A pH imbalance is linked to autophagic dysregulation of inner ear hair cells in Atp6v1ba-deficient zebrafish.

V-ATPase is an ATP hydrolysis-driven proton pump involved in the acidification of intracellular organelles and systemic acid-base homeostasis through H+ secretion in the renal collecting ducts. V-ATPase dysfunction is associated with hereditary distal renal tubular acidosis (dRTA). ATP6V1B1 encodes the B1 subunit of V-ATPase that is integral to ATP hydrolysis and subsequent H+ transport. Patients with pathogenic ATP6V1B1 mutations often exhibit an early onset of sensorineural hearing loss. However, the mechanisms underlying this association remain unclear. We employed morpholino oligonucleotide-mediated knockdown and CRISPR/Cas9 gene editing to generate Atp6v1ba-deficient (atp6v1ba-/-) zebrafish as an ortholog model for ATP6V1B1. The atp6v1ba-/- zebrafish exhibited systemic acidosis and significantly smaller otoliths compared to wild-type siblings. Moreover, deficiency in Atp6v1ba led to degeneration of inner ear hair cells, with ultrastructural changes indicative of autophagy. Our findings indicate a critical role of ATP6V1B1 in regulating lysosomal pH and autophagy in hair cells, and the results provide insights into the pathophysiology of sensorineural hearing loss in dRTA. Furthermore, this study demonstrates that the atp6v1ba-/- zebrafish model is a valuable tool for further investigation into disease mechanisms and potential therapies for acidosis-related hearing impairment.

Cardiac manifestations of human ACTA2 variants recapitulated in a zebrafish model.

The ACTA2 gene encodes actin α2, a major smooth muscle protein in vascular smooth muscle cells. Missense variants in the ACTA2 gene can cause inherited thoracic aortic diseases with characteristic symptoms, such as dysfunction of smooth muscle cells in the lungs, brain vessels, intestines, pupils, bladder, or heart. We identified a heterozygous missense variant of Gly148Arg (G148R) in a patient with a thoracic aortic aneurysm, dissection, and left ventricular non-compaction. We used zebrafish as an in vivo model to investigate whether or not the variants might cause functional or histopathological abnormalities in the heart. Following the fertilization of one-cell stage embryos, we injected in vitro synthesized ACTA2 mRNA of wild-type, novel variant G148R, or the previously known pathogenic variant Arg179His (R179H). The embryos were maintained and raised for 72 h post-fertilization for a heart analysis. Shortening fractions of heart were significantly reduced in both pathogenic variants. A histopathological evaluation showed that the myocardial wall of ACTA2 pathogenic variants was thinner than that of the wild type, and the total cell number within the myocardium was markedly decreased in all zebrafish with pathogenic variants mRNAs. Proliferating cell numbers were also significantly decreased in the endothelial and myocardial regions of zebrafish with ACTA2 variants compared to the wild type. These results demonstrate the effects of ACTA2 G148R and R179H on the development of left ventricle non-compaction and cardiac morphological abnormalities. Our study highlights the previously unknown significance of the ACTA2 gene in several aspects of cardiovascular development.

Early defibrotide therapy and risk factors for post-transplant veno-occlusive disease/sinusoidal obstruction syndrome in childhood.

BACKGROUND: Veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome (SOS), is a life-threatening complications of hematopoietic cell transplantation (HCT). METHODS: We studied the impact of early defibrotide (DF) therapy on the outcomes of pediatric patients with VOD/SOS after transplantation, focusing on recent immunotherapies. A total of 111 pediatric patients who underwent HCT for malignant disease between February 2017 and March 2023 at Kyushu University Hospital were included. RESULTS: Among 111 patients of less than 20 years of age who underwent HCT for malignancy at a single institution between 2017 and 2023, VOD/SOS occurred in 25 (23%) patients. VOD/SOS developed more frequently in the post-DF era (2020-2023, n = 58) than in the pre-DF era (31% vs. 13%, p = .04). The proportion of patients with relapsed/refractory acute lymphoblastic leukemia (ALL) was higher in the post-DF era than in the pre-DF era (44% vs. 8%, p = .04). Early DF therapy that was started at two European Society for Blood and Marrow Transplantation diagnostic criteria reduced the severity of VOD/SOS (p < .01) in comparison to non-early therapy started at less than two criteria. A multivariate analysis indicated that a history of cytokine release syndrome (odds ratio [OR] = 10.4, p = .01) and juvenile myelomonocytic leukemia (OR = 8.98, p = .04), but not an endothelial activation and stress index (EASIX) score of greater than 0.85, were independent risk factors for VOD/SOS. CONCLUSIONS: Early DF therapy improves the severity and survival outcomes of post-transplant VOD/SOS in children. However, its incidence is increasing in the era of immunotherapy for progressive diseases.

