Clinical course of congenital hypothyroidism with gland in situ and necessity of L-thyroxine therapy after re-evaluation.

CONTEXT: Clinical course and need for long-term L-thyroxine (LT4) therapy of congenital hypothyroidism (CH) with gland in situ (GIS) remain unclear. OBJECTIVE: To describe the clinical history of CH with GIS and evaluate the proportion of patients who can suspend therapy during follow-up. DESIGN AND SETTING: Retrospective evaluation of patients followed at referral regional center for CH of Pisa. PATIENTS: 77 patients with confirmed primary CH and GIS after positive neonatal screening were included. All children started LT4 at CH confirm. INTERVENTIONS: At 3 years of age, 55 children underwent a clinical re-evaluation after withdrawal of therapy with hormonal examinations, imaging of the thyroid gland with ultrasonography and 123-iodine with perchlorate discharge test. Subsequent periodic controls of thyroid function were executed and, when possible, a new attempt to stop LT4 was performed. Adequate follow-up data (at least 6 months after treatment suspension trial) were available for 49 patients. RESULTS: Among the 55 patients who were reassessed, 18 (32.7%) were euthyroid. Considering subsequent follow-up, 49% of patients were no longer treated and 51% were taking therapy. No differences in neonatal parameters were observed between the two groups; LT4 dose before the last trial off medication was higher in permanent CH (p 0.016). CONCLUSION: Monitoring of thyroid function in children with CH and GIS is necessary to evaluate the need for substitution and avoid overtreatment. Even if therapy can be suspended, patients need to be monitored because apparently normal thyroid function may decline several months after withdrawal of LT4.

The longitudinal growth trajectory of children with congenital hypothyroidism during the first 3 years of life.

Congenital hypothyroidism (CH) is detected through a newborn screening program in Iran, enabling early detection and prompt treatment. This study addresses the longitudinal growth trajectory of Iranian children with CH and explores associated factors during the first 3 years of life. Data from 1474 children with CH in Isfahan, Iran (2002-2022), were analyzed. Weight, height, and head circumference were measured, and z-scores for age were calculated. Group-based trajectory modeling was applied to distinct growth trajectories. Factors influencing growth patterns, including gender, treatment initiation age, delivery method, parental consanguinity, history of familial hypothyroidism, and thyroid-stimulating hormone (TSH) levels at 3-7 days, were investigated. Thirty-seven percent of children diagnosed with CH faced a delay in weight, while 36.6% experienced stunted height, and 25.7% showed a retardation in head circumference growth. The initiation of treatment, parental consanguinity, and family history of hypothyroidism varied among these groups. Children exhibiting an optimal growth pattern in the initial 3 years of life demonstrated lower average TSH levels. CONCLUSION: This research emphasizes the complexity of managing CH and stresses the importance of tailoring interventions based on individualized characteristics and the ongoing growth patterns of the children. Future research is required to understand the intricate relationships between growth patterns and various determinants and optimize the growth and developmental outcomes of children with CH. WHAT IS KNOWN: • Iran has a higher prevalence of congenital hypothyroidism (CH) with a nationwide screening program. • There are concerns about delayed growth in CH children, but limited research on long-term patterns and contributing factors. WHAT IS NEW: • Distinct patterns in weight, height, and head circumference among children with CH were identified. • Factors such as consanguinity, parental hypothyroidism, and TSH levels impact growth outcomes. • CH management is complicated, and there is a need for individualized interventions.

Genetic etiology in patients diagnosed with congenital hypothyroidism with new-generation sequencing: A single-center experience.

