Differentiated Thyroid Cancer in Children: Prevalence and Predictors in a Large Cohort with Thyroid Nodules Followed Prospectively.

We retrospectively analyzed the findings of a prospective cohort of 75 children referred for thyroid nodules between 2008 and 2013. Prevalence of papillary differentiated thyroid carcinoma was 18.7%. Thyrotropin >2.5 mIU/L, multinodular goiter, solid nodules, irregular margins, and pathologic lymphadenopathies were identified as independent predictors of malignancy.

Congenital goitrous hypothyroidism: mutation analysis in the thyroid peroxidase gene.

BACKGROUND: Iodide organification defect (IOD) is characterized by a reduced ability of the thyroid gland to retain iodide resulting in hypothyroidism. Mutations in thyroid peroxidase (TPO) gene appear to be the most common cause of IOD and are commonly inherited in an autosomal recessive fashion. The TPO gene is located on the chromosome 2p25. It comprises 17 exons, covers approximately 150 kb of genomic DNA and codes 933 amino acids. OBJECTIVES: In this study, we characterize the clinical and molecular basis of seven patients from four unrelated families with congenital hypothyroidism (CH) because of IOD. DESIGN AND METHODS: All patients underwent clinical, biochemical and imaging evaluation. The promoter and the complete coding regions of the human TPO along with the flanking intronic regions were analysed by single-strand conformation polymorphism analysis and direct DNA sequencing. Segregation analysis of mutations was carried out, and the effect of the novel missense identified mutations was investigated by 'in silico' studies. RESULTS: All subjects had congenital and persistent primary hypothyroidism. Three novel mutations: c.796C>T [p.Q266X], c.1784G>A [p.R595K] and c.2000G>A [p.G667D] and a previously reported mutation: c.1186_1187insGGCC [p.R396fsX472] have been identified. Four patients were compound heterozygous for p.R396fsX472/p.R595K mutations, two patients were homozygous for p.R595K, and the remaining patient was a compound heterozygous for p.Q266X/p.G667D. CONCLUSIONS: Our findings confirm the genetic heterogeneity of TPO defects and the importance of the implementation of molecular studies to determinate the aetiology of the CH with dyshormonogenesis.

Differentiated thyroid carcinoma: presentation and follow-up in children and adolescents.

UNLABELLED: To review our Pediatric Endocrinology Division's experience with differentiated thyroid carcinoma (DTC) we analyzed retrospectively the records of patients with DTC that had been seen between June 1988 and June 2008. RESULTS: Forty-five patients (median age 13.7 years, 36 female) were diagnosed (papillary: 40, follicular: 5) with DTC presenting as a solitary nodule (n: 25), thyroid nodule with cervical adenopathy (n: 9) and multinodular goiter (n: 11). All underwent total thyroidectomy with resection of suspicious cervical lymph nodes (CLN). DTC was multicentric in 59% and revealed extrathyroidal extension in 44%. Initially, 44% had CLN metastases and 24% distant metastases. All patients underwent thyroid remnant ablation with 131I and suppressive treatment. Median follow-up was 5.1 years with a disease-free survival rate at 5 years of follow-up of 75%. Eleven percent presented recurrences. CONCLUSION: Pediatric DTC has an aggressive behavior at presentation. Higher preoperative TSH levels were significantly associated with a more advanced disease at diagnosis. CLT was present concomitantly in a quarter of the patients and further studies are needed to establish differences in these patients' outcome. Diagnostic approach, total thyroidectomy, 131I treatment and thyrotropin suppression allowed a good progression-free survival rate.

Molecular analysis of congenital goitres with hypothyroidism caused by defective thyroglobulin synthesis. Identification of a novel c.7006C>T [p.R2317X] mutation and expression of minigenes containing nonsense mutations in exon 7.

BACKGROUND: Thyroglobulin (TG) deficiency is an autosomal-recessive disorder that results in thyroid dyshormonogenesis. A number of distinct mutations have been identified as causing human hypothyroid goitre. OBJECTIVES: The purpose of this study was to identify and characterize new mutations in the TG gene in an attempt to increase the understanding of the genetic mechanism responsible for this disorder. A total of six patients from four nonconsanguineous families with marked impairment of TG synthesis were studied. METHODS: Single-strand conformation polymorphism (SSCP) analysis, sequencing of DNA, genotyping, expression of chimeric minigenes and bioinformatic analysis were performed. RESULTS: Four different inactivating TG mutations were identified: one novel mutation (c.7006C>T [p.R2317X]) and three previously reported (c.886C>T [p.R277X], c.6701C>A [p.A2215D] and c.6725G>A [p.R2223H]). Consequently, one patient carried a compound heterozygous for p.R2223H/p.R2317X mutations; two brothers showed a homozygous p.A2215D substitution and the remaining three patients, from two families with typical phenotype, had a single p.R277X mutated allele. We also showed functional evidences that premature stop codons inserted at different positions in exon 7, which disrupt exonic splicing enhancer (ESE) sequences, do not interfere with exon definition and processing. CONCLUSIONS: In this study, we have identified a novel nonsense mutation p.R2317X in the acetylcholinesterase homology domain of TG. We have also observed that nonsense mutations do not interfere with the pre-mRNA splicing of exon 7. The results are in accordance with previous observations confirming the genetic heterogeneity of TG defects.