Dried blood spot-based newborn screening for bile acid synthesis disorders, Zellweger spectrum disorder, and Niemann-Pick type C1 by detection of bile acid metabolites.

OBJECTIVE: To examine whether it is possible to screen for bile acid synthesis disorders (BASDs) including peroxisome biogenesis disorder 1a (PBD1A) and Niemann-Pick type C1 (NPC1) at the time of newborn mass screening by measuring the intermediary metabolites of bile acid (BA) synthesis. METHODS: Patients with 3ß-hydroxy-ΔSuchy et al. (2021)5-C27-steroid dehydrogenase/isomerase (HSD3B7) deficiency (n = 2), 3-oxo-ΔPandak and Kakiyama (n.d.)4-steroid 5ß-reductase (SRD5B1) deficiency (n = 1), oxysterol 7α-hydroxylase (CYP7B1) deficiency (n = 1), PBD1A (n = 1), and NPC1 (n = 2) with available dried blood spot (DBS) samples collected in the neonatal period were included. DBSs from healthy neonates at 4 days of age (n = 1055) were also collected for the control. Disease specific BAs were measured by newly optimized liquid chromatography-tandem mass spectrometry with short run cycle (5-min/run). The results were validated by comparing with those obtained by the conventional condition with longer run cycle (76-min/run). RESULTS: In healthy specimens, taurocholic acid and cholic acid were the two major BAs which constituted approximately 80% in the measured BAs. The disease marker BAs presented <10%. In BASDs, the following BAs were determined for the disease specific markers: Glyco/tauro 3ß,7α,12α-trihydroxy-5-cholenoic acid 3-sulfate for HSD3B7 deficiency (>70%); glyco/tauro 7α,12α-dihydroxy-3-oxo-4-cholenoic acid for SRD5B1 deficiency (54%); tauro 3ß-hydroxy-5-cholenoic acid 3-sulfate for CYP7B1 deficiency (94%); 3α,7α,12α-trihydroxy-5ß-cholestanoic acid for PBD1A (78%); and tauro 3ß,7ß-dihydroxy-5-cholenoic acid 3-sulfate for NPC1 (26%). *The % in the parenthesis indicates the portion found in the patient's specimen. CONCLUSIONS: Early postnatal screening for BASDs, PBD1A and NPC1 is feasible with the described DBS-based method by measuring disease specific BAs. The present method is a quick and affordable test for screening for these inherited diseases.

Acute myeloid leukemia associated with CHARGE syndrome.

CHARGE syndrome is a malformation disorder with diverse phenotypes that shows autosomal dominance with heterozygous variants in the chromodomain helicase DNA-binding 7 (CHD7) gene. Only a few cases of CHARGE syndrome accompanied by neoplasm during childhood have been reported. We report the case of a girl with CHARGE syndrome who developed acute myelogenous leukemia at 12 years old. She had mild intellectual disability, and hearing loss with inner ear malformation, myopia, astigmatism, laryngotracheal malacia, hypogonadism, and clival hypoplasia, with a history of patent ductus arteriosus. The patient was genetically diagnosed with CHARGE syndrome based on the detection of a novel heterozygous frameshift pathogenic variant in the CHD7 gene. We review the reported pediatric cases of CHARGE syndrome with malignancy and suggest a possible molecular mechanism of carcinogenesis involving pathogenic variants of the CHD7 gene.

Multifaceted support for quality of life in childhood cancer survivors: Questionnaire survey.