AIM: Congenital hypothyroidism (CH) is the most common endocrine disorder of the newborn; it is seen in every 3000-4000 births. Genetic features can guide treatment for patients with in situ glands. The present study aimed to contribute to the literature on CH variants and to show the benefit that genetic analysis can provide to patients in follow-up. METHOD: A total of 52 patients (47 families) diagnosed with CH were included in the study. Overall, 32 target genes involved in thyroid physiology were investigated by next-generation sequencing (NGS). RESULTS: In total, 29 (55 %) of the patients were male, and the rate of dysgenesis was 19.2 %. In this study, 29 of 52 patients had at least one variant in one gene involved in CH (n = 29, 33 different variants) (Including likely benign variants and variants of unknown significance). There were 21 patients (40.3 %) with gland in situ. The most common variant was DUOX2 (20 %). The second most common variants were those in the TPO and TG genes (15 % and 15 %, respectively); 41.1 % of these were variants of uncertain significance (VUS), 26.4 % were pathogenic, 23.5 % were likely benign, and 11.7 % were likely pathogenic. On the basis of their zygosity, we identified 73.5 % heterozygous, 17.6 % homozygous, and 8.9 % combined heterozygous variants. There were mutant variants in two genes in six patients and three in one patient. CONCLUSION: This study found a variant in 55 % of the patients and shed light on the etiology of some cases of CH. The frequency of VUS was high. Although variants were identified in this study, their implication in the etiology of CH is not certain and, for most of the patients, it is also not sufficient for explaining the pathology with the current state of knowledge.

Insights into Central Congenital Hypothyroidism: A Multicenter Retrospective Analysis.

CONTEXT: Central congenital hypothyroidism (CCH) is a thyroid hormone deficiency at birth caused by inadequate pituitary stimulation of the thyroid gland. Although primary CH has been studied extensively, studies on CCH are sparse. OBJECTIVES: To assess the prevalence of CCH in Israel and describe its clinical features, neonatal screening results, and outcomes. DESIGN: Multicenter cross-sectional retrospective chart review. SETTING: Nine pediatric endocrine units throughout Israel. PATIENTS: Patients diagnosed with CCH in 1987-2021 were categorized into early (within 14 days of life) and late (after 14 days) diagnosis groups. Newborn screening (NBS) results were retrospectively retrieved from the national NBS program dataset. RESULTS: CCH prevalence in Israel was about 1:42,800 live births. Subjects were 94 patients (54 males), of these, 84% had multiple pituitary hormone deficiencies and 16% had isolated CCH. The median age at diagnosis was 50 days (range, 1-8760), with 66% having moderate to severe hypothyroidism. NBS detected only three infants. Early diagnosis occurred in 34% due to hypopituitarism, while 66% were diagnosed later due to growth and developmental delays. Neurodevelopmental sequelae included mental retardation (12%), learning difficulties (18%), delayed speech (27%), and motor clumsiness (19%), with no significant differences in outcomes between early and late diagnosis. CONCLUSIONS: Despite high rates of neurodevelopmental sequelae, no differences were found between early and late diagnosis groups. Further research is needed to assess the impact of delayed diagnosis on neurological outcomes in newborns with CCH. Improved strategies for detecting CHH in newborns are also necessary.

Unusual congenital goiter due to maternal Hashimoto thyroiditis: a case report.

Congenital hypothyroidism (CH) is the most common cause of endocrinopathy in the newborn Its incidence lies between 1 in 3,000 and 1 in 2,000, However, congenital goiter is a rare form of presentation. Hypothyroidism secondary to autoimmune etiology is extremely rare, with an incidence of 1:84.700-1:31.000 newborns. Anti-thyroid peroxidase antibodies (TPOAb) are able to cross the placenta but rarely induce hypothyroidism in the newborn, much less goiter. A case of congenital goiter in a male newborn secondary to maternal high TPOAb levels is reported. The mother was diagnosed of Hashimoto thyroiditis prior to the pregnancy. At birth, a grade 3 goiter was detected in the newborn. Laboratory testings revealed hypothyroidism with free thyroxine of 7.6 pmol/L, thyroid-stimulating hormone of 108 mUI/L and high TPOAb levels. Treatment with Levothyroxine was started the second day of life with progressive thyroid function normalization. Neurological development has been normal until the date.

Incidence and associated risk factors of congenital hypothyroidism among newborns in Hainan, China: a retrospective study.

