Loss of function of ENT3 drives histiocytosis and inflammation through TLR-MAPK signaling.

Histiocytoses are inflammatory myeloid neoplasms often driven by somatic activating mutations in mitogen-activated protein kinase (MAPK) cascade genes. H syndrome is an inflammatory genetic disorder caused by germ line loss-of-function mutations in SLC29A3, encoding the lysosomal equilibrative nucleoside transporter 3 (ENT3). Patients with H syndrome are predisposed to develop histiocytosis, yet the mechanism is unclear. Here, through phenotypic, molecular, and functional analysis of primary cells from a cohort of patients with H syndrome, we reveal the molecular pathway leading to histiocytosis and inflammation in this genetic disorder. We show that loss of function of ENT3 activates nucleoside-sensing toll-like receptors (TLR) and downstream MAPK signaling, inducing cytokine secretion and inflammation. Importantly, MEK inhibitor therapy led to resolution of histiocytosis and inflammation in a patient with H syndrome. These results demonstrate a yet-unrecognized link between a defect in a lysosomal transporter and pathological activation of MAPK signaling, establishing a novel pathway leading to histiocytosis and inflammation.

CLDN1 Arg81His founder variant causes ichthyosis, leukocyte vacuoles, alopecia, and sclerosing cholangitis (ILVASC) syndrome in Moroccan Jews.

Neonatal ichthyosis and sclerosing cholangitis syndrome (NISCH), also known as ichthyosis, leukocyte vacuoles, alopecia, and sclerosing cholangitis (ILVASC), is an extremely rare disease of autosomal recessive inheritance, resulting from loss of function of the tight junction protein claudin-1. Its clinical presentation is highly variable, and is characterized by liver and ectodermal involvement. Although most ILVASC cases described to date were attributed to homozygous truncating variants in CLDN1, a single missense variant CLDN1 p.Arg81His, associated with isolated skin ichthyosis phenotype, has been recently reported in a family of Moroccan Jewish descent. We now describe seven patients with ILVASC, originating from four non consanguineous families of North African Jewish ancestry (including one previously reported family), harboring CLDN1 p.Arg81His variant, and broaden the phenotypic spectrum attributed to this variant to include teeth, hair, and liver/bile duct involvement, characteristic of ILVASC. Furthermore, we provide additional evidence for pathogenicity of the CLDN1 p.Arg81His variant by transmission electron microscopy of the affected skin, revealing distorted tight junction architecture, and show through haplotype analysis in the vicinity of the CLDN1 gene, that this variant represents a founder variant in Jews of Moroccan descent with an estimated carrier frequency of 1:220.

The natural history of dihydrolipoamide dehydrogenase deficiency in Israel.

Dihydrolipoamide dehydrogenase (DLD) deficiency is an ultra-rare autosomal-recessive inborn error of metabolism, affecting no less than five mitochondrial multienzyme complexes. With approximately 30 patients reported to date, DLD deficiency was associated with three major clinical presentations: an early-onset encephalopathic phenotype with metabolic acidosis, a predominantly hepatic presentation with liver failure, and a rare myopathic phenotype. To elucidate the demographic, phenotypic, and molecular characteristics of patients with DLD deficiency within the Israeli population, data were collected from metabolic disease specialists in four large tertiary medical centers in the center and south of Israel. Pediatric and adult patients with biallelic variants in DLD were included in the study. A total of 53 patients of 35 families were included in the cohort. Age at presentation ranged between birth and 10 years. Wide phenotypic variability was observed, from asymptomatic individuals in their sixth decade of life, to severe, neonatal-onset disease with devastating neurological sequelae. Six DLD variants were noted, the most common of which was the c.685G>T (p.G229C) variant in homozygous form (24/53 patients, 45.3%; 13/35 families), observed mostly among patients of Ashkenazi-Jewish descent, followed by the homozygous c.1436A>T (p.D479V) variant, found in 20 patients of Bedouin descent (37.7%; 16/35 families). Overall, patients did not necessarily present as one of the previously described distinct clinical phenotypes. DLD deficiency is a panethnic disorder, with significant phenotypic variability, and comprises a continuum, rather than three distinct clinical presentations.

Hypoparathyroidism-Retardation-Dysmorphism Syndrome due to a Variant in the Tubulin-Specific Chaperone E Gene as a Cause of Combined Immune Deficiency.

