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.

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.

Identification of the first promoter-specific gain-of-function SOX9 missense variant (p.E50K) in a patient with 46,XX ovotesticular disorder of sex development.

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.

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.

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.

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.

Myhre syndrome: a rare craniofacial disorder.

AIMS: Myhre syndrome is a rare disorder characterized by abnormal growth of the skeleton, muscles, and joints. The relationship of this syndrome to craniofacial growth and development is unknown. To the authors' knowledge, this is the first Japanese case ever studied. METHODOLOGY: At 10 years and 7 months of age, the patient was referred to the Department of Pediatric Dentistry in the authors' hospital, complaining of a dental problem. RESULTS: The craniofacial region exhibited a long lower face, high and narrowed palate with submucous cleft palate, maxillary constriction, prognathism, open bite, and crowding of the dental arch. Some of these morphological disorders could be affected by the functional manifestations of muscular hypertrophy of the cheek region, muscle tenseness, or the low position of the tongue. General disorders of muscular hypertrophy, thickened bones, and limited joint mobility are consistent with craniofacial findings of muscle tension in the cheek region, thickened calvarium, and limitation of temporomandibular joint movement. The submucous cleft palate and crown deformation of the mandibular central incisor may be affected by dysfunctions of SMAD4 signaling. CONCLUSIONS: Craniofacial growth and development is affected by the general characteristics of Myhre syndrome, and could be important in its diagnosis.

Bone marrow transplantation in Schimke immuno-osseous dysplasia.

Schimke immuno-osseous dysplasia (SIOD, OMIM 242900) is a rare autosomal recessive multisystem childhood disorder characterized by short stature, renal failure, T-cell immunodeficiency, and hypersensitivity to genotoxic agents. SIOD is associated with biallelic mutations in SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1), which encodes a DNA stress response enzyme with annealing helicase activity. Two features of SIOD causing much morbidity and mortality are bone marrow failure and T-cell deficiency with the consequent opportunistic infections. To address the safety and efficacy of bone marrow transplantation (BMT) in SIOD, we reviewed the outcomes of the only five SIOD patients known to us in whom bone marrow or hematopoietic stem cell transplantation has been attempted. We find that only one patient survived the transplantation procedure and that the existing indicators of a good prognosis for bone marrow transplantation were not predictive in this small cohort. Given these observations, we also discuss some considerations for the poor outcomes.

Risks of Myocarditis and Pericarditis Following Vaccination with SARS-CoV-2 mRNA Vaccines in Japan: An Analysis of Spontaneous Reports of Suspected Adverse Events.

OBJECTIVE: To identify the risks of myocarditis or pericarditis after vaccination with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in Japan. METHODS: We conducted an observed-to-expected analysis (OE analysis) of spontaneous reports of suspected adverse events from pharmaceutical companies, calculating rate ratios with myocarditis and pericarditis after the vaccination of the mRNA vaccines Comirnaty (BNT162b2) and Spikevax (mRNA-1273) and expected rate of myocarditis and pericarditis in the population before the COVID-19 pandemic. These reports dated from 17/2/2021 to 14/11/2021 and from 22/5/2021 to 14/11/2021 for Comirnaty and Spikevax, respectively. The observed-to-expected ratios (OE ratios) for each vaccine were estimated by age groups and sex. RESULTS: We identified 281 and 195 cases of myocarditis or pericarditis for Comirnaty and Spikevax, respectively, which were administrated 163,059,502 and 31,768,352 doses for Comirnaty and Spikevax until the 14th of November 2021, respectively. The OE ratios were statistically significantly higher in adolescent and young adult males in their age of teens and twenties after the second dose in a two-dose series [Comirnaty in teens male: 6.15 (95% CI, 2.26-21.98), Comirnaty in twenties male: 2.86 (95% CI, 1.13-8.38), Spikevax in teens male: 41.59 (95% CI, 5.64-43,281.94), Spikevax in twenties male: 16.84 (95%CI, 6.77-57.49)]. CONCLUSIONS: Risks of myocarditis and pericarditis following SARS-CoV-2 mRNA vaccines in Japan seems to be significantly elevated for adolescent and young adult males.

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.

A patient with Pendred syndrome whose goiter progressed with normal serum thyrotropin and iodine organification.

Biallelic mutations of SLC26A4 (encoding pendrin) cause Pendred syndrome (PS), an autosomal recessive genetic disorder with deafness and goiter. The mechanism underlying the development of the goiter is unknown. Here, we report clinical and molecular findings of a patient with PS. This 27-year-old woman was born to nonconsanguineous healthy parents. She was seen at our hospital due to hearing loss at age 3 years, and subsequently developed goiter at age 10 years. From age 15 years, her thyroid gland showed progressive enlargement accompanied by elevation of serum thyroglobulin reaching 10-fold the normal amount. Thyroidal iodine uptake was also increased during goiter progression ((123)I uptake at 24 hr: 20.2% at age 17 years; 69.4% at age 24 years; reference, 8-40), while serum thyrotropin (TSH) levels and iodine organification (examined by the perchrolate or thiocyanate discharge test) remained normal. We sequenced SLC26A4 using standard PCR-based technique, and found one novel (p.T537P) and one recurrent (p.H723R) mutations in a compound heterozygous state. Expression experiments using COS-7 cells showed that the two mutants were entrapped in the endoplasmic reticulum and were poorly localized at the plasma membrane. In summary, a molecularly confirmed PS patient showed goiter progression accompanied by elevated serum thyroglobulin and increased thyroidal iodine uptake, but normal serum TSH levels and normal iodine organification. This implies that some pendrin mutations may involve direct stimulation of thyroid cell proliferation with no TSH hyperstimulation and no iodine organification defect.

