GWAS of thyroid dysgenesis identifies a risk locus at 2q33.3 linked to regulation of Wnt signaling.

Congenital hypothyroidism due to thyroid dysgenesis (TD), presented as thyroid aplasia, hypoplasia or ectopia, is one of the most prevalent rare diseases with an isolated organ malformation. The pathogenesis of TD is largely unknown, although a genetic predisposition has been suggested. We performed a genome-wide association study (GWAS) with 142 Japanese TD cases and 8380 controls and found a significant locus at 2q33.3 (top single nucleotide polymorphism, rs9789446: P = 4.4 × 10-12), which was replicated in a German patient cohort (P = 0.0056). A subgroup analysis showed that rs9789446 confers a risk for thyroid aplasia (per allele odds ratio = 3.17) and ectopia (3.12) but not for hypoplasia. Comprehensive epigenomic characterization of the 72-kb disease-associated region revealed that it was enriched for active enhancer signatures in human thyroid. Analysis of chromosome conformation capture data showed long-range chromatin interactions of this region with promoters of two genes, FZD5 and CCNYL1, mediating Wnt signaling. Moreover, rs9789446 was found to be a thyroid-specific quantitative trait locus, adding further evidence for a cis-regulatory function of this region in thyroid tissue. Specifically, because the risk rs9789446 allele is associated with increased thyroidal expression of FDZ5 and CCNYL1 and given the recent demonstration of perturbed early thyroid development following overactivation of Wnt signaling in zebrafish embryos, an enhanced Wnt signaling in risk allele carriers provides a biologically plausible TD mechanism. In conclusion, our work found the first risk locus for TD, exemplifying that in rare diseases with relatively low biological complexity, GWAS may provide mechanistic insights even with a small sample size.

Classification of pseudohypoaldosteronism type II as type IV renal tubular acidosis: results of a literature review.

Pseudohypoaldosteronism (PHA) type II (PHA2) is a genetic disorder that leads to volume overload and hyperkalemic metabolic acidosis. PHA2 and PHA type I (PHA1) have been considered to be genetic and pediatric counterparts to type IV renal tubular acidosis (RTA). Type IV RTA is frequently found in adults with chronic kidney disease and is characterized by hyperchloremic hyperkalemic acidosis with normal anion gap (AG). However, we recently observed that PHA1 was not always identical to type IV RTA. In this study, we focused on the acid-base balance in PHA2. Through a literature search published between 2008-2020, 46 molecularly diagnosed cases with PHA2 were identified (median age of 14 years). They comprised 11 sets of familial and 16 sporadic cases and the pathology was associated with mutations in WNK 4 (n = 1), KLHL3 (n = 17), and CUL3 (n = 9). The mean potassium (K+) level was 6.2 ± 0.9 mEq/L (n = 46, range 4.0-8.6 mEq/L), whereas that of chloride (Cl-) was 110 ± 3.5 mEq/L (n = 41, 100-119 mEq/L), with 28 of 41 cases identified as hyperchloremic. More than half of the cases (18/35) presented with metabolic acidosis. Although AG data was obtained only in 16 cases, all but one cases were within normal AG range. Both Cl- and HCO3- levels showed significant correlations with K+ levels, which suggested that the degree of hyperchloremia and acidosis reflect the clinical severity, and is closely related to the fundamental pathophysiology of PHA2. In conclusion, our study confirmed that PHA2 is compatible with type IV RTA based on laboratory findings.

Quantification of serum thyroid hormones using tandem mass spectrometry in patients with Down syndrome.

