Association Between Plasma Rituximab Concentration and the Risk of Major Relapse in Antineutrophil Cytoplasmic Antibody-Associated Vasculitides During Rituximab Maintenance Therapy.

OBJECTIVE: Interindividual variability in response to rituximab remains unexplored in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides. Rituximab pharmacokinetics (PK) and pharmacodynamics (PD) as well as genetic polymorphisms could contribute to variability. This ancillary study of the MAINRITSAN 2 trial aimed to explore the relationship between rituximab plasma concentration, genetic polymorphisms in PK/PD candidate genes, and clinical outcomes. METHODS: Patients included in the MAINRITSAN2 trial (ClinicalTrials.gov identifier: NCT01731561) were randomized to receive a 500-mg fixed-schedule rituximab infusion or an individually tailored regimen. Rituximab plasma concentrations at month 3 (CM3) were assessed. DNA samples (n = 53) were genotyped for single-nucleotide polymorphisms within 88 putative PK/PD candidate genes. The relationship between PK/PD outcomes and genetic variants was investigated using logistic linear regression in additive and recessive genetic models. RESULTS: One hundred and thirty-five patients were included. The frequency of underexposed patients (<4 µg/ml) in the fixed-schedule group was statistically lower compared to that in the tailored-infusion group (2.0% versus 18.0%; P = 0.02, respectively). Low rituximab plasma concentration at 3 months (CM3 <4 µg/ml) was an independent risk factor for major relapse (odds ratio 6.56 [95% confidence interval (95% CI) 1.26-34.09]; P = 0.025) at month 28 (M28). A sensitivity survival analysis also identified CM3 <4 µg/ml as an independent risk factor for major relapse (hazard ratio [HR] 4.81 [95% CI 1.56-14.82]; P = 0.006) and relapse (HR 2.70 [95% CI 1.02-7.15]; P = 0.046). STAT4 rs2278940 and PRKCA rs8076312 were significantly associated with CM3 but not with major relapse onset at M28. CONCLUSION: These results suggest that drug monitoring could be useful to individualize the schedule of rituximab administration within the maintenance phase.

A shared pattern of altered gene expression in human embryos affected by mitochondrial diseases.

STUDY QUESTION: Does mitochondrial deficiency affect human embryonic preimplantation development? SUMMARY ANSWER: The presence of a pathogenic mitochondrial variant triggers changes in the gene expression of preimplantation human embryos, compromising their development, cell differentiation, and survival. WHAT IS KNOWN ALREADY: Quantitative and qualitative anomalies of mitochondrial DNA (mtDNA) are reportedly associated with impaired human embryonic development, but the underlying mechanisms remain unexplained. STUDY DESIGN, SIZE, DURATION: Taking advantage of the preimplantation genetic testing for mitochondrial disorders in at-risk couples, we have compared gene expression of 9 human embryos carrying pathogenic variants in either mtDNA genes or nuclear genes encoding mitochondrial protein to 33 age-matched control embryos. PARTICIPANTS/MATERIALS, SETTING, METHODS: Single-embryo transcriptomic analysis was performed on whole human blastocyst embryos donated to research. MAIN RESULTS AND THE ROLE OF CHANCE: Specific pathogenic mitochondrial variants downregulate gene expression in preimplantation human embryos [566 genes in oxidative phosphorylation (OXPHOS)-deficient embryos], impacting transcriptional regulators, differentiation factors, and nuclear genes encoding mitochondrial proteins. These changes in gene expression primarily alter OXPHOS and cell survival pathways. LIMITATIONS, REASONS FOR CAUTION: The number of OXPHOS-deficient embryos available for the study was limited owing to the rarity of this material. However, the molecular signature shared by all these embryos supports the relevance of the findings. WIDER IMPLICATIONS OF THE FINDINGS: While identification of reliable markers of normal embryonic development is urgently needed in ART, our study prompts us to consider under-expression of the targeted genes reported here, as predictive biomarkers of mitochondrial dysfunction during preimplantation development. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the 'Association Française contre les Myopathies (AFM-Téléthon)' and the 'La Fondation Maladies Rares'. No competing interests to declare. TRIAL REGISTRATION NUMBER: N/A.

