Published papers

Hypogonadotropic hypogonadism (HH) is a genetically heterogeneous condition that occurs either as an isolated disorder or as a component of congenital malformation syndromes. SOX2 is a causative gene of syndromic HH characterized by anophthalmia, microphthalmia, or coloboma and other neurological defects such as epilepsy. To date, the causal relationship between SOX2 abnormalities and non-syndromic HH remains speculative. Here, we identified a nonsense mutation of SOX2 in a male patient clinically diagnosed with non-syndromic HH. The patient had epilepsy but no additional clinical features. Ophthalmological examination revealed no abnormalities except for decreased thickness of the retinal nerve fiber layer. Audiometry showed mild sensorineural hearing impairment of both ears. Hormonal evaluation suggested isolated gonadotropin deficiency. Next-generation sequencing-based mutation screening of 13 major causative genes for HH identified a p.Lys35* mutation in SOX2 and excluded pathogenic mutations in other tested genes. The p.Lys35* mutation appeared to encode a non-functioning SOX2 protein that lacks 283 of 317 amino acids. The SOX2 mutation was absent in the maternal DNA sample, while a paternal sample was unavailable for sequence analysis. These results expand the clinical consequences of SOX2 haploinsufficiency to include non-syndromic HH. Systematic mutation screening using a next-generation sequencer and detailed evaluation of nonspecific ocular/neurological features may help identify SOX2 mutation-positive individuals among HH patients.

This study provides supporting evidence for the association between SOX9 and liquid-liquid phase separation. We show that SOX9 colocalized with a paraspeckle protein NONO in many, but not all, of the immortalized and primary murine Sertoli cells examined. In addition, we confirmed that SOX9 has structural characteristics of intrinsically disordered proteins.

Thyroid-specific transcription factor PAX8 has an indispensable role in the thyroid gland development, which is evidenced by the facts that PAX8/Pax8 mutations cause congenital hypothyroidism in humans and mice. More than 90% of known PAX8 mutations were located in the paired domain, suggesting the central role of the domain in exerting the molecular function. Structure-function relationships of PAX8, as well as other PAX family transcription factors, have never been investigated in a systematic manner. Here, we conducted the first alanine scanning mutagenesis study, in which 132 alanine variants located in the paired domain of PAX8 were created and systematically evaluated in vitro. We found that 76 alanine variants (55%) were loss of function (LOF) variants (defined by <30% activity as compared with wild type PAX8). Importantly, the distribution of LOF variants were skewed, with more frequently observed in the N-subdomain (65% of the alanine variants in the N-subdomain) than in the C-subdomain (45%). Twelve out of 13 alanine variants in residues that have been affected in patients with congenital hypothyroidism were actually LOF, suggesting that the alanine scanning data can be used to evaluate the functional importance of mutated residues. Using our in vitro data, we tested the accuracy of seven computational algorithms for pathogenicity prediction, showing that they are sensitive but not specific to evaluate on the paired domain alanine variants. Collectively, our experiment-based data would help better understand the structure-function relationships of the paired domain, and would provide a unique resource for pathogenicity prediction of future PAX8 variants.

Background: Bilateral adrenalectomy is performed in cases with infantile-onset Cushing syndrome due to bilateral adrenal hyperplasia in McCune-Albright syndrome (MAS) because severe Cushing syndrome with heart failure and liver dysfunction can have a lethal outcome. This procedure can completely ameliorate hypercortisolism, although lifetime steroid replacement therapy and steps to prevent adrenal crisis are necessary. Recently, the efficacy of unilateral adrenalectomy has been reported in adult cases of bilateral macronodular adrenal hyperplasia, but there is no consensus regarding the appropriate surgical treatment for bilateral adrenal hyperplasia in MAS. Objective: A 6-month-old girl presented with café-au-lait spots, short stature, central obesity, a moon face, and hypertension. Endocrinological tests and imaging studies led to the diagnosis of ACTH-independent Cushing syndrome due to bilateral adrenal hyperplasia induced by MAS. "Three-quarters adrenalectomy", namely right-sided total adrenalectomy and left-sided half adrenalectomy, was carried out. An activating mutation of the GNAS1 gene (p.Arg201Cys) was identified in the adrenal tissues. Since the operation, our patient has been in a state of clinical remission for more than 2 years. Conclusion: Our original surgical intervention, three-quarters adrenalectomy, may be a new treatment option for Cushing syndrome associated with MAS.