BACKGROUND: Along with improvements in curative treatment for childhood cancer, childhood cancer survivors (CCSs) often face numerous problems such as late complications of cancer treatment, social issues at school, struggles in employment, and financial difficulties. These children have received a wide range of support from the medical, educational, and administrative sectors. However, it was unclear how this multifaceted support contributed to quality of life (QOL) of CCSs in Japan. METHODS: The subjects were 46 CCSs of 16 years of age or older at the time of the survey, who had been diagnosed and treated for pediatric cancer. A self-administered questionnaire survey was conducted to investigate the in-hospital status during treatment, adjustment when returning to school, and administrative social support. The QOL of CCSs was also evaluated by the Medical Outcome Study 36-Item Short-Form Health Survey. RESULTS: Twenty-four CCSs answered the questions. The respondents who had experienced school-life problems tended to have lower role/social QOL scores (p = 0.046), whereas the CCSs who had experienced administrative counseling tended to have lower physical QOL scores (p = 0.036). The mental QOL scores tended to be higher in respondents who were informed of the exact diagnosis of cancer during hospitalization. The role/social QOL scores tended to be lower in respondents who advanced to their preferred career path. CONCLUSIONS: It is essential for three stakeholders-health-care providers, education offices, and public administrative agencies-to collaborate to share long-term psychosocial issues or concerns related to employment or daily living that CCSs may encounter, and to establish a coordinated approach to support CCSs.

Celiac Disease Genetics, Pathogenesis, and Standard Therapy for Japanese Patients.

Celiac disease is an autoimmune disease primarily affecting the small intestine that is caused by the ingestion of gluten in genetically susceptible individuals. The development of celiac disease is based on a complex immune response to gluten proteins. The global average prevalence in the general population is about 1%. In recent years, it has become clear that celiac disease is not less common in Asian countries than in Western countries but often remains undiagnosed. Although the number of patients with celiac disease in Asia is expected to increase with improving disease recognition and advances in diagnostic techniques, there remain few reports of celiac disease in the Far East region of Asia, especially in Japan. In this paper, we outline the epidemiology, diagnosis, and treatment of celiac disease. In addition, we summarize the reported Japanese cases of celiac disease with an overview in Japan.

Stability of amino acids, free and acyl-carnitine in stored dried blood spots.

BACKGROUND: Newborn screening of inborn errors of metabolism using tandem mass spectrometry has become a public health strategy in many developed countries. Retrospective analyses using stored dried blood specimens have been limited, mainly due to a lack of biochemical information on the long-term stability of acylcarnitines and amino acids in stored specimens. We studied the characteristic profiles of the stability of amino acid, free carnitine, and acyl carnitines in dried blood specimens stored in a refrigerator after newborn screening. METHODS: Dried blood specimens from 198 healthy newborns, which had been stored in a refrigerator at 5 °C after newborn screening, were prospectively subjected to tandem mass spectrometry analyses after 1, 3, 6 months, 1 and 2 years of storage. We also retrospectively re-analyzed the stored samples from 90 newborns, which had been analyzed and stored at 5 °C for 4 years. RESULTS: We found that proline (Pro) and tyrosine (Tyr) were stable for 2 years, and that alanine (Ala), arginine (Arg), and phenylalanine (Phe) decayed with linear regression. The C0 increased during the time-course of 2 years, whereas most acylcarnitines gradually decayed and some showed a linear correlation. The retrospective analysis of samples stored for 4 years revealed that Ala, Phe, Pro and Tyr were almost stable, leucine (Leu), valine (Val) decayed with linear regression, C0 increased, and C10, C12, C14, C14:1, C16, C18, C18:1 decreased, while maintaining a linear correlation. CONCLUSIONS: These data suggested that some metabolic parameters from refrigerator-stored dried blood specimens were applicable for the detection of inborn errors of metabolism.

Rothmund-Thomson syndrome investigated by two nationwide surveys in Japan.

BACKGROUND: Rothmund-Thomson syndrome (RTS) is an autosomal recessive genetic disorder characterized by poikiloderma of the face, small stature, sparse scalp hair, juvenile cataract, radial aplasia, and predisposition to cancers. Due to the rarity of RTS, the situation of patients with RTS in Japan has not been elucidated. METHODS: In 2010 and 2020, following the results of a primary questionnaire survey, a secondary questionnaire survey on RTS was conducted nationwide to investigate the number of RTS cases and their associated skin lesions, bone lesions, other clinical features, and quality of life in Japan. RESULTS: In 2010 and 2020, 10 and eight patients with RTS were recruited, respectively. Skin lesions such as poikiloderma, erythema, pigmentation, and abnormal scalp hair were observed in almost all cases. Bone lesions were observed in four cases in the 2010 and 2020 surveys, respectively. Two cases had mutations in the RECQL4 gene in the 2020 survey. CONCLUSIONS: Two nationwide surveys have shown the actual situation of patients with RTS in Japan. Cutaneous and bone manifestations are important for the diagnosis of RTS. However, many patients have no RECQL4 mutations. The novel causative gene of RTS should be further elucidated.