17alpha-hydroxyprogesterone and cortisol serum levels in neonates and young children: influence of age, gestational age, gender and methodological procedures.

To determine the influence of age, gestational age, gender and methodological protocol on serum 17OHP and cortisol concentrations. 17OHP in non-extracted (NE) and extracted (E) sera was measured by RIA in 319 full-term (FT) (1 d-5 yr) infants, 38 pre-term (PT) and in 19 neonates with classical CAH at diagnosis. 17OHP (NE- and E-) decreased with age in normal children. The extraction procedure significantly reduced 17OHP by eliminating interfering steroids in children < 1 year. Sexual dimorphism was only observed in NE-17OHP. 17OHP in PT was always higher than in FT up to 2 months of age (p < 0.001). Neither NE- nor E-17OHP in CAH overlapped with those of FT or PT (p < 0.001) allowing to omit the extraction procedure to confirm CAH diagnosis. Cortisol levels were within normal range in neonates with CAH, thus not adding useful information about adrenal function. Chronological and gestational age, gender, and extraction for 17OHP measurement are important factors to know when assessing adrenal function during the first year of life.

Genotyping of resistance to thyroid hormone in South American population. Identification of seven novel missense mutations in the human thyroid hormone receptor beta gene.

Thyroid Hormone Receptor beta (THRB) defects, typically transmitted as autosomal dominant traits, cause Resistance to Thyroid Hormone (RTH). We analyzed the THRB gene in thirteen South American patients with clinical evidence RTH from eleven unrelated families. Sequence analysis revealed seven novel missense mutations. Four novel mutations were identified in exon 9. The first, a c.991A>G transition which originates a substitution of asparagine by aspartic acid (p.N331D). The second nucleotide alteration consists of a guanine to cytosine transversion at position 1003 (c.1003G>C) and results in substitution of the alanine at codon 335 by proline (p.A335P). The third mutation, a c.1022T>C transition produces a change of leucine by proline (p.L341P). The fourth mutation detected in exon 9 was a c.1036C>T transition which replaces the leucine at codon 346 by phenylalanine (p.L346F). The sequencing of the exon 10 detected three novel missense mutations. The first, a c.1293A>G transition changing isoleucine 431 for methionine (p.I431M). The second, the cytosine at position 1339 was replaced by adenine (c.1339C>A) resulting in the replacement of proline by threonine (p.P447T). The third mutation detected in exon 10 was a c.1358C>T transition resulting in the substitution of proline at codon 453 by leucine (p.P453L). Finally, sequencing analysis of the THRB gene revealed three substitutions previously described (p.A268G, p.P453T and p.F459C). The p.P453T was found in two patients. In conclusion, we report thirteen patients with RTH caused by heterozygous mutations of the THRB gene. Seven of the identified mutations correspond to novel substitutions.

Thyroid disorders of neonates born to mothers with Graves' disease.

Maternal hyperthyroidism implies the risk of thyroid abnormalities in the newborn. We describe retrospectively the clinical presentation, treatment and follow up of 28 children born of hyperthyroid mothers. Patients were subdivided as follows: Group A (neonatal hyperthyroidism) (n=9): born from eight hyperthyroid mothers and one thyroidectomized mother. Children born from untreated mothers consulted between 1 and 7 days of life, while those born from treated mothers consulted between 8 and 17 days. Eight needed treatment. All remitted completely. Group B (primary hypothyroidism) (n=14): born from treated mothers, detected by neonatal screening. Eleven had transient hypothyroidism and three needed treatment. Group C (hypothalamic-pituitary hypothyroidism) (n=5): born from uncontrolled hyperthyroid mothers and found during follow up (age 9-28 days). The infants were treated with thyroid hormone, and recovered before 8 months of life. Every child born from a mother with autoimmune thyroid disease needs paediatric endocrinological assessment for detection of possible thyroid disorders.