Thyroid dysfunction is common in patients with Down syndrome (DS), the most common chromosomal disorder. Thyroid hormones (THs) are important for normal growth, neurodevelopment, and metabolism, highlighting the importance of quantifying the levels in patients with DS. However, current methods possess cross-reactivity that results in inaccuracies in quantification. We aimed at developing a new analytical method for quantifying the total 3,3',5-triiodo-l-thyronine (TT3), total 3,3',5,5'-tetraiodo-l-thyronine (TT4), 3,3',5'-triiodo-l-thyronine, and reverse T3 (rT3) levels using LC-MS/MS. Repeatability and reproducibility with coefficient of variation values of 2-9 and 3-13%, respectively, were acceptable, suggesting that the assay was suitable for measuring serum THs. We measured the serum TH levels of patients with DS but without thyroid dysfunction (age, 3-20 years) and compared the levels to those of controls (patients with idiopathic short stature; age, 3-17 years). When TH levels were summarized by age group, the serum TT4 concentrations were not significantly different between the controls and patients with DS across all age groups. Meanwhile, the serum TT3 concentrations differed according to age. In addition, the serum rT3 concentrations were significantly higher in patients with DS than in controls, except for those in the 12-14 age group. We also calculated the T3/T4 and rT3/T4 ratios to elucidate the reason for the higher rT3 in patients with DS; however, no useful findings were obtained. Thus, further investigation is needed to clarify our findings.

Clinical performance of a novel chemiluminescent enzyme immunoassay for FGF23.

INTRODUCTION: Measurement of fibroblast growth factor 23 (FGF23) has been reported to be clinically useful for the differential diagnosis of chronic hypophosphatemia. However, assays for research use only are available in Japan. Thus, the objective of this study was to examine the clinical utility of a novel and automated chemiluminescent enzyme immunoassay for the measurement of FGF23. MATERIALS AND METHODS: Participants were recruited from July 2015 to January 2017 at six facilities in Japan. Thirty-eight patients with X-linked hypophosphatemic rickets (XLH 15 males, 23 females, age 0-66 years), five patients with tumour-induced osteomalacia (TIO 3 males, 2 females, age 60-73 years), and twenty-two patients with hypophosphatemia (11 males, 11 females, age 1-75 years) caused due to other factors participated in this study. RESULTS: With the clinical cut-off value of FGF23 at 30.0 pg/mL indicated in the Diagnostic Guideline of Rickets/Osteomalacia in Japan, the sensitivity and specificity of FGF23-related hypophosphatemic rickets/osteomalacia without vitamin D deficiency (disease group-1) were 100% and 81.8%, respectively, which distinguished it from non-FGF23-related hypophosphatemia (disease group-2). Furthermore, the diagnostic sensitivity of FGF23-related hypophosphatemia with vitamin D deficiency remained at 100%. Among the four patients with FGF23 levels ≥ 30.0 pg/mL in disease group-2, two patients with relatively higher FGF23 values were suspected to have genuine FGF23-related hypophosphatemia, due to the ectopic production of FGF23 in pulmonary and prostate small cell carcinomas. CONCLUSION: The novel FGF23 assay tested in this study is useful for the differential diagnosis of hypophosphatemic rickets/osteomalacia in a clinical setting.

Metreleptin worked in a diabetic woman with a history of hematopoietic stem cell transplantation (HSCT) during infancy: further support for the concept of 'HSCT-associated lipodystrophy'.

A 17-year-old woman with a history of childhood leukemia and hematopoietic stem cell transplantation (HSCT), preceded by total body irradiation, developed diabetes, dyslipidemia, fatty liver, and marked insulin resistance. Based on Dunnigan phenotype, HSCT-associated lipodystrophy was suspected. Because of rapid deterioration of diabetes control, metreleptin was introduced at 23 years of age upon receipt of her caregiver's documented consent. This trial was initially planned as a prospective 18 month-long study, with regular assessments of the patient's physical activity, food intake, and body composition analysis. However, because an abrupt and transient attenuation of the metreleptin effect occurred 16 months after the treatment initiation, the entire course of 28 months is reported here. Over the period, her HbA1c decreased from 10.9% to 6.7% despite no significant increase of physical activity and with a stable food intake. Decreased levels of triglyceride and non-HDL cholesterol were found. Her liver function improved, indicating the amelioration of fatty liver. In addition, a 25% reduction in the subcutaneous fat area at umbilical level was found, accompanied by a decrease in fat percentage of both total-body and trunk. The formation of neutralizing antibodies to metreleptin may be responsible for the transient loss of efficacy, considering a sudden elevation in her serum leptin level. In conclusion, metreleptin is useful for the management of HSCT-associated lipodystrophy, supporting the concept that adipose tissue dysfunction is responsible for diverse post-HSCT metabolic aberrations.

Growth impairment in individuals with citrin deficiency.