Sensorineural Hearing Loss in Sjögren's Syndrome.

Sjögren's syndrome is a chronic autoimmune disease characterized by systemic dysfunction of exocrine glands, mainly the salivary and lachrymal glands. Sjögren's syndrome consists of two forms: primary Sjögren's syndrome, which is characterized by dry eyes and dry mouth without autoimmune diseases; and secondary Sjögren's syndrome, which is characterized by symptoms associated with other autoimmune diseases, such as systemic lupus erythematosus. Disease severities vary considerably from mild glandular dryness to severe glandular involvement with numerous extraglandular and systemic features. Sensorineural hearing loss is sometimes observed in both primary and secondary Sjögren's syndrome. This review article consists of (1) Pathology of Sjögren's syndrome, (2) Clinical manifestation of Sjögren's syndrome, (3) Autoimmune inner ear disease, (4) Histoanatomical features of the inner ear, (5) Immunological characteristics of the inner ear, (6) Pathophysiology of autoimmune inner ear disease, (7) Treatment for sensorineural hearing loss in Sjögren's syndrome, and (8) Future direction. Finally, we introduce a recently developed disease model of salivary gland inflammation and discuss future expectations for the treatment of sensorineural hearing loss in Sjögren's syndrome.

Psoriasis with short stature improved by adalimumab.

Few cases of pediatric psoriasis with short stature, possibly resulting from chronic systemic inflammation, have been reported. We present the case of a child with short stature occurring after the onset of psoriasis wherein treatment with adalimumab resulted in the improvement of not only the psoriasis but also the child's short stature. Pediatric psoriasis associated with short stature may benefit from the early induction of biologic therapy.

Tyrosine pre-transfer RNA fragments are linked to p53-dependent neuronal cell death via PKM2.

Fragments of transfer RNA (tRNA), derived either from pre-tRNA or mature tRNA, have been discovered to play an essential role in the pathogenesis of various disorders such as neurodegenerative disease. CLP1 is an RNA kinase involved in tRNA biogenesis, and mutations in its encoding gene are responsible for pontocerebellar hypoplasia type-10. Mutation of the CLP1 gene results in the accumulation of tRNA fragments of several different kinds. These tRNA fragments are expected to be associated with the disease pathogenesis. However, it is still unclear which of the tRNA fragments arising from the CLP1 gene mutation has the greatest impact on the onset of neuronal disease. We found that 5' tRNA fragments derived from tyrosine pre-tRNA (5' Tyr-tRF) caused p53-dependent neuronal cell death predominantly more than other types of tRNA fragment. We also showed that 5' Tyr-tRF bound directly to pyruvate kinase M2 (PKM2). Injection of zebrafish embryos with PKM2 mRNA ameliorated the neuronal defects induced in zebrafish embryos by 5' Tyr-tRF. Our findings partially uncovered a mechanistic link between 5' Tyr-tRF and neuronal cell death that is regulated by PKM2.

Early Recovery of Height Velocity in Prepubertal Children With Acute Lymphoblastic Leukemia Treated by a Short Intensive Phase Without Cranial Radiation Therapy.

PURPOSE: There have been few reports on height disturbance in childhood acute lymphoblastic leukemia (ALL) patients treated without cranial radiation therapy (CRT). Our study aimed to clarify the critical period of growth in pediatric patients who were treated by the Japan Childhood Leukemia Study (JACLS) ALL-02 protocol, which involved short-term intensive treatment without CRT. PATIENTS AND METHODS: A retrospective, cohort study was conducted for prepubertal children with B-precursor ALL who were diagnosed from July 2002 to November 2011 and treated by the JACLS ALL-02 protocol at Oita University Hospital. The heights were chronologically measured at pretreatment, after the intensive phase (INT), at the end of treatment (END), and at 1 to 5 year(s) posttreatment (POST 1 to 5). RESULTS: Nine boys and 4 girls were enrolled. Z score of the height was reduced at INT and END. Delta Z scores of the height and Z score of height velocity were reduced from pretreatment to INT, and they demonstrated an early recovery during maintenance treatment in INT to END. CONCLUSIONS: Early recovery of delta Z scores of the height and Z score of height velocity was observed during the INT to END period. The shortened intensive phase without CRT may result in an adequate height in prepubertal ALL patients.

