Published papers

Premature aging syndrome, Penttinen type (Penttinen syndrome) is a progeroid syndrome with facial alterations (thin hair and progressive recession of the maxillozygomatic bones with pseudoprognathism), skin abnormalities (scleroderma with epidermal and dermal atrophy, lipoatrophy, chronic ulcers, and keloid-like hypertrophic lesions), corneal changes (vascularization and opacity), cerebral vascular anomalies, and acroosteolysis. This syndrome is caused by heterozygous, gain-of-function pathogenic variants in the PDGFRB gene. Only 10 affected individuals have been reported to date, and thus the phenotypic spectrum of the disorder, particularly in early childhood, remains elusive. We reported here the clinical course of an affected male from early childhood to young adulthood. Thin limbs and short fingers attracted medical attention at age 3 years, at which time he had already developed maxillary hypoplasia, keloids, and acroosteolysis, all of which progressively worsened with age. Joint contractures and scoliosis became apparent during adolescence. Progressive maxillary recession and scleroderma remarkably altered his facial gestalt over time, including the development of exophthalmos, small auricles, short philtrum, and small mouth. Sanger sequencing identified a recurrent, de novo pathogenic variant in the PDGFRB gene (c.1994T > C, p.Val665Ala). This report on the clinical course through childhood provides additional insight into the natural history of Penttinen syndrome.

PAX8 is a transcription factor that is expressed in the thyroid gland and kidneys. Monoallelic loss-of-function PAX8 variants cause congenital hypothyroidism (CH), and urogenital malformations are infrequent complications seen in less than 10% of PAX8 variant carriers. Herein, we report the case of a 3-yr-old female patient with CH who was diagnosed during newborn screening. She was treated with levothyroxine, and she showed normal growth and development at a minimal dose (0.7 µg/kg/d of levothyroxine at 3 yr of age). At 5 mo of age, she visited an emergency department for fever and was incidentally found to have differently sized kidneys by ultrasonography, which was subsequently diagnosed as unilateral multicystic dysplastic kidney. Her serum creatinine and cystatin C levels were normal. Next-generation sequencing-based genetic analysis revealed that the patient was heterozygous for a PAX8 frameshift variant (p.Thr320ProfsTer106) and a DUOX2 missense variant (p.Arg885Gln). Our patient is the first truncating PAX8 variant carrier to have a urogenital malformation with CH. Genetic analysis for PAX8 should be considered in patients with CH and urogenital malformations.

We report a male infant with congenital nephrogenic diabetes insipidus (NDI) who presented with hypercalcemia and hyperphosphatemia since birth. Serum sodium started to increase at 39 days. Although there was no polyuria, urine osmolality was 71 mOsm/kg, when serum osmolality was 296 mOsm/kg with plasma arginine vasopressin 22.5 pg/mL. He was thus diagnosed as NDI. An undetectable level of urine calcium and unsuppressed intact parathyroid hormone suggested hyperparathyroidism including calcium-sensing receptor mutations that could cause hypercalcemia-induced NDI. Polyuria became apparent after the initiation of i.v. infusion for the treatment of hypernatremia. Low calcium and low sodium formula with hypotonic fluid infusion did not correct hypernatremia, hypercalcemia, or hyperphosphatemia. Hydrochlorothiazide and subsequently added celecoxib effectively decreased urine output and corrected electrolytes abnormalities. Normal serum electrolytes were maintained after the discontinuation of low calcium formula. The genetic analysis revealed a large deletion of the arginine vasopressin receptor-2 (AVPR2) gene but no pathogenic variant in the calcium-sensing receptor (CASR) gene. Whether hypercalcemia and hyperphosphatemia were caused by dehydration alone or in combination with other mechanisms remains to be clarified.

Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder that causes gonadotropin-releasing hormone (GnRH) deficiency and sexual immaturity. CHH may accompany an abnormal sense of smell (Kallmann syndrome, KS) or no such manifestation (normosmic-CHH). This unusual combination of manifestations is explained by the fact that GnRH neurons originate in the olfactory placode and migrate to the forebrain during embryogenesis. We describe the case of a 31-year-old man with normosmic-CHH, who also had obesity, type 2 diabetes and intellectual disability. He was noticed to have sexual immaturity (small testes with no pubic hair) at age 20 years, when diabetic ketoacidosis developed. Basal and GnRH-stimulated levels of LH (1.0→12.0 IU/L) and FSH (1.9→6.1 IU/L) were detectable but low. The results of the T&T olfactometer and the Alinamin test were definitely normal, with an anatomically normal olfactory system on MRI. Sequencing of 22 CHH-related genes was performed, and compound heterozygous PROKR2 variants were identified: one was a previously known loss-of-function variant (p.Trp178Ser) and the other was a nonsense variant (p.Trp212*). Through a literature review, we found 22 patients (including our patient) with CHH due to biallelic PROKR2 variants, which led us to recognize that most of the patients (86%) were diagnosed with KS. Clinical observations in this study indicate that, even though they have CHH, biallelic PROKR2 variant carriers may have a normal olfactory system as well as presumably normal migration of GnRH neurons. This suggests that the PROK2-PROKR2 pathway affects the function of GnRH neurons after their migration.

There have been no reports comparing neonatal external genitalia of 5α-reductase deficiency (5αRD) with those of other 46,XY differences of sex differentiation (DSD). This study enrolled 31 Japanese cases of 46,XY DSD whose external genitalia was examined during the neonatal period; four were diagnosed as 5αRD and 15 were defined as non-5αRD by genetic analysis of SRD5A2 or urinary steroid metabolites. We compared the following characteristics between 5αRD and non-5αRD groups, adjusting the severity of undermasculinization of the external genitalia: stretched penile length (SPL), glans width, location of the external urethral opening, and proportion of undescended testis. The external genitalia of all the 5αRD cases were Quigley classification grade 2 or 3. We compared the phenotypes between the four 5αRD cases and 11 non-5αRD cases with grade 2 or 3. The median (range) of SPL in the 5αRD group (14 mm [11-16]) was significantly lower than that in the non-5αRD group (22 mm [15-29]) (p = 0.003). An SPL cut-off value of <15 mm yielded a sensitivity of 50% (95% confidence interval [CI]; 7–93%) and specificity of 100% (95% CI, 72–100%) for discriminating between the groups. The median glans width, location of the external urethral opening, and proportion of undescended testis were not significantly different between the groups. The SPL of 5αRD in Quigley classification grade 2 or 3 was significantly shorter than that of other 46,XY DSDs with the equivalent grade.

Complete androgen insensitivity syndrome (CAIS) is caused by mutations in the androgen receptor gene. Patients with this syndrome have a 46,XY karyotype, male gonads, and normal female external genitalia. While the pre-pubertal risk of developing gonadal tumors is low in these patients, it increases with age. Most gonadal tumors arise from germ cells; stromal cell tumors are uncommon. Herein, we report a CAIS patient with a feminizing Sertoli cell tumor. The patient presented at 8 yr of age with breast enlargement and growth acceleration, concomitant with elevated serum estradiol levels and suppressed serum gonadotropin levels; these findings were inconsistent with CAIS. The patient underwent gonadectomy at 10 yr of age, and histology demonstrated presence of a non-malignant Sertoli cell tumor in the right gonad. We conclude that this is the first reported case of CAIS with accelerated onset of puberty resulting from a Sertoli cell tumor.

Introduction: The testicular regression syndrome (TRS) is a form of differences of sex development (DSD) in which the testes differentiate and function during early embryonic development, but subsequently regress. The clinical phenotype of TRS often overlaps with that of partial gonadal dysgenesis (PGD). Previous studies have demonstrated a causal association between TRS/ PGD and heterozygous missense variants of DHX37. Methods: We enrolled 11 Japanese 46,XY individuals (from 10 families) with TRS/PGD who exhibited undetected or hypoplastic testes, Müllerian duct regression, and low serum testosterone or anti- Müllerian hormone levels. The subjects underwent targeted sequencing of 36 known causative genes for DSD, PCR-based Sanger sequencing of DHX37, or whole-exome sequencing. Results: Previously described pathogenic variants or novel nonsense variants (SRY, NR5A1, and DMRT1) were observed in four out of 10 families. Additionally, we identified two heterozygous rare variants of DHX37 in four families: a previously reported pathogenic variant (c.923G>A, p.Arg308Gln) in three and a novel likely pathogenic variant (c.1882A>C, p.Thr628Pro) in one. The external genitalia of patients with the DHX37 variants varied from female-type to male-type without micropenis. Eighty percent of Japanese patients with TRS/PGD had monogenic disorders including DHX37 variant being the most commonly identified (40%). The external or internal genital phenotype of TRS/PGD overlaps between DHX37 variant carriers and others. Conclusions: DHX37 variant is one of the common genetic causes in Japanese patients with TRS/PGD without Müllerian derivatives. Genetic test is helpful in detecting DHX37- related TRS/PGD because of the phenotypic diversity of the external genitalia in this disorder.