OBJECTIVES: This study aims to investigate the incidence and risk factors of congenital hypothyroidism (CH) in newborns in Hainan Province, China, to provide a reference for early and effective prevention strategies. METHODS: Newborns born in Hainan Province from 2017 to 2021 were the subjects of this study. Time-resolved immunofluorescence was used for initial screening and chemiluminescence for confirmatory diagnosis. Based on the diagnosis, newborns were classified into CH and non-CH groups. Statistical analysis was conducted on the initial screening and confirmed CH cases in newborns in Hainan Province, and potential risk factors for CH were explored. RESULTS: From 2017 to 2021, a total of 585,886 newborns were screened, revealing 6,856 initial positive results, 614 positive rescreens, and 420 confirmed CH cases, yielding an incidence rate of 1/1,395 (420/585,886). The annual initial positive screening rate of newborns in Hainan Province showed a rising trend from 2017 to 2021 (p=0.000). No significant differences were found regarding gender (p=0.400) and ethnicity (p=0.836). Multivariate logistic regression analysis indicated that residing in coastal areas, especially those with salt fields (OR=2.151, 95 % CI: 1.364-3.390), was risk factors for the development of CH in newborns. CONCLUSIONS: The incidence of CH in newborns showed a year-on-year increase in Hainan Province from 2017 to 2021. Residing in coastal areas, particularly those with salt fields, was identified as a risk factor for the development of CH.

Revealing the genetic complexity of hypothyroidism: integrating complementary association methods.

Hypothyroidism is a common endocrine disorder whose prevalence increases with age. The disease manifests itself when the thyroid gland fails to produce sufficient thyroid hormones. The disorder includes cases of congenital hypothyroidism (CH), but most cases exhibit hormonal feedback dysregulation and destruction of the thyroid gland by autoantibodies. In this study, we sought to identify causal genes for hypothyroidism in large populations. The study used the UK-Biobank (UKB) database, reporting on 13,687 cases of European ancestry. We used GWAS compilation from Open Targets (OT) and tuned protocols focusing on genes and coding regions, along with complementary association methods of PWAS (proteome-based) and TWAS (transcriptome-based). Comparing summary statistics from numerous GWAS revealed a limited number of variants associated with thyroid development. The proteome-wide association study method identified 77 statistically significant genes, half of which are located within the Chr6-MHC locus and are enriched with autoimmunity-related genes. While coding GWAS and PWAS highlighted the centrality of immune-related genes, OT and transcriptome-wide association study mostly identified genes involved in thyroid developmental programs. We used independent populations from Finland (FinnGen) and the Taiwan cohort to validate the PWAS results. The higher prevalence in females relative to males is substantiated as the polygenic risk score prediction of hypothyroidism relied mostly from the female group genetics. Comparing results from OT, TWAS, and PWAS revealed the complementary facets of hypothyroidism's etiology. This study underscores the significance of synthesizing gene-phenotype association methods for this common, intricate disease. We propose that the integration of established association methods enhances interpretability and clinical utility.

Identification of southern Taiwan genetic variants in thyroid dyshormonogenesis through whole-exome sequencing.

Thyroid dyshormonogenesis (TDH) is responsible for 15%-25% of congenital hypothyroidism (CH) cases. Pathogenetic variants of this common inherited endocrine disorders vary geographically. Unraveling the genetic underpinnings of TDH is essential for genetic counseling and precise therapeutic strategies. This study aims to identify genetic variants associated with TDH in Southern Taiwan using whole exome sequencing (WES). We included CH patients diagnosed through newborn screening at a tertiary medical center from 2011 to 2022. Permanent TDH was determined based on imaging evidence of bilateral thyroid structure and the requirement for continuous medication beyond 3 years of age. Genomic DNA extracted from blood was used for exome library construction, and pathogenic variants were detected using an in-house algorithm. Of the 876 CH patients reviewed, 121 were classified as permanent, with 47 (40%) confirmed as TDH. WES was conducted for 45 patients, and causative variants were identified in 32 patients (71.1%), including DUOX2 (15 cases), TG (8 cases), TSHR (7 cases), TPO (5 cases), and DUOXA2 (1 case). Recurrent variants included DUOX2 c.3329G>A, TSHR c.1349G>A, TG c.1348delT, and TPO c.2268dupT. We identified four novel variants based on genotype, including TSHR c.1135C>T, TSHR c.1349G>C, TG c.2461delA, and TG c.2459T>A. This study underscores the efficacy of WES in providing definitive molecular diagnoses for TDH. Molecular diagnoses are instrumental in genetic counseling, formulating treatment, and developing management strategies. Future research integrating larger population cohorts is vital to further elucidate the genetic landscape of TDH.

