An N-terminal and ankyrin repeat domain interactome of Shank3 identifies the protein complex with the splicing regulator Nono in mice.

An autism-associated gene Shank3 encodes multiple splicing isoforms, Shank3a-f. We have recently reported that Shank3a/b-knockout mice were more susceptible to kainic acid-induced seizures than wild-type mice at 4 weeks of age. Little is known, however, about how the N-terminal and ankyrin repeat domains (NT-Ank) of Shank3a/b regulate multiple molecular signals in the developing brain. To explore the functional roles of Shank3a/b, we performed a mass spectrometry-based proteomic search for proteins interacting with GFP-tagged NT-Ank. In this study, NT-Ank was predicted to form a variety of complexes with a total of 348 proteins, in which RNA-binding (n = 102), spliceosome (n = 22), and ribosome-associated molecules (n = 9) were significantly enriched. Among them, an X-linked intellectual disability-associated protein, Nono, was identified as a NT-Ank-binding protein. Coimmunoprecipitation assays validated the interaction of Shank3 with Nono in the mouse brain. In agreement with these data, the thalamus of Shank3a/b-knockout mice aberrantly expressed splicing isoforms of autism-associated genes, Nrxn1 and Eif4G1, before and after seizures with kainic acid treatment. These data indicate that Shank3 interacts with multiple RNA-binding proteins in the postnatal brain, thereby regulating the homeostatic expression of splicing isoforms for autism-associated genes after birth.

C-Type Lectin Receptor DCAR Recognizes Mycobacterial Phosphatidyl-Inositol Mannosides to Promote a Th1 Response during Infection.

Phosphatidyl-inositol mannosides (PIM) are glycolipids unique to mycobacteria and other related bacteria that stimulate host immune responses and are implicated in mycobacteria pathogenicity. Here, we found that the FcRγ-coupled C-type lectin receptor DCAR (dendritic cell immunoactivating receptor; gene symbol Clec4b1) is a direct receptor for PIM. Mycobacteria activated reporter cells expressing DCAR, and delipidation of mycobacteria abolished this activity. Acylated PIMs purified from mycobacteria were identified as ligands for DCAR. DCAR was predominantly expressed in small peritoneal macrophages and monocyte-derived inflammatory cells in lungs and spleen. These cells produced monocyte chemoattractant protein-1 (MCP-1) upon PIM treatment, and absence of DCAR or FcRγ abrogated MCP-1 production. Upon mycobacterial infection, Clec4b1-deficient mice showed reduced numbers of monocyte-derived inflammatory cells at the infection site, impaired IFNγ production by T cells, and an increased bacterial load. Thus, DCAR is a critical receptor for PIM that functions to promote T cell responses against mycobacteria.

Pretransplant ribavirin and interferon-α therapy for rhinovirus interstitial pneumonia in a RAG1-deficient infant.

Severe combined immunodeficiency (SCID) is one of the most serious inborn errors of immunity leading to a fatal infection in early infancy. Allogeneic hematopoietic cell transplantation (HCT) or elective gene therapy prior to infection or live-attenuated vaccination is the current standard of curative treatment. Even in the era of newborn screening for SCID, pretransplant control of severe infection is challenging for SCID. Multiple pathogens are often isolated from immunocompromised patients, and limited information is available regarding antiviral strategies to facilitate curative HCT. We herein present a case of successfully controlled pretransplant pneumonia after ribavirin and interferon-α therapy in an infant with RAG1-deficiency. A four-month-old infant presented with severe interstitial pneumonia due to a co-infection of rhinovirus and Pneumocystis jirovecii. The tentative diagnosis of SCID prompted to start antibiotics and trimethoprim-sulfamethoxazole on ventilatory support. Because of the progressive respiratory failure four days after treatment, ribavirin and then pegylated interferon-α were started. He showed a drastic response to the treatment that led to a curative HCT 32 days after admission. This patient received the genetic diagnosis of RAG1-deficiency. Currently, he is an active 3-year-old boy with normal growth and development. The review of literature indicated that rhinovirus had a comparable or rather greater impact on the mortality of pediatric patients than respiratory syncytial virus. Considered the turn-around time to the genetic diagnosis of SCID, prompt ribavirin plus interferon-α therapy may help to control severe rhinovirus pneumonia and led to the early curative HCT for the affected infants.

Heterogeneity and mitochondrial vulnerability configurate the divergent immunoreactivity of human induced microglia-like cells.