BACKGROUND: Hypoparathyroidism-retardation-dysmorphism (HRD) syndrome is a disease composed of hypoparathyroidism, growth retardation, severe developmental delay, and typical dysmorphic features caused by the tubulin-specific chaperone E gene variant. Many patients succumb in infancy to HRD due to overwhelming infections mainly caused by Pneumococcus spp. Knowledge related to the immune system in these patients is scarce. PURPOSE: To define the immune phenotype of a cohort of HRD patients including their cellular, humoral, and neutrophil functions. METHODS: The study included HRD patients followed at Soroka University Medical Center. Clinical and immunological data were obtained, including immunoglobulin concentrations, specific antibody titers, lymphocyte subpopulations, lymphocyte proliferation, and neutrophil functions. RESULTS: Nine patients (5 females and 4 males) were enrolled, aged 6 months to 15 years. All received amoxicillin prophylaxis as part of a routine established previously. Three patients had bacteremia with Klebsiella, Shigella spp., and Candida. Three patients had confirmed coronavirus disease 19 (COVID-19), and two of them died from this infection. All patients had normal blood counts. Patients showed high total IgA and IgE levels, low anti-pneumococcal antibodies in spite of a routine vaccination schedule, and reduced frequency of naive B cells with increased frequency of CD21lowCD27- B cells. All patients had abnormal T-cell population distributions, including reduced terminally differentiated effector memory CD8, inverted CD4/CD8 ratios, and impaired phytohemagglutinin (PHA)-induced lymphocyte proliferation. Neutrophil superoxide production and chemotaxis were normal in all patients tested. CONCLUSION: HRD is a combined immunodeficiency disease with syndromic features, manifesting in severe invasive bacterial and viral infections.

Glomerular involvement in children with H syndrome.

BACKGROUND: H syndrome is a multisystem inflammatory disease caused by mutations in the SLC29A3 gene (OMIM #602782). The protein product, hENT3, is a nucleoside transporter essential for DNA salvage synthesis. Clinical manifestations are hyperpigmentation, hypertrichosis, hepatosplenomegaly, hearing loss, heart anomalies, hypogonadism, short stature, skeletal deformities, and diabetes mellitus. Laboratory findings are consistent with inflammatory processes. Structural kidney anomalies have been described in 6% of patients. CASE REPORTS: Three family members with genetically diagnosed H syndrome (c.1279G>A, p.Gly427Ser). Two of them presented with hypoalbuminemia and nephrotic range proteinuria. Kidney ultrasound was normal. Kidney biopsy performed in one patient presenting with generalized peripheral pitting edema revealed membranous nephropathy. Different treatments including ACE inhibitors, corticosteroids, and immunomodulatory agents failed to improve the clinical outcome. CONCLUSIONS: Generalized peripheral pitting edema and glomerulopathy broaden the clinical spectrum of H syndrome. Periodic bloodwork and urinalysis are recommended.

Pituitary stalk interruption syndrome broadens the clinical spectrum of the TTC26 ciliopathy.

Ciliopathies are a heterogeneous group of disorders, related to abnormal ciliary function. Severe biliary ciliopathy, caused by bi-allelic mutations in TTC26, has been recently described in the context of a syndrome of polydactyly and severe neonatal cholestasis, with brain, kidney and heart involvement. Pituitary involvement has not been previously reported for patients with this condition. Pituitary stalk interruption syndrome (PSIS) is a congenital anomaly of the pituitary gland, diagnosed by characteristic MRI findings. We now describe four patients with TTC26 ciliopathy due to a homozygous c.695A>G p.Asn232Ser mutation and delineate PSIS as a novel clinical feature of this disorder, highlighting an important role of TTC26 in pituitary development.

Urinary tract infections in children < 2 years of age hospitalized in a tertiary medical center in Southern Israel: epidemiologic, imaging, and microbiologic characteristics of first episode in life.