Different Forms of Hypothyroidism in Infants with Maternal Graves' Disease: A Case Series.

Infants of mothers with Graves' disease (GD) may develop central hypothyroidism (CH) due to exposure of the foetal hypothalamic-pituitary-thyroid axis to higher-than-normal thyroid hormone concentrations, primary hypothyroidism (PH) due to transplacental passage of maternal thyroid stimulating hormone receptor antibody (TRAb), antithyroid drugs (ATD) or thyroid dysgenesis secondary to maternal uncontrolled hyperthyroidism. We describe two infants with PH and four infants with CH born to mothers with poorly controlled Graves' disease. All infants required levothyroxine and had normal developmental milestones. While national guideline consensus for high thyroid stimulating hormone (TSH) on neonatal screening is well-established, thyroid function tests (TFTs) should be serially monitored in infants with low TSH on screening, as not all mothers with Graves' disease are diagnosed antenatally.

Hypothyroidism in Patients with Down Syndrome: Prevalence and Association with Congenital Heart Defects.

This population-based study aimed to assess the prevalence of congenital hypothyroidism (CH) and overt hypothyroidism (OH) and their association with congenital heart defects (CHDs) in patients with Down syndrome (DS). The population included all live births residing in Tuscany (Italy) diagnosed with DS recorded in the Registry of Congenital Defects and in the Registry of Rare Diseases of Tuscany in the years 2003-2017. The prevalence of CH and OH in DS patients was calculated by sex and by period. The association of CH and OH with CHDs in DS patients was assessed using multivariate logistic regression. The cohort included 228 subjects. The prevalence of CH and OH was 11.4% (95%CI: 7.4-16.7%) and 12.7% (95%CI: 8.5-12.3%), respectively, with no significant difference by sex. A significant increase in the prevalence of CH (p < 0.0001) was found in the years 2010-2017 compared to the previous period, and among preterm infants (p = 0.009). The presence of CH was associated with a higher prevalence of CHDs (adjusted OR = 2.24, p = 0.082). A significant association between ventricular septal defects (VSDs) and the occurrence of OH (adjusted OR = 3.07, p = 0.025) was also observed. This study confirmed the higher prevalence of both CH and OH in DS compared to the general population. Furthermore, the risk of association between DS and CHDs was higher in the presence of CH, while VSDs are associated with OH, providing relevant insights into the epidemiology of hypothyroidism in DS and associated anomalies.

Evaluation of the First Three Years of Treatment of Children with Congenital Hypothyroidism Identified through the Alberta Newborn Screening Program.

The effectiveness of newborn screening (NBS) for congenital hypothyroidism (CH) relies on timely screening, confirmation of diagnosis, and initiation and ongoing monitoring of treatment. The objective of this study was to ascertain the extent to which infants with CH have received timely and appropriate management within the first 3 years of life, following diagnosis through NBS in Alberta, Canada. Deidentified laboratory data were extracted between 1 April 2014 and 31 March 2019 from Alberta Health administrative databases for infants born in this time frame. Time to lab collection was anchored from date of birth. Timeliness was assessed as the frequency of monitoring of Thyroid Stimulating Hormone (TSH) and appropriateness as the frequency of children maintaining biochemical euthyroidism. Among 160 term infants, 95% had confirmation of diagnosis by 16 days of age. The cohort had a median of 2 (range 0-5) TSH measurements performed in the time interval from 0 to 1 month, 4 (0-12) from 1 to 6 months, 2 (0-10) from 6 to 12 months, and 7 (0-21) from 12 to 36 months. Approximately half were still biochemically hypothyroid (TSH > 7 mU/L) at 1 month of age. After becoming euthyroid, at least some period of hypo- (60%) or hyperthyroidism (TSH < 0.2 mU/L) (39%) was experienced. More work needs to be performed to discern factors contributing to prolonged periods of hypothyroidism or infrequent lab monitoring.