Microglia play versatile roles in progression of and protection against neuroinflammatory diseases. Little is known, however, about the mechanisms underlying the diverse reactivity of microglia to inflammatory conditions. We investigated how human induced microglia-like (iMG) cells respond to innate immune ligands. Quantitative PCR showed that poly-I:C and lipopolysaccharide (LPS) activated the expression of IL1B and TNF. Immunoreactivity of iMG did not differ between controls (n = 11) and patients with neuroinflammatory diseases (n = 24). Flow cytometry revealed that CD14high cells expressed interleukin (IL) -1ß after LPS treatment. Immunoblotting showed that poly-I:C and LPS differentially activated inflammatory pathways but commonly induced mitochondrial instability and the expression of pyruvate kinase isoform M2 (PKM2). Furthermore, a potent stimulator of PKM2 (DASA-58) alleviated IL-1ß production after LPS treatment. These data indicate that heterogeneous cell populations and mitochondrial stability underlie the divergent immunoreactivity of human iMG in environments.

A Japanese retrospective study of non-tuberculous mycobacterial infection in children, adolescents, and young adult patients with hematologic-oncologic diseases.

Non-tuberculous mycobacterial infection (NTM) is rare in healthy children, with lymphadenitis being the most common presentation. Immunocompromised populations are known to be at high risk, but the clinical picture of NTM infection in pediatric hematology/oncology patients is unclear. In this nationwide retrospective analysis of patients under the age of 40 treated in Japanese pediatric hematology/oncology departments who developed NTM infection between January 2010 and December 2020, 36 patients (21 patients with hematopoietic stem cell transplantation (HSCT) and 15 nontransplant patients) were identified. Post-transplant patients were infected with NTM at 24 sites, including the lungs (n = 12), skin and soft tissues (n = 6), bloodstream (n = 4), and others (n = 2). Nine of twelve patients with pulmonary NTM infection had a history of pulmonary graft-versus-host disease (GVHD), and rapid-growing mycobacteria (RGM) were isolated from five of them. In nontransplant patients, the primary diseases were acute lymphoblastic leukemia (ALL; n = 5), inborn errors of immunity (IEI; n = 6), and others (n = 4). All cases of ALL had bloodstream infections with RGM, whereas all cases of IEI were infected with slow-growing mycobacteria (SGM). In summary, three typical clinical scenarios for pediatric hematology/oncology patients have been established: RGM-induced pulmonary disease in patients with pulmonary GVHD, RGM bloodstream infection in patients with ALL, and SGM infection in patients with IEI. Our findings suggest that NTM must be regarded as a pathogen for infections in these high-risk patients, especially those with pulmonary GVHD, who may require active screening for NTM.

Post-transplant Schizophyllum commune abscess in a pediatric patient with chronic granulomatous disease.

Schizophyllum commune is a widely distributed basidiomycete fungus that occasionally causes sinusitis or allergic bronchopulmonary mycosis. The invasive infection mostly occurs in immunocompromised adults. The number of reports on S. commune infection have increased in this decade due to the expansion of diagnostic techniques and awareness in clinical practice. However, S.commune infection in patients with primary immunodeficiencies has not been reported yet. Here, we described S. commune-abscesses developed in the brain and lung of a boy with chronic granulomatous disease (CGD) after allogenic hematopoietic cell transplantation (HCT). A 12-year-old CGD patient developed febrile neutropenia from day 4 after HCT, followed by chest pain on day 23. He had no obvious infection before HCT. Diagnostic imaging revealed disseminated lung and brain abscesses. He received administration of voriconazole, and his symptoms improved after engraftment. Chronic administration of voriconazole had also a favorable therapeutic response to brain lesion. A part of the fungus ball exhaled by the patient was cultured to develop a filamentous fungus. S. commune was identified by the analysis of the 28S rRNA gene. The catalase test was positive for S. commune, indicating that S. commune had virulence in this patient with CGD. The assessment of specific-IgG to S. commune suggested peri-transplant infection, although colonization was not excluded. This rare pediatric case of S. commune infection highlights that CGD patients are vulnerable to invasive infection, especially when undergoing HCT.

Optimal Teicoplanin Dosing Regimen in Neonates and Children Developed by Leveraging Real-World Clinical Information.

