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Introduction: Congenital hypothyroidism (CH) is the most common preventable cause of mental retardation, and the two important causes of CH are thyroid dysgenesis and dyshormonogenesis. Thyroid imaging is an integral part of identifying the specific aetiology of CH. We aimed to study the aetiological profile of CH and compare the imaging findings of ultrasonography (USG) and nuclear scintigraphy. Methods: It is a prospective, cross-sectional study conducted over 3 years. The clinical, USG, and technetium-99 m (99 mTc) scintigraphy reports of CH children were analysed. Results: Sixty-two CH children were included in the study with an equal male-to-female ratio (1.1:1). There was a significant association between parental consanguinity and CH observed in 35.5% of cases (P = 0.006). In USG neck, 44 (71%) had normal and/or enlarged thyroid glands at the eutopic location, 16 (27.4%) cases had an absent gland, and ectopic as well as hypoplastic unilateral gland was observed in one (1.6%) each. Among 35 children, who underwent scintigraphy, 12 (34.3%) had absent uptake, 4 (11.4%) had ectopic uptake, and 1 (2.8%) child had unilateral normal uptake. The remaining 18 (51.5%) children, whose scintigraphy showed normal or avid uptakes, were diagnosed with dyshormonogenesis. Three cases were diagnosed as apparent athyreosis. Conclusion: Dyshormonogeneis is the more commonly observed etiology of CH as compared to thyroid agenesis in the present study. A combined imaging approach with scintigraphy and USG is needed to delineate the specific etiology of CH. We need long-term Indian data to know the paradigm shift in the etiological pattern of CH as compared to Western studies.

Introduction: Congenital hypothyroidism (CH) is the most common preventable cause of mental retardation, and the two important causes of CH are thyroid dysgenesis and dyshormonogenesis. Thyroid imaging is an integral part of identifying the specific aetiology of CH. We aimed to study the aetiological profile of CH and compare the imaging findings of ultrasonography (USG) and nuclear scintigraphy. Methods: It is a prospective, cross-sectional study conducted over 3 years. The clinical, USG, and technetium-99 m (99 mTc) scintigraphy reports of CH children were analysed. Results: Sixty-two CH children were included in the study with an equal male-to-female ratio (1.1:1). There was a significant association between parental consanguinity and CH observed in 35.5% of cases (P = 0.006). In USG neck, 44 (71%) had normal and/or enlarged thyroid glands at the eutopic location, 16 (27.4%) cases had an absent gland, and ectopic as well as hypoplastic unilateral gland was observed in one (1.6%) each. Among 35 children, who underwent scintigraphy, 12 (34.3%) had absent uptake, 4 (11.4%) had ectopic uptake, and 1 (2.8%) child had unilateral normal uptake. The remaining 18 (51.5%) children, whose scintigraphy showed normal or avid uptakes, were diagnosed with dyshormonogenesis. Three cases were diagnosed as apparent athyreosis. Conclusion: Dyshormonogeneis is the more commonly observed etiology of CH as compared to thyroid agenesis in the present study. A combined imaging approach with scintigraphy and USG is needed to delineate the specific etiology of CH. We need long-term Indian data to know the paradigm shift in the etiological pattern of CH as compared to Western studies. [ABSTRACT FROM AUTHOR]

Biallelic loss-of-function variants in the IYD gene cause hypothyroidism resulting from iodine wasting. We describe 8 patients (from 4 families in which the parents are first cousins) who are homozygous for a variant in IYD (including a novel missense deleterious variant, c.791C>T [P264L], in 1 family). Seven patients presented between 5 and 16 years of age with a large goiter, overt hypothyroidism, and a high serum thyroglobulin. The goiter subsided with levothyroxine therapy in most. Upon stopping levothyroxine in 5 patients, goiter and hypothyroidism reappeared in 3. In these 3 patients, a rising serum thyroglobulin concentration preceded hypothyroidism and goiter and urinary iodine excretion was low. In patients who remained euthyroid, urinary iodine was normal. In conclusion, these patients bearing biallelic pathogenic variants in IYD developed a large goiter, a high serum thyroglobulin, and overt hypothyroidism when their iodine intake was low. [ABSTRACT FROM AUTHOR]

Background and Objectives: Congenital thyroid dyshormonogenesis is caused by alterations in the synthesis of thyroid hormones in a newborn. Additionally, 10 to 20% of these cases are hereditary, caused by defects in proteins involved in hormonal synthesis. One of the most common causes is mutations in the thyroid peroxidase (TPO) enzyme gene, an autosomal recessive disease. We aimed to detect mutations of the TPO gene in 12 Chilean patients with congenital hypothyroidism due to dyshormonogenesis (CHD) and to characterize these patients clinically and molecularly. Materials and Methods: Twelve patients under 20 years of age with CHD, controlled at San Juan de Dios Hospital in Santiago, Chile, were selected according to the inclusion criteria: elevated neonatal TSH, persistent hypothyroidism, and thyroid normotopic by imaging study. Those with deafness, Down syndrome, and central or transient congenital hypothyroidism were excluded. Blood samples were taken for DNA extraction, and the 17 exons and exon–intron junctions of the TPO gene were amplified by PCR. The PCR products were sequenced by Sanger. Results: Two possibly pathogenic mutations of the TPO gene were detected: c.2242G>A (p.Val748Met) and c.1103C>T (p.Pro368Leu). These mutations were detected in 2 of 12 patients (16.6%): 1 was compound heterozygous c.1103C>T/c.2242G>A, and the other was heterozygous for c.2242G>A. In the diagnostic confirmation test, both patients presented diffuse hyper-uptake goiter on thyroid scintigraphy and high TSH in venous blood (>190 uIU/mL). Conclusions: The frequency of patients with possibly pathogenic mutations in TPO with CHD was 16.6%. Its study would allow for genetic counseling to be offered to the families of affected patients. [ABSTRACT FROM AUTHOR]

Background and Objectives: Congenital thyroid dyshormonogenesis is caused by alterations in the synthesis of thyroid hormones in a newborn. Additionally, 10 to 20% of these cases are hereditary, caused by defects in proteins involved in hormonal synthesis. One of the most common causes is mutations in the thyroid peroxidase (TPO) enzyme gene, an autosomal recessive disease. We aimed to detect mutations of the TPO gene in 12 Chilean patients with congenital hypothyroidism due to dyshormonogenesis (CHD) and to characterize these patients clinically and molecularly. Materials and Methods: Twelve patients under 20 years of age with CHD, controlled at San Juan de Dios Hospital in Santiago, Chile, were selected according to the inclusion criteria: elevated neonatal TSH, persistent hypothyroidism, and thyroid normotopic by imaging study. Those with deafness, Down syndrome, and central or transient congenital hypothyroidism were excluded. Blood samples were taken for DNA extraction, and the 17 exons and exon–intron junctions of the TPO gene were amplified by PCR. The PCR products were sequenced by Sanger. Results: Two possibly pathogenic mutations of the TPO gene were detected: c.2242G>A (p.Val748Met) and c.1103C>T (p.Pro368Leu). These mutations were detected in 2 of 12 patients (16.6%): 1 was compound heterozygous c.1103C>T/c.2242G>A, and the other was heterozygous for c.2242G>A. In the diagnostic confirmation test, both patients presented diffuse hyper-uptake goiter on thyroid scintigraphy and high TSH in venous blood (>190 uIU/mL). Conclusions: The frequency of patients with possibly pathogenic mutations in TPO with CHD was 16.6%. Its study would allow for genetic counseling to be offered to the families of affected patients.