Citrin deficiency causes neonatal intrahepatic cholestasis (NICCD), failure to thrive and dyslipidemia (FTTDCD), and adult-onset type II citrullinemia (CTLN2). Owing to a defect in the NADH-shuttle, citrin deficiency impairs hepatic glycolysis and de novo lipogenesis leading to hepatic energy deficit. To investigate the physiological role of citrin, we studied the growth of 111 NICCD-affected subjects (51 males and 60 females) and 12 NICCD-unaffected subjects (five males and seven females), including the body weight, height, and genotype. We constructed growth charts using the lambda-mu-sigma (LMS) method. The NICCD-affected subjects showed statistically significant growth impairment, including low birth weight and length, low body weight until 6 to 9 months of age, low height until 11 to 13 years of age, and low body weight in 7 to 12-year-old males and 8-year-old females. NICCD-unaffected subjects showed similar growth impairment, including low birth weight and height, and growth impairment during adolescence. In the third trimester, de novo lipogenesis is required for deposition of body fat and myelination of the developing central nervous system, and its impairment likely causes low birth weight and length. The growth rate is the highest during the first 6 months of life and slows down after 6 months of age, which is probably associated with the onset and recovery of NICCD. Adolescence is the second catch-up growth period, and the proportion and distribution of body fat change depending on age and sex. Characteristic growth impairment in citrin deficiency suggests a significant role of citrin in the catch-up growth via lipogenesis.

Hyponatremia secondary to severe atopic dermatitis in early infancy.

BACKGROUND: Infants with atopic dermatitis who developed hyponatremia and hyperkalemia with raised aldosterone have been repeatedly described in the Japanese-language literature, but similar reports from other countries are scarce. METHODS: We collected reports of atopic dermatitis complicated with hyponatremia (≤130 mEq/L), written either in English or in Japanese, to delineate the characteristics and to elucidate the pathophysiology of this condition. RESULTS: Of a total of 36 patients, 35 were Japanese. All patients were infants younger than 9 months. Mean height SD score (SDS) at presentation was -2.1 ± 1.4 (n = 25), with mean body mass index 14.1 ± 1.7 kg/m2 (n = 28). Mean sodium was 120.7 ± 6.1 mEq/L. While 28 patients had hyperkalemia, seven patients had normokalemia. Elevated aldosterone was documented in 15 patients. Nutrition mainly with breast-feeding (97%), parental refusal of steroid ointment (77%), and the association of hypoalbuminemia (73%) were frequent findings. Diminished urinary sodium was verified in all 12 patients tested, indicating that sodium loss from the skin exudates, with limited supply of sodium from breast milk, is the primary cause of hyponatremia. Hyperkalemia seems to result from decreased delivery of sodium to the distal nephron and from the mechanism of the so-called "aldosterone paradox", which inhibits potassium secretion. In addition, physiological aldosterone insensitivity during infancy, low muscle volume, and impaired Na+ ,K+ -ATPase function due to protein deficiency seems to exaggerate the hyperkalemia. CONCLUSIONS: Hyponatremia secondary to severe atopic dermatitis is an age-dependent manifestation, elicited by inappropriate treatment that leads to sodium loss from the damaged skin and resultant hyperkalemia via multifaceted mechanisms.

Spontaneous virilization around puberty in NR5A1-related 46,XY sex reversal: additional case and a literature review.

A heterozygous NR5A1 mutation is one of the most frequent causes of 46,XY DSD (disorders of sex development). We here reported a NR5A1-related 46,XY DSD patient, who first received endocrinological attention at 10 years of age for clitoromegaly. The patient had been reared as a girl, and no signs of virilization had been detected before. On examination, her clitoris was 35 mm long and 10 mm wide, with Tanner 3° pubic hair. Urogenital sinus and labial fusion was absent, while her uterus was found to be severely hypoplastic. Her basal testosterone level was 94.8 ng/dL, suggesting the presence of functioning Leydig cells. Gonadal histology revealed bilateral dysplastic testes consisting of mostly Sertoli cell-only tubules and Leydig cell hyperplasia. Novel heterozygous Arg313Leu substitution in NR5A1 was identified in the patient. Literature search confirmed twelve other cases of this scenario, namely, severe under-virilization in utero followed by spontaneous virilization around puberty in NR5A1-related 46,XY DSD. Of interest, Leydig cell hyperplasia was documented in 6 out of 9 patients for whom testicular histology was available. To keep in mind about the possible restoration of Leydig cell function around puberty, even in patients without discernible in utero androgen effect, may be of clinical significance, because it will give a great impact on the judgement about sex assignment.