BACKGROUND: Teicoplanin is a glycopeptide antibiotic used for the treatment of methicillin-resistant Staphylococcus aureus infections. To ensure successful target attainment, therapeutic drug monitoring-informed dosage adjustment is recommended. However, it relies on the experience of the clinician and the frequency of drug measurements. This study aimed to design a new optimal dosing regimen of teicoplanin with a maintenance dosing strategy for neonates and children based on their physiological characteristics. METHODS: Data from teicoplanin-treated patients (n = 214) were collected from electronic medical records. Covariate analyses were performed using population pharmacokinetic (PK) modeling with 399 serum teicoplanin concentrations from 48 neonates and 166 children. Multiple PK simulations were conducted to explore optimal dosing regimens that would allow control of the trough concentration to the target of 15-30 mg/L quicker than the current standard regimen. RESULTS: Allometrically scaled body weight, postmenstrual age (PMA), renal function, and serum albumin were implemented as substantial covariates for teicoplanin clearance in a two-compartment PK model. Covariate analyses and comprehensive simulation assessments recommended the following modifications to the current regimen: (1) decreased dose for premature babies (PMA ≤28 weeks), (2) decreased dose for children with renal dysfunction, and (3) increased dose for children (0.5-11 years) with an estimated glomerular filtration rate of ≥90 mL/min/1.73 m2. CONCLUSIONS: This study leverages real-world clinical information and proposes new optimal dosing regimens for teicoplanin in neonates and children through PK modeling and simulation analyses, taking into account the age, including PMA, and renal function of patients.

Characteristics of intussusception in the period of arbitrary Rotavirus vaccination.

BACKGROUND: In November 2011, rotavirus (RV) vaccine was launched in Japan as a voluntary vaccination to prevent RV-associated gastroenterocolitis. We examined the characteristics of intussusception following RV vaccination in our two centers. METHODS: We investigated intussusception patients <16 years old from January 2006 to September 2020. Patients were categorized according to the period (before [Group A] or after the introduction of arbitrary RV vaccination [Group B]). The patient characteristics and treatment of intussusception were retrospectively investigated. RESULTS: During the study period, 560 patients (group A, n = 233; group B, n = 327) were identified. The distribution of patients who were 0-6 months old was not significantly different between the groups (group A, n = 12, 5.2%; group B, n = 18, 5.5%). Among these 18 patients in Group B, 7 were vaccinated against RV, and 10 were not. One patient was excluded due to incomplete data. On comparing patients with and without RV vaccination, the mean age at the onset of intussusception was 3.3 ± 0.4 versus 4.0 ± 0.3 months (P = 0.19), the mean interval from the onset to treatment was 7.5 ± 2.4 versus 16.0 ± 2.2 h (P = 0.03), the time of the contrast enema for treatment was 9.1 ± 3.3 versus 7.7 ± 2.8 min (P = 0.76), and the final pressure of the contrast enema was 92.5 ± 4.4 versus 92.2 ± 4.4 cmH2 O (P = 0.97). CONCLUSIONS: Arbitrary RV vaccination did not influence the age distribution of intussusception, and the interval from the onset to treatment was significantly shorter in the patients with RV vaccination than in those without it. Recognizing the presence of intussusception following RV vaccination enables accurate treatment.

Acute isolated Aspergillus appendicitis in pediatric leukemia.

Aspergillus is a widespread fungus in the environment, usually invades through the respiratory tract. Invasive aspergillosis is a fatal disseminated infection in immunocompromised hosts. Appendicitis occurs scarcely in patients with leukemia. We report a case of Aspergillus appendicitis that underwent an urgent appendectomy. An 11-year-old boy received the diagnosis of acute myeloid leukemia, because of the bone pain and results of the bone marrow study. He obtained a complete remission after cancer chemotherapy and received peripheral blood stem cell transplantation from a histocompatible sibling. Leukemia relapsed 5 months post-transplant. Induction therapy with etoposide, cytarabine and mitoxantrone was started on Candida prophylaxis. Fifteen days after the end of chemotherapy, he presented with febrile neutropenia and abdominal pain, that did not respond to broad-spectrum antibiotics. Serum levels of C-reactive protein, ß-D-glucan and procalcitonin were unremarkable. Computed tomography scan revealed a swollen appendix and the adjacent tissue inflammation. An urgent appendectomy led to a tentative diagnosis of Aspergillus appendicitis based on the histopathological findings of many fungal hyphal forms. Panfungal polymerase chain reaction using DNA extracted from the lesion determined the pathogen of Aspergillus niger. There was no evidence of invasive aspergillosis. During the prolonged anti-fungal therapy, he achieved a remission of leukemia and underwent the second hematopoietic cell transplantation. To our knowledge, Aspergillus appendicitis was reported to occur in 5 leukemia patients. Four of them survived after appendectomy and one died from intestinal perforation. Early surgical intervention is mandatory for a cure of Aspergillus appendicitis in neutropenic patients on Candida prophylaxis.