The objectives of the study were to describe the epidemiologic, microbiologic, and imaging characteristics of first 44 UTI episode in hospitalized infants and children < 2 years of age. A UTI episode was diagnosed based on suprapubic aspiration or urinary catheterization and report of a significant bacterial growth of true uropathogens. Two thousand two hundred ninety-four UTI episodes were recorded during 2009-2013 in 1694 patients; 1350 (79.7%), 223 (13.2%), and 66 (3.9%) had one, two, and three episodes, respectively. Of 1955 pathogens isolated, the most frequent were E. coli, Klebsiella spp., and Enterococcus spp. (56.9%, 14.1%, and 11%, respectively). E. coli percentages increased with increase in patient age while Klebsiella spp. and Enterococcus spp. decreased with decrease in age. 136/344 (39.5%) renal ultrasound examinations performed were reported abnormal. The percentages of abnormal ultrasound examinations in Enterococcus spp.-UTI were higher than in E. coli and Klebsiella spp.-UTI (P < 0.001 and P = 0.007, respectively). The E. coli nonsusceptibility to ampicillin, TMP/SMX, ceftriaxone, amoxicillin/clavulanic acid, cefuroxime, and gentamicin was 71%, 31%, 14.9%, 14.7%, 7%, and 4.4%, respectively. Nonsusceptibility of Klebsiella spp. to ampicillin, amoxicillin/clavulanic acid, TMP/SMX, ceftriaxone, gentamicin, and cefuroxime was 98.7%, 10.4%, 9.5%, 8.4%, 4.8%, and 4.3%, respectively. E. coli nonsusceptibility to amoxicillin/clavulanate, TMP/SMX, and ciprofloxacin decreased during the study period. E. coli percentages increased and those of Klebsiella spp. and Enterococcus spp. decreased with increase in patient age. Enterococcus. spp.-UTI was associated with older age and more severe findings on renal ultrasound. E. coli and Klebsiella spp. nonsusceptibility to amoxicillin/clavulanate, TMP/SMX, cefuroxime, and ceftriaxone was low.

Urinary tract infection in young infants discharged from the emergency room with normal urinalysis.

AIM: We describe the clinical, microbiologic, therapeutic, and outcome characteristics of infants under three months of age with a positive urine culture reported after discharge from emergency department with normal urinalysis. METHODS: We enrolled all infants with a urine culture obtained during an emergency room visit during 2004-2012, discharged without antibiotic therapy and subsequently reported with a positive urine culture. RESULTS: Three hundred and ninety-three positive urine cultures were reported; 46/393 (11.7%, 42 in patients under two months of age) had positive urine cultures following normal urinalysis at first visit. Fifteen (33%) had positive urine cultures at second visit; 11/15 (73%) infants with second positive urine culture were under one month of age, eight were asymptomatic and seven had mild symptoms at second visit. Pathogens isolated in all 15 infants were identical between first and second visit. All 27 infants re-examined at second visit at the emergency room were hospitalised, completed sepsis work/up and received antibiotic treatment. None developed serious bacterial infections. CONCLUSION: We propose a new management approach for young infants with normal urinalysis and positive urine culture and suggest restricting the management option including hospitalisation, sepsis work/up and antibiotic treatment at second visit only to infants under one month of age.

X-linked C1GALT1C1 mutation causes atypical hemolytic uremic syndrome.

Hemolytic-uremic syndrome (HUS), mostly secondary to infectious diseases, is a common cause of acute kidney injury in children. It is characterized by progressive acute kidney failure due to severe thrombotic microangiopathy, associated with nonimmune, Coombs-negative hemolytic anemia and thrombocytopenia. HUS is caused mostly by Shiga toxin-producing E. Coli, and to a lesser extent by Streptococcus pneumonia. In Streptococcus pneumonia HUS (pHUS), bacterial neuraminidase A exposes masked O-glycan sugar residues on erythrocytes, known as the T antigen, triggering a complement cascade causing thrombotic microangiopathy. Atypical HUS (aHUS) is a life-threatening genetic form of the disease, whose molecular mechanism is only partly understood. Through genetic studies, we demonstrate a novel X-linked form of aHUS that is caused by a de-novo missense mutation in C1GALT1C1:c.266 C > T,p.(T89I), encoding a T-synthase chaperone essential for the proper formation and incorporation of the T antigen on erythrocytes. We demonstrate the presence of exposed T antigen on the surface of mutant erythrocytes, causing aHUS in a mechanism similar to that suggested in pHUS. Our findings suggest that both aHUS caused by mutated C1GALT1C1 and pHUS are mediated by the lectin-complement-pathway, not comprehensively studied in aHUS. We thus delineate a shared molecular basis of aHUS and pHUS, highlighting possible therapeutic opportunities.

Hyper IgM in tricho-hepato-enteric syndrome due to TTC37 mutation.