Background: Newborn screening (NBS) has largely eliminated the physical and neurodevelopmental effects of untreated congenital hypothyroidism (CH). Many countries, including Australia, have progressively lowered NBS bloodspot thyroid‐stimulating hormone (b‐TSH) thresholds. The impact of these changes is still unclear. Objectives: To evaluate the performance of CH NBS following the reduction of b‐TSH thresholds in New South Wales (NSW) and the Australian Capital Territory (ACT), Australia, from 15 to 8 mIU/L, and to determine the clinical outcomes of cases detected by these thresholds. Methods: NBS data of 346 849 infants born in NSW/ACT, Australia from 1 November, 2016–1 March, 2020 inclusive were analysed. A clinical audit was conducted on infants with a preliminary diagnosis of CH born between 1 January, 2016–1 December, 2020 inclusive. Results: The lowered b‐TSH threshold (≥8 mIU/L, ~99.5th centile) detected 1668 infants (0.48%), representing an eight‐fold increase in recall rate, of whom 212 of 1668 (12.7%) commenced thyroxine treatment. Of these 212 infants, 62 (29.2%) (including eight cases with a preliminary diagnosis of thyroid dysgenesis) had an initial b‐TSH 8–14.9 mIU/L. The positive predictive value for a preliminary diagnosis of CH decreased from 74.3% to 12.8% with the lowered threshold. Proportionally, more pre‐term infants received a preliminary CH diagnosis on screening with the lower threshold (16.1% of 62) than with the higher threshold (8.0% of 150). Conclusion: Clinically relevant CH was detected using the lowered threshold, albeit at the cost of an eight‐fold increase in recall rate. Further clinical and economic studies are required to determine whether benefits of lowered screening thresholds outweigh potential harms from false‐positive results on infants, their families and NBS programs. [ABSTRACT FROM AUTHOR]

Abstract Background Primary congenital hypothyroidism (CH) is a rare endocrine disorder in cats with a largely unknown genetic cause. Objectives Describe the clinical presentation of CH in 11 affected cats and identify the causal genetic variant. Animals Eleven CH‐cats from 10 unrelated families, 11 CH‐free family members, 21 unrelated CH‐free cats, and 155 unrelated nondiagnosed cats from different breeds. Methods Case control study of CH‐cats and their siblings (2019‐2021). Diagnosis was based on low to low‐normal serum thyroxine (T4) concentrations, high thyroid‐stimulating hormone (TSH) concentrations and clinical signs compatible with CH. We identified the causal variant using Sanger sequencing, genotyping via PCR‐RFLP and variant interpretation using ACMG/AMP guidelines. Results All CH‐cats (5 weeks‐8 years) had disproportionate dwarfism. A goiter was not palpable in all. Thyroid scintigraphy with radiopertechnetate showed abnormally high uptake by thyroid glands, whereas scintigraphy with radioiodine showed abnormally low uptake, compatible with a defect in iodine organification by thyroid peroxidase (TPO). All cases were homozygous for TPO variant XM_006930524.4:c.430G>A(p.(Gly144Arg)), while none of the CH‐free cats were. All sampled parents were heterozygous for this recessive variant. This variant was found in 15 cat breeds with an estimated allele frequency of 9%. Conclusions and Clinical Importance Disproportionate dwarfism, abnormally high TSH and abnormally low to low‐normal T4 concentrations are diagnostic for CH in cats. All cases had dyshormonogenesis demonstrated by thyroid scintigraphy. This novel TPO missense variant (not described in humans) causes CH in cats and awareness of it can assist in diagnosis and breeding.

Background: More than 40 years have passed since the introduction of newborn screening (NBS) for congenital hypothyroidism (CH), and many early diagnosed patients have reached adulthood. Their thyroid morphology and function have been little studied. This cross-sectional, observational study was conducted to characterize the thyroid morphology and function of adult CH patients diagnosed in the framework of NBS for CH. Methods: A total of 103 adult CH patients born after 1979 were enrolled at Ito Hospital, Tokyo, Japan, and were classified into Goiter, Normal gland, and Dysgenesis groups based on ultrasonographic findings. For 60 patients, genetic analysis was performed. Thyroid function test results and the proportion of patients with thyroid nodules were compared among the three groups and between 56 female CH patients and 168 non-CH women matched for thyrotropin levels. Results: A significantly low serum free triiodothyronine/free thyroxine ratio (0.22) was observed in the Dysgenesis group. Thyroid nodules were detected in 14.3% (8/56) of female CH patients, more frequently than in non-CH women. Thyroid nodules were detected most frequently in the Goiter group (71%, 10/14). Genetic defects were identified in 89% (8/9) of patients belonging to the Goiter group, including thyroglobulin defect (33%, 3/9), thyroid peroxidase defect (33%, 3/9), and dual oxidase 2 defect (22%, 2/9). Conclusions: Our results suggest that adults with thyroid dysgenesis on levothyroxine replacement therapy have relative triiodothyronine deficiency. Most adults with goitrous CH have genetic dyshormonogenesis. They are at high risk of developing thyroid nodules. Our findings support the current guideline recommendation that CH patients with dyshormonogenesis should undergo periodic thyroid ultrasonography. [ABSTRACT FROM AUTHOR]

ABSTRACT Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder and one of the most common preventable causes of intellectual disability in the world. CH may be due to developmental or functional thyroid defects (primary or peripheral CH) or be hypothalamic‐pituitary in origin (central CH). In most cases, primary CH is caused by a developmental malformation of the gland (thyroid dysgenesis, TD) or by a defect in thyroid hormones synthesis (dyshormonogenesis, DH). TD represents about 65% of CH and a genetic cause is currently identified in fewer than 5% of patients. The remaining 35% are cases of DH and are explained with certainty at the molecular level in more than 50% of cases. The etiology of CH is mostly unknown and may include contributions from individual and environmental factors. In recent years, the detailed phenotypic description of patients, high‐throughput sequencing technologies, and the use of animal models have made it possible to discover new genes involved in the development or function of the thyroid gland. This paper reviews all the genetic causes of CH. The modes by which CH is transmitted will also be discussed, including a new oligogenic model. CH is no longer simply a dominant disease for cases of CH due to TD and recessive for cases of CH due to DH, but a far more complex disorder.

Aim:Congenital hypothyroidism (CH) is one of the most common endocrinological problems in the neonatal period. CH, which occurs in 1:3,000-4,000 births, is a preventable cause of mental retardation. In the literature, the most common cause of CH is dysgenesis of the thyroid gland, followed by thyroid dyshormonogenesis. We aimed to determine the prevalence of permanent (P-CH) and transient (T-CH) CH in cases followed up with a diagnosis of CH and to identify a prediction method for persistency.Materials and Methods:We retrospectively analyzed the medical records of 105 children with CH. TSH levels in a screening program, TSH and fT4 levels of the first venous sample, 10-15th day of treatment, monthly in the first 6 months, 2-3 monthly until 18th months, and 6-monthly until 3 years of age were recorded. L-T4 doses (per microgram per body weight) in each visit were also recorded.Results:From the 105 children (58 males, 47 females) enrolled in this study, 38 (36.2 %) were referred from the National Newborn Screening Program. Treatment was discontinued during the 3rd year follow-up period in 44 (41.9 %) of the cases with normal thyroid gland morphology. L-thyroxine (L-T4) therapy was discontinued at a median age of 1.9+-1.08 years.TSH levels at the time of diagnosis were higher in the P-CH group, but this difference was not statistically significant (p=0.165). At the sixth month, first and second years of follow-up, L-T4 doses were significantly higher in the P-CH than in the T-CH group (p

Background and aims: Although the significance of primary congenital hypothyroidism (CH) is supported by an increasing amount of evidence, the clinical and genetic characteristics of this condition are still poorly understood. This study aimed to explore the underlying genetic etiologies in a cohort of primary CH patients. Subjects and Methods: The clinical data of 33 patients with primary CH were collected and analyzed via a cross-sectional study. Genetic analysis was performed by high-throughput sequencing and Sanger verification, and the pathogenicity of the novel missense variants was predicted using a variety of comprehensive bioinformatic tools. Results: Among the 33 patients, 22 (22/33, 66.7%) harbored pathogenic variants in the causative genes of thyroid dysgenesis or dyshormonogenesis, with DUOX2 (15/33, 45.5%) topping the list, followed by TG, TPO, DUOXA2 and PAX8. Four novel genetic variants were detected, including a pathogenic frameshift and three likely pathogenic missense variants. Positive neonatal screening for TSH, neonatal jaundice and abnormal thyroid morphology were the main positive findings among all cases. Although 31 of the total 33 CH patients exhibited normal anthropometric and social performance, the other 2 had poor prognosis in this study. Conclusions: This study reported 33 new CH patients bearing four novel genetic variants, which enriched the variant spectrum of CH genes. In this cohort, genetic factors causing thyroid dyshormonogenesis were the main etiologies of CH development. Most patients exhibited a favorable prognosis; however, systematic management remains a challenge in achieving improved clinical outcomes for CH patients. [ABSTRACT FROM AUTHOR]