Agonists of prostaglandin E2 receptors as potential first in class treatment for nephronophthisis and related ciliopathies.

Nephronophthisis (NPH) is an autosomal recessive tubulointerstitial nephropathy belonging to the ciliopathy disorders and known as the most common cause of hereditary end-stage renal disease in children. Yet, no curative treatment is available. The major gene, NPHP1, encodes a protein playing key functions at the primary cilium and cellular junctions. Using a medium-throughput drug-screen in NPHP1 knockdown cells, we identified 51 Food and Drug Administration-approved compounds by their ability to alleviate the cellular phenotypes associated with the loss of NPHP1; 11 compounds were further selected for their physicochemical properties. Among those compounds, prostaglandin E1 (PGE1) rescued ciliogenesis defects in immortalized patient NPHP1 urine-derived renal tubular cells, and improved ciliary and kidney phenotypes in our NPH zebrafish and Nphp1 knockout mouse models. Furthermore, Taprenepag, a nonprostanoid prostaglandin E2 receptor agonist, alleviated the severe retinopathy observed in Nphp1−/− mice. Finally, comparative transcriptomics allowed identification of key signaling pathways downstream PGE1, including cell cycle progression, extracellular matrix, adhesion, or actin cytoskeleton organization. In conclusion, using in vitro and in vivo models, we showed that prostaglandin E2 receptor agonists can ameliorate several of the pleotropic phenotypes caused by the absence of NPHP1; this opens their potential as a first therapeutic option for juvenile NPH-associated ciliopathies.

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.

OTC deficiency in females: Phenotype-genotype correlation based on a 130-family cohort.

OTC deficiency, an inherited urea cycle disorder, is caused by mutations in the X-linked OTC gene. Phenotype-genotype correlations are well understood in males but still poorly known in females. Taking advantage of a cohort of 130 families (289 females), we assessed the relative contribution of OTC enzyme activity, X chromosome inactivation, and OTC gene sequencing to genetic counseling in heterozygous females. Twenty two percent of the heterozygous females were clinically affected, with episodic (11%), chronic (7.5%), or neonatal forms of the disease (3.5%). Overall mortality rate was 4%. OTC activity, ranging from 0% to 60%, did not correlate with phenotype at the individual level. Analysis of multiple samples from 4 mutant livers showed intra-hepatic variability of OTC activity and X inactivation profile (range of variability: 30% and 20%, respectively) without correlation between both parameters for 3 of the 4 livers. Ninety disease-causing variants were found, 27 of which were novel. Mutations were classified as "mild" or "severe," based on male phenotypes and/or in silico prediction. In our cohort, a serious disease occurred in 32% of females with a severe mutation, compared to 4% in females with a mild mutation (odds ratio = 1.365; P = 1.6e-06). These data should help prenatal diagnosis for heterozygous females and genetic counseling after fortuitous findings of OTC variants in pangenomic sequencing.

Whole Locus Sequencing Identifies a Prevalent Founder Deep Intronic RPGRIP1 Pathologic Variant in the French Leber Congenital Amaurosis Cohort.

Leber congenital amaurosis (LCA) encompasses the earliest and most severe retinal dystrophies and can occur as a non-syndromic or a syndromic disease. Molecular diagnosis in LCA is of particular importance in clinical decision-making and patient care since it can provide ocular and extraocular prognostics and identify patients eligible to develop gene-specific therapies. Routine high-throughput molecular testing in LCA yields 70%-80% of genetic diagnosis. In this study, we aimed to investigate the non-coding regions of one non-syndromic LCA gene, RPGRIP1, in a series of six families displaying one single disease allele after a gene-panel screening of 722 LCA families which identified 26 biallelic RPGRIP1 families. Using trio-based high-throughput whole locus sequencing (WLS) for second disease alleles, we identified a founder deep intronic mutation (NM_020366.3:c.1468-128T>G) in 3/6 families. We employed Sanger sequencing to search for the pathologic variant in unresolved LCA cases (106/722) and identified three additional families (two homozygous and one compound heterozygous with the NM_020366.3:c.930+77A>G deep intronic change). This makes the c.1468-128T>G the most frequent RPGRIP1 disease allele (8/60, 13%) in our cohort. Studying patient lymphoblasts, we show that the pathologic variant creates a donor splice-site and leads to the insertion of the pseudo-exon in the mRNA, which we were able to hamper using splice-switching antisense oligonucleotides (AONs), paving the way to therapies.