Genetic defects of hormone receptors are the most common form of end-organ hormone resistance. One example of such defects is TSH resistance, which is caused by biallelic inactivating mutations in the TSH receptor gene (TSHR). TSH, a master regulator of thyroid functions, affects virtually all cellular processes involving thyroid hormone production, including thyroidal iodine uptake, thyroglobulin iodination, reuptake of iodinated thyroglobulin and thyroid cell growth. Resistance to TSH results in defective thyroid hormone production from the neonatal period, namely congenital hypothyroidism. Classically, clinical phenotypes of TSH resistance due to inactivating TSHR mutations were thought to vary depending on the residual mutant receptor activity. Nonfunctional mutations in the two alleles produce severe thyroid hypoplasia with overt hypothyroidism (uncompensated TSH resistance), while hypomorphic mutations in at least one allele produce normal-sized thyroid gland with preserved hormone-producing capacity (compensated TSH resistance). More recently, a new subgroup of TSH resistance (nonclassic TSH resistance) that is characterized by paradoxically high thyroidal iodine uptake has been reported. In this article, the pathophysiology and clinical features of TSH resistance due to inactivating TSHR mutations are reviewed, with particular attention to the nonclassic form.

Objectives: To establish age-specific reference values for the arm span and arm span/height ratio of the Japanese population in children and adolescence and elucidate their characteristics compared with those of other populations. Study Design: We analyzed data from a national survey on the body sizes of Japanese people conducted between 1992 and 1994 by the Research Institute of Human Engineering for Quality Life. This study was an observational cross-sectional study, including 6089 boys and 4970 girls aged between 5.5 and 18.5 years. We constructed the reference values and delineated the reference curves for the arm span and arm span/height ratio of the Japanese population in childhood and adolescence using the LMS method. The references were compared with those of the Dutch and Turkish populations using the reference curve of 0 standard deviation. Results: The arm span of the Japanese population increased throughout childhood, with a particularly large increase at the age of puberty. The arm span/height ratio also increased slowly throughout childhood. The Japanese population had a smaller arm span/height ratio than the Dutch and Turkish populations of all ages in childhood and adolescence. Moreover, the arm span/height ratio of the Japanese population reached a constant value at an earlier age than in the Dutch and Turkish populations. Conclusions: We constructed the first reference values for the arm span of Japanese children and adolescents. The Japanese population has shorter arm lengths in relation to their height, and their arm span/height ratio reaches a constant value at an earlier age, compared with the Dutch and Turkish populations.

OBJECTIVES: To evaluate the real-world frequency of post-vaccination fever in Japanese infants and to identify factors associated with fever. METHODS: Data on vaccination and daily body temperature were collected using the smartphone application Papatto Ikuji, used by caregivers to record data on their children's daily activities. Mixed-effect logistic regression analysis was conducted to evaluate factors associated with post-vaccination fever. RESULTS: The study included 5690 vaccination events in 2563 infants and toddler aged 2-23 months. Post-vaccination fever was observed most frequently in infants aged 3 months (14.0 %), 4 months (11.6 %), and 12-23 months (9.8 %). Season of vaccination was also a significant factor, with higher fever frequency in summer (9.3 %; odds ratio (OR) 1.59, 95 % confidence interval (CI) 1.16-2.17) compared with winter (6.3 %). A higher fever frequency was observed when PCV13 (13-valent pneumococcal conjugate vaccine), Hib (Haemophilus influenzae type b), and DPT-IPV (Diphtheria, Pertussis, Tetanus, and Inactivated Poliovirus) were administered together (16.8 %; OR 15.40, 95 % CI 6.54-36.26) than vaccination without either of them (1.3 %). CONCLUSIONS: The study identified male, age, vaccine combinations (PCV13 and DPT-IPV), and summer as factors associated with post-vaccination fever in Japanese infants using real-world data from a childcare application.