Next generation sequencing-based mutation screening of 86 patients with idiopathic short stature.

Although mutations in ACAN, FGFR3, NPR2, and SHOX typically lead to skeletal dysplasia, and mutations in GHRHR, GH1, GHR, STAT5B, IGF1, IGFALS, and IGF1R usually underlie hormonal defects of the growth hormone (GH)-insulin-like growth factor 1 (IGF1) axis, such mutations have also been identified in patients with idiopathic short stature (ISS). Of these, SHOX abnormalities are known to account for a certain percentage of ISS cases, whereas the frequency of mutations in the other 10 genes in ISS cohorts remains unknown. Here, we performed next-generation sequencing-based mutation screening of the 10 genes in 86 unrelated Japanese ISS patients without SHOX abnormalities. We searched for rare protein-altering variants. The functional significance of the identified variants was assessed by in silico analyses. Consequently, we identified 18 heterozygous rare variants in 19 patients, including four probable damaging variants in ACAN, six pathogenicity-unknown variants in FGFR3, GHRHR, GHR, and IGFALS, and eight possible benign variants. Pathogenic variants in NPR2, GH1, and IGF1 were absent from our cohort. Unlike previously reported patients with ACAN mutations, our four patients with ACAN variants manifested non-specific short stature with age-appropriate or mildly delayed bone ages, and had parents of normal stature. These results indicate that ACAN mutations can underlie ISS without characteristic skeletal features, and that such mutations are possibly associated with de novo occurrence or low penetrance. In addition, our data imply that mutations in FGFR3, NPR2, and GH-IGF1 axis genes play only limited roles in the etiology of ISS.

Systematic molecular analyses of SHOX in Japanese patients with idiopathic short stature and Leri-Weill dyschondrosteosis.

The etiology of idiopathic short stature (ISS) and Leri-Weill dyschondrosteosis (LWD) in European patients is known to include SHOX mutations and copy-number variations (CNVs) involving SHOX and/or the highly evolutionarily conserved non-coding DNA elements (CNEs) flanking the gene. However, the frequency and types of SHOX abnormalities in non-European patients and the clinical importance of mutations in the CNEs remains to be clarified. Here, we performed systematic molecular analyses of SHOX for 328 Japanese patients with ISS or LWD. SHOX abnormalities accounted for 3.8% of ISS and 50% of LWD cases. CNVs around SHOX were identified in 16 cases, although the ~47 kb deletion frequently reported in European patients was absent in our cases. Probably damaging mutations and benign/silent substitutions were detected in four cases, respectively. Although CNE-linked substitutions were detected in 15 cases, most of them affected poorly conserved nucleotides and were shared by unaffected individuals. These results suggest that the frequency and mutation spectrum of SHOX abnormalities are comparable between Asian and European patients, with the exception of a European-specific downstream deletion. Furthermore, this study highlights the clinical importance and genetic heterogeneity of the SHOX-flanking CNVs, and indicates a limited clinical significance of point mutations in the CNEs.

Rare pseudoautosomal copy-number variations involving SHOX and/or its flanking regions in individuals with and without short stature.

Pseudoautosomal region 1 (PAR1) contains SHOX, in addition to seven highly conserved non-coding DNA elements (CNEs) with cis-regulatory activity. Microdeletions involving SHOX exons 1-6a and/or the CNEs result in idiopathic short stature (ISS) and Leri-Weill dyschondrosteosis (LWD). Here, we report six rare copy-number variations (CNVs) in PAR1 identified through copy-number analyzes of 245 ISS/LWD patients and 15 unaffected individuals. The six CNVs consisted of three microduplications encompassing SHOX and some of the CNEs, two microduplications in the SHOX 3'-region affecting one or four of the downstream CNEs, and a microdeletion involving SHOX exon 6b and its neighboring CNE. The amplified DNA fragments of two SHOX-containing duplications were detected at chromosomal regions adjacent to the original positions. The breakpoints of a SHOX-containing duplication resided within Alu repeats. A microduplication encompassing four downstream CNEs was identified in an unaffected father-daughter pair, whereas the other five CNVs were detected in ISS patients. These results suggest that microduplications involving SHOX cause ISS by disrupting the cis-regulatory machinery of this gene and that at least some of microduplications in PAR1 arise from Alu-mediated non-allelic homologous recombination. The pathogenicity of other rare PAR1-linked CNVs, such as CNE-containing microduplications and exon 6b-flanking microdeletions, merits further investigation.