Genome-wide association study of resistance to Mycobacterium tuberculosis infection identifies a locus at 10q26.2 in three distinct populations.

The natural history of tuberculosis (TB) is characterized by a large inter-individual outcome variability after exposure to Mycobacterium tuberculosis. Specifically, some highly exposed individuals remain resistant to M. tuberculosis infection, as inferred by tuberculin skin test (TST) or interferon-gamma release assays (IGRAs). We performed a genome-wide association study of resistance to M. tuberculosis infection in an endemic region of Southern Vietnam. We enrolled household contacts (HHC) of pulmonary TB cases and compared subjects who were negative for both TST and IGRA (n = 185) with infected individuals (n = 353) who were either positive for both TST and IGRA or had a diagnosis of TB. We found a genome-wide significant locus on chromosome 10q26.2 with a cluster of variants associated with strong protection against M. tuberculosis infection (OR = 0.42, 95%CI 0.35-0.49, P = 3.71×10-8, for the genotyped variant rs17155120). The locus was replicated in a French multi-ethnic HHC cohort and a familial admixed cohort from a hyper-endemic area of South Africa, with an overall OR for rs17155120 estimated at 0.50 (95%CI 0.45-0.55, P = 1.26×10-9). The variants are located in intronic regions and upstream of C10orf90, a tumor suppressor gene which encodes an ubiquitin ligase activating the transcription factor p53. In silico analysis showed that the protective alleles were associated with a decreased expression in monocytes of the nearby gene ADAM12 which could lead to an enhanced response of Th17 lymphocytes. Our results reveal a novel locus controlling resistance to M. tuberculosis infection across different populations.

Mitochondrial DNA mutations do not impact early human embryonic development.

Mitochondrial DNA (mtDNA) mutations cause severe maternally inherited disorders, although mechanisms regulating mother-to-offspring transmission have not yet been elucidated. To investigate if mtDNA mutations affect embryonic development, we compared morphology, viability and mtDNA content in control (n = 165) and mitochondrial (n = 16) human embryos at the cleavage-stage. mtDNA copy number (CN) was assessed in one or two embryonic cells, by real-time PCR. The presence of a maternal or embryonic mtDNA mutation did not impact on either embryonic quality or viability. mtDNA CN was not altered by mtDNA mutations, suggesting that mtDNA defects do not modify mtDNA metabolism at this early stage.

Human C-terminal CUBN variants associate with chronic proteinuria and normal renal function.

BACKGROUNDProteinuria is considered an unfavorable clinical condition that accelerates renal and cardiovascular disease. However, it is not clear whether all forms of proteinuria are damaging. Mutations in CUBN cause Imerslund-Gräsbeck syndrome (IGS), which is characterized by intestinal malabsorption of vitamin B12 and in some cases proteinuria. CUBN encodes for cubilin, an intestinal and proximal tubular uptake receptor containing 27 CUB domains for ligand binding.METHODSWe used next-generation sequencing for renal disease genes to genotype cohorts of patients with suspected hereditary renal disease and chronic proteinuria. CUBN variants were analyzed using bioinformatics, structural modeling, and epidemiological methods.RESULTSWe identified 39 patients, in whom biallelic pathogenic variants in the CUBN gene were associated with chronic isolated proteinuria and early childhood onset. Since the proteinuria in these patients had a high proportion of albuminuria, glomerular diseases such as steroid-resistant nephrotic syndrome or Alport syndrome were often the primary clinical diagnosis, motivating renal biopsies and the use of proteinuria-lowering treatments. However, renal function was normal in all cases. By contrast, we did not found any biallelic CUBN variants in proteinuric patients with reduced renal function or focal segmental glomerulosclerosis. Unlike the more N-terminal IGS mutations, 37 of the 41 proteinuria-associated CUBN variants led to modifications or truncations after the vitamin B12-binding domain. Finally, we show that 4 C-terminal CUBN variants are associated with albuminuria and slightly increased GFR in meta-analyses of large population-based cohorts.CONCLUSIONCollectively, our data suggest an important role for the C-terminal half of cubilin in renal albumin reabsorption. Albuminuria due to reduced cubilin function could be an unexpectedly common benign condition in humans that may not require any proteinuria-lowering treatment or renal biopsy.FUNDINGATIP-Avenir program, Fondation Bettencourt-Schueller (Liliane Bettencourt Chair of Developmental Biology), Agence Nationale de la Recherche (ANR) Investissements d'avenir program (ANR-10-IAHU-01) and NEPHROFLY (ANR-14-ACHN-0013, to MS), Steno Collaborative Grant 2018 (NNF18OC0052457, to TSA and MS), Heisenberg Professorship of the German Research Foundation (KO 3598/5-1, to AK), Deutsche Forschungsgemeinschaft (DFG) Collaborative Research Centre (SFB) KIDGEM 1140 (project 246781735, to CB), and Federal Ministry of Education and Research (BMB) (01GM1515C, to CB).