Gastric Carcinoma as Second Malignant Neoplasm in a Survivor From High-risk Neuroblastoma.

Childhood cancer survivors (CCSs) from high-grade malignancies, such as high-risk neuroblastoma, have been increased, and second malignant neoplasm, becomes a serious problem for CCSs. However, detailed reports about rare types of second cancer such as gastric cancer remain limited. We herein reported a female patient who developed diffuse type gastric carcinoma after 21 years from completion of treatment to high-risk neuroblastoma. We reviewed the previous cohort studies for second gastrointestinal cancer in CCSs and the case reports with second gastric carcinoma for CCSs. We presumed second gastric cancer was refractory for CCSs as well as for adult cancer survivors.

Pediatric procedural sedation in Japan: A single-facility study of 1,436 cases.

BACKGROUND: Pediatric procedural sedation (PPS) has been established worldwide as standard practice for several decades. However, there are no comprehensive guidelines or multi-facility databases of PPS in Japan, and the current status of PPS and PPS-related adverse events is unclear. The objectives of this study were to investigate the status of PPS in Japan and clarify the adverse events and risk factors. METHODS: This study was a single-facility, database survey performed at Oita University Hospital from September 2016 to March 2019. Children under 18 years of age who had been kept sedated for medical procedures with intravenous sedatives were enrolled in this study. Adverse events were recorded and defined according to the Quebec Guideline. RESULTS: During the study period, PPS was performed for 1,436 consecutive cases. The majority (94%) of the sedatives used were thiamylal alone or thiamylal combined with ketamine. There were a total of 253 adverse events in 233 cases (16.2%), including oxygen desaturation, airway hypersensitivity, and vomiting. Patients recovered from respiratory-related adverse events immediately with simple intervention. No patient required endotracheal intubation and no severe adverse event occurred. Four risk factors (a higher American Society of Anesthesiologists classification, longer procedure time, non-compliance of nil per os status, and no Pediatric Advanced Life Support certification for sedation personnel) were associated with the occurrence of adverse events. CONCLUSIONS: Adverse events occurred in 16.2% of all PPS cases. Further studies are needed to analyze the serious adverse events and risk factors for PPS in Japan.

Language delay and developmental catch-up would be a clinical feature of pseudohypoparathyroidism type 1A during childhood.

Pseudohypoparathyroidism type 1A (PHP1A) is characterized by resistance to multiple hormones, the Albright Hereditary Osteodystrophy phenotype, obesity, and developmental delay. Developmental delay usually appears prior to hypocalcemia due to parathyroid hormone resistance and could be a clinically important feature for early diagnosis of PHP1A. To date, however, the details have not been documented. With regard to developmental delays, we conducted a multicenter retrospective study of 22 PHP1A patients from 18 families who were diagnosed clinically or genetically from 2005 to 2015. For quantitative analysis of their development, we calculated the ratios of the milestone ages of the patients to those in normal reference data. The ratio of the ages with respect to speech development, i.e., speaking a first meaningful word (median: 1.67), was significantly higher than that for gross motor development, walking unassisted (median: 1.34). The ratio of age at stringing a two-word sentence (median: 1.32) was significantly lower than that of saying a first word (median: 1.84). Ten out of 11 (91%) patients exhibited two or three of the following clinical phenotypes: developmental delay, obesity, and hyperthyrotropinemia. These results suggest two possible clinical features of developmental delays in PHP1A patients: developmental delay is more obvious in speech acquisition than in gross motor skills, and speech delays could be attenuated during later childhood. Further, the presence of multiple of three clinical symptoms could be an important indicator to differentiate the diagnosis of PHP1A during early childhood.

Comprehensive screening for monogenic diabetes in 89 Japanese children with insulin-requiring antibody-negative type 1 diabetes.