Genetic variants involving steroidogenic acute regulatory protein cause lipoid congenital adrenal hyperplasia, which is characterized by impaired steroidogenesis in the adrenal glands and gonads. Functional assessment of variant STAR proteins is necessary for an accurate genetic diagnosis. Ideally, steroidogenic cells should be used to assess the functionality of STAR proteins, but the presence of endogenous STARs in steroidogenic cells precludes such a method. Here, we generated Star-edited cells from steroidogenic Y1 mouse adrenocortical tumor cells by genome editing. Star-edited Y1 cells exhibited very low but measurable cAMP-dependent pregnenolone production. Furthermore, stimulation of the cAMP pathway for 2 weeks resulted in the formation of lipid droplets in the cytoplasm of Star-edited Y1 cells, which resembled the histology of the adrenal glands of patients with lipoid congenital adrenal hyperplasia. The steroidogenic defect of Star-edited Y1 cells can be restored by transient overexpression of mouse Star. We found that human STAR can also restore defective steroidogenesis in Star-edited Y1 cells, and we were able to construct a novel in vitro system to evaluate human STAR variants. Collectively, we established Star-edited Y1 cells that retain the steroidogenic pathway downstream of the Star protein. Star-edited Y1 cells recapitulate the functional and morphological changes of lipoid congenital adrenal hyperplasia and can be used to evaluate the functionality of human STAR variants.

Introduction: Non-autoimmune hyperthyroidism (NAH) is a rare genetic disorder caused by germline-activating variants in the TSH receptor (TSHR) gene. While most NAH-related TSHR variants are located in the seven-transmembrane domain (7TMD), three variants (p.Leu267Phe, p.Ser281Asn, and p.Asn406Ser) have been identified in the extracellular domain (ECD), with p.Leu267Phe previously not showing constitutively active in vitro. Methods: We searched for TSHR variants in a Japanese family with NAH using PCR-based direct sequencing. We created three ECD variants (p.Leu267Phe, p.Ser281Asn, and p.Asn406Ser) and a series of variants in which Leu267 was mutated to 18 amino acids other than Leu and Phe. Based on the cryo-electron microscopic structures, we evaluated the structure-function relationship of TSHR. We compared their cAMP-producing capacities to WT-TSHR in the luciferase activity assay using HEK293 cells. Western blot and fluorescence immunostaining were performed using HA-tagged TSHR vectors to compare Leu267Phe-TSHR with WT-TSHR. Results: A heterozygous TSHR variant (p.Leu267Phe) was identified. Comparison of the cryo-electron microscopy structures of the activated and inactivated TSHRs revealed a significant change in the ECD structure around Leu267. The ligand-independent cAMP-producing capacities compared to WT-TSHR were 238 ± 20% (mean ± SEM) for Leu267Phe. Of all 19 possible variants created through systematic mutagenesis, only Leu267Phe-TSHR and Leu267Tyr-TSHR exhibited significantly higher ligand-independent cAMP-producing capacities. Immunoblotting and fluorescence immunostaining showed that the Leu267Phe variant did not affect protein expression levels and intracellular localization of TSHR. Discussion/Conclusion: Leu267Phe-TSHR causes NAH. Substituting Leu267 to aromatic amino acids may shift the equilibrium of the TSHR state toward activation.