Human IFN-γ immunity to mycobacteria is governed by both IL-12 and IL-23.

Hundreds of patients with autosomal recessive, complete IL-12p40 or IL-12Rß1 deficiency have been diagnosed over the last 20 years. They typically suffer from invasive mycobacteriosis and, occasionally, from mucocutaneous candidiasis. Susceptibility to these infections is thought to be due to impairments of IL-12-dependent IFN-γ immunity and IL-23-dependent IL-17A/IL-17F immunity, respectively. We report here patients with autosomal recessive, complete IL-12Rß2 or IL-23R deficiency, lacking responses to IL-12 or IL-23 only, all of whom, unexpectedly, display mycobacteriosis without candidiasis. We show that αß T, γδ T, B, NK, ILC1, and ILC2 cells from healthy donors preferentially produce IFN-γ in response to IL-12, whereas NKT cells and MAIT cells preferentially produce IFN-γ in response to IL-23. We also show that the development of IFN-γ-producing CD4+ T cells, including, in particular, mycobacterium-specific TH1* cells (CD45RA-CCR6+), is dependent on both IL-12 and IL-23. Last, we show that IL12RB1, IL12RB2, and IL23R have similar frequencies of deleterious variants in the general population. The comparative rarity of symptomatic patients with IL-12Rß2 or IL-23R deficiency, relative to IL-12Rß1 deficiency, is, therefore, due to lower clinical penetrance. There are fewer symptomatic IL-23R- and IL-12Rß2-deficient than IL-12Rß1-deficient patients, not because these genetic disorders are rarer, but because the isolated absence of IL-12 or IL-23 is, in part, compensated by the other cytokine for the production of IFN-γ, thereby providing some protection against mycobacteria. These experiments of nature show that human IL-12 and IL-23 are both required for optimal IFN-γ-dependent immunity to mycobacteria, both individually and much more so cooperatively.

Tuberculosis and impaired IL-23-dependent IFN-γ immunity in humans homozygous for a common TYK2 missense variant.

Inherited IL-12Rß1 and TYK2 deficiencies impair both IL-12- and IL-23-dependent IFN-γ immunity and are rare monogenic causes of tuberculosis, each found in less than 1/600,000 individuals. We show that homozygosity for the common TYK2 P1104A allele, which is found in about 1/600 Europeans and between 1/1000 and 1/10,000 individuals in regions other than East Asia, is more frequent in a cohort of patients with tuberculosis from endemic areas than in ethnicity-adjusted controls (P = 8.37 × 10-8; odds ratio, 89.31; 95% CI, 14.7 to 1725). Moreover, the frequency of P1104A in Europeans has decreased, from about 9% to 4.2%, over the past 4000 years, consistent with purging of this variant by endemic tuberculosis. Surprisingly, we also show that TYK2 P1104A impairs cellular responses to IL-23, but not to IFN-α, IL-10, or even IL-12, which, like IL-23, induces IFN-γ via activation of TYK2 and JAK2. Moreover, TYK2 P1104A is properly docked on cytokine receptors and can be phosphorylated by the proximal JAK, but lacks catalytic activity. Last, we show that the catalytic activity of TYK2 is essential for IL-23, but not IL-12, responses in cells expressing wild-type JAK2. In contrast, the catalytic activity of JAK2 is redundant for both IL-12 and IL-23 responses, because the catalytically inactive P1057A JAK2, which is also docked and phosphorylated, rescues signaling in cells expressing wild-type TYK2. In conclusion, homozygosity for the catalytically inactive P1104A missense variant of TYK2 selectively disrupts the induction of IFN-γ by IL-23 and is a common monogenic etiology of tuberculosis.