Polyostotic osteolysis and hypophosphatemic rickets with elevated serum fibroblast growth factor 23: A case report.

We report on a boy who presented with hypophosphatemic rickets with elevated serum fibroblast growth factor 23 (FGF23) and polyostotic osteolytic lesions at age 2 years. Tumor-induced hypophosphatemic rickets was suspected; however, bone biopsy for osteolytic changes revealed no tumorous change, except for irregularly dilated vessels associated with osteoclasts and fibrous proliferation. Venous sampling failed to point to FGF23-producing foci. After alfacalcidol and phosphate supplementation, the rachitic skeletal changes improved, but FGF23 increased and new osteolytic lesions developed. Serum levels of neopterin and a few cytokines, including plasma transforming growth factor-ß and soluble tumor necrosis factor receptor type II, were elevated. At age 4 years, high doses of phosphate resulted in increased serum phosphate levels, decreased neopterin and cytokines, decreased FGF23, and stabilization of osteolysis. We excluded germline mutations in PHEX, FGF23, DMP1, and ENPP1 (genes for hereditary hypophosphatemic rickets) and somatic mutations in the GNAS and HRAS/KRAS (the disease-causing genes for McCune-Albright syndrome and linear nevus sebaceous syndrome, respectively). We could not perform octreotide scintigraphy or fluorodeoxyglucose-positron emission tomography, and thus could not completely exclude occult FGF23-producing tumors. However, considering the course of the disease, it is intriguing to assume that dysregulation of osteoclast-macrophage lineage may have induced increased neopterin levels, increased cytokine levels, osteolytic process, and possibly FGF23 overproduction.

Clinical manifestations and enzymatic activities of mitochondrial respiratory chain complexes in Pearson marrow-pancreas syndrome with 3-methylglutaconic aciduria: a case report and literature review.

Pearson marrow-pancreas syndrome (PS) is a rare mitochondrial disorder. Impaired mitochondrial respiratory chain complexes (MRCC) differ among individuals and organs, which accounts for variable clinical pictures. A subset of PS patients develop 3-methylglutaconic aciduria (3-MGA-uria), but the characteristic symptoms and impaired MRCC remain unknown. Our patient, a girl, developed pancytopenia, hyperlactatemia, steatorrhea, insulin-dependent diabetes mellitus, liver dysfunction, Fanconi syndrome, and 3-MGA-uria. She died from cerebral hemorrhage at 3 years of age. We identified a novel 5.4-kbp deletion of mitochondrial DNA. The enzymatic activities of MRCC I and IV were markedly reduced in the liver and muscle and mildly reduced in skin fibroblasts and the heart. To date, urine organic acid analysis has been performed on 29 PS patients, including our case. Eight patients had 3-MGA-uria, while only one patient did not. The remaining 20 patients were not reported to have 3-MGA-uria. In this paper, we included these 20 patients as PS patients without 3-MGA-uria. PS patients with and without 3-MGA-uria have similar manifestations. Only a few studies have examined the enzymatic activities of MRCC. CONCLUSION: No clinical characteristics distinguish between PS patients with and without 3-MGA-uria. The correlation between 3-MGA-uria and the enzymatic activities of MRCC remains to be elucidated. WHAT IS KNOWN: • The clinical characteristics of patients with Pearson marrow-pancreas syndrome and 3-methylglutaconic aciduria remain unknown. WHAT IS NEW: • No clinical characteristics distinguish between Pearson marrow-pancreas syndrome patients with and without 3-methylglutaconic aciduria.

Overall usefulness of newborn screening for congenital hypothyroidism by using free thyroxine measurement.