Recurrence of the p.R277X/p.R1511X compound heterozygous mutation in the thyroglobulin gene in unrelated families with congenital goiter and hypothyroidism: haplotype analysis using intragenic thyroglobulin polymorphisms.

Thyroglobulin (TG) functions as the matrix for thyroid hormone synthesis. Thirty-five different loss-of-function mutations in the TG gene have been reported. These mutations are transmitted in an autosomal recessive mode. The objective of this study is to analyze the recurrence of the p.R277X/p.R1511X compound heterozygous mutation in the TG gene in two unrelated families (one Argentinian and another Brazilian) with congenital hypothyroidism, goiter and impairment of TG synthesis. The first and last exon of the TG gene, the exons where previously mutations and single nucleotide polymorphisms (SNPs) were detected, as well as the TG promoter, were analyzed by automatic sequencing in one affected member of the each family. Four microsatellite markers localized in introns 10, 27, 29 and 30 of the TG gene, one insertion/deletion intragenic polymorphism and 15 exonic SNPs were used for haplotype analysis. A p.R277X/p.R1511 compound heterozygous mutation in the TG gene was found in two members of an Argentinian family. The same mutations had been also reported previously in two members of a Brazilian family. We constructed mutation-associated haplotypes by genotyping members of the two families. Our results suggest that the cosegregating haplotype is different in each one of these families. Different haplotypes segregated with the p.R277X and p.R1511 mutations demonstrating the absence of a founder effect for these mutations between Argentinian and Brazilian populations. However, haplotyping of Argentinian patients showed the possibility that the p.R277X alleles might be derived from a common ancestral chromosome.

Pilot Neonatal Screening Program for Central Congenital Hypothyroidism: Evidence of Significant Detection.

BACKGROUND/AIM: Congenital hypothyroidism (CH) is a heterogeneous entity. Neonatal screening programs based on thyrotropin (TSH) determination allow primary CH diagnosis but miss central CH (CCH). CCH causes morbidity, alerts to other pituitary deficiencies, and is more prevalent than previously thought. We aimed at developing a pilot neonatal screening program for CCH detection. PATIENTS AND METHODS: A prospective 2-year pilot neonatal screening study based on simultaneous dried blood specimen TSH and thyroxine (T4) measurements was implemented in term newborns aged 2-7 days. Those with T4 ≤4.5 µg/dL (-2.3 SDS) and TSH <10 mIU/L were recalled (suspicious of CCH) and underwent clinical and biochemical assessment performed by expert pediatric endocrinologists. RESULTS: A total of 67,719 newborns were screened. Primary CH was confirmed in 24 (1: 2,821). Forty-four newborns with potential CCH were recalled (recall rate 0.07%) at a mean age of 12.6 ± 4.8 days. In this group, permanent CCH was confirmed in 3 (1: 22,573), starting L-T4 treatment at a mean age of 12.3 ± 6.6 days; 14 boys showed T4-binding globulin deficiency (1: 4,837); 24 had transient hypothyroxinemia (21 non-thyroidal illness and 3 healthy); and 3 died before the confirmation stage. According to initial free T4 measurements, CCH patients had moderate hypothyroidism. CONCLUSIONS: Adding T4 to TSH measurements enabled the identification of CCH as a prevalent condition and contributed to improving the care of newborns with congenital hypopituitarism and recognizing other thyroidal disorders.

[Transient congenital hypothyroidism due to biallelic defects of DUOX2 gene. Two clinical cases]. / Hipotiroidismo congénito transitorio por defectos bialélicos del gen DUOX2. Dos casos clínicos.

Congenital hypothyroidism affects 1:2000-3000 newborns detected by neonatal screening programs. Dual oxidases, DUOX1 and 2, generate hydrogen peroxide needed for the thyroid hormone synthesis. Hipotiroidismo congénito transitorio por defectos bialélicos del gen DUOX2. Dos casos clínicos Transient congenital hypothyroidism due to biallelic defects of DUOX2 gene. Two clinical cases Mutations in the DUOX2 gene have been described in transient and permanent congenital hypothyroidism. Two brothers with congenital hypothyroidism detected by neonatal screening with eutopic gland and elevated thyroglobulin are described. They were treated with levothyroxine until it could be suspended in both during childhood, assuming the picture as transient. Organification disorder was confirmed. Both patients were compounds heterozygous for a mutation in exon 9 of the paternal allele (c.1057_1058delTT, p.F353PfsX36 or p.F353fsX388) and in exon 11 of the maternal allele (c.1271T > G, p.Y425X) of DUOX2 gene. Our finding confirms that the magnitude of the defect of DUOX2 is not related to the number of inactivated alleles, suggesting compensatory mechanisms in the peroxide supply.