Congenital hypothyroidism (CH) is the most frequent neonatal endocrine disorder and the most common preventable cause of development delay and growth failure if diagnosed and treated early. The thyroid is the first endocrine gland to develop during embryonic life and to be recognizable in humans. Thyroid development and maturation can be divided into 2 phases: a first phase of embryogenesis and a second phase of folliculogenesis and differentiation with thyroid hormone production at the final steps. Regulation of the thyroid function requires normal development of the hypothalamic-pituitary-thyroid axis, which occurs during the embryonic and neonatal period. Defects in any of steps of thyroid development, differentiation, and regulation lead to permanent CH. Newborn screening programs, established in only one-third of countries worldwide, detect CH and are cost-effective and highly sensitive and specific. During the last decade, epidemiology of CH has changed with increased frequency of thyroid in situ in primary CH. Advances in molecular testing have expanded knowledge and understanding of thyroid development and function. However, a molecular cause is identified in only 5% of CH due to thyroid dysgenesis. The purpose of this article is to describe the clinical approach to the child with CH, focusing on diagnostic work-up and future challenges on optimizing thyroid replacement therapy and regenerative medicine. The review is written from the perspective of the case of 2 girls referred for CH after newborn screening and diagnosed with thyroid ectopy. The genetic work-up revealed novel mutations in TUBB1 gene, associated with large platelets and abnormal platelet physiology. [ABSTRACT FROM AUTHOR]

Background: Primary congenital hypothyroidism (CH) is a rare endocrine disorder in cats with a largely unknown genetic cause. Objectives: Describe the clinical presentation of CH in 11 affected cats and identify the causal genetic variant. Animals: Eleven CH‐cats from 10 unrelated families, 11 CH‐free family members, 21 unrelated CH‐free cats, and 155 unrelated nondiagnosed cats from different breeds. Methods: Case control study of CH‐cats and their siblings (2019‐2021). Diagnosis was based on low to low‐normal serum thyroxine (T4) concentrations, high thyroid‐stimulating hormone (TSH) concentrations and clinical signs compatible with CH. We identified the causal variant using Sanger sequencing, genotyping via PCR‐RFLP and variant interpretation using ACMG/AMP guidelines. Results: All CH‐cats (5 weeks‐8 years) had disproportionate dwarfism. A goiter was not palpable in all. Thyroid scintigraphy with radiopertechnetate showed abnormally high uptake by thyroid glands, whereas scintigraphy with radioiodine showed abnormally low uptake, compatible with a defect in iodine organification by thyroid peroxidase (TPO). All cases were homozygous for TPO variant XM_006930524.4:c.430G>A(p.(Gly144Arg)), while none of the CH‐free cats were. All sampled parents were heterozygous for this recessive variant. This variant was found in 15 cat breeds with an estimated allele frequency of 9%. Conclusions and Clinical Importance: Disproportionate dwarfism, abnormally high TSH and abnormally low to low‐normal T4 concentrations are diagnostic for CH in cats. All cases had dyshormonogenesis demonstrated by thyroid scintigraphy. This novel TPO missense variant (not described in humans) causes CH in cats and awareness of it can assist in diagnosis and breeding. [ABSTRACT FROM AUTHOR]

Thyroglobulin gene abnormalities cause thyroid dyshormonogenesis. A 6-yr-old boy of consanguineous parents presented with a large goiter and mild hypothyroidism (thyroid-stimulating hormone [TSH] 7.2 μIU/mL, free T3 [FT3] 3.4 pg/mL, free T4 [FT4] 0.6 ng/dL). Despite levothyroxine (LT4) administration and normal TSH levels, the goiter progressed slowly and increased rapidly in size at the onset of puberty. Thyroid scintigraphy revealed a remarkably high 123I uptake of 75.2%, with a serum thyroglobulin level of 13 ng/ml, which was disproportionately low for the goiter size. DNA sequencing revealed a novel homozygous missense variant, c.434G>A [p.Gly145Glu], in the thyroglobulin gene. Goiter growth was suppressed by increasing the LT4 dose. Thyroidectomy was performed at 17-yr-of-age. Thyroglobulin analysis of the thyroid tissue detected mutant thyroglobulin present in the endoplasmic reticulum, demonstrating that thyroglobulin transport from the endoplasmic reticulum to the Golgi apparatus was impaired by the Gly145Glu variant. During the clinical course, an elevated FT3/FT4 ratio was observed along with thyroid enlargement. A high FT3/FT4 ratio and goiter seemed to be compensatory responses to impaired hormone synthesis. Thyroglobulin defects with goiter should be treated with LT4, even if TSH levels are normal. [ABSTRACT FROM AUTHOR]

Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder and one of the most common preventable causes of intellectual disability in the world. CH may be due to developmental or functional thyroid defects (primary or peripheral CH) or be hypothalamic‐pituitary in origin (central CH). In most cases, primary CH is caused by a developmental malformation of the gland (thyroid dysgenesis, TD) or by a defect in thyroid hormones synthesis (dyshormonogenesis, DH). TD represents about 65% of CH and a genetic cause is currently identified in fewer than 5% of patients. The remaining 35% are cases of DH and are explained with certainty at the molecular level in more than 50% of cases. The etiology of CH is mostly unknown and may include contributions from individual and environmental factors. In recent years, the detailed phenotypic description of patients, high‐throughput sequencing technologies, and the use of animal models have made it possible to discover new genes involved in the development or function of the thyroid gland. This paper reviews all the genetic causes of CH. The modes by which CH is transmitted will also be discussed, including a new oligogenic model. CH is no longer simply a dominant disease for cases of CH due to TD and recessive for cases of CH due to DH, but a far more complex disorder. [ABSTRACT FROM AUTHOR]

The sodium-iodide symporter (NIS, SLC5A5) is expressed at the basolateral membrane of the thyroid follicular cell, and facilitates the thyroidal iodide uptake required for thyroid hormone biosynthesis. Biallelic loss-of-function mutations in NIS are a rare cause of dyshormonogenic congenital hypothyroidism. Affected individuals typically exhibit a normally sited, often goitrous thyroid gland, with absent uptake of radioiodine in the thyroid and other NIS-expressing tissues. We report a novel homozygous NIS mutation (c.1067 C>T, p.S356F) in four siblings from a consanguineous Indian kindred, presenting with significant hypothyroidism. Functional characterization of the mutant protein demonstrated impaired plasma membrane localization and cellular iodide transport. [ABSTRACT FROM AUTHOR]

Aim: Congenital hypothyroidism (CH) is one of the most common endocrinological problems in the neonatal period. CH, which occurs in 1:3,000-4,000 births, is a preventable cause of mental retardation. In the literature, the most common cause of CH is dysgenesis of the thyroid gland, followed by thyroid dyshormonogenesis. We aimed to determine the prevalence of permanent (P-CH) and transient (T-CH) CH in cases followed up with a diagnosis of CH and to identify a prediction method for persistency. Materials and Methods: We retrospectively analyzed the medical records of 105 children with CH. TSH levels in a screening program, TSH and fT4 levels of the first venous sample, 10-15th day of treatment, monthly in the first 6 months, 2-3 monthly until 18th months, and 6-monthly until 3 years of age were recorded. L-T4 doses (per microgram per body weight) in each visit were also recorded. Results: From the 105 children (58 males, 47 females) enrolled in this study, 38 (36.2 %) were referred from the National Newborn Screening Program. Treatment was discontinued during the 3rd year follow-up period in 44 (41.9 %) of the cases with normal thyroid gland morphology. L-thyroxine (L-T4) therapy was discontinued at a median age of 1.9+-1.08 years. TSH levels at the time of diagnosis were higher in the P-CH group, but this difference was not statistically significant (p=0.165). At the sixth month, first and second years of follow-up, L-T4 doses were significantly higher in the P-CH than in the T-CH group (p<0.001, p<0.001, p<0.001 respectively). TSH levels were also higher in the P-CH group than in the T-CH group (p=0.123, p=0.038, p=0.049 respectively). Consistent with these results, measured fT4 levels were found to be lower in the P-CH group compared to the T-CH group (p=0.431, p=0.361, p=0.028 respectively). Conclusion: L-T4 doses at 6, 12 and 24 months may predict transient hypothyroidism in patients with normal thyroid gland morphology before 36 months. [ABSTRACT FROM AUTHOR]

Abstract Indications and administration of intra‐amniotic infusions of L‐thyroxine in the context of non‐immune fetal hypothyroidism with goiter lack of standardization. Systematic follow‐up of clinical features related to thyroid hormonal homeostasis may be useful to evaluate their efficiency and develop standardized management guidelines.