Associations between OGTT results during pregnancy and offspring TSH levels: a birth cohort study.

BACKGROUND: Limited evidence exists regarding the association between gestational diabetes mellitus (GDM) and elevated levels of thyroid-stimulating hormone (TSH) in newborns. Therefore, this study aimed to investigate the potential risk of elevated TSH levels in infants exposed to maternal GDM, considering the type and number of abnormal values obtained from the 75-gram oral glucose tolerance test (OGTT). METHODS: A population-based, prospective birth cohort study was conducted in Wuhan, China. The study included women who underwent GDM screening using a 75-g OGTT. Neonatal TSH levels were measured via a time-resolved immunofluorescence assay. We estimated and stratified the overall risk (adjusted Risk Ratio [RR]) of elevated TSH levels (defined as TSH > 10 mIU/L or > 20 mIU/L) in offspring based on the type and number of abnormal OGTT values. RESULTS: Out of 15,236 eligible mother-offspring pairs, 11.5% (1,753) of mothers were diagnosed with GDM. Offspring born to women diagnosed with GDM demonstrated a statistically significant elevation in TSH levels when compared to offspring of non-GDM mothers, with a mean difference of 0.20 [95% CI: 0.04-0.36]. The incidence of elevated TSH levels (TSH > 10 mIU/L) in offspring of non-GDM women was 6.3 per 1,000 live births. Newborns exposed to mothers with three abnormal OGTT values displayed an almost five-fold increased risk of elevated TSH levels (adjusted RR 4.77 [95% CI 1.64-13.96]). Maternal fasting blood glucose was independently and positively correlated with neonatal TSH levels and elevated TSH status (TSH > 20 mIU/L). CONCLUSIONS: For newborns of women with GDM, personalized risk assessment for elevated TSH levels can be predicated on the type and number of abnormal OGTT values. Furthermore, fasting blood glucose emerges as a critical predictive marker for elevated neonatal TSH status.

Late-onset dyshormonogenic goitrous hypothyroidism due to a homozygous mutation of the SLC26A7 gene: a case report.

BACKGROUND: In this study, we used targeted next-generation sequencing (NGS) to investigate the genetic basis of congenital hypothyroidism (CH) in a 19-year-old Tunisian man who presented with severe hypothyroidism and goiter. CASE PRESENTATION: The propositus reported the appearance of goiter when he was 18. Importantly, he did not show signs of mental retardation, and his growth was proportionate. A partial organification defect was detected through the perchlorate-induced iodide discharge test. NGS identified a novel homozygous mutation in exon 18 of the SLC26A7 gene (P628Qfs*11), which encodes for a new iodide transporter. This variant is predicted to result in a truncated protein. Notably, the patient's euthyroid brother was heterozygous for the same mutation. No renal acid-base abnormalities were found and the administration of 1 mg of iodine failed to correct hypothyroidism. CONCLUSIONS: We described the first case of goitrous CH due to a homozygous mutation of the SLC26A7 gene diagnosed during late adolescence.

Mapping Thyroid Hormone Action in the Human Brain.

Background: Normal brain development, mood, and cognitive functions depend on thyroid hormone (TH) action. However, little is known about how TH mediates its actions in the human brain. This is due to limited access to human brains deprived of TH during fetal and early postnatal life, as well as from adults with altered thyroid status. One way to partially bypass these limitations is by using magnetic resonance imaging and spectroscopy, two neuroimaging techniques that provide detailed, noninvasive information on human brain structure and function. Another way is using human-induced pluripotent stem cell (hiPSCs)-derived three-dimensional in vitro systems, known as brain organoids, which allow for the study of fundamental aspects of the early stages of human brain development. Summary: This narrative review focuses on neuroimaging and brain organoid studies. Neuroimaging of human brains performed in individuals with different thyroid conditions provides information on the volume, myelination, blood flow, neural activity, and connectivity of different areas. Such studies show that suboptimal thyroid status can impact human brain development and its normal function throughout life. This is true not only for patients with sporadic congenital hypothyroidism, during pregnancy or early after birth, but also for adult patients with hypo- or hyperthyroidism, patients carrying mutations that manifest as impaired sensitivity to TH, and even for normal individuals during aging. Studies using brain organoids generated from hiPSCs of healthy individuals or patients with thyroid genetic conditions provide insights into how TH can impact the early development of the human cerebral cortex. Conclusions: The developmental alterations in children born to mothers with different degrees of gestational hypothyroidism or who developed hypothyroidism early in life are remarkable, affecting multiple brain regions and pathways, including the cerebral cortex, hippocampus, cerebellum, interhemispheric and corticospinal tracts, and associative nuclei. The data connecting such changes to poor neurological outcomes in adult patients with hypothyroidism represent an objective link between thyroid-specific functional brain alterations and behavior. Growing brain organoids require TH, which is critical for human neurogenesis and oligodendrogenesis. These models have proven useful in screening drugs with potential therapeutic effects for patients with genetic thyroid diseases.