Late-onset sepsis and encephalopathy after bicycle-spoke injury: a case report.

BACKGROUND: Bicycle-spoke injuries rarely cause late complications of infection, including sepsis and sepsis-associated encephalopathy, with appropriate treatments. CASE PRESENTATION: We experienced a 2-year-old girl who developed the signs of encephalopathy with fever 6 months after a spoke-injury. On admission, the injured skin was inflamed with cellulitis. The blood culture was positive for methicillin-sensitive Staphylococcus aureus. Electroencephalogram showed diffuse slow-wave activity. Diffusion-weighted magnetic resonance imaging detected a high-intensity lesion with decreased diffusivity at the right frontal cortex. She received immunoglobulin and combined antibiotics treatments in the intensive care unit, and successfully overcame the sepsis-associated encephalopathy without neurological impairments. CONCLUSION: This is the first report demonstrating that sepsis and its associated encephalopathy occurs in a remote period after the bicycle-spoke injury.

Tracheal Size and Morphology on the Reconstructed CT Imaging.

OBJECTIVES: To characterize the real size and morphology of tracheas in childhood for the optimal selection of endotracheal tube. DESIGN: A retrospective cohort study of pediatric patients who received CT scan of the cervical spine from July 2011 to March 2018. Cross-sectional CT images vertical to trachea were reconstructed and the accurate tracheal diameters were measured. The validity of the traditional age-based formula for predicting the endotracheal tube size was assessed for the best fit to trachea. SETTING: Tertiary Emergency and Critical Care Center of Kyushu University Hospital. PATIENTS: Children, who are 1 month to 15 years old, received CT scan of the cervical spine. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We enrolled 86 children with median age of 53 months. The cross-sectional shape of pediatric trachea was circular at the cricoid level and elliptical at the infraglottic level. The narrowest part of pediatric trachea was the transverse diameter at the infraglottic level at any age. Significant positive correlation between age and the narrowest diameter was observed. When compared the transverse diameter at the infraglottic level with the outer diameter of endotracheal tubes, uncuffed endotracheal tubes selection based on the traditional age-based formula ran a significant risk of oversized endotracheal intubation until 10 years old compared with cuffed endotracheal tubes selection (60.0% vs 23.8%; p < 0.05). CONCLUSIONS: These findings indicate the safety and efficacy of cuffed endotracheal tubes in infants and children and the reconsideration for the airway management in pediatric anesthesia and intensive care.

Streptococcus pyogenes-purpura fulminans as an invasive form of group A streptococcal infection.

BACKGROUND: Streptococcus pyogenes is an uncommon pathogen of purpura fulminans, and the pathogenesis of S. pyogenes-purpura fulminans remains unclear because of paucity of cases. We reported a pediatric case of S. pyogenes-purpura fulminans with literature review of the disease. CASE PRESENTATION: A 3-year-old boy showed limping, lethargy and acral gangrene within 24 h. A diagnosis of S. pyogenes-purpura fulminans was made for bacterial isolation from throat and peripheral blood. Intensive therapy led to a survival with amputation of the left distal metatarsal bone, and normal development. The isolated M12 carried no mutation of csrS/R or rgg. Thrombophilia or immunodeficiency was excluded. DISCUSSION: Twelve-reported cases (9 pediatric and 3 elderly) of S. pyogenes-purpura fulminans started with shock and coagulopathy. Five patients age < 8 years had no underlying disease and survived. One youngest and two immunocompromised patients died. CONCLUSION: Streptococcus pyogenes-acute infectious purpura fulminans is a distinctive rare form of aggressive GAS infections.

Activation of an innate immune receptor, Nod1, accelerates atherogenesis in Apoe-/- mice.