Differentiated thyroid carcinoma (DTC) combined with congenital hypothyroidism (CH) is a rare situation, and there is no well-established caus al relationship. CH is a common congenital endocrine, while DTC occurring in childhood represents 0.4-3% of all malignancies at this stage of life. The association of CH w ith DTC could be related to dyshormonogenetic goiter (DHG) or developmental abnormalities. This review will explore the clinical features and the molecular mechanisms potentially associated with the appearance of DTC in CH: sporadic somatic driver mutations, chronic increase of thyroid-stimulating hormone (TSH) levels, higher concentrations of hydrogen peroxide (H2O2), cell division cycle associated 8 (Borelain/CDC8) gene mutations, and in others genes associated with CH -- either alone or associated with the mechanisms involved in dyshormonogenesis. There are some pitfalls in the diagnosis of thyroid cancer in patients with CH with nodular goiter, as the proper cytological diagnosis of nodules of patients with dyshormonogenesis might be demanding due to the specific architectural and cytological appearance, which may lead to an erroneous interpretation of malignancy. The purpose of this article is to suggest an analytical framewo rk that embraces the fundamental relationships between the various aspects of CH and CDT. In face of this scenario, the entire genetic and epigenetic context, the complex functioning, and cross talk of cell signaling may determine cellular mechanisms promoting both the maintenance of the differentiated state of the thyroid follicular cell and the disruption of its homeostasis leading to cancer. Whereas, the exact mechanisms for thyroid cancer development in CH remain to be elucidated. [ABSTRACT FROM AUTHOR]

Indications and administration of intra‐amniotic infusions of L‐thyroxine in the context of non‐immune fetal hypothyroidism with goiter lack of standardization. Systematic follow‐up of clinical features related to thyroid hormonal homeostasis may be useful to evaluate their efficiency and develop standardized management guidelines. [ABSTRACT FROM AUTHOR]

The prevalence of congenital hypothyroidism is high in India at 5.7 per 10,000 infants and an incidence rate of 1 in 244 in Kerala state. Neonatal mass screening programs have been largely successful in early diagnosis of congenital hypothyroidism. Both, very young and advanced maternal age are considered at risk for adverse pregnancy outcomes which in turn may be a factor for development of congenital hypothyroidism in neonates. The studies related to the role of maternal age as a risk factor for development of congenital hypothyroidism are minimal. Not much studies are available which analyse the association of adequately treated maternal hypothyroidism on the neonatal thyroid dysgenesis and other causes of neonatal congenital hypothyroidism. The study collected data about the age and thyroid status of 120 mothers of neonates in which n=60 cases were Mothers of the neonates with congenital hypothyroidism (TSH > 15.2 µIU/mL) and n=60 controls mothers of euthyroid healthy neonates (TSH ≤ 15.2 µIU/mL). Data collected regarding the maternal thyroid status was evaluated in the antenatal period during first trimester and neonatal thyroid status was evaluated at birth from cord blood. All the mothers included in the study with hypothyroidism (both cases and controls) were either already on treatment or were treated appropriately during pregnancy. The mean maternal age in cases (n=60) was 34.8± 5.7 years while that in control (n=60) was 25.43± 4.3 years. There is a high statistically significant (p<0.0001) increase in maternal age in cases compared to controls. The odds of being ≥35 years were higher in mothers of neonates with congenital hypothyroidism as compared to mothers of normal children with Odds ratio of 5.06; and highly significant P value 0.0001. The odds of mothers of neonates with congenital hypothyroidism having hypothyroidism, compared mothers of euthyroid neonates having hypothyroidism is not statistically significant with Odds ratio of 3.14; with P value 0.06. The risks of acquiring congenital hypothyroidism in neonates increase with advanced maternal age. Neonatal TSH levels are dynamic and are affected by several factors including maternal hypothyroidism. Pre-conceptional consultation and evaluation of thyroid status as well as first trimester universal screening and adequate treatment of maternal hypothyroidism may play an effective role in decreasing the incidence of neonatal congenital hypothyroidism, especially in high risk pregnancies due to advanced maternal age. [ABSTRACT FROM AUTHOR]

Background: An ENDO-European Reference Network (ERN) initiative was launched that was endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology with 22 participants from the ENDO-ERN and the two societies. The aim was to update the practice guidelines for the diagnosis and management of congenital hypothyroidism (CH). A systematic literature search was conducted to identify key articles on neonatal screening, diagnosis, and management of primary and central CH. The evidence-based guidelines were graded with the Grading of Recommendations, Assessment, Development and Evaluation system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. Summary: The recommendations include the various neonatal screening approaches for CH as well as the etiology (also genetics), diagnostics, treatment, and prognosis of both primary and central CH. When CH is diagnosed, the expert panel recommends the immediate start of correctly dosed levothyroxine treatment and frequent follow-up including laboratory testing to keep thyroid hormone levels in their target ranges, timely assessment of the need to continue treatment, attention for neurodevelopment and neurosensory functions, and, if necessary, consulting other health professionals, and education of the child and family about CH. Harmonization of diagnostics, treatment, and follow-up will optimize patient outcomes. Lastly, all individuals with CH are entitled to a well-planned transition of care from pediatrics to adult medicine. Conclusions: This consensus guidelines update should be used to further optimize detection, diagnosis, treatment, and follow-up of children with all forms of CH in the light of the most recent evidence. It should be helpful in convincing health authorities of the benefits of neonatal screening for CH. Further epidemiological and experimental studies are needed to understand the increased incidence of this condition. [ABSTRACT FROM AUTHOR]

Introduction: Congenital hypothyroidism (CH) is the most frequent neonatal endocrine disorder and one of the most common preventable forms of mental retardation worldwide. CH is due to thyroid development or thyroid function defects (primary) or may be of hypothalamic-pituitary origin (central). Primary CH is caused essentially by abnormal thyroid gland morphogenesis (thyroid dysgenesis, TD) or defective thyroid hormone synthesis (dyshormonogenesis, DH). TD accounts for about 65% of CH, however a genetic cause is identified in less than 5% of patients. Purpose: The pathogenesis of CH is largely unknown and may include the contribution of individual and environmental factors. During the last years, detailed phenotypic description of patients, next-generation sequence technologies and use of animal models allowed the discovery of novel candidate genes in thyroid development, function and pathways. Results and conclusion: We provide an overview of recent genetic causes of primary and central CH. In addition, mode of inheritance and the oligogenic model of CH are discussed. [ABSTRACT FROM AUTHOR]

Introduction: Thyroid dyshormonogenesis (TDH) is a subgroup of congenital hypothyroidism with recessive inheritance resulting from disease-causing variants in thyroid hormone biosynthesis pathway genes, like DUOX2, TG, TPO, SLC5A5, SLC26A4, IYD, DUOXA2, and SLC26A7. Thyroid peroxidase (TPO) is a crucial enzyme involved in thyroid hormone biosynthesis and is one of the frequently mutated genes in patients with TDH. The purpose of the study was to describe the in silico and functional characterization of novel variants in TPO gene identified in patients with TDH., Methods: We performed exome sequencing in Indian patients with TDH. In the current study, we describe the results of patients with TPO gene mutations. Exome sequencing results were further analysed by Sanger sequencing, computational studies, and in vitro functional studies such as immunofluorescence and enzyme assay., Results: We identified nine biallelic disease-causing variants in the TPO gene in 12 patients from nine unrelated Indian families. Eight of the nine variants were novel. No recurrent variants were identified. Computational analysis of six missense variants showed that these amino acid substitutions caused changes in non-covalent interactions with the adjacent residues that may affect the TPO protein structure and function. In vitro experimental data using immunofluorescence assay showed that these variants did not affect the plasma membrane localization of the TPO protein but caused a significant loss of TPO enzymatic activity compared to the wild type., Conclusion: Our study revealed multiple novel pathogenic variants in TPO gene in Indian patients, thereby expanding the genotype spectrum. Functional studies helped us to reveal the pathogenicity of the missense variants., (© 2024 S. Karger AG, Basel.)