In Kanagawa Prefecture, Japan, simultaneous measurements of free T4 (FT4) and TSH levels are performed during newborn screening for congenital hypothyroidism (CH). FT4 measurement enables the detection of CH of central origin (CH-C), the incidence of which is estimated to be 1 in 30,833 live births in Kanagawa Prefecture. In this study, we aimed to evaluate the efficacy of FT4 screening when transient CH-C and thyroidal CH (CH-T) with delayed TSH elevation are included as screening targets. Data collected on CH-C patients using a regional survey, as well as data from a database created by a screening organization, were used. Of the 24 CH-C patients who had been born in Kanagawa Prefecture between 1999 and 2008, a positive screening result for FT4 (<0.7 ng/dL) was obtained in 13 newborns; of these, 12 were identified solely through newborn screening. Of the 113 patients for whom positive screening results were obtained during the study period, 5 and 6 were found to have transient CH-C and CH-T with delayed TSH elevation, respectively. Remarkably, 4 out of 5 patients with transient CH-C and all patients with CH-T with delayed TSH elevation were diagnosed through the evaluation of low FT4 at screening. These results indicate that the use of this FT4 screening system facilitates the identification of transient CH-C and CH-T with delayed TSH elevation, thus justifying the inclusion of these entities as screening targets.

Neonatal case of classic maple syrup urine disease: usefulness of (1) H-MRS in early diagnosis.

We describe a male neonate with classic maple syrup urine disease (MSUD) in metabolic crisis. On day 7 of life, he was referred to hospital because of coma and metabolic acidosis with maple syrup odor. On day 4 after admission, brain magnetic resonance imaging findings were consistent with encephalopathy due to MSUD. Proton magnetic resonance spectroscopy ((1) H-MRS) showed a large methyl resonance peak at 0.9 p.p.m. The diagnosis of MSUD was confirmed on low branched-chain α-keto acid dehydrogenase complex activity in lymphocyte. (1) H-MR spectra were obtained in 10 min, while it took at least several days to obtain the results of other diagnostic examinations. In convalescence, the peak at 0.9 p.p.m. decreased. The large methyl resonance peak at 0.9 p.p.m. in brain (1) H-MRS would be one of the earliest clues to the diagnosis of classic MSUD in the neonatal period, especially in metabolic crisis.

Pseudo-Bartter syndrome in an infant without obvious underlying conditions: A case report.

Pseudo-Bartter syndrome (PBS) develops owing to renal or extrarenal chloride loss, leading to hypokalemic alkalosis. Whereas most adult cases result from diuretic/laxative abuse, many infantile cases occur secondary to cystic fibrosis. Rarely, infantile PBS is caused by renal salt loss with anomalies of the kidney/urinary tract or genetic disorders, such as Dent disease. Here, we report the case of a 10-mo-old girl with a one-month history of decreased formula intake and 5.6% body weight loss. She showed typical laboratory findings as PBS, including hypokalemia (2.7 mEq/L) and high levels of bicarbonate (32.7 mEq/L) with a plasma renin activity of 399 ng/mL/h. With minimum supplementation of potassium and sodium, an improvement in body mass index, from -1.13 SD to +0.52 SD, with complete resolution of laboratory data was obtained in approximately one month. No causative mutations were identified in candidate genes for Bartter-Gitelman syndrome. Due to profound hypochloruria (< 15 mEq/L), PBS of renal origin was unlikely. In addition, extrarenal chloride loss did not seem to be the case, because the patient never manifested gastrointestinal symptoms. Therefore, we speculate that a temporary decrease in chloride intake, coupled with the putative genetic/epigenetic disadvantage of chloride retention, such as a subtle renal leak, may be responsible for the PBS in our patient.

First case of a Japanese girl with Myhre syndrome due to a heterozygous SMAD4 mutation.