Introduction: Little is known about the association between hypospadias and small fetuses, as well as the pathological implications of fetal growth restriction (FGR). Thus, we aimed to investigate the association between hypospadias and small fetuses using a database of fetal ultrasound and obstetric events. Methods: A cohort of male singleton infants delivered after 22 weeks of gestation at Keio University Hospital between 2013 and 2019 was retrospectively reviewed. FGR was defined according to the Delphi criteria. Logistic regression analysis was performed to identify the significant predictors of hypospadias. Placental pathology was reviewed in cases with hypospadias. Results: Of the 2,040 male infants included in the present study, 23 had hypospadias. The prevalences of a single umbilical artery (SUA), small for gestational age, maternal hypertensive disorders of pregnancy, and a small placenta, were significantly higher in infants with hypospadias. Multiple logistic regression analysis revealed that FGR (odds ratio [OR] = 9.39; 95% confidence interval [CI], 2.50–35.3) and the presence of a SUA (OR = 33.4; 95% CI, 8.00–139.5) were independently and significantly associated with hypospadias. When FGR was stratified by the time of onset, its association with hypospadias was significant regardless of the time of onset. Moreover, placental histological findings suggested that fetal vascular malperfusion might play a role in hypospadias. Discussion: FGR and SUAs are independent prenatal predictors of the development of hypospadias, and fetal vascular malperfusion of the placenta may be involved in the etiology of hypospadias.

Objectives: The role of serum fibroblast growth factor 23 (FGF23) level in early neonatal period on the diagnosis of X-linked hypophosphatemic rickets (XLH) remains unclear. Case presentation: Two female patients from the first pedigree had an affected mother, and the other female from the second pedigree had an affected father. In all three cases, FGF23 levels were high in cord blood and peripheral blood at day 4-5. Additionally, the FGF23 levels considerably increased from birth to day 4-5. We identified a PHEX pathogenic variant and initiated treatment during infancy in each case. Conclusions: In neonates with a parent diagnosed as PHEX-associated XLH, FGF23 in cord blood and peripheral blood at day 4-5 may be useful markers for predicting the presence of XLH.

A 43-year-old woman with genetically confirmed glycogen storage disease type Ib was suspected to have left breast cancer. Fluorodeoxyglucose-positron emission tomography showed high fluorodeoxyglucose accumulation in the whole liver as well as left mammary gland. We consider that high fluorodeoxyglucose accumulation in the liver of patients with glycogen storage disease type I is caused by impaired glucose-6-phosphate metabolism due to the congenital deficiency of glucose-6-phosphatase activities in hepatocytes. This study describes fluorodeoxyglucose-positron emission tomography as a potential alternative tool to diagnose glycogen storage disease type I functionally.

Insufficient thyroid hormone production in newborns is referred to as congenital hypothyroidism. Multinodular goiter (MNG), characterized by an enlarged thyroid gland with multiple nodules, is usually seen in adults and is recognized as a separate disorder from congenital hypothyroidism. Here we performed a linkage analysis of a family with both nongoitrous congenital hypothyroidism and MNG and identified a signal at 15q26.1. Follow-up analyses with whole-genome sequencing and genetic screening in congenital hypothyroidism and MNG cohorts showed that changes in a noncoding TTTG microsatellite on 15q26.1 were frequently observed in congenital hypothyroidism (137 in 989) and MNG (3 in 33) compared with controls (3 in 38,722). Characterization of the noncoding variants with epigenomic data and in vitro experiments suggested that the microsatellite is located in a thyroid-specific transcriptional repressor, and its activity is disrupted by the variants. Collectively, we presented genetic evidence linking nongoitrous congenital hypothyroidism and MNG, providing unique insights into thyroid abnormalities.