ObjectiveTo elucidate the molecular cause in a well-characterized cohort of patients with Congenital Hypothyroidism (CH) and Dyshormonogenesis (DH) by using targeted next-generation sequencing (TNGS).Study designWe studied 19 well-characterized patients diagnosed with CH and DH by targeted NGS including genes involved in thyroid hormone production. The pathogenicity of novel mutations was assessed based on in silico prediction tool results, functional studies when possible, variant location in important protein domains, and a review of the recent literature.ResultsTNGS with variant prioritization and detailed assessment identified likely disease-causing mutations in 10 patients (53%). Monogenic defects most often involved TG, followed by DUOXA2, DUOX2, and NIS and were usually homozygous or compound heterozygous. Our review shows the importance of the detailed phenotypic description of patients and accurate analysis of variants to provide a molecular diagnosis.ConclusionsIn a clinically well-characterized cohort, TNGS had a diagnostic yield of 53%, in accordance with previous studies using a similar strategy. TG mutations were the most common genetic defect. TNGS identified gene mutations causing DH, thereby providing a rapid and cost-effective genetic diagnosis in patients with CH due to DH.

Neonatal screening in Macedonia detects congenital hypothyroidism (CH) with an incidence of 1 in 1,585, and more than 50% of cases exhibit a normally located gland-in-situ (GIS). Monogenic mutations causing dyshormonogenesis may underlie GIS CH; additionally, a small proportion of thyroid hypoplasia has a monogenic cause, such as TSHR and PAX8 defects. The genetic architecture of Macedonian CH cases has not previously been studied. We recruited screening-detected, non-syndromic GIS CH or thyroid hypoplasia cases (n = 40) exhibiting a spectrum of biochemical thyroid dysfunction ranging from severe permanent to mild transient CH and including 11 familial cases. Cases were born at term, with birth weight >3,000 g, and thyroid morphologies included goiter (n = 11), thyroid hypoplasia (n = 6), and apparently normal-sized thyroid. A comprehensive, phenotype-driven, Sanger sequencing approach was used to identify genetic mutations underlying CH, by sequentially screening known dyshormonogenesis-associated genes and TSHR in GIS cases and TSHR and PAX8 in cases with thyroid hypoplasia. Potentially pathogenic variants were identified in 14 cases, of which four were definitively causative; we also detected digenic variants in three cases. Seventeen variants (nine novel) were identified in TPO (n = 4), TG (n = 3), TSHR (n = 4), DUOX2 (n = 4), and PAX8 (n = 2). No mutations were detected in DUOXA2, NIS, IYD, and SLC26A7. The relatively low mutation frequency suggests that factors other than recognized monogenic causes (oligogenic variants, environmental factors, or novel genes) may contribute to GIS CH in this region. Future non–hypothesis-driven, next-generation sequencing studies are required to confirm these findings.

Thyroid dyshormonogenesis is characterized by impairment in one of the several stages of thyroid hormone synthesis and accounts for 10%–15% of congenital hypothyroidism (CH). Seven genes are known to be associated with thyroid dyshormonogenesis: SLC5A5 (NIS), SCL26A4 (PDS), TG, TPO, DUOX2, DUOXA2, and IYD (DHEAL1). Depending on the underlying mechanism, CH can be permanent or transient. Inheritance is usually autosomal recessive, but there are also cases of autosomal dominant inheritance. In this review, we describe the molecular basis, clinical presentation, and genetic diagnosis of CH due to thyroid dyshormonogenesis, with an emphasis on the benefits of targeted exome sequencing as an updated diagnostic approach.

Objective: To elucidate the molecular cause in a well-characterized cohort of patients with Congenital Hypothyroidism (CH) and Dyshormonogenesis (DH) by using targeted next-generation sequencing (TNGS). Study design: We studied 19 well-characterized patients diagnosed with CH and DH by targeted NGS including genes involved in thyroid hormone production. The pathogenicity of novel mutations was assessed based on in silico prediction tool results, functional studies when possible, variant location in important protein domains, and a review of the recent literature. Results: TNGS with variant prioritization and detailed assessment identified likely disease-causing mutations in 10 patients (53%). Monogenic defects most often involved TG , followed by DUOXA2 , DUOX2 , and NIS and were usually homozygous or compound heterozygous. Our review shows the importance of the detailed phenotypic description of patients and accurate analysis of variants to provide a molecular diagnosis. Conclusions: In a clinically well-characterized cohort, TNGS had a diagnostic yield of 53%, in accordance with previous studies using a similar strategy. TG mutations were the most common genetic defect. TNGS identified gene mutations causing DH, thereby providing a rapid and cost-effective genetic diagnosis in patients with CH due to DH. [ABSTRACT FROM AUTHOR]

Objective: Congenital hypothyroidism (CH) is a common cause of preventable severe neurocognitive impairment in children. Previously conducted studies describing the natural history of CH in Saudi Arabia were either of shorter duration or a limited number of patients. In this study, we aim to assess our experience in the clinical course and therapeutic outcome of CH in two large tertiary centers in Saudi Arabia. Methods: This is a retrospective chart review of patients <18 years of age diagnosed with CH at King Abdulaziz Medical City in Jeddah and Riyadh, Saudi Arabia, between 2000 and 2018. Data were collected from the patients’ medical records, including epidemiological, clinical, laboratory, and radiological features as well as a long-term outcome of CH. Statistical analysis was carried out using the JMP statistical software. This study was approved by the Institutional Review Board (IRB) at King Abdullah International Medical Research Center (KAIMRC). Results: Out of the 71 cases, 53.5% were female, and 80.3% of these cases were diagnosed in the 1st week of life. The estimated incidence of CH is 1:2470 in the two study centers. Ectopic thyroid (43%, n = 25/58), dyshormonogenesis (34.5%, n = 20/58), and thyroid agenesis and hypoplasia (22.4%, n = 13/58). Learning difficulty was significantly associated with delayed treatment onset (P = 0.044) and lower compliance with treatment (P = 0.001). Conclusion: In our study, the incidence of dyshormonogenesis in CH is higher than international rates (34.5% vs. 20%), possibly because of consanguinity. Effective neonatal screening program facilitates early diagnosis that leads to prompt management of CH and avoidance of long-term outcome of neurocognitive impairment. [ABSTRACT FROM AUTHOR]

Fetal goitrous hypothyroidism is a rare condition associated with important obstetrical, neonatal complications, and neurodevelopmental impairments. Prenatal treatment remains controversial, and the risk to benefit ratio must be accurately assessed and considered for individualized management. The objective of this review was to evaluate the feasibility, safety, and effectiveness of the conservative in utero treatment of fetal goitrous hypothyroidism. In total, 25 reports that met our inclusion criteria were selected and the management of 38 cases was analyzed. Prenatal diagnosis consisted mainly of ultrasonographic findings. Fetal thyroid status was assessed by cordocentesis. Prenatal treatment varied widely in terms of levothyroxine (LT4) route of administration, dosage, number of injections, and frequency. Although different regimens and routes of administration were proposed, they seem to have similar results regarding fetal goiter reduction and thyroid status at birth. At birth, most babies had hypothyroidism, but the long-term follow-up indicated a normal psycho-neuromotor development. Our data confirm the feasibility of conservative treatment with LT4 for fetal goitrous hypothyroidism. Further studies are needed to determine the optimal management of this disorder. [ABSTRACT FROM AUTHOR]