This article reports the first case of a Japanese girl with molecularly confirmed Myhre syndrome (MS). The patient was 9 years old at her first visit, and she had been diagnosed with unknown skeletal dysplasia. Her phenotype fulfilled the clinical and radiological criteria for MS, such as typical facies with prognathism, hearing impairment, short stature, square body shape, and limited joint mobility. The thick calvarium and thick skin were clues to the clinical diagnosis of MS. A heterozygous mutation in the mothers-against-DPP homolog 4 (SMAD4) gene has been reported to cause MS. We sequenced SMAD4 using standard PCR-based technique and identified a recurrent mutation (p.Ile500 Thr). She attained menarche before 11 years of age; however, she developed oligomenorrhea after a few years of 40-day cycles, necessitating hormone replacement therapy. The luteinizing hormone-releasing hormone (LHRH) tests suggested abnormalities related to hypothalamo-hypophyseal malfunction. Previous reports on MS described early menarche in girls and early or delayed puberty and cryptorchidism in boys. Therefore, we recommend performing an endocrinological evaluation of the hypothalamo-hypophyseal-gonadal axis in patients with MS to clarify whether hormonal abnormalities are associated with the syndrome.

Acid-Base Imbalance in Pseudohypoaldosteronism Type 1 in Comparison With Type IV Renal Tubular Acidosis.

Context: Pseudohypoaldosteronism type 1 (PHA1) has been treated as a genetic variant of type IV renal tubular acidosis (RTA), leading to the conception that PHA1 develops hyperchloremic acidosis with a normal anion gap (AG). Objective: To delineate the acid-base imbalance in PHA1A (dominant type) and PHA1B (recessive type). Methods: We conducted the following: (1) a retrospective chart review of our patient with PHA1B, and (2) a literature search of PHA1 cases focusing on acid-base balance. The main outcome measures were the incidence and nature of acidosis, including chloride levels and AG. Results: In our patient with PHA1B, 7 salt-wasting episodes were analyzed. Acidosis was ascertained each time, and it was accompanied by hypochloremia except in 1 episode. AG was elevated in 5 episodes, while hyperlacticaemia was present in 3. In the literature, 41 cases of PHA1A and 65 cases of PHA1B have been identified. During salt-wasting crises, acidosis developed in 85% of PHA1A cases and 87% of PHA1B cases. Hypochloremia was present in 69% of PHA1A cases with available data (n = 13) and 54% of eligible PHA1B cases (n = 13), with mean chloride levels of 96 mEq/L and 95 mEq/L, respectively. Increased AG was less frequently reported (14% in PHA1A and 44% in PHA1B). Conclusions: Patients with PHA1 frequently presented with metabolic acidosis. However, hyperchloremia may not be a universal finding, whereas hypochloremia and increased AG may occur in a substantial proportion of the patients.

A patient with congenital hypothyroidism due to a PAX8 frameshift variant accompanying a urogenital malformation.

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.

Genetic Analysis of Japanese Children Clinically Diagnosed with Familial Hypercholesterolemia.

AIM: This study aimed to elucidate the gene and lipid profiles of children clinically diagnosed with familial hypercholesterolemia (FH). METHODS: A total of 21 dyslipidemia-related Mendelian genes, including FH causative genes (LDLR, APOB, and PCSK9) and LDL-altering genes (APOE, LDLRAP1, and ABCG5/8), were sequenced in 33 Japanese children (mean age, 9.7±4.2 years) with FH from 29 families. RESULTS: Fifteen children (45.5%) with pathogenic variants in LDLR (eight different heterozygous variants) and one child (3.0%) with the PCSK9 variant were found. Among 17 patients without FH causative gene variants, 3 children had variants in LDL-altering genes, an APOE variant and two ABCG8 variants. The mean serum total cholesterol (280 vs 246 mg/dL), LDL-cholesterol (LDL-C, 217 vs 177 mg/dL), and non-HDL cholesterol (228 vs 188 mg/dL) levels were significantly higher in the pathogenic variant-positive group than in the variant-negative group. In the variant-positive group, 81.3% of patients had LDL-C levels ≥ 180 mg/dL but 35.3% in the variant-negative group. The mean LDL-C level was significantly lower in children with missense variants, especially with the p.Leu568Val variant, than in children with other variants in LDLR, whereas the LDL-altering variants had similar effects on the increase in serum LDL-C to LDLR p.Leu568Val. CONCLUSION: Approximately half of the children clinically diagnosed with FH had pathogenic variants in FH causative genes. The serum LDL-C levels tend to be high in FH children with pathogenic variations, and the levels are by the types of variants. Genetic analysis is useful; however, further study on FH without any variants is required.