BACKGROUND: Mutations in causative genes for neonatal diabetes or maturity-onset diabetes of the young have been identified in multiple patients with autoantibody-negative type 1 diabetes (T1D). OBJECTIVES: We aimed to clarify the prevalence and phenotypic characteristics of monogenic abnormalities among 89 children with autoantibody-negative insulin-requiring T1D. METHODS: Mutations in 30 genes were screened using next-generation sequencing, and copy-number alterations of 4 major causative genes were examined using multiplex-ligation-dependent probe amplification. We compared the clinical characteristics between mutation carriers and non-carriers. RESULTS: We identified 11 probable pathogenic substitutions (6 in INS , 2 in HNF1A , 2 in HNF4A , and 1 in HNF1B ) in 11 cases, but no copy-number abnormalities. Only 2 mutation carriers had affected parents. De novo occurrence was confirmed for 3 mutations. The non-carrier group, but not the carrier group, was enriched with susceptible HLA alleles. Mutation carriers exhibited comparable phenotypes to those of non-carriers, except for a relatively normal body mass index (BMI) at diagnosis. CONCLUSIONS: This study demonstrated significant genetic overlap between autoantibody-negative T1D and monogenic diabetes. Mutations in INS and HNF genes, but not those in GCK and other monogenic diabetes genes, likely play critical roles in children with insulin-requiring T1D. This study also suggests the relatively high de novo rates of INS and HNF mutations, and the etiological link between autoimmune abnormalities and T1D in the non-carrier group. Carriers of monogenic mutations show non-specific phenotypes among all T1D cases, although they are more likely to have a normal BMI at diagnosis than non-carriers.

Metabolic and immunological assessment of small-for-gestational-age children during one-year treatment with growth hormone: the clinical impact of apolipoproteins.

Children born small for gestational age (SGA) are at a higher risk for metabolic disorders later in life. In this study, we aimed to characterize young SGA children without catch-up growth and evaluate the effects of GH treatment on endocrinological, metabolic, and immunological parameters. Study design is a one-year single hospital-based study included prospective observation of SGA patients during 12 months of GH treatment. Clinical and laboratory profiles of SGA children at baseline were compared with controls born appropriate size for age. Twenty-six SGA children (median age, 3.4 years) and 26 control children (median age, 3.8 years) were enrolled. Anthropometric, hematologic, biochemical, immunological, and endocrinological parameters were assessed at baseline and 1, 3, 6, 9, and 12 months after the start of GH treatment. As a result, median height SD score (SDS) of SGA children increased by +0.42 with 12-month GH treatment. Body mass index SDS was lower in SGA children than in controls. Serum apolipoprotein A1 increased, whereas apolipoprotein B decreased during GH treatment. Serum leptin and resistin levels, which were lower in SGA children than in controls at baseline, did not change remarkably with GH treatment. Monocyte counts, which were lower in SGA patients at baseline, increased after GH treatment. Neutrophil counts significantly increased after GH treatment. Natural killer cell ratios, which were higher in SGA patients, decreased after GH treatment. In conclusion, there was no evidence suggesting metabolic abnormalities in SGA children. Serum apolipoprotein changes might predict the beneficial role of GH treatment in lowering cardiometabolic risk.

Incidence rate and characteristics of symptomatic vitamin D deficiency in children: a nationwide survey in Japan.

There is concern that vitamin D deficiency is prevalent among children in Japan as well as worldwide. We conducted a nationwide epidemiologic survey of symptomatic vitamin D deficiency to observe its incidence rate among Japanese children. A questionnaire inquiring the number of new patients with vitamin D deficiency rickets and/or hypocalcemia for 3 years was sent to 855 randomly selected hospitals with a pediatrics department in Japan. In this survey, we found that 250 children were diagnosed with symptomatic vitamin D deficiency. The estimated number of patients with symptomatic vitamin D deficiency per year was 183 (95% confidence interval (CI): 145-222). The overall annual incidence rate among children under 15 years of age was 1.1 per 100,000 population (95% CI: 0.9-1.4). The second survey has provided detailed information on 89 patients with symptomatic vitamin D deficiency under 5 years of age in hospitals in the current research group. The nationwide and second surveys estimated the overall annual incidence rate of symptomatic vitamin D deficiency in children under 5 years of age to be 3.5 (2.7-4.2) per 100,000 population. The second survey revealed 83% had bowed legs, 88% had exclusive breastfeeding, 49% had a restricted and/or unbalanced diet and 31% had insufficient sun exposure among the 89 patients. This is the first nationwide survey on definitive clinical vitamin D deficiency in children in Japan. Elucidating the frequency and characteristics of symptomatic vitamin D deficiency among children is useful to develop preventative public health strategies.