Introduction: The incidence of fetal goiters is reported to be around 1 per 40,000 births. The risk of complications is first of all obstetric, directly related to goiter size, but it may also affect longer term fetal and child development, depending on whether the goiter is due to hypo- or hyperthyroidism. Management is multidisciplinary, but not yet consensual and not always optimal by either endocrinologists or obstetricians.Objectives: The principal objective of this retrospective study was to analyze the data that enabled the physicians to assess whether the goiter was hypo- or hyperthyroid and then to analyze the obstetric practices used in the Pays de Loire network to describe in detail the tools used to diagnose and characterize the goiters and the management chosen in these cases. The secondary objectives are to assess, in our small cohort, the effectiveness of the in utero treatments provided, based on the examination of the children at birth and their outcome at 6 months of life, and to suggest a strategy for monitoring these women at risk that takes current guidelines into consideration.Materials and methods: This multicenter retrospective study covers a 6-year period and focused on the prenatal diagnosis centers (CPDPN) of the Pays de Loire perinatal network: in Nantes, Angers, and Le Mans. The network is responsible for around 42,000 births a year, and the study included 17 women, for a prevalence of 1 per 15,000 births.Results: Ten of the 17 fetuses had a hypothyroid goiter, 4 a hyperthyroid goiter, and 3 normal thyroid findings on fetal blood sample (FBS). For four women, these goiters were secondary to fetal dyshormonogenesis, for 9 more to Graves disease with TSH receptor antibodies (TRAb), and for four women to thyrotoxicosis at the start of pregnancy, managed by synthetic antithyroid drugs. Two newborns had severe complications associated with maternal transmission of Graves disease (TRAb positive at birth): one with exophthalmos and one with neonatal tachycardia. The other 14 had normal psychomotor development at 6 months, based on a clinical examination by a pediatric endocrinologist; only one child was lost to follow-up.Conclusion: Together, ultrasound and multidisciplinary expertise (of an endocrinologist and an obstetrician experienced with this disease) remain the best means for avoiding, or otherwise for accurately characterizing fetal goiter. An ultrasound diagnostic score, of the type proposed by Luton et al. in 2009, may make it possible to homogenize practices and thus to defer or delay the - currently too common - performance of invasive FBS procedures, which must remain rare in this management to limit comorbidities. A threshold TRAb value (>5 IU/l) makes it possible to define this group of women as at risk of fetal and neonatal hyperthyroidism and thus requiring close monitoring. The value of prenatal intra-amniotic thyroxine treatment for hypothyroid goiters (including dyshormonogenesis) remains to be demonstrated. [ABSTRACT FROM AUTHOR]

Neonatal screening in Macedonia detects congenital hypothyroidism (CH) with an incidence of 1 in 1,585, and more than 50% of cases exhibit a normally located gland- in-situ (GIS). Monogenic mutations causing dyshormonogenesis may underlie GIS CH; additionally, a small proportion of thyroid hypoplasia has a monogenic cause, such as TSHR and PAX8 defects. The genetic architecture of Macedonian CH cases has not previously been studied. We recruited screening-detected, non-syndromic GIS CH or thyroid hypoplasia cases (n = 40) exhibiting a spectrum of biochemical thyroid dysfunction ranging from severe permanent to mild transient CH and including 11 familial cases. Cases were born at term, with birth weight >3,000 g , and thyroid morphologies included goiter (n = 11), thyroid hypoplasia (n = 6), and apparently normal-sized thyroid. A comprehensive, phenotype-driven, Sanger sequencing approach was used to identify genetic mutations underlying CH, by sequentially screening known dyshormonogenesis-associated genes and TSHR in GIS cases and TSHR and PAX8 in cases with thyroid hypoplasia. Potentially pathogenic variants were identified in 14 cases, of which four were definitively causative; we also detected digenic variants in three cases. Seventeen variants (nine novel) were identified in TPO (n = 4), TG (n = 3), TSHR (n = 4), DUOX2 (n = 4), and PAX8 (n = 2). No mutations were detected in DUOXA2, NIS, IYD , and SLC26A7. The relatively low mutation frequency suggests that factors other than recognized monogenic causes (oligogenic variants, environmental factors, or novel genes) may contribute to GIS CH in this region. Future non–hypothesis-driven, next-generation sequencing studies are required to confirm these findings. [ABSTRACT FROM AUTHOR]

Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder with a genetic origin. The purpose of the present study was to analyze the mutation spectrum of CH patients in China. A targeted next-generation sequencing panel covering all exons of 29 CH-related causative genes was used in 43 Han Chinese patients with CH [11 dysgenesis and 32 glands in situ (GIS)]. The functional impact and pathogenicity of detected variants were analyzed using a comprehensive bioinformatics approach and co-segregation studies. A total of 47 rare non-polymorphic variants in 9 target genes associated with thyroid hormone synthesis (DUOX2, DUOXA2, TPO, TG, SLC26A4 and SLC5A5), thyroid stimulating hormone resistance (TSHR) and central hypothyroidism (PROP1 and TRHR) were identified in 31 patients (31/43, 72%). Of these variants, 8 were novel, including 3 in DUOX2, 2 in TPO, 3 in TSHR and 1 in SLC5A5. Variants were mostly affected by DUOX2, TG, TPO and TSHR. Approximately 44% of the patients (19/43) carried DUOX2 variants. The mutation detection rates in patients with GIS were higher compared with patients with dysgenesis [25/32 (78%) vs. 6/11 (54%)]. Oligogenic mutations were detected in 25.6% of the total cases and 35% of the mutated cases. Genetic basis was ascertained in 13 patients, reaching a diagnosis detection rate of 30%. In conclusion, genetic defects in dyshormonogenesis, mainly in DUOX2, were the main genetic cause of CH in the Chinese population. Oligogenicity is highly involved in CH pathogenesis and may thus be an important factor in common phenotypic variability observed in patients with CH. [ABSTRACT FROM AUTHOR]

Congenital hypothyroidism (CH) occurs due to thyroid dysgenesis, thyroid ectopy, and dyshormonogenesis. A proportion of CH is transient which might be due to iodine deficiency/excess or maternal antibody-mediated. Certain forms of dyshormonogenetic defects may cause transient hypothyroidism. Here is a report of a neonate with overt clinical and biochemical hypothyroidism, who on evaluation was found to have dyshormonogenesis with a homozygous mutation in dual oxidase 2 (DUOX2) gene. During infancy, she became euthyroid. Severe in utero deficiency of thyroid hormone, very short duration of hypothyroidism and first-reported mutation of the DUOX2 gene in the Indian subcontinent were interesting features in this infant. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the diagnostic contribution of gray-scale ultrasonography, color Doppler, superb microvascular imaging and shear wave elastography in thyroid dyshormonogenesis (TD). From October 2017 to February 2018, the prospective study included 31 patients (13.6 y; 11-14 y) diagnosed with TD based on thyroid scintigraphy and perchlorate discharge tests and 40 healthy pediatric volunteers (12.8 y; 10-16 y). Median resistive indices (RIs), peak systolic and end-diastolic velocities, vascularity indices (VIs) via superb microvascular imaging and shear wave elastography parameters were evaluated. Median VI values were significantly higher and median RI values were significantly lower in the study group than the control group. No significant difference was found between shear wave elastography parameters of the TD and control group. VI was significantly correlated with median total thyroid gland volumes (p = 0.002, r = 0.28), medication dosage (p = 0.03, r = 0.48) and 2-h radioactive iodine uptake values (p = 0.008, r = 0.57). VI is a clinically significant and novel parameter useful for diagnosing TD. [ABSTRACT FROM AUTHOR]