Schimke immunoosseous dysplasia: defining skeletal features.

Schimke immunoosseous dysplasia (SIOD) is an autosomal recessive multisystem disorder characterized by prominent spondyloepiphyseal dysplasia, T cell deficiency, and focal segmental glomerulosclerosis. Biallelic mutations in swi/snf-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1) are the only identified cause of SIOD, but approximately half of patients referred for molecular studies do not have detectable mutations in SMARCAL1. We hypothesized that skeletal features distinguish between those with or without SMARCAL1 mutations. Therefore, we analyzed the skeletal radiographs of 22 patients with and 11 without detectable SMARCAL1 mutations. We found that patients with SMARCAL1 mutations have a spondyloepiphyseal dysplasia (SED) essentially limited to the spine, pelvis, capital femoral epiphyses, and possibly the sella turcica, whereas the hands and other long bones are basically normal. Additionally, we found that several of the adolescent and young adult patients developed osteoporosis and coxarthrosis. Of the 11 patients without detectable SMARCAL1 mutations, seven had a SED indistinguishable from patients with SMARCAL1 mutations. We conclude therefore that SED is a feature of patients with SMARCAL1 mutations and that skeletal features do not distinguish who of those with SED have SMARCAL1 mutations.

Increased Na reabsorption via the Na-Cl cotransporter in autosomal recessive pseudohypoaldosteronism.

BACKGROUND: The autosomal recessive form of pseudohypoaldosteronism type 1 (AR-PHA1) is caused by loss-of-function mutations in the epithelial sodium channel subunit genes and is characterized by a multisystemic and lifelong severe salt-wasting tendency. However, we observed a male AR-PHA1 patient who exhibited less frequent salt wasting with advancing age, despite the cessation of daily salt supplementation. OBJECTIVE: To elucidate the mechanism for the above phenomenon. METHODS: We evaluated the sodium-reabsorption ability of his distal nephrons (from the distal convoluted tubules to the collecting ducts) and compared it to that of a patient with the dominant form of PHA1 (AD-PHA1) carrying a heterozygous NR3C2 (mineralocorticoid receptor) gene mutation. In addition, immunoblotting of the thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC) protein was conducted using urine samples from the AR- and AD-PHA1 patients. RESULTS: The levels of sodium reabsorption that occurred via the distal nephrons were almost identical in the two PHA1 patients, despite their different molecular pathogeneses. Immunoblotting showed an increased urinary NCC protein level in the AR-PHA1 patient. CONCLUSION: Taken together, increased sodium reabsorption via the upregulation of the expression of NCC might have been responsible, at least in part, for the clinical improvement seen in an AR-PHA1 patient.

Growth hormone response to GH-releasing peptide-2 in children.

The insulin tolerance test (ITT) has been considered the most reliable test in the diagnosis of growth hormone deficiency (GHD), but it is contraindicated in some patients. Recently, the use of GH-Releasing Peptide-2 (GHRP-2) has been validated and reported as a safe and reliable test for the diagnosis of adult severe GHD. We evaluated the GH response to GHRP-2 in 56 children with growth disorders to assess its efficacy. A dose of 2 microg/kg of GHRP-2 was administered intravenously and serum GH concentrations were determined. The Spearman correlation coefficient for GH peak values indicated a favorable correlation with the ITT (P<0.0001). Peak GH concentrations were significantly (p<0.0001) lower in children with (median: 3.39 microg/l (ng/ml)) than without (25.10 microg/l (ng/ml)) GHD. In the analysis of sensitivity-specificity curves, the serum concentration at the point where sensitivity crosses specificity was 15 microg/l (ng/ml). The GHRP-2 test was safe and required only one hour or less, and was capable of diagnosing GHD in children.

Congenital Hypothyroidism Due to Truncating PAX8 Mutations: A Case Series and Molecular Function Studies.

CONTEXT: PAX8 is a transcription factor required for thyroid development, and its mutation causes congenital hypothyroidism (CH). More than 20 experimentally verified loss-of-function PAX8 mutations have been described, and all but one were located in the DNA-binding paired domain. OBJECTIVE: We report the identification and functional characterization of 3 novel truncating PAX8 mutations located outside the paired domain. METHODS: Three CH probands, diagnosed in the frame of newborn screening, had thyroid hypoplasia and were treated with levothyroxine. Next-generation sequencing-based mutation screening was performed. Functionality of the identified mutations were verified with Western blotting, intracellular localization assays, and transactivation assays with use of HeLa cells. Luciferase complementation assays were used to evaluate the effect of mutations on the interaction between PAX8 and its partner, NKX2-1. RESULTS: Each proband had novel truncating PAX8 mutations that were I160Sfs*52, Q213Efs*27, and F342Rfs*85. Western blotting showed destabilization of the I160fs-PAX8 protein. Q213fs-PAX8 and F342fs-PAX8 showed normal protein expression levels and normal nuclear localization, but showed loss of transactivation of the luciferase reporter. By luciferase complementation assays, we showed that PAX8-NKX2-1 interaction was defective in Q213fs-PAX8. We also characterized the recombinant PAX8 proteins, and found that the protein sequence corresponding to exon 10 (363-400 aa residues) was essential for the PAX8-NKX2-1 interaction. CONCLUSIONS: Clinical and molecular findings of 3 novel truncating PAX8 mutations located outside the paired domain were reported. Experiments using cultured cells and recombinant proteins showed that the C-terminal portion (ie, 363-400 aa) of PAX8 is required for the PAX8-NKX2-1 interaction.