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Biallelic changes in the ZNFX1 gene have been recently reported to cause severe familial immunodeficiency. Through a search of our bio/databank with information from genetic testing of >55 000 individuals, we identified nine additional patients from seven families with six novel homozygous ZNFX1 variants. Consistent with the previously described phenotype, our patients suffered from monocytosis, thrombocytopenia, hepatosplenomegaly, recurrent infections, and lymphadenopathy. The two most severely affected probands also had renal involvement and clinical presentations compatible with hemophagocytic lymphohistiocytosis. The disease was less lethal among our patients than previously reported. We identified two missense changes, two variants predicted to result in complete protein loss through nonsense-mediated decay, and two frameshift changes that likely introduce a truncation. Our findings (i) independently confirm the role of ZNFX1 in primary genetic immunodeficiency, (ii) expand the genetic and clinical spectrum of ZNFX1-related disease, and (iii) illustrate the utility of large, well-curated, and continually updated genotype-phenotype databases in resolving molecular diagnoses of patients with initially negative genetic testing findings.

Human C2orf69 is an evolutionary-conserved gene whose function is unknown. Here, we report 9 children from 5 unrelated families with a fatal syndrome consisting of severe auto-inflammation, progredient leukoencephalopathy with recurrent seizures that segregate homozygous loss-of-function C2orf69 variants. C2ORF69 orthologues, which can be found in most eukaryotic genomes including that of unicellular phytoplanktons, bear homology to esterase enzymes. We find that human C2ORF69 is loosely bound to the mitochondrion and its depletion affects mitochondrial membrane potential in human fibroblasts and neurons. Moreover, we show that CRISPR/Cas9-inactivation of zebrafish C2orf69 results in lethality by 8 months of age due to spontaneous epileptic seizures which is accompanied by persistent brain inflammation. Collectively, our results delineate a novel auto-inflammatory Mendelian disorder of C2orf69 deficiency that disrupts the development/homeostasis of the immune and central nervous systems as demonstrated in patients and in a zebrafish model of the disease.One Sentence SummaryC2orf69 is a putative enzyme whose inactivation in humans and zebrafish causes a hitherto unknown auto-inflammatory syndrome.

Emerging evidence has demonstrated that (pro)renin receptor (PRR)-mediated activation of intrarenal renin-angiotensin system (RAS) plays an essential role in renal handling of Na+ and water balance and blood pressure. The present study tested the possibility that the intrarenal RAS served as a molecular target for the protective action of ELABELA (ELA), a novel endogenous ligand of apelin receptor, in the distal nephron. By RNAscope and immunofluorescence, mRNA and protein expression of endogenous ELA was consistently localized to the collecting duct (CD). Apelin was also found in the medullary CDs as assessed by immunofluorescence. In cultured CD-derived M1 cells, exogenous ELA induced parallel decreases of full-length PRR (fPRR), soluble PRR (sPRR), and prorenin/renin protein expression as assessed by immunoblotting and medium sPRR and prorenin/renin levels by ELISA, all of which were reversed by 8-bromoadenosine 3′,5′-cyclic monophosphate. Conversely, deletion of PRR in the CD or nephron in mice elevated Apela and Apln mRNA levels as well as urinary ELA and apelin excretion, supporting the antagonistic relationship between the two systems. Administration of exogenous ELA-32 infusion (1.5 mg·kg−1·day−1, minipump) to high salt (HS)-loaded Dahl salt-sensitive (SS) rats significantly lowered mean arterial pressure, systolic blood pressure, diastolic blood pressure, and albuminuria, accompanied with a reduction of urinary sPRR, angiotensin II, and prorenin/renin excretion. HS upregulated renal medullary protein expression of fPRR, sPRR, prorenin, and renin in Dahl SS rats, all of which were significantly blunted by exogenous ELA-32 infusion. Additionally, HS-induced upregulation of inflammatory cytokines ( IL-1β, IL-2, IL-6, IL-17A, IFN-γ, VCAM-1, ICAM-1, and MCP-1), fibrosis markers ( TGF-β1, FN, Col1A1, PAI-1, and TIMP-1), and kidney injury markers ( NGAL, Kim-1, albuminuria, and urinary NGAL excretion) were markedly blocked by exogenous ELA infusion. Together, these results support the antagonistic interaction between ELA and intrarenal RAS in the distal nephron that appears to exert a major impact on blood pressure regulation.

Human C2orf69 is an evolutionarily conserved gene whose function is unknown. Here, we report eight unrelated families from which 20 children presented with a fatal syndrome consisting of severe autoinflammation and progredient leukoencephalopathy with recurrent seizures; 12 of these subjects, whose DNA was available, segregated homozygous loss-of-function C2orf69 variants. C2ORF69 bears homology to esterase enzymes, and orthologs can be found in most eukaryotic genomes, including that of unicellular phytoplankton. We found that endogenous C2ORF69 (1) is loosely bound to mitochondria, (2) affects mitochondrial membrane potential and oxidative respiration in cultured neurons, and (3) controls the levels of the glycogen branching enzyme 1 (GBE1) consistent with a glycogen-storage-associated mitochondriopathy. We show that CRISPR-Cas9-mediated inactivation of zebrafish C2orf69 results in lethality by 8 months of age due to spontaneous epileptic seizures, which is preceded by persistent brain inflammation. Collectively, our results delineate an autoinflammatory Mendelian disorder of C2orf69 deficiency that disrupts the development/homeostasis of the immune and central nervous systems.

Emerging evidence has demonstrated that (pro)renin receptor (PRR)-mediated activation of intrarenal renin-angiotensin system (RAS) plays an essential role in renal handling of Na + and water balance and blood pressure. The present study tested the possibility that the intrarenal RAS served as a molecular target for the protective action of ELABELA (ELA, also known as Toddler/Apela), a novel endogenous ligand of APJ receptor (also known as APLNR) in the distal nephron. By RNAscope and immunofluorescence, mRNA and protein expression of endogenous ELA was consistently localized to the collecting duct (CD). In cultured CD-derived M1 cells, exogenous ELA induced parallel decreases of fPRR (by 31.6%), soluble PRR (sPRR) (by 46.5%), and prorenin (by 45.7%) protein expression as assessed by immunoblotting, and medium sPRR (by 66.7%) and prorenin/renin (by 60%) levels by ELISA. Conversely, deletion of PRR in the CD in mice elevated ELA mRNA levels (1.5-fold), and urinary ELA excretion (2.0-fold), supporting the antagonistic relationship between the two systems. Administration of exogenous ELA (5 mg/kg/day, minipump) to high salt (HS)-loaded Dahl salt-sensitive (SS) rats significantly lowered mean arterial pressure (113.0 ± 1.7 vs . 133.8 ± 1.5 mmHg, P vs . 142.9 ± 2.6 mmHg, P vs . 127.4 ± 0.9 mmHg, P vs . 394.1 ± 5.3 bpm, P vs . 5.1 ± 1.1 mg/24h, P