Congenital Hypothyroidism with Thyroid in situ: A Case Report with NKX2-1 and DUOX2 Hypomorphic Variants.

INTRODUCTION: NK2 homeobox 1 (NKX2-1) encodes a transcription factor, NKX2-1, that is expressed in the thyroid gland, lung, and brain. Dual oxidase 2 (DUOX2) encodes an enzyme which generates hydrogen peroxide and is involved in the thyroid hormone synthesis. Cases of congenital hypothyroidism (CH) with dyshormonogenesis showing two or more genetic variants are increasingly reported. We describe the first case of transient dyshormonogenesis who had experimentally verified a loss-of-function NKX2-1 variant and DUOX2 variants. CASE PRESENTATION: The proband was a 15-year-old female patient with CH who was diagnosed in the frame of newborn screening for CH. She had a mildly elevated serum TSH level (14.56 mU/L), a low free thyroxine level (0.87 ng/dL), and a high thyroglobulin (Tg) level (>800 ng/mL). Ultrasonography revealed goiter. She was followed clinically without levothyroxine treatment and showed normal growth and development. She had slightly high Tg levels throughout the clinical course. Next-generation sequencing-based genetic analysis revealed that the patient was heterozygous for an NKX2-1 variant (p.Ile228Ser), a nonsense DUOX2 variant (p.[Lys530*;His678Arg]), and a functional DUOX2 polymorphism (p.His678Arg). NKX2-1 p.Ile228Ser showed about 50% reduced residual activity on the Tg promoter. CONCLUSION: A partial loss-of-function NKX2-1 variant with a monoallelic nonsense DUOX2 variant and a DUOX2 functional polymorphism can cause transient CH with high serum Tg levels.

Identification of Eukaryotic Translation Initiation Factor 4B as a Novel Candidate Gene for Congenital Hypothyroidism.

CONTEXT: Congenital hypothyroidism (CH) is the most common endocrine disorder in neonates, but its etiology is still poorly understood. OBJECTIVE: We performed whole exome sequencing to identify novel causative gene for CH and functional studies to validate its role in the occurrence of CH. METHODS: Whole exome sequencing in 98 CH patients not harboring known CH candidate genes and bioinformatic analysis were performed. Functional analysis was performed using morpholino, a synthetic short antisense oligonucleotide that contains 25 DNA bases on a methylene morpholine backbone, in zebrafish and CRISPR‒Cas9-mediated gene knockout in mice. RESULTS: Eukaryotic translation initiation factor 4B (EIF4B) was identified as the most promising candidate gene. The EIF4B gene was inherited in an autosomal recessive model, and one patient with thyroid dysgenesis carried EIF4B biallelic variants (p.S430F/p.P328L). In zebrafish, the knockdown of eif4ba/b expression caused thyroid dysgenesis and growth retardation. Thyroid hormone levels were significantly decreased in morphants compared with controls. Thyroxine treatment in morphants partially rescued growth retardation. In mice, the homozygous conceptuses of Eif4b+/- parents did not survive. Eif4b knockout embryos showed severe growth retardation, including thyroid dysgenesis and embryonic lethality before E18.5. CONCLUSION: These experimental data supported a role for EIF4B function in the pathogenesis of the hypothyroid phenotype seen in CH patients. Our work indicated that EIF4B was identified as a novel candidate gene in CH. EIF4B is essential for animal survival, but further studies are needed to validate its role in the pathogenesis of CH.