Atherosclerosis is essentially a vascular inflammatory process in the presence of an excess amount of lipid. We have recently reported that oral administration of a nucleotide-binding oligomerization domain (Nod)-1 ligand, FK565, induced vascular inflammation in vivo. No studies, however, have proven the association between Nod1 and atherosclerosis in vivo. To investigate a potential role of NOD1 in atherogenesis, we orally administered FK565 to apolipoprotein E knockout (Apoe(-/-)) mice for 4 wk intermittently and performed quantification of atherosclerotic lesions in aortic roots and aortas, immunohistochemical analyses, and microarray-based gene expression profiling of aortic roots. FK565 administration accelerated the development of atherosclerosis in Apoe(-/-) mice, and the effect was dependent on Nod1 in non-bone marrow origin cells by bone marrow transplantation experiments. Immunohistochemical studies revealed the increases in the accumulation of macrophages and CD3 T cells within the plaques in aortic roots. Gene expression analyses of aortic roots demonstrated a marked upregulation of the Ccl5 gene during early stage of atherogenesis, and the treatment with Ccl5 antagonist significantly inhibited the acceleration of atherosclerosis in FK565-administered Apoe(-/-) mice. Additionally, as compared with Apoe(-/-) mice, Apoe and Nod1 double-knockout mice showed reduced development of atherosclerotic lesions from the early stage as well as their delayed progression and a significant reduction in Ccl5 mRNA levels at 9 wk of age. Data in the present study show that the Nod1 signaling pathway in non-bone marrow-derived cells contributes to the development of atherosclerosis.

Identification of Pathogenic Cardiac CD11c+ Macrophages in Nod1-Mediated Acute Coronary Arteritis.

OBJECTIVE: Nod1 is an intracellular pattern recognition receptor for bacterial peptidoglycan fragments. We previously reported that a synthetic Nod1 ligand, FK565, induced acute coronary arteritis in mice similar to that of Kawasaki disease. However, the molecular mechanisms underlying this characteristic inflammation have remained elusive. APPROACH AND RESULTS: We found that CD11c(+)MHC class II(+) cells accumulated in the heart of FK565-treated mice before arteritis development. Morphological features and gene expression signatures of the cardiac CD11c(+)MHC class II(+) cells suggested that this population is closely related to macrophages, and thus, we designated them cardiac CD11c(+) macrophages. Nod1 in nonhematopoietic cells, rather than hematopoietic cells, was required for the increase of cardiac CD11c(+) macrophages and arteritis development. Among nonhematopoietic cells, cardiac endothelial cells produced a large amount of chemokines in response to FK565. Endothelial cell-specific blockade of Nod1 signaling suppressed FK565-induced expression of these chemokines, accumulation of cardiac CD11c(+) macrophages, and subsequent coronary arteritis development. We also found that CCR2(+)Ly6C(hi) inflammatory monocytes in peripheral blood supplied precursors of cardiac CD11c(+) macrophages. CCR2-deficient mice or pertussis toxin-treated mice exhibited decreased numbers of cardiac CD11c(+) macrophages and reduced arteritis. CONCLUSIONS: These results suggest that Ly6C(hi) monocytes are recruited to FK565-activated endothelial cells to generate cardiac CD11c(+) macrophages, which play a pivotal role in the pathogenesis of acute coronary arteritis.

ATP1A3 regulates protein synthesis for mitochondrial stability under heat stress.

Pathogenic variants in ATP1A3, the gene encoding the α3 subunit of the Na+/K+-ATPase, cause alternating hemiplegia of childhood (AHC) and related disorders. Impairments in Na+/K+-ATPase activity are associated with the clinical phenotype. However, it remains unclear whether additional mechanisms are involved in the exaggerated symptoms under stressed conditions in patients with AHC. We herein report that the intracellular loop (ICL) of ATP1A3 interacted with RNA-binding proteins, such as Eif4g (encoded by Eif4g1), Pabpc1 and Fmrp (encoded by Fmr1), in mouse Neuro2a cells. Both the siRNA-mediated depletion of Atp1a3 and ectopic expression of the p.R756C variant of human ATP1A3-ICL in Neuro2a cells resulted in excessive phosphorylation of ribosomal protein S6 (encoded by Rps6) and increased susceptibility to heat stress. In agreement with these findings, induced pluripotent stem cells (iPSCs) from a patient with the p.R756C variant were more vulnerable to heat stress than control iPSCs. Neurons established from the patient-derived iPSCs showed lower calcium influxes in responses to stimulation with ATP than those in control iPSCs. These data indicate that inefficient protein synthesis contributes to the progressive and deteriorating phenotypes in patients with the p.R756C variant among a variety of ATP1A3-related disorders.

CD14 down-modulation as a real-time biomarker in Kawasaki disease.