Six patients are described with bi-allelic DUOX2 variants and widely variable phenotypes. Patient 1 is an infant with a compressive hypothyroid goiter causing respiratory distress, which was promptly alleviated by levothyroxine (LT4). He was a compound heterozygote for DUOX2 variants, including a novel deletion of 540 base pairs. Patients 2 and 3 are siblings with the same compound heterozygous mutations of DUOX2, yet one had overt hypothyroidism at 14 months and the other lifelong euthyroidism. Patient 4 is a compound heterozygote individual and has mild persistent congenital hypothyroidism; his sister (patient 5) only had a borderline thyrotropin elevation at newborn screening, consistent with homozygous DUOX2 variants with a mild impact on enzyme activity. Their euthyroid mother (patient 6) is a compound heterozygote for the same DUOX2 mutations as her son. Targeted exome sequencing did not reveal any relevant modifiers. It is concluded that (i) prompt LT4 replacement in infants with respiratory distress due to a hypothyroid goiter makes surgery unnecessary; and (ii) the clinical expression of DUOX2 deficiency varies widely between individuals and over time, justifying periodic reevaluation of the need for LT4 replacement. [ABSTRACT FROM AUTHOR]

Background: The etiology, course, and most appropriate management of borderline congenital hypothyroidism (CH) are poorly defined, such that the optimal threshold for diagnosis with bloodspot screening thyrotropin (bsTSH) measurement remains controversial. Dual oxidase 2 (DUOX2) mutations may initially cause borderline elevation of bsTSH, which later evolves into significant hypothyroidism on venous blood measurement. It was hypothesized that mutations in both DUOX2 and its accessory protein DUOXA2 may occur frequently, even in patients with borderline bsTSH elevation, such that higher diagnostic thresholds in bsTSH screening may fail to detect such cases, with consequent risk of undiagnosed neonatal hypothyroidism of sufficient magnitude to require thyroxine therapy. This study aimed to investigate the frequency and characteristics of DUOX2 and DUOXA2 mutations in a borderline CH cohort. Methods: A cross-sectional study of patients with borderline CH was undertaken at Great Ormond Street Hospital, a tertiary British pediatric center. DUOX2 was sequenced in 52 patients with a bsTSH of 6–19.9 mIU/L, venous TSH of >25 mIU/L, and eutopic thyroid gland in situ. DUOXA2 was sequenced in DUOX2 mutation-negative cases, and novel DUOXA2 mutations were functionally characterized. Results: A total of 26 (50%) patients harbored likely pathogenic mutations in DUOX2 (n = 20; 38%) or DUOXA2 (n = 6; 12%), including novel gene variants (DUOX2, n = 3; DUOXA2, n = 7). Two recurrent DUOX2 mutations (p.Q570L, p.F966Sfs*29) occurred frequently in population databases (MAF ≥0.01). Despite bsTSH being <10 mIU/L in 46% of DUOX2 and DUOXA2 mutation-positive cases, venous free thyroxine levels in these patients were in the moderate CH range (M = 9.3 pmol/L, range <3.9–15.8 pmol/L), Conclusions: Targeted DUOX2 and DUOXA2 sequencing in a borderline CH cohort has a high diagnostic yield. These findings might argue for a lowering of bsTSH thresholds, but follow-up studies are required to assess whether cases with borderline bsTSH harboring DUOX2/DUOXA2 mutations will benefit from an early diagnosis and subsequent levothyroxine treatment. [ABSTRACT FROM AUTHOR]

Background: Thyroid hormones are critical for early neurocognitive development as well as growth and development throughout childhood. Prompt recognition and treatment of hypothyroidism is, therefore, of utmost importance to optimize physical and neurodevelopmental outcomes. Data sources: A PubMed search was completed in Clinical Queries using the key terms "hypothyroidism". Results: Hypothyroidism may be present at birth (congenital hypothyroidism) or develop later in life (acquired hypothyroidism). Thyroid dysgenesis and dyshormonogenesis account for approximately 85% and 15% of permanent cases of congenital primary hypothyroidism, respectively. More than 95% of infants with congenital hypothyroidism have few, if any, clinical manifestations of hypothyroidism. Newborn screening programs allow early detection of congenital hypothyroidism. In developed countries, Hashimoto thyroiditis is the most common cause of goiter and acquired hypothyroidism in children and adolescents. Globally, iodine deficiency associated with goiter is the most common cause of hypothyroidism. Central hypothyroidism is uncommon and may be associated with other congenital syndromes and deficiencies of other pituitary hormones. Familiarity of the clinical features would allow prompt diagnosis and institution of treatment. Conclusions: To optimize neurocognitive outcome in infants with congenital hypothyroidism, treatment with levothyroxine should be started as soon as possible, preferably within the first 2 weeks of life. Children with acquired hypothyroidism should also be treated early to ensure normal growth and development as well as cognitive outcome. The target is to keep serum TSH < 5 mIU/L and to maintain serum free T4 or total T4 within the upper half of the age-specific reference range, with elimination of all symptoms and signs of hypothyroidism. [ABSTRACT FROM AUTHOR]

Resistance to thyroid hormone alpha (RTHα) is caused by mutations in thyroid hormone receptor α (THRA). Little is known about the natural history and treatment of RTHα, and diagnosis before the age of 1 year has not been previously reported. A de novo heterozygous THRA mutation (pC380SfsX9) was identified in a 10-month-old female investigated for developmental delay, hypotonia, macrocephaly, and severe constipation. Treatment with levothyroxine was accompanied by an appropriate rise in thyroxine (T4), triiodothyronine (T3), as well as decrease in thyrotropin levels and in the T3/T4 ratio with a trend toward normalization of peripheral markers of thyroid hormone action. THRA pC380SfsX9 results in extreme RTHα. [ABSTRACT FROM AUTHOR]

ABSTRACT Objectives To describe the findings of thyroid ultrasonography (T-US), its contribution to diagnose congenital hypothyroidism (CH) and the best time to perform it. Subjects and methods Forty-four patients with CH were invited to undergo T-US and 41 accepted. Age ranged from 2 months to 45 years; 23 patients were females. All were treated with L-thyroxine; 16 had previously undergone scintigraphy and 30 had previous T-US, which were compared to current ones. Results At the current T-US, the thyroid gland was not visualized in its normal topography in 10 patients (24.5%); 31 T-US showed topic thyroid, 17 with normal or increased volume due to probable dyshormonogenesis, 13 cases of hypoplasia and one case of left-lobe hemiagenesis. One patient had decreased volume due to central hypothyroidism. Scintigraphy scans performed 3-4 years earlier showed 100% agreement with current results. Comparisons with previous T-US showed concordant results regarding thyroid location, but a decrease in current volume was observed in eight due to the use of L-thyroxine, calling the diagnosis of hypoplasia into question. Conclusions The role of T-US goes beyond complementing scintigraphy results. It allows inferring the etiology of CH, but it must be performed in the first months of life. An accurate diagnosis of CH will be attained with molecular study and the T-US can guide this early assessment, without therapy withdrawal.