Thyroid hormone deficiency affects anxiety-related behaviors and expression of hippocampal glutamate transporters in male congenital hypothyroid rat offspring.

Thyroid hormones are crucial for brain development and their deficiency during fetal and postnatal periods can lead to mood and cognitive disorders. We aimed to examine the consequences of thyroid hormone deficiency on anxiety-related behaviors and protein expression of hippocampal glutamate transporters in congenital hypothyroid male offspring rats. Possible beneficial effects of treadmill exercise have also been examined. Congenital hypothyroidism was induced by adding propylthiouracil (PTU) to drinking water of pregnant Wistar rats from gestational day 6 until the end of the weaning period (postnatal day 28). Next, following 4 weeks of treadmill exercise (5 days per week), anxiety-related behaviors were examined using elevated plus maze (EPM) and light/dark box tests. Thereafter, protein expression of astrocytic (GLAST and GLT-1) and neuronal (EAAC1) glutamate transporters were measured in the hippocampus by immunoblotting. Hypothyroid rats showed decreased anxiety-like behavior, as measured by longer time spent in the open arms of the EPM and in the light area of the light/dark box, compared to control rats. Hypothyroid rats had significantly higher GLAST and GLT-1 and lower EAAC1 protein levels in the hippocampus than did the euthyroid rats. Following exercise, anxiety levels decreased in the euthyroid group while protein expression of EAAC1 increased and returned to normal levels in the hypothyroid group. Our findings indicate that thyroid hormone deficiency was associated with alterations in protein expression of glutamate transporters in the hippocampus. Up-regulation of hippocampal GLAST and GLT-1 could be at least one of the mechanisms associated with the anxiolytic effects of congenital hypothyroidism.

Newborn screening in Colombia: The experience of a private program in Bogotá / Tamizaje neonatal en Colombia: la experiencia de un programa privado en Bogotá.

Introduction. The first neonatal screening program in Colombia ­ PREGEN ­ was set up in the medical private sector of Bogotá in 1988. We report the results from recent years that, given the scarcity of similar information in our country, may help estimate the frequency of the evaluated neonatal disorders and which ones should be included in the neonatal screening programs in our country. Objective. To describe the results of PREGEN´s newborn screening program between 2006 and 2019. Materials and methods. We analyzed databases and other informative documents preserved in PREGEN from the 2006-2019 period. Results. One in every 164 newborns screened in our program had an abnormal hemoglobin variant, and one in every 194 carried some hemoglobin S variant. Glucose-6- phosphate dehydrogenase deficiency and congenital hypothyroidism are next as the more common disorders. Conclusions. Abnormal hemoglobin causes the most frequent monogenic disorder in the world. Glucose-6-phosphate dehydrogenase deficiency is the most common enzymopathy affecting nearly 400 million individuals worldwide. Since both disorders are more common in people of African descent and confer some resistance to malaria, we believe that screening for both disorders may be more relevant in the areas with African ancestry in our country.

Introducción. En Colombia, el primer programa de tamizaje neonatal, PREGEN, inició labores en el sector privado de Bogotá en 1988. En este artículo se presentan los resultados obtenidos en los últimos años, que, dada la carencia de estos estudios en el país, pueden servir para evaluar la frecuencia de aparición de los trastornos congénitos evaluados y estimar cuáles de ellos deben ser objeto de tamizaje neonatal a nivel nacional. Objetivos. Reportar los resultados del programa de tamizaje PREGEN entre el 2006 y el 2019. Materiales y métodos. Para este análisis se examinaron las bases de datos y otros documentos informativos de PREGEN para el periodo 2006-2019. Resultados. Uno de cada 164 recién nacidos tamizados en el programa PREGEN en Bogotá presentó una variante anormal de la hemoglobina y uno de cada 194 es portador de hemoglobina S. Los siguientes dos trastornos más frecuentes encontrados fueron la deficiencia de la enzima glucosa-6-fosfato deshidrogenasa (frecuencia 1:2.231) y el hipotiroidismo congénito (frecuencia 1:3.915). Conclusiones. Las hemoglobinopatías mostraron ser uno de los desórdenes monogénicos más comunes, seguidos por la deficiencia de glucosa-6-fosfato deshidrogenasa y el hipotiroidismo congénito. Se calcula que cerca de 400 millones de personas en el mundo están afectadas por la deficiencia de glucosa-6-fosfato deshidrogenasa, por lo cual es la enzimopatía más común en el mundo. Como ambos desórdenes son más frecuentes en poblaciones de origen africano y confieren algún grado de resistencia a la malaria, es de prever que su tamizaje debe ser de mayor importancia en las zonas con ancestros africanos en Colombia.