Objectives: The objectives of this study were to investigate the pathophysiology of Kawasaki disease (KD) from immunological and oxidative stress perspectives, and to identify real-time biomarkers linked to innate immunity and oxidative stress in KD. Methods: We prospectively enrolled 85 patients with KD and 135 patients with diverse conditions including immune, infectious and non-infectious diseases for this investigation. Flow cytometry was used to analyse the surface expression of CD14, CD38 and CD62L on monocytes, along with a quantitative assessment of CD14 down-modulation. Additionally, oxidative stress levels were evaluated using derivatives of reactive oxygen metabolites (d-ROMs) and antioxidant capacity measured by a free radical elective evaluator system. Results: During the acute phase of KD, we observed a prominent CD14 down-modulation on monocytes, reflecting the indirect detection of circulating innate immune molecular patterns. Moreover, patients with KD showed a significantly higher CD14 down-modulation compared with infectious and non-infectious disease controls. Notably, the surface expression of CD14 on monocytes was restored concurrently with responses to intravenous immunoglobulin and infliximab treatment in KD. Furthermore, d-ROM levels in patients with KD were significantly elevated compared with patients with infectious and non-infectious diseases. Following intravenous immunoglobulin treatment, oxidative stress levels decreased in patients with KD. Conclusion: Monitoring CD14 down-modulation on monocytes in real-time is a valuable strategy for assessing treatment response, distinguishing KD relapse from concomitant infections and selecting second-line therapy after IVIG treatment in KD patients. The interplay between inflammation and oxidative stress likely plays a crucial role in the development of KD.

Williamsia muralis bacteraemia in a patient with Fanconi anaemia after haematopoietic cell transplantation.

Introduction: Williamsia muralis is an environmental bacterium first detected in 1999. Infections with W. muralis isolated have been reported in two elderly patients, and were associated with the surgical intervention of artificial objects. We present a case of bacteraemia caused by W. muralis following haematopoietic cell transplantation (HCT). Case presentation: A 10-year-old Japanese boy presented with fever and the swelling of the left cheek 8 days after HCT for the treatment of Fanconi anaemia. Gram-positive, rod-shaped bacteria were isolated from the blood cultures after 5 days incubation. 16S rRNA sequencing, but not mass spectrometry, identified a strain of W. muralis (1 414 bp, %ID 100 %). The phlegmon did not respond to antimicrobial therapy, but remitted with defervescence after a successful engraftment with teicoplanin and meropenem therapy on day 16 after HCT. The patient experienced recurrence of the bacteraemia, leading to central venous catheter (CVC) line removal. The same strain of W. muralis was isolated from the cultured tip of the CVC. To our knowledge, this is the first reported case of W. muralis bacteraemia and was complicated by CVC infection after HCT. Conclusion: W. muralis bacteraemia developed in an immunocompromised child. Introduction of artificial objects into the body raises a risk of rare infection with slowly growing environmental bacteria.

Critical diseases in neonates after discharge home from birth hospital: A retrospective study from a tertiary hospital in Japan.

INTRODUCTION: To establish actionable neonatal screening during the first month of life, we investigated critical diseases in seemingly healthy newborns discharged from birth hospitals. METHODS: This retrospective study enrolled previously healthy full-term infants who visited our hospital, a tertiary hospital in Japan, from home between 5 and 28 days after birth from 2009 to 2018. Infants with known perinatal or congenital diseases, positive newborn screening results, or accidental injuries were excluded. Data were collected from electronic medical records, including principal diagnosis, clinical details, and prognosis at 18 months of age. RESULTS: Ninety-seven (58 %) of 168 eligible neonates were admitted to the hospital, and 71 (42 %) were not. The median admission rate in patients with disease onset at ≤14 days after birth (80 %) was significantly higher than that in patients with disease onset at ≥15 days (42 %). Among 45 patients who received intensive medical care, 5 died and 10 developed neurodevelopmental sequelae. Four of 5 patients died by 100 days. Among 25 diseases treated in intensive care unit, 17 (68 %) diseases had a prevalence of <1 per 2000 live births. The commonly used diagnostic methods were imaging (n = 58, 35 %) and physical examination (n = 34, 20 %). CONCLUSION: Critical diseases due to rare and heterogeneous causes in ostensibly healthy newborns occurred predominantly in the first two weeks of life. Optimal newborn screening and health check-up protocols may benefit from the wide spectrum of life-threatening diseases occurring in home after birth.