Context: Thyroglobulin (Tg), encoded by TG, is essential for thyroid hormone synthesis. TG defects result in congenital hypothyroidism (CH). Most reported patients were born before the introduction of newborn screening (NBS). Objective: We aimed to clarify the phenotypic features of patients with TG defects diagnosed and treated since the neonatal period. Methods: We screened 1061 patients with CH for 13 CH-related genes and identified 30 patients with TG defects. One patient was diagnosed due to hypothyroidism-related symptoms and the rest were diagnosed via NBS. Patients were divided into 2 groups according to their genotypes, and clinical characteristics were compared. We evaluated the functionality of the 7 missense variants using HEK293 cells. Results: Twenty-seven rare TG variants were detected, including 15 nonsense, 3 frameshift, 2 splice-site, and 7 missense variants. Patients were divided into 2 groups: 13 patients with biallelic truncating variants and 17 patients with monoallelic/biallelic missense variants. Patients with missense variants were more likely to develop thyroid enlargement with thyrotropin stimulation than patients with biallelic truncating variants. Patients with biallelic truncating variants invariably required full hormone replacement, whereas patients with missense variants required variable doses of levothyroxine. Loss of function of the 7 missense variants was confirmed in vitro. Conclusion: To our knowledge, this is the largest investigation on the clinical presentation of TG defects diagnosed in the neonatal period. Patients with missense variants showed relatively mild hypothyroidism with compensative goiter. Patients with only truncating variants showed minimal or no compensative goiter and required full hormone replacement.

Rationale:Paraganglioma (PGL), an extra-adrenal pheochromocytoma, is a rare tumor, especially in children. While hypersecretion of catecholamines causes the classic triad of headaches, palpitations, and profuse sweating, prompt diagnosis is still challenging.Patient concerns:For 7 months, an 8-year-old boy complained of polyuria and weight loss, followed by proteinuria and headache for 1 month prior to admission. He was admitted to our hospital due to an afebrile seizure.Diagnosis:His blood pressure remained markedly elevated even after cessation of the convulsion. Magnetic resonance imaging of the brain revealed posterior reversible encephalopathy syndrome. Abdominal computed tomography showed a mass lesion encasing the left renal artery, measuring 41 mm in length along its major axis. The plasma and urine levels of normetanephrine were elevated. Additionally, iodine-123-metaiodobenzylguanidine scintigraphy showed an abnormal uptake in the abdominal mass with no evidence of metastasis. Based on these findings, we tentatively diagnosed him with PGL.Intervention:Substantial alpha-and beta-blocking procedures were performed, followed by a tumor resection and an extended left nephrectomy on day 31 of hospitalization. Pathological findings confirmed the diagnosis of PGL.Outcome:The postoperative course was uneventful, and his blood pressure normalized without the use of antihypertensive agents. Genetic testing revealed a known SDHB germline mutation. The same mutation was also detected on his father and paternal grandfather without any history of hypertension or malignant tumor.Lesson:It remains challenging to diagnose pheochromocytoma/paraganglioma (PPGL) promptly because PPGL can present with a variety of symptoms. Preceding symptoms of the presented case might be caused by PGL. Although PPGL is a rare disease, especially in children, it should be considered in differential diagnosis when various unexplained symptoms persist.

For salt-wasting 21-hydroxylase deficiency (21OHD), fludrocortisone (FC) is usually supplemented at 0.05–0.2 mg/d dose. To date, no report has described 21OHD neonates requiring > 0.4 mg/d of FC. Our female 21OHD patient was lethargic and experienced weight loss with hyponatremia (133 mEq/L), hyperkalemia (6.5 mEq/L), and elevated active renin concentration (ARC, 1942.2 pg/mL) at 6 days of life. Hydrocortisone and FC replacement were initiated. FC dose was gradually increased to 0.4 mg/d at 21 days of life, but her hyperkalemia (6.4 mEq/L) and high ARC (372.3 pg/mL) persisted. We increased FC to 0.6 mg/d and used a low-potassium and high-sodium formula. Hyperkalemia subsequently improved. At 33 days of life, the ARC decreased to 0.6 pg/mL and FC dosage was gradually decreased. At 3 months of age, the low-potassium and high-sodium formula was discontinued, but the serum potassium level was normal and ARC remained low at 0.1 mg/d of FC. We speculated that severe mineralocorticoid resistance was the reason why her hyperkalemia persisted even with 0.4 mg/d of FC; however, the pathophysiology of transiently severe resistance to FC in this patient is unknown. In conclusion, 21OHD neonates may show severe salt-wasting that transiently require > 0.4 mg/d of FC.