El hipotiroidismo congénito afecta a 1:2000-3000 recién nacidos detectados por pesquisa neonatal. Las oxidasas duales, DUOX1 y 2, generan agua oxigenada, lo que constituye un paso crítico en la síntesis hormonal. Se han comunicado mutaciones en el gen DUOX2 en casos de hipotiroidismo congénito transitorio y permanente. Se describen dos hermanos con hipotiroidismo congénito detectados por pesquisa neonatal, con glándula tiroides eutópica y tiroglobulina elevada. Recibieron levotiroxina hasta su reevaluación en la infancia con suspensión del tratamiento. Su función tiroidea fue normal y se consideró el cuadro como transitorio por un posible defecto de organificación. Ambos pacientes eran heterocigotos compuestos para una mutación en el exón 9 del alelo paterno (c.1057_1058delTT, p.F353PfsX36 o p.F353fsX388) y otra en el exón 11 del alelo materno (c.1271T>G, p.Y425X) del gen DUOX2. Nuestro hallazgo confirma que la magnitud del defecto de DUOX2 no se relaciona con el número de alelos afectados, lo que sugiere mecanismos compensadores en la generación de peróxido.

Efficacy of congenital hypothyroidism neonatal screening in preterms less than 32 weeks of gestational age: more evidence.

OBJECTIVE: To evaluate the double screening performed for congenital hypothyroidism (CH) to preterm infants <32 weeks of gestational age (GA) between 1994 and 2003. INFANTS AND METHODS: TSH was assessed by IFMA. Infants were classified as: term (T) (>37 weeks GA); preterm (PT) (33-37 weeks GA); and very preterm (VPT) (< or =32 weeks GA). RESULTS: In 585,221 screened infants, CH was confirmed in 228 T, 23 PT and seven VPT. An increasing incidence of CH was found with decreasing GA, affecting 1:1,603 PT and 1:585 VPT. PT infants had 1.5 times more risk than full-term infants of suffering CH, and VPT 4 times more. Only 4/7 affected VPT had an adequate double screening as requested. Three had elevated TSH values in the first sample and in one a normal TSH (10.3 mIU/l) at 3 days rose to 240 mIU/l after day 15. In the remaining three VPT, TSH in the unique filter paper sample (21 to 34 days) was markedly elevated. CONCLUSIONS: Our findings reinforce the need for awareness in neonatal settings for adequate screening of VPT infants. Screening in the first week of life was effective in detection of most but not all affected VPT. Larger studies are needed in order to establish accurate screening recommendations for VPT newborns. Until this step is reached, repeated screening is advised in these infants.

Five novel inactivating mutations in the thyroid peroxidase gene responsible for congenital goiter and iodide organification defect.

Thyroid peroxidase (TPO) defects, typically transmitted as autosomal recessive traits, result in hypothyroid goiters with failure to convert iodide into organic iodine. We analyzed the TPO gene in 14 unrelated patients with clinical evidence of iodide organification defects. Seven of the affected individuals harbored mutations in the TPO gene; one was compound heterozygous, the others were simply heterozygous for TPO mutations. Five novel mutations have been identified, one of which was found to be a single nucleotide deletion, while the other four were single nucleotide substitutions. A frameshift mutation c.387delC was detected in exon 5 which leads to an early termination signal in exon 7 (p.N129fsX208). Two missense mutations were identified in exon 8. The first, a c.920A>C transversion that results in a p.N307T substitution, was found in two patients. The second, a c.1297G>A transition, results in p.V433M. A c.1496C>T transition was detected in exon 9 that caused the substitution p.P499L. Finally, in exon 14 a c.2422T>C transition was identified, causing a p.C808R change. In addition, the previously reported GGCC duplication in exon 8 (c.1186_1187insGGCC; p.R396fsX472) was also detected in two affected individuals, one of whom was a compound heterozygous (p.R396fsX472/p.V433M).

Congenital secondary hypothyroidism due to a mutation C105Vfs114X thyrotropin-beta mutation: genetic study of five unrelated families from Switzerland and Argentina.

