%, 31.1%, and 23.0% of EVR‐treated patients had chronic kidney disease stages 1, 2, and 3, respectively, versus 25.7%, 45.7%, and 28.6% of TAC‐treated patients (P = 0.05). Treated biopsy‐proven acute rejection affected 4 EVR‐treated patients and 2 TAC patients during months 6‐24. Adverse events led to study discontinuation in 15.4% and 7.7% of EVR‐treated and TAC‐treated patients, respectively. Grade 3 or 4 hematological events were rare in both groups. A CNI‐free EVR‐based maintenance regimen appears feasible in approximately half of liver transplant patients. It preserves renal function effectively with good efficacy without compromising safety or hematological tolerance.
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.
Epstein-Barr virus (EBV) infection can engender severe B cell lymphoproliferative diseases
. The primary infection is often asymptomatic or causes infectious mononucleosis (IM), a self-limiting ...lymphoproliferative disorder
. Selective vulnerability to EBV has been reported in association with inherited mutations impairing T cell immunity to EBV
. Here we report biallelic loss-of-function variants in IL27RA that underlie an acute and severe primary EBV infection with a nevertheless favourable outcome requiring a minimal treatment. One mutant allele (rs201107107) was enriched in the Finnish population (minor allele frequency = 0.0068) and carried a high risk of severe infectious mononucleosis when homozygous. IL27RA encodes the IL-27 receptor alpha subunit
. In the absence of IL-27RA, phosphorylation of STAT1 and STAT3 by IL-27 is abolished in T cells. In in vitro studies, IL-27 exerts a synergistic effect on T-cell-receptor-dependent T cell proliferation
that is deficient in cells from the patients, leading to impaired expansion of potent anti-EBV effector cytotoxic CD8
T cells. IL-27 is produced by EBV-infected B lymphocytes and an IL-27RA-IL-27 autocrine loop is required for the maintenance of EBV-transformed B cells. This potentially explains the eventual favourable outcome of the EBV-induced viral disease in patients with IL-27RA deficiency. Furthermore, we identified neutralizing anti-IL-27 autoantibodies in most individuals who developed sporadic infectious mononucleosis and chronic EBV infection. These results demonstrate the critical role of IL-27RA-IL-27 in immunity to EBV, but also the hijacking of this defence by EBV to promote the expansion of infected transformed B cells.
Hearing loss and visual impairment in childhood have mostly genetic origins, some of them being related to sensorial neuronal defects. Here, we report on eight subjects from four independent families ...affected by auditory neuropathy and optic atrophy. Whole-exome sequencing revealed biallelic mutations in FDXR in affected subjects of each family. FDXR encodes the mitochondrial ferredoxin reductase, the sole human ferredoxin reductase implicated in the biosynthesis of iron-sulfur clusters (ISCs) and in heme formation. ISC proteins are involved in enzymatic catalysis, gene expression, and DNA replication and repair. We observed deregulated iron homeostasis in FDXR mutant fibroblasts and indirect evidence of mitochondrial iron overload. Functional complementation in a yeast strain in which ARH1, the human FDXR ortholog, was deleted established the pathogenicity of these mutations. These data highlight the wide clinical heterogeneity of mitochondrial disorders related to ISC synthesis.
Gillespie syndrome (GS) is a rare variant form of aniridia characterized by non-progressive cerebellar ataxia, intellectual disability, and iris hypoplasia. Unlike the more common dominant and ...sporadic forms of aniridia, there has been no significant association with PAX6 mutations in individuals with GS and the mode of inheritance of the disease had long been regarded as uncertain. Using a combination of trio-based whole-exome sequencing and Sanger sequencing in five simplex GS-affected families, we found homozygous or compound heterozygous truncating mutations (c.4672C>T p.Gln1558∗, c.2182C>T p.Arg728∗, c.6366+3A>T p.Gly2102Valfs5∗, and c.6664+5G>T p.Ala2221Valfs23∗) and de novo heterozygous mutations (c.7687_7689del p.Lys2563del and c.7659T>G p.Phe2553Leu) in the inositol 1,4,5-trisphosphate receptor type 1 gene (ITPR1). ITPR1 encodes one of the three members of the IP3-receptors family that form Ca2+ release channels localized predominantly in membranes of endoplasmic reticulum Ca2+ stores. The truncation mutants, which encompass the IP3-binding domain and varying lengths of the modulatory domain, did not form functional channels when produced in a heterologous cell system. Furthermore, ITPR1 p.Lys2563del mutant did not form IP3-induced Ca2+ channels but exerted a negative effect when co-produced with wild-type ITPR1 channel activity. In total, these results demonstrate biallelic and monoallelic ITPR1 mutations as the underlying genetic defects for Gillespie syndrome, further extending the spectrum of ITPR1-related diseases.