Aim: Runaway behavior, defined as leaving home without parental permission and not returning, is associated with adverse educational, physical, and mental health outcomes. In Japan, since around 2018, a group of runaway adolescents known as “Toyoko Kids” has emerged in Tokyo's Kabukicho area, reportedly engaging in substance use, violence, and prostitution. This study aimed to examine the psychosocial characteristics of Toyoko Kids who were transported to emergency care due to impaired consciousness from drug overdose or alcohol intoxication. Methods: We conducted a retrospective chart review of eight female adolescents under 18 years old, transported from Kabukicho to Keio University Hospital between June 2022 and August 2023. Inclusion criteria included having run away for at least two nights (or one night for those under 15) and being transported by a third party. A multidisciplinary team assessed psychosocial risks using a Bio-Psycho-Social model. Data on consciousness level, pregnancy, substance use, self-harm, psychiatric history, family structure, school attendance, abuse, and child welfare involvement were analyzed and compared with national statistics. Results: All subjects were female, aged 12–16. The most common reason for transport was impaired consciousness due to overdose, primarily involving over-the-counter medications. Self-harm was confirmed in 86% and abuse in 67% of cases. Although several had prior psychiatric or welfare intervention, support was often temporary and insufficient. Most came from single-parent households, and over half had a history of school absenteeism. Conclusions: This study identified severe psychosocial vulnerabilities among Toyoko Kids. Findings highlight gaps in mental health and child protection systems.

Genetic variants affecting the function of dual oxidase 2 (DUOX2), the catalytic subunit of membrane-bound enzymes that produce hydrogen peroxide, are associated with very early-onset inflammatory bowel disease (VEO-IBD). We report the case of a 1-year-old boy diagnosed with VEO-IBD after presenting with bloody diarrhea. He had pancolitis and an extensive small intestinal ulcerative lesion at age 4 years. Infliximab treatment was successful but was discontinued due to delayed reaction. At age 7 years, treatment with ustekinumab was started, and remission has been maintained for more than 2 years. Whole-exome sequencing identified compound heterozygous missense DUOX2 variants of unknown significance (p.[R1212H];[F1490Y]). Protein expression in the whole-cell lysate and plasma membrane was lower in F1490Y-DUOX2 than in wild-type (WT)-DUOX2. Hydrogen peroxide generation upon ionomycin stimulation was lower in cells expressing R1212H-DUOX2 and F1490Y-DUOX2 than in those expressing WT-DUOX2. The novel, inherited, biallelic DUOX2 mutations may be molecular risk factors of VEO-IBD.

Arg (R)-rich dipeptide repeat proteins (DPRs; poly(PR): Pro-Arg and poly(GR): Gly-Arg), encoded by a hexanucleotide expansion in the C9ORF72 gene, induce neurodegeneration in amyotrophic lateral sclerosis (ALS). Although R-rich DPRs undergo liquid–liquid phase separation (LLPS), which affects multiple biological processes, mechanisms underlying LLPS of DPRs remain elusive. Here, using in silico, in vitro, and in cellulo methods, we determined that the distribution of charged Arg residues regulates the complex coacervation with anionic peptides and nucleic acids. Proteomic analyses revealed that alternate Arg distribution in poly(PR) facilitates entrapment of proteins with acidic motifs via LLPS. Transcription, translation, and diffusion of nucleolar nucleophosmin (NPM1) were impaired by poly(PR) with an alternate charge distribution but not by poly(PR) variants with a consecutive charge distribution. We propose that the pathogenicity of R-rich DPRs is mediated by disturbance of proteins through entrapment in the phase-separated droplets via sequence-controlled multivalent protein–protein interactions.