Objective: To establish normative ultrasound data for thyroid gland volume in South Indian neonates and infants and compare with abnormal sonological features of thyroid in congenital hypothyroidism (CH) to explore thyroid ultrasound utility as a supportive screening tool to newborn screening programs for early detection of CH.Methods: In view of impact of geo ethnic factors, varying growth velocities and body mass indices of human population worldwide, specific regional, age and gender related reference data for thyroid gland size and volume are vital. This study was an offshoot of ICMR pilot New Born Screening (NBS) project for CH. Formula used for thyroid volume estimation was ellipsoidal formula D1 x D2 x D3 × 0.523. It was a prospective observational study. The neonates who screened negative for Thyroid Stimulating Hormone (TSH) with repeat normal serum TSH and free thyroxine were selected. One hundred fifty seven infants were enrolled which included 99 boys and 58 girls. The study population included children in age groups from 3 d to 1 y six months.Results: Data analysis was done by descriptive method and unpaired t test. Mean thyroid volume was 0.26 ml with 0.27 ml in boys and 0.24 ml in girls. Statistically significant "p value" was noted in single lobe measurements among boys and girls.Conclusions: Thyroid gland volume normative data play a key role in evaluation of thyroid sonological abnormalities in CH and there is effective utility of ultrasound as a supportive diagnostic and prognostic screening tool for early detection of CH. [ABSTRACT FROM AUTHOR]

Congenital hypothyroidism is the most frequent inborn endocrine disorder and the most frequent disease diagnosed by nation-wide newborn screeening. 80-85% of permanent cases is caused by a defective thyroid development - thyroid dysgenesis. Remaining cases are caused by defects of thyroid hormone biosynthesis - dyshormonogenesis. Early and adequate substitution treatment together with a good family compliance are the main factors playing role in psychomotor, mental and somatic development of the majority of children with congenital hypothyroidism. [ABSTRACT FROM AUTHOR]

Background: Primary congenital hypothyroidism (CH) affects about 1:3000 newborns worldwide and is mainly caused by defects in thyroid gland development (thyroid dysgenesis [TD]) or hormone synthesis. A genetic cause is identified in <10% of TD patients. The aim was to identify novel candidate genes in patients with TD using next-generation sequencing tools. Patient Findings: Whole exome sequencing was used to study two families: a consanguineous Tunisian family (one child with severe thyroid hypoplasia) and a French family (two newborn siblings, with a thyroid in situ that was not enlarged on ultrasound at diagnosis). Variants in candidate genes were filtered according to type of variation, frequency in public and in-house databases, in silico prediction tools, and inheritance mode. Unexpectedly, three different variants of the thyroid peroxidase ( TPO ) gene were identified. A homozygous missense mutation (c.875C>T, p.S292F) was found in the Tunisian patient with severe thyroid hypoplasia. The two French siblings were compound heterozygotes (c.387delC/c.2578G>A, p.N129Kfs*80/p.G860R) for TPO mutations. All three mutations have been previously described in patients with goitrous CH. In these patients, treatment was initiated immediately after diagnosis, and the effect, if any, of thyrotropin stimulation of these thyroids remains unclear. Conclusions: The first cases are reported of thyroid hypoplasia at diagnosis during the neonatal period in patients with CH and TPO mutations. These cases highlight the importance of screening for TPO mutations not only in goitrous CH, but also in normal or small-size thyroids, and they broaden the clinical spectrum of described phenotypes. [ABSTRACT FROM AUTHOR]

Congenital hypothyroidism (CH) is the one of the most common preventable cause of mental retardation. In the majority of patients, CH is caused by an abnormal development of the thyroid gland (thyroid dysgenesis) that is a sporadic disorder and accounts for 85% of cases and the remaining 15% of cases are caused by dyshormonogenesis. The clinical features of congenital hypothyroidism are so subtle that many newborn infants remain undiagnosed at birth and delayed diagnosis leads to the most severe outcome of CH, mental retardation, emphasizing the importance of neonatal screening. Dried capillary blood is used for screening and it is taken from heel prick optimally between 2 and 5 days of age. Blood spot TSH or thyroxine (T4) or both are being used for CH screening in different programs around the world. Neonates with abnormal thyroid screening tests should be recalled immediately for examination and a venipuncture blood sample should be drawn for confirmatory serum testing. Confirmatory serum should be tested for TSH and free T4, or total T4. Serum TSH and T4 undergo dynamic changes in the first weeks of life; it is important to compare serum results with age-normal reference ranges. Treatment should be started promptly and infant should be rendered euthyroid as early as possible, as there is an inverse relationship between intelligence quotient (IQ) and the age at diagnosis. Levothyroxine (l-thyroxine) is the treatment of choice and American academy of pediatrics and European society of pediatric endocrinology recommend 10-15μgm/kg/day as initial dose. The immediate goal of therapy is to normalize T4 within 2 weeks and TSH within one month. The overall goal of treatment is to ensure growth and neurodevelopmental outcomes as close as possible to their genetic potential.

Congenital hypothyroidism (CH) is a preventable cause of mental retardation. The principal causes include thyroid dysgenesis and dyshormonogenesis. Central CH is rare. Due to absence of overt symptoms at birth, diagnosis is often delayed. There are some known syndromic associations with extrathyroidal anomalies. Neonatal screening programs help in early detection and categorization of cases requiring immediate treatment or close follow-up. Results of screening tests could guide further tests required for confirmation diagnosis and urgency of replacement therapy. A diagnostic protocol starting with an ultrasonography of thyroid and serum thyroglobulin levels can aid identify the probable underlying etiology and dictate the cases requiring scintigraphy or genetic tests. Early initiation of treatment with oral levothyroxine improves neurocognitive outcomes. Some cases might have transient hypothyroidism and reevaluation at 3 years of age may help in further discontinuation of treatment. [ABSTRACT FROM AUTHOR]

Congenital hypothyroidism (CH) is one of the most common causes of preventable mental retardation. Thyroid hormone has an essential role in the brain development during the first 2-3 years of life. Incidence of CH is 1:3000-1:4000 live births, but there is evidence that its incidence is increasing. Majority of newborn babies do not exhibit obvious clinical signs and symptoms until the age of 3 months due to either some residual thyroid function or transplacental passage of maternal thyroid hormone. Common clinical symptoms include lethargy, sleepiness, poor feeding, constipation, and prolonged jaundice. Other common findings on clinical examination include macroglossia, large fontanels, umbilical hernia, and hypotonia. Neonatal screening for CH is practiced in the developed countries for the last three decades, and various studies show that normal cognitive function is attainable with early detection and treatment. This review discusses different protocols being used for screening. It highlights recent recommendation of screening and retesting cutoffs. Thyroid imaging can help in differentiating underlying etiology, either thyroid dysgenesis or dyshormonogenesis. Treatment with levothyroxine (L-T4) 10-15 mcg/kg should be started immediately after diagnosis without delaying for imaging purposes. Frequent and vigilant monitoring with L-T4 dose adjustment is mandatory in infancy and childhood to achieve normal physical growth and neurodevelopment. Children with CH are followed by different pediatric specialties including general pediatricians, neonatologists, developmental pediatricians, and endocrinologists and in primary care; therefore, it is essential to increase the awareness of monitoring protocols among all physicians. [ABSTRACT FROM AUTHOR]

After the identification of thyroid H 2 O 2 generation system (DUOX) and of its maturation factors (DUOXA), defects in DUOX2 and/or DUOXA2 were rapidly recognized as the possible cause of congenital hypothyroidism (CH) due to thyroid dyshormonogenesis. The present Review reports data on the prevalence of DUOX2 mutations, which is variable among different series but invariably high, pointing to DUOX2 defects as one of the leading causes of dyshormonogenesis. Differently, DUOXA defects seem to be rarely involved in the pathogenesis of CH. Genotype-phenotype correlations are also reported, highlighting the great intra- and inter-familial phenotype variability which appears to be a constant feature of the defects in the H 2 O 2 generation systems. Finally, the hypotheses to explain the phenotypic variability of the DUOX2/A2 mutations are discussed, such as the existence of other H 2 O 2 generating systems, the age variability in thyroid hormones requirements, the differences in ethnicity, in iodine intake, and in the methodological approaches. [ABSTRACT FROM AUTHOR]

Background: Considering the high prevalence of congenital hypothyroidism (CH) in Isfahan and its different etiologies in comparison with other countries, the high rate of parental consanguinity, and the role of NIS gene in permanent CH due to dyshormonogenesis, the aim of this study was to investigate the G395R mutation of the NIS gene in patients with permanent CH due to dyshormonogenesis Methods: In this case-control study, patients diagnosed with permanent CH due to dyshormonogenesis during CH screening program were selected. Venous blood sample was obtained to determine the G395R mutations of NIS gene using polymerase chain reaction (PCR) sequencing method. Results: In this study, 35 CH patients with permanent CH due to dyshormonogenesis and 35 neonates with normal screening results as a control group were studied. We did not find any changes of the mentioned mutation of NIS gene in the patients′ group. Conclusion: Considering the findings of the current study, it seems that further studies with larger sample size and with consideration of other gene mutations such as pendrin and thyroglobulin are needed for more accurate conclusion.