TUBB1 mutations cause thyroid dysgenesis associated with abnormal platelet physiology.

The genetic causes of congenital hypothyroidism due to thyroid dysgenesis (TD) remain largely unknown. We identified three novel TUBB1 gene mutations that co-segregated with TD in three distinct families leading to 1.1% of TUBB1 mutations in TD study cohort. TUBB1 (Tubulin, Beta 1 Class VI) encodes for a member of the ß-tubulin protein family. TUBB1 gene is expressed in the developing and adult thyroid in humans and mice. All three TUBB1 mutations lead to non-functional α/ß-tubulin dimers that cannot be incorporated into microtubules. In mice, Tubb1 knock-out disrupted microtubule integrity by preventing ß1-tubulin incorporation and impaired thyroid migration and thyroid hormone secretion. In addition, TUBB1 mutations caused the formation of macroplatelets and hyperaggregation of human platelets after stimulation by low doses of agonists. Our data highlight unexpected roles for ß1-tubulin in thyroid development and in platelet physiology. Finally, these findings expand the spectrum of the rare paediatric diseases related to mutations in tubulin-coding genes and provide new insights into the genetic background and mechanisms involved in congenital hypothyroidism and thyroid dysgenesis.

Disruption of an antimycobacterial circuit between dendritic and helper T cells in human SPPL2a deficiency.

Human inborn errors of IFN-γ immunity underlie mycobacterial diseases. We describe patients with Mycobacterium bovis (BCG) disease who are homozygous for loss-of-function mutations of SPPL2A. This gene encodes a transmembrane protease that degrades the N-terminal fragment (NTF) of CD74 (HLA invariant chain) in antigen-presenting cells. The CD74 NTF therefore accumulates in the HLA class II+ myeloid and lymphoid cells of SPPL2a-deficient patients. This toxic fragment selectively depletes IL-12- and IL-23-producing CD1c+ conventional dendritic cells (cDC2s) and their circulating progenitors. Moreover, SPPL2a-deficient memory TH1* cells selectively fail to produce IFN-γ when stimulated with mycobacterial antigens in vitro. Finally, Sppl2a-/- mice lack cDC2s, have CD4+ T cells that produce small amounts of IFN-γ after BCG infection, and are highly susceptible to infection with BCG or Mycobacterium tuberculosis. These findings suggest that inherited SPPL2a deficiency in humans underlies mycobacterial disease by decreasing the numbers of cDC2s and impairing IFN-γ production by mycobacterium-specific memory TH1* cells.

The human CIB1-EVER1-EVER2 complex governs keratinocyte-intrinsic immunity to ß-papillomaviruses.

Patients with epidermodysplasia verruciformis (EV) and biallelic null mutations of TMC6 (encoding EVER1) or TMC8 (EVER2) are selectively prone to disseminated skin lesions due to keratinocyte-tropic human ß-papillomaviruses (ß-HPVs), which lack E5 and E8. We describe EV patients homozygous for null mutations of the CIB1 gene encoding calcium- and integrin-binding protein-1 (CIB1). CIB1 is strongly expressed in the skin and cultured keratinocytes of controls but not in those of patients. CIB1 forms a complex with EVER1 and EVER2, and CIB1 proteins are not expressed in EVER1- or EVER2-deficient cells. The known functions of EVER1 and EVER2 in human keratinocytes are not dependent on CIB1, and CIB1 deficiency does not impair keratinocyte adhesion or migration. In keratinocytes, the CIB1 protein interacts with the HPV E5 and E8 proteins encoded by α-HPV16 and γ-HPV4, respectively, suggesting that this protein acts as a restriction factor against HPVs. Collectively, these findings suggest that the disruption of CIB1-EVER1-EVER2-dependent keratinocyte-intrinsic immunity underlies the selective susceptibility to ß-HPVs of EV patients.