Tricho-hepato-enteric syndrome (THES) (OMIM #222,470) is a rare autosomal recessive syndromic enteropathy whose primary manifestations are dysmorphism, intractable diarrhea, failure to thrive, hair abnormalities, liver disease, and immunodeficiency with low serum IgG concentrations. THES is caused by mutations of either Tetratricopeptide Repeat Domain 37 (TTC37) or Ski2 like RNA Helicase (SKIV2L), genes that encode two components of the human SKI complex. Here, we report a patient with a TTC37 homozygous mutation phenotypically typical for tricho-hepato-enteric syndrome in whom extremely elevated IgM with low IgG was present at the time of diagnosis. These manifestations were not previously described in THES patients and this raised our index of suspicion towards "atypical" hyper IgM syndrome. Although the pathogenesis of immunoglobulin production dysfunction in THES is still elusive, this disorder should be considered in the differential diagnosis in patients with elevated IgM and syndromic features.

The Effects of a Ketogenic Diet on Patients with Dihydrolipoamide Dehydrogenase Deficiency.

BACKGROUND: Dihydrolipoamide dehydrogenase (DLD lipoamide dehydrogenase, the E3 subunit of the pyruvate dehydrogenase complex (PDHC)) is the third catalytic enzyme of the PDHC, which converts pyruvate to acetyl-CoA catalyzed with the introduction of acetyl-CoA to the tricyclic acid (TCA) cycle. In humans, PDHC plays an important role in maintaining glycose homeostasis in an aerobic, energy-generating process. Inherited DLD-E3 deficiency, caused by the pathogenic variants in DLD, leads to variable presentations and courses of illness, ranging from myopathy, recurrent episodes of liver disease and vomiting, to Leigh disease and early death. Currently, there is no consensus on treatment guidelines, although one suggested solution is a ketogenic diet (KD). OBJECTIVE: To describe the use and effects of KD in patients with DLD-E3 deficiency, compared to the standard treatment. RESULTS: Sixteen patients were included. Of these, eight were from a historical cohort, and of the other eight, four were on a partial KD. All patients were homozygous for the D479V (or D444V, which corresponds to the mutated mature protein without the mitochondrial targeting sequence) pathogenic variant in DLD. The treatment with partial KD was found to improve patient survival. However, compared to a historical cohort, the patients' quality of life (QOL) was not significantly improved. CONCLUSIONS: The use of KD offers an advantage regarding survival; however, there is no significant improvement in QOL.

The effects of the COVID-19 pandemic on patients with lysosomal storage disorders in Israel.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) is the causative agent of the current COVID-19 pandemic. Lysosomal storage disorders (LSD) comprise of 70 inherited inborn errors of metabolism. Affected individuals suffer from multi-systemic involvement with variable severity and rate of disease progression between different diseases. Some of the LSDs have established treatments, whether parenteral or oral therapies. The full impact of the COVID-19 pandemic together with the lockdown on the wellbeing and medical management of patients with rare diseases, such as LSDs, is widely unknown. Herein, we describe the effects of the COVID-19 pandemic and its associated mandatory home lockdown on patients with LSDs in Israel. RESULTS: We present a prospective multi-center questionnaire study including 48 LSD patients from four medical centers in Israel. The study objective was to assess the impact of the COVID-19 pandemic restrictions on individuals with LSDs in Israel, as reported by their caregivers. Secondary objectives were to assess the morbidity from SARS CoV-2 in LSD patients and the impact of changes in mood and behavior on compliance to treatment and to assess the relationship between changes in mood to changes in cognition and behavior. Thirty one of 38 patients (82%) who received any kind of regular treatment did not miss treatments. Among patients receiving enzyme replacement therapy (ERT) in the in-hospital setting, 5 patients (20%) experienced treatment disruptions. Four patients had tested positive for SARS-Cov-2 virus infection by PCR. Seven out of the 48 patients (14%) described mood changes with cognitive and motor deterioration during the home quarantine. CONCLUSIONS: We observed high rates of treatment adherence and low morbidity through the COVID-19 pandemic in patients with LSDs in Israel. LSDs patients can be a model for patients with complex chronic diseases requiring routine treatments and surveillance during a pandemic or other disruption of daily routine.

Group A streptococcal brain abscess in children: two case reports and a review of the literature.

Brain abscesses caused by group A Streptococcus (GAS) are infrequently encountered in children. We present two cases of brain abscess (one cerebellar and one located in the temporal lobe) due to GAS infection occurring in close temporal proximity in previously healthy young children living in different geographic areas of southern Israel. The relevant literature since 2000, in the context of recent epidemiological data reporting an increase in the incidence of invasive GAS infections, is reviewed.