KLF11 is the causative gene for maturity-onset diabetes of the young 7 (MODY7). KLF11 regulates insulin gene expression through binding to the GC box in the promoter. To date, only two KLF11 mutations have been identified in three families with early-onset type 2 diabetes. Here, we report a novel KLF11 variant associated with early childhood-onset type 1B diabetes. The proband and his younger sister exhibited hyperglycemia at age 1 year, and their mother developed diabetes at age 4 years. These three individuals required insulin injection from the initial phase of the disease. Being negative for islet cell autoantibodies, they were diagnosed with type 1B diabetes. Mutation screening for 30 diabetes-associated genes identified a heterozygous KLF11 variant (p.His418Gln) in the proband and his sister. The variant was also detected in the affected mother, as well as in the allegedly unaffected maternal grandmother. In silico analyses indicated that this variant involves a highly conserved histidine residue in the first C2 H2 zinc finger domain which ligates a zinc ion. In vitro analyses showed that expression levels and intracellular localization of His418Gln-KLF11 were comparable to those of wildtype (WT)-KLF11. Luciferase assays demonstrated that while WT-KLF11 suppressed the activity of a 6 × GC box-containing reporter, His418Gln-KLF11 lacked the suppressive effect. Notably, His418Gln-KLF11 canceled the suppressive effect of co-transfected WT-KLF11. Such a dominant-negative effect was absent in the previously reported Ala347Ser-KLF11 variant. These results indicate that specific variants of KLF11 (MODY7) with a dominant-negative effect underlie early childhood-onset type 1B diabetes with incomplete penetrance. This study documents a novel monogenic mutation associated with diabetes in children.

Thyroid peroxidase (TPO) deficiency, caused by biallelic TPO mutations, is a well-established genetic form of congenital hypothyroidism (CH). More than 100 patients have been published, and the patients have been diagnosed mostly in the frame of newborn screening (NBS) programs. Correlation between clinical phenotypes and TPO activity remains unclear. Here, we report clinical and molecular findings of two unrelated TPO mutation-carrying mildly hypothyroid patients. The two patients were born at term after an uneventful pregnancy and delivery, and were NBS negative. They sought medical attention due to goiter at age 8 years. Evaluation of the thyroid showed mild elevation of serum TSH levels, normal or slightly low serum T-4 levels, high serum T-3 to T-4 molar ratio, high serum thyroglobulin levels, and high thyroidal I-123 uptake. We performed next-generation sequencing-based genetic screening, and found that one patient was compound heterozygous for two novel TPO mutations (p.Asp224del; c.820-2A>G), and the other was homozygous for a previously known mutation (p.Trp527Cys). In vitro functional analyses using HEK293 cells showed that the two amino acid-altering mutations (p.Asp224del and p.Trp527Cys) caused partial loss of the enzymatic activity. In conclusion, we report that TPO mutations with residual activity are associated with mild TPO deficiency, which is clinically characterized by marked goiter, mild TSH elevation, high serum T-3 to T-4 molar ratio, and high serum thyroglobulin levels. Our findings illuminate the hitherto under-recognized correlation between clinical phenotypes and residual enzymatic activity among patients with TPO deficiency.

BACKGROUND: MIRAGE syndrome, a congenital multisystem disorder due to pathogenic SAMD9 variants, describes a constellation of clinical features including 46,XY disorders of sex development (DSD), small for gestational age (SGA) and adrenal insufficiency (AI). It is poorly understood whether SAMD9 variants underlie 46,XY DSD patients born SGA (46,XY DSD SGA) without AI. This study aimed to define the frequency and phenotype of SAMD9 variants in 46,XY DSD SGA without AI. METHODS: Forty-nine Japanese patients with 46,XY DSD SGA (Quigley scale, 2 to 6; gestational age-matched birth weight percentile, <10) without history of AI were enrolled. The single coding exon of SAMD9 was PCR-amplified and sequenced for each patient. Pathogenicity of an identified variant was verified in vitro. Placenta tissues were obtained from the variant-carrying patient, as well as from another previously described patient, and were analyzed histologically. RESULTS: In one 46,XY DSD SGA patient, a novel heterozygous SAMD9 variant, p.Phe1017Val, was identified. Pathogenicity of the mutant was experimentally confirmed. In addition to DSD and SGA, the patient had neonatal thrombocytopenia, severe postnatal grow restriction, chronic diarrhea and susceptibility to infection, all features consistent with MIRAGE, leading to premature death at age 14 months. The patient did not have any manifestations or laboratory findings suggesting AI. Placenta tissues of the two variant-carrying patients were characterized by maldevelopment of distal villi without other findings of maternal underperfusion. CONCLUSIONS: MIRAGE syndrome is a rare cause of 46,XY DSD SGA without AI. This study exemplifies that AI is a common feature of MIRAGE syndrome but that the absence of AI should not rule out a diagnosis of the syndrome.