Auriculocondylar syndrome (ACS) is a rare craniofacial disorder with mandibular hypoplasia and question-mark ears (QMEs) as major features. QMEs, consisting of a specific defect at the lobe-helix ...junction, can also occur as an isolated anomaly. Studies in animal models have indicated the essential role of endothelin 1 (EDN1) signaling through the endothelin receptor type A (EDNRA) in patterning the mandibular portion of the first pharyngeal arch. Mutations in the genes coding for phospholipase C, beta 4 (PLCB4) and guanine nucleotide binding protein (G protein), alpha inhibiting activity polypeptide 3 (GNAI3), predicted to function as signal transducers downstream of EDNRA, have recently been reported in ACS. By whole-exome sequencing (WES), we identified a homozygous substitution in a furin cleavage site of the EDN1 proprotein in ACS-affected siblings born to consanguineous parents. WES of two cases with vertical transmission of isolated QMEs revealed a stop mutation in EDN1 in one family and a missense substitution of a highly conserved residue in the mature EDN1 peptide in the other. Targeted sequencing of EDN1 in an ACS individual with related parents identified a fourth, homozygous mutation falling close to the site of cleavage by endothelin-converting enzyme. The different modes of inheritance suggest that the degree of residual EDN1 activity differs depending on the mutation. These findings provide further support for the hypothesis that ACS and QMEs are uniquely caused by disruption of the EDN1-EDNRA signaling pathway.
BENTA disease is genetically linked to germline-encoded, gain-of-function mutations in caspase recruitment domain 11 (CARD11), a scaffolding protein largely expressed in lymphocytes and required for ...antigen receptor (AgR)-induced NF-κB activation.3,4 Like somatic mutations found in approximately 10% of diffuse large B-cell lymphomas, CARD11 mutations in patients with BENTA fall within or immediately adjacent to the coiled-coil (CC) domain.5 CC mutations likely abrogate the requirement for AgR-triggered phosphorylation of the inhibitory linker domain, which supports the "open" conformational change necessary for BCL10-MALT1 recruitment and downstream signal transduction via the IκB kinase complex.6 We recently encountered 3 new patients with disease symptoms suggesting BENTA, including moderate, polyclonal B-cell lymphocytosis with a markedly diminished memory B-cell compartment (Table I). The CARD domain is critical for BCL10 interaction and downstream TCR signaling, as well as regulatory T-cell development.7 This mutation was previously reported in 1 case of diffuse large B-cell lymphoma,8 and identified in an unbiased screen for gain-of-function CARD11 mutants capable of activating NF-κB and promoting human diffuse large B-cell lymphoma tumor growth in vitro.6 Indeed, we confirmed that transfection of the C49Y CARD11 mutant into the CARD11-deficient Jurkat T-cell line JPM50.6 resulted in spontaneous protein aggregation, colocalization with MALT1 and active IκB kinase,9 and constitutive NF-κB activation in the absence of AgR stimulation, comparable to other BENTA mutants described (Fig 1, C and D).
Renal hypodysplasia (RHD) is a heterogeneous condition encompassing a spectrum of kidney development defects including renal agenesis, hypoplasia, and (cystic) dysplasia. Heterozygous mutations of ...several genes have been identified as genetic causes of RHD with various severity. However, these genes and mutations are not associated with bilateral renal agenesis, except for RET mutations, which could be involved in a few cases. The pathophysiological mechanisms leading to total absence of kidney development thus remain largely elusive. By using a whole-exome sequencing approach in families with several fetuses with bilateral renal agenesis, we identified recessive mutations in the integrin α8-encoding gene ITGA8 in two families. Itga8 homozygous knockout in mice is known to result in absence of kidney development. We provide evidence of a damaging effect of the human ITGA8 mutations. These results demonstrate that mutations of ITGA8 are a genetic cause of bilateral renal agenesis and that, at least in some cases, bilateral renal agenesis is an autosomal-recessive disease.
Ciliopathies are a group of hereditary disorders associated with defects in cilia structure and function. The distal appendages (DAPs) of centrioles are involved in the docking and anchoring of the ...mother centriole to the cellular membrane during ciliogenesis. The molecular composition of DAPs was recently elucidated and mutations in two genes encoding DAPs components (CEP164/NPHP15, SCLT1) have been associated with human ciliopathies, namely nephronophthisis and orofaciodigital syndrome. To identify additional DAP components defective in ciliopathies, we independently performed targeted exon sequencing of 1,221 genes associated with cilia and 5 known DAP protein-encoding genes in 1,255 individuals with a nephronophthisis-related ciliopathy. We thereby detected biallelic mutations in a key component of DAP-encoding gene, CEP83, in seven families. All affected individuals had early-onset nephronophthisis and four out of eight displayed learning disability and/or hydrocephalus. Fibroblasts and tubular renal cells from affected individuals showed an altered DAP composition and ciliary defects. In summary, we have identified mutations in CEP83, another DAP-component-encoding gene, as a cause of infantile nephronophthisis associated with central nervous system abnormalities in half of the individuals.
TLR7 recognizes pathogen-derived single-stranded RNA (ssRNA), a function integral to the innate immune response to viral infection. Notably, TLR7 can also recognize self-derived ssRNA, with ...gain-of-function mutations in human TLR7 recently identified to cause both early-onset systemic lupus erythematosus (SLE) and neuromyelitis optica. Here, we describe two novel mutations in TLR7, F507S and L528I. While the L528I substitution arose de novo, the F507S mutation was present in three individuals from the same family, including a severely affected male, notably given that the TLR7 gene is situated on the X chromosome and that all other cases so far described have been female. The observation of mutations at residues 507 and 528 of TLR7 indicates the importance of the TLR7 dimerization interface in maintaining immune homeostasis, where we predict that altered homo-dimerization enhances TLR7 signaling. Finally, while mutations in TLR7 can result in SLE-like disease, our data suggest a broader phenotypic spectrum associated with TLR7 gain-of-function, including significant neurological involvement.
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