A Variety of Alu-Mediated Copy Number Variations Can Underlie IL-12Rß1 Deficiency.

PURPOSE: Inborn errors of IFN-γ immunity underlie Mendelian susceptibility to mycobacterial disease (MSMD). Autosomal recessive complete IL-12Rß1 deficiency is the most frequent genetic etiology of MSMD. Only two of the 84 known mutations are copy number variations (CNVs), identified in two of the 213 IL-12Rß1-deficient patients and two of the 164 kindreds reported. These two CNVs are large deletions found in the heterozygous or homozygous state. We searched for novel families with IL-12Rß1 deficiency due to CNVs. METHODS: We studied six MSMD patients from five unrelated kindreds displaying adverse reactions to BCG vaccination. Three of the patients also presented systemic salmonellosis, two had mucocutaneous candidiasis, and one had disseminated histoplasmosis. We searched for CNVs and other variations by IL12RB1-targeted next-generation sequencing (NGS). RESULTS: We identified six new IL-12Rß1-deficient patients with a complete loss of IL-12Rß1 expression on phytohemagglutinin-activated T cells and/or EBV-transformed B cells. The cells of these patients did not respond to IL-12 and IL-23. Five different CNVs encompassing IL12RB1 (four deletions and one duplication) were identified in these patients by NGS coverage analysis, either in the homozygous state (n = 1) or in trans (n = 4) with a single-nucleotide variation (n = 3) or a small indel (n = 1). Seven of the nine mutations are novel. Interestingly, four of the five CNVs were predicted to be driven by nearby Alu elements, as well as the two previously reported large deletions. The IL12RB1 locus is actually enriched in Alu elements (44.7%), when compared with the rest of the genome (10.5%). CONCLUSION: The IL12RB1 locus is Alu-enriched and therefore prone to rearrangements at various positions. CNVs should be considered in the genetic diagnosis of IL-12Rß1 deficiency.

Segregation of mitochondrial DNA mutations in the human placenta: implication for prenatal diagnosis of mtDNA disorders.

BACKGROUND: Mitochondrial DNA (mtDNA) disorders have a high clinical variability, mainly explained by variation of the mutant load across tissues. The high recurrence risk of these serious diseases commonly results in requests from at-risk couples for prenatal diagnosis (PND), based on determination of the mutant load on a chorionic villous sample (CVS). Such procedures are hampered by the lack of data regarding mtDNA segregation in the placenta.The objectives of this report were to determine whether mutant loads (1) are homogeneously distributed across the whole placentas, (2) correlate with those in amniocytes and cord blood cells and (3) correlate with the mtDNA copy number. METHODS: We collected 11 whole placentas carrying various mtDNA mutations (m.3243A>G, m.8344A>G, m.8993T>G, m.9185T>C and m.10197G>A) and, when possible, corresponding amniotic fluid samples (AFSs) and cord blood samples. We measured mutant loads in multiple samples from each placenta (n= 6-37), amniocytes and cord blood cells, as well as total mtDNA content in placenta samples. RESULTS: Load distribution was homogeneous at the sample level when average mutant load was low (<20%) or high (>80%) at the whole placenta level. By contrast, a marked heterogeneity was observed (up to 43%) in the intermediate range (20%-80%), the closer it was to 40%-50% the mutant load, the wider the distribution. Mutant loads were found to be similar in amniocytes and cord blood cells, at variance with placenta samples. mtDNA content correlated to mutant load in m.3243A>G placentas only. CONCLUSION: These data indicate that (1) mutant load determined from CVS has to be interpreted with caution for PND of some mtDNA disorders and should be associated with/substituted by a mutant load measurement on amniocytes; (2) the m.3243A>G mutation behaves differently from other mtDNA mutations with respect to the impact on mtDNA copy number, as previously shown in human preimplantation embryogenesis.

An eQTL variant of ZXDC is associated with IFN-γ production following Mycobacterium tuberculosis antigen-specific stimulation.