Aspiration pneumonia is a common complication of myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy (MIRAGE) syndrome. However, the detailed clinical course of aspiration pneumonia in neonates and infants diagnosed with this disorder remains unclear. We report a case of a 2-yr-old girl diagnosed with MIRAGE syndrome during the early neonatal period. The patient developed 3 episodes of aspiration pneumonia until 4 mo of age, and this complication was attributed to esophageal hypoperistalsis secondary to achalasia and gastroesophageal reflux. Enteral feeding via a duodenal tube effectively prevented further episodes of aspiration pneumonia in this patient.

CLINICAL CHARACTERISTICS: MIRAGE syndrome is an acronym for the major findings of myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy. Cytopenias are typically seen soon after birth; Thrombocytopenia is the most common followed by anemia and pancytopenia. Recurrent infections from early infancy include pneumonia, urinary tract infection, gastroenteritis, meningitis, otitis media, dermatitis, subcutaneous abscess, and sepsis. Reported genital phenotypes in those with 46,XY karyotype included hypospadias, microphallus, bifid shawl scrotum, ambiguous genitalia, or complete female genitalia. Hypoplastic or dysgenetic ovaries have been reported in females. Gastrointestinal complications include chronic diarrhea and esophageal dysfunction. Moderate-to-severe global developmental delay is reported in most affected individuals. Autonomic dysfunction and renal dysfunction are also reported. DIAGNOSIS/TESTING: The diagnosis of MIRAGE syndrome is established in a proband with suggestive findings and a heterozygous germline gain-of-abnormal-function pathogenic variant in SAMD9 identified by molecular genetic testing. MANAGEMENT: Treatment of manifestations: Individuals with severe anemia and thrombocytopenia due to bone marrow failure should be treated with standard transfusion approaches; bacterial infection prevention including antibiotic prophylaxis and fever precautions in individuals with severe neutropenia. Individuals with severe neutropenia and chronic transfusion requirements, along with individuals who develop monosomy 7 myelodysplastic syndrome should be considered for hematopoietic stem cell transplantation. Standard treatment of infections with antibiotics, antiviral or antifungal agents as needed; consider prophylactic intravenous immunoglobulin if endogenous immunoglobulin levels are low; management by nutritionist to ensure adequate caloric intake and to assist with elemental diet for chronic diarrhea; hydrocortisone and fludrocortisone as needed for adrenal hypoplasia; surgical removal of dysgenetic gonads or surgical intervention may be considered for those with external genital anomalies; consider duodenal tube feeding in those with recurrent aspiration pneumonia; early intervention with occupational, physical, speech and feeding therapy for developmental delay; artificial tear solutions and treatment per ophthalmologist for ocular manifestations of autonomic dysfunction such as hypolacrima; management of ambient temperature for those with temperature instability; management of renal dysfunction per nephrologist. Surveillance: Complete blood count with differential every four to six months; annual bone marrow aspirate and biopsy (with analysis for somatic alterations including chromosome 7 abnormalities) in those with cytopenias including anemia, thrombocytopenia, or neutropenia; at least annual assessment of height, weight, head circumference, physical examination for features of adrenal hypoplasia, and measurement of serum sodium, potassium, glucose, cortisol, and ACTH. Assess for diarrhea, feeding issues, and esophageal dysfunction as needed; monitor developmental milestones every three to six months in the first year of life and at least annually thereafter; assess for keratoconjunctivitis sicca, corneal ulcer, and temperature instability as needed; at least annual measurement of serum creatinine, blood urea nitrogen, and urinalysis to evaluate renal function. Evaluation of relatives at risk: It is appropriate to clarify the genetic status of apparently asymptomatic at-risk relatives of an affected individual in order to identify as early as possible those who would benefit from evaluation for myelodysplasia. GENETIC COUNSELING: MIRAGE syndrome is an autosomal dominant disorder typically caused by a de novo pathogenic variant. Rarely, individuals diagnosed with MIRAGE syndrome have the disorder as the result of a variant inherited from a heterozygous parent with no apparent features of MIRAGE syndrome. If the proband has an SAMD9 pathogenic variant that is not detected in the leukocyte DNA of either parent, the recurrence risk to sibs is slightly greater than that of the general population because of the possibility of parental germline mosaicism or the possibility of a false negative result in a parent due to preferential loss of the chromosome with the SAMD9 pathogenic variant. Once the SAMD9 pathogenic variant has been identified in an affected family member, prenatal and preimplantation genetic testing are possible.