A novel useful marker in the early discrimination of transient hyperthyrotropinemia/hypothyroxinemia and congenital hypothyroidism in preterm infants: thyroid-stimulating hormone/free thyroxine ratio.

OBJECTIVES: Transient hyperthyrotropinemia/transient hypothyroxinaemia and congenital hypothyroidism (CH) have completely different treatment and clinical outcomes. However, a powerful, highly sensitive and cost-effective marker for the differentiation of these clinical entities in the early postnatal period is not available. Therefore, we aimed to test the potential, early predictive, diagnostic power of the thyroid-stimulating hormone (TSH)/free thyroxine (fT4) ratio for differentiation of the two clinical entities in the early period of life. METHODS: TSH and fT4 levels were recorded on the postnatal day 7 of premature infants<32 weeks of gestational age. TSH/fT4 ratio was calculated. The significance degree of TSH/fT4 ratio was analyzed for the differentiation of transient hyperthyrotropinemia or transient hypothyroxinaemia and CH. RESULTS: The study included 1,204 preterm infants<32 weeks of gestational age. Of the 1,204 infants, 978 (81.2 %) had normal thyroid function. Eighty-eight infants (7.3 %) were diagnosed with CH and 138 (11.5 %) with transient hyperthyrotropinemia or transient hypothyroxinemia. Initial TSH/fT4 ratio>4.8 was found to be an early diagnostic warning sign with high power in favor of transient hyperthyrotropinemia or transient hypothyroxinemia (AUC value: 0.947) and TSH/fT4 ratio>12.5 (AUC value: 0.999) was found to be an early diagnostic warning sign with high power in favor of CH (p=0.0001). CONCLUSIONS: We found for the first time that the TSH/fT4 ratio can be used for the early differentiation of transient hyperthyrotropinemia/transient hypothyroxinaemia and CH in preterm infants without additional cost and with high power.

TSHR Variant Screening and Phenotype Analysis in 367 Chinese Patients With Congenital Hypothyroidism.

Background: Genetic defects in the human thyroid-stimulating hormone (TSH) receptor (TSHR) gene can cause congenital hypothyroidism (CH). However, the biological functions and comprehensive genotype-phenotype relationships for most TSHR variants associated with CH remain unexplored. We aimed to identify TSHR variants in Chinese patients with CH, analyze the functions of the variants, and explore the relationships between TSHR genotypes and clinical phenotypes. Methods: In total, 367 patients with CH were recruited for TSHR variant screening using whole-exome sequencing. The effects of the variants were evaluated by in-silico programs such as SIFT and polyphen2. Furthermore, these variants were transfected into 293T cells to detect their Gs/cyclic AMP and Gq/11 signaling activity. Results: Among the 367 patients with CH, 17 TSHR variants, including three novel variants, were identified in 45 patients, and 18 patients carried biallelic TSHR variants. In vitro experiments showed that 10 variants were associated with Gs/cyclic AMP and Gq/11 signaling pathway impairment to varying degrees. Patients with TSHR biallelic variants had lower serum TSH levels and higher free triiodothyronine and thyroxine levels at diagnosis than those with DUOX2 biallelic variants. Conclusions: We found a high frequency of TSHR variants in Chinese patients with CH (12.3%), and 4.9% of cases were caused by TSHR biallelic variants. Ten variants were identified as loss-of-function variants. The data suggest that the clinical phenotype of CH patients caused by TSHR biallelic variants is relatively mild. Our study expands the TSHR variant spectrum and provides further evidence for the elucidation of the genetic etiology of CH.