There is a large inter-individual variability in the response to Mycobacterium tuberculosis infection. In previous linkage analyses, we identified a major locus on chromosome region 8q controlling IFN-γ production after stimulation with live BCG (Bacillus Calmette-Guérin), and a second locus on chromosome region 3q affecting IFN-γ production triggered by the 6-kDa early secretory antigen target (ESAT-6), taking into account the IFN-γ production induced by BCG (IFNγ-ESAT6BCG). High-density genotyping and imputation identified ~100,000 variants within each linkage region, which we tested for association with the corresponding IFN-γ phenotype in families from a tuberculosis household contact study in France. Significant associations were replicated in a South African familial sample. The most convincing association observed was that between the IFNγ-ESAT6BCG phenotype and rs9828868 on chromosome 3q (p = 9.8 × 10-6 in the French sample). This variant made a significant contribution to the linkage signal (p < 0.001), and a trend towards the same association was observed in the South African sample. This variant was reported to be an eQTL of the ZXDC gene, biologically linked to monocyte IL-12 production through CCL2/MCP1. The identification of rs9828868 as a genetic driver of IFNγ production in response to mycobacterial antigens provides new insights into human anti-tuberculosis immunity.

Inherited GINS1 deficiency underlies growth retardation along with neutropenia and NK cell deficiency.

Inborn errors of DNA repair or replication underlie a variety of clinical phenotypes. We studied 5 patients from 4 kindreds, all of whom displayed intrauterine growth retardation, chronic neutropenia, and NK cell deficiency. Four of the 5 patients also had postnatal growth retardation. The association of neutropenia and NK cell deficiency, which is unusual among primary immunodeficiencies and bone marrow failures, was due to a blockade in the bone marrow and was mildly symptomatic. We discovered compound heterozygous rare mutations in Go-Ichi-Ni-San (GINS) complex subunit 1 (GINS1, also known as PSF1) in the 5 patients. The GINS complex is essential for eukaryotic DNA replication, and homozygous null mutations of GINS component-encoding genes are embryonic lethal in mice. The patients' fibroblasts displayed impaired GINS complex assembly, basal replication stress, impaired checkpoint signaling, defective cell cycle control, and genomic instability, which was rescued by WT GINS1. The residual levels of GINS1 activity reached 3% to 16% in patients' cells, depending on their GINS1 genotype, and correlated with the severity of growth retardation and the in vitro cellular phenotype. The levels of GINS1 activity did not influence the immunological phenotype, which was uniform. Autosomal recessive, partial GINS1 deficiency impairs DNA replication and underlies intra-uterine (and postnatal) growth retardation, chronic neutropenia, and NK cell deficiency.

Major Loci on Chromosomes 8q and 3q Control Interferon γ Production Triggered by Bacillus Calmette-Guerin and 6-kDa Early Secretory Antigen Target, Respectively, in Various Populations.

BACKGROUND: Interferon γ (IFN-γ) release assays (IGRAs) provide an in vitro measurement of antimycobacterial immunity that is widely used as a test for Mycobacterium tuberculosis infection. IGRA outcomes are highly heritable in various populations, but the nature of the involved genetic factors remains unknown. METHODS: We conducted a genome-wide linkage analysis of IGRA phenotypes in families from a tuberculosis household contact study in France and a replication study in families from South Africa to confirm the loci identified. RESULTS: We identified a major locus on chromosome 8q controlling IFN-γ production in response to stimulation with live bacillus Calmette-Guerin (BCG; LOD score, 3.81; P = 1.40 × 10(-5)). We also detected a second locus, on chromosome 3q, that controlled IFN-γ levels in response to stimulation with 6-kDa early secretory antigen target, when accounting for the IFN-γ production shared with that induced by BCG (LOD score, 3.72; P = 1.8 × 10(-5)). Both loci were replicated in South African families, where tuberculosis is hyperendemic. These loci differ from those previously identified as controlling the response to the tuberculin skin test (TST1 and TST2) and the production of TNF-α (TNF1). CONCLUSIONS: The identification of 2 new linkage signals in populations of various ethnic origins living in different M. tuberculosis exposure settings provides new clues about the genetic control of human antimycobacterial immunity.