BACKGROUND: Recently, a patient with maternal uniparental disomy of chromosome 16 (UPD(16)mat) presenting with Silver-Russell syndrome (SRS) phenotype was reported. SRS is characterised by growth failure and dysmorphic features. OBJECTIVE: To clarify the prevalence of UPD(16)mat in aetiology-unknown patients with SRS phenotype and phenotypic differences between UPD(16)mat and SRS. METHODS: We studied 94 patients with SRS phenotype of unknown aetiology. Sixty-three satisfied the Netchine-Harbison clinical scoring system (NH-CSS) criteria, and 25 out of 63 patients showed both protruding forehead and relative macrocephaly (clinical SRS). The remaining 31 patients met only three NH-CSS criteria, but were clinically suspected as having SRS. To detect UPD(16)mat, we performed methylation analysis for the ZNF597:TSS-differentially methylated region (DMR) on chromosome 16 and subsequently performed microsatellite, SNP array and exome analyses in the patients with hypomethylated ZNF597:TSS-DMR. RESULTS: We identified two patients (2.1%) with a mixture of maternal isodisomy and heterodisomy of chromosome 16 in 94 aetiology-unknown patients with SRS phenotype. Both patients exhibited preterm birth and prenatal and postnatal growth failure. The male patient had ventricular septal defect and hypospadias. Whole-exome sequencing detected no gene mutations related to their phenotypes. CONCLUSION: We suggest considering genetic testing for UPD(16)mat in SRS phenotypic patients without known aetiology.

Background: DUOX2 is one of the major causative genes of congenital hypothyroidism (CH). Still, the mutation spectrum and clinical outcomes of biallelic DUOX2 variants are not fully understood. This study aimed to elucidate the molecular features and long-term clinical manifestations of CH caused by multiple pathogenic DUOX2 variants. Methods: A total of 255 patients with CH were screened for rare variants of 11 known causative genes. DUOX2 variants were classified according to their protein structure and residual activity. In vitro assays were performed for several variants of unknown functions. Clinical analyses were conducted for patients with multiple pathogenic variants of DUOX2 but not of other genes. Results: We identified 24 pathogenic variants of DUOX2, together with two benign variants and seven variants of uncertain significance, in 63 patients. The pathogenic variants included three missense substitutions and one frameshift variant that have not yet been linked to CH. Twenty-one patients carried multiple pathogenic DUOX2 variants without any other pathogenic gene variants. Three of the 21 patients harbored homozygous variants. Family analysis, long-read amplicon sequencing, and haplotype phasing confirmed compound heterozygosity of the DUOX2 variants in 14 patients, whereas the allelic positions of the variants in the remaining four patients could not be determined. Of the 21 patients, 19 were treated with levothyroxine; their ages at drug withdrawal ranged from 9 months to 21.4 years. Three patients required retreatment after drug-free intervals of 6 months, 8 months, and 10 years. There were no differences in clinical severity among patients with DUOX2 amorphic/amorphic, amorphic/hypomorphic, and hypomorphic/hypomorphic variants. Conclusions: These results broaden the mutational spectrum of DUOX2. Furthermore, our data imply that patients with multiple pathogenic DUOX2 variants typically exhibit transient CH without significant genotype-phenotype correlations. Most importantly, this study demonstrated for the first time that these patients are at risk of developing recurrent hypothyroidism after a long drug-free interval.

Germline mutations in TP53 are the primary cause of Li-Fraumeni syndrome (LFS). Most mutations are reported within the DNA-binding domain. We report a case of a 15-year-old boy with LFS who developed early-stage nodular lymphocyte-predominant Hodgkin lymphoma, a rare subtype of Hodgkin lymphomas. His sister was diagnosed with embryonal rhabdomyosarcoma at the age of 1.5 years. Sequence analysis revealed a germline mutation in the transactivation domain of TP53, c.145G>C (p.D49H), in the patient, his sister, and father. One family with LFS with a germline TP53 D49H mutation has previously been reported. This report supports the pathogenicity of this mutation.