SOX9, a transcription factor, is expressed in the undifferentiated XX and XY gonads. SRY induces significant upregulation of SOX9 expression in XY gonads. Loss-of-function SOX9 variants cause testicular dysgenesis in 46,XY patients, while duplication of the total gene or the upstream regulatory region results in testicular development in 46,XX patients. However, gain-of-function (GoF) SOX9 variants have not been reported previously. We report the case of a 16-year-old female patient with a 46,XX karyotype who had masculinized external genitalia and unilateral ovotestis. Next-generation sequencing-based genetic screening for disorders of sex development led to the identification of a novel SOX9 variant (p.Glu50Lys), transmitted from the phenotypically normal father. Expression analysis showed that E50K-SOX9 enhanced transactivation of the luciferase reporter containing the testis enhancer sequence core element compared with that containing the wildtype-SOX9. This GoF activity was not observed in the luciferase reporter containing Amh, the gene for anti-Müllerian hormone. We genetically engineered female mice (Sox9E50K/E50K), and they showed no abnormalities in the external genitalia or ovaries. In conclusion, a novel SOX9 variant with a promoter-specific GoF activity was identified in vitro; however, the disease phenotype was not recapitulated by the mouse model. At present, the association between the GoF SOX9 variant and the ovotestis phenotype remains unclear. Future studies are needed to verify the possible association.

Aim: During the coronavirus disease 2019 pandemic, the governments of many countries responded to high levels of infection with lockdowns. As a result, some children were reported to experience weight gain. The aim of the present study was to examine the impact of school closures on body mass index (BMI) in Japanese children. Methods: This was a retrospective study of students enrolled in the participating schools (6- to 11-year-old elementary school students and 12- to 14-year-old junior high school students) between 2015 and 2020. Using school health check-up data, annual changes in the BMI standard deviation score (ΔBMI-SDS) were calculated. We compared ΔBMI-SDS in 2019–2020 with the corresponding control years. Results: 19 565 children with complete data were included in the analysis. Median ΔBMI-SDS in 2019–2020 were 0.24–0.35 in elementary school boys, 0.10–0.13 in junior high school boys, −0.02 to 0.15 in elementary school girls and −0.14 to −0.10 in junior high school girls. In comparison with every control year, ΔBMI-SDS in 2019–2020 were significantly higher in elementary school boys (control years: −0.07 to 0.14) and junior high school boys (control years: −0.04 to 0.06), and significantly lower in junior high school girls (control years: −0.06 to 0.09). Conclusion: BMI-SDS increased significantly in elementary and junior high school boys, but decreased significantly in junior high school girls. The pandemic appears to have had an impact on Japanese children that was different from other countries.

Context: Inactivating variants of thyrotropin (thyroid-stimulating hormone; TSH) receptor (TSHR) cause congenital hypothyroidism. More than 60 such variants have been reported so far, most of which were located in the extracellular or transmembrane domain. Objective: We report the identification and characterization of a frameshift TSHR variant in the intracytoplasmic C-tail region. Methods: Sequencing of TSHR was performed in a patient with congenital hypothyroidism. The functionality of the identified variants was assessed by expressing TSHR in HEK293 cells and measuring TSH-dependent activation of the cAMP-response element-luciferase reporter. A series of systematic mutagenesis experiments were performed to characterize the frameshifted amino acid sequence. Results: The proband was heterozygous for a known TSHR variant (p.Arg519His) and a novel frameshift TSHR variant (p.Val711Phefs∗18), which removed 54 C-terminal residues and added a 17-amino acid frameshifted sequence. The loss of function of Val711Phefs∗18-TSHR was confirmed in vitro, but the function of Val711∗-TSHR was found to be normal. Western blotting showed the low protein expression of Val711Phefs∗18-TSHR. Fusion of the frameshift sequence to green fluorescent protein or luciferase induced inactivation of them, indicating that the sequence acted as a degron. A systematic mutagenesis study revealed that the density of hydrophobic residues in the frameshift sequence determined the stability. Eight additional frameshift TSHR variants that covered all possible shifted frames in C-tail were created, and another frameshift variant (Thr748Profs∗27) with similar effect was found. Conclusions: We characterized a naturally occurring frameshift TSHR variant located in C-tail, and provided a unique evidence that hydrophobicity in the C-terminal region of the receptor affects protein stability.