We identified five patients with congenital secondary hypothyroidism with isolated thyrotropin (TSH) deficiency originating from three and two unrelated Argentinean and Swiss families, respectively. The affected patients presented with both low TSH as well as low thyroid hormone levels. Further, TSH-releasing hormone (TRH) stimulation failed to increase serum TSH, whereas prolactin increased adequately. These affected children were homozygous for a 1-bp deletion (822delT) in the TSH-beta subunit gene leading to a cysteine 105 to valine conversion (C105V) and to a frameshift with a premature stop codon at position 114 (C105Vfs114X). In a total of 22 families five different mutations located within the coding region of the TSH-beta subunit gene responsible for congenital secondary hypothyroidism have been reported so far (E12X; G29R; Q49X; IVS2 +5, G --> A; C105Vfs114X). Importantly, out of 13 families, including our five families, the C105Vfs114X mutation has been described in 12 unrelated and non-consanguineous families, whereas the remaining four TSH-beta subunit gene mutations have been described in consanguineous families only. Therefore the C105Vfs114X mutation within the TSH-beta subunit gene is the most frequent alteration causing congenital secondary hypothyroidism (13 of 22; 59%) and occurs mainly in unrelated and non-consanguineous families (12 of 13; 92%). As we could exclude a common ancestry by microsatellite marker analysis in our five independent families we concluded that the codon 105 in the TSH-beta subunit gene might be a "hot spot," although a founder effect has been reported in certain cases clustered in a highly specific and restricted geographical area.

Pediatric Graves' disease: outcome and treatment.

UNLABELLED: Graves' disease treatment in children and adolescents includes antithyroid drugs (ATD), 131I (RI) or subtotal thyroidectomy (CX), all of which present beneficial effects and disadvantages. OBJECTIVE: To review our experience in the management of pediatric patients with Graves' disease considering the therapeutic strategies used. PATIENTS AND METHODS: Clinical and biochemical data of 116 children (23 boys) aged 11.2 +/- 3.7 years at diagnosis were reviewed. Outcome and remission were evaluated and persistency at 10 years calculated with Kaplan Meier analysis. RESULTS: Initially 113/116 patients received ATD, two RI and one CX. After 10 years of follow up, 38 remitted with ATD, 23 were persistently hyperthyroid with ATD, 38 received RI, one underwent CX, and 13 were lost to follow up. The cumulative proportion with persistent hyperthyroidism at 10 years was 31%. CONCLUSIONS: ATD, although the first choice of treatment, was long-lasting and achieved a low remission rate at 10 years of follow up. Conversely, RI was shown to be a safe, low cost, efficient and definitive alternative for Graves' disease treatment in children and adolescents.

Prevalence and etiology of congenital hypothyroidism detected through an argentine neonatal screening program (1997-2010).

INTRODUCTION: We retrospectively assessed the incidence of congenital hypothyroidism (CH) detected through our neonatal screening program between 1997 and 2010. We describe the diagnostic characteristics of the detected population and verify the impact of a TSH cutoff (CO) change. PATIENTS AND METHODS: Screening was based on TSH determination on dried blood spot on filter paper samples (IFMA) using a 15 mU/l blood CO until 12/2002 (P1) and 10 mU/l thereafter (P2). Patients were classified as having transient or permanent CH (athyreotic, ectopic, eutopic, with goiter and unknown etiology). Global and diagnostic-related incidences were calculated for the whole studied period with the same CO, and P1 and P2 were compared. RESULTS: Incidences of permanent CH were 1:3,108 (P1) and 1:2,367 (P2). The lower CO detected 22 extra CH, 13 of them definitive (70% with eutopic glands). Only a significant increase (p < 0.05) in eutopic CH was found, partially related to the lower CO applied. A statistically significant association with time was seen for total definitive and ectopic cases (p < 0.05). CONCLUSION: Our findings revealed some changes in the detected population partially related to the CO applied, with only eutopic dysfunctional disorders being more prevalent in the later years. Total permanent CH and ectopic thyroid disorders showed a trend toward higher detection over time, but their prevalence has not changed significantly in our screening program.

Nódulos tiroideos en pediatría: predictores de malignidad / Pediatric thyroid nodules: predictors of malignancy

Introducción: La caracterización de los nódulos tiroideos en pediatría no ha sido aún bien comunicada. El riesgo de malignidad es mayor que en adultos por lo que requieren una evaluación exhaustiva. Objetivo: caracterizar una cohorte de pacientes pediátricos con nódulos tiroideos e identificar predictores de malignidad. Pacientes y métodos: se analizaron los hallazgos demográficos, clínicos, bioquímicos, ecográficos y citológicos de una cohorte prospectiva de 106 pacientes <19 años que consultó por nódulo tiroideo a nuestro centro entre 2008-2017. 89 pacientes alcanzaron el diagnóstico de nódulo benigno o maligno por cirugía y 17 luego de un seguimiento clínico mínimo de 2 años. Retrospectivamente se analizaron las diferencias entre los nódulos benignos y malignos. Resultados: la edad mediana fue 13,9 años, con franco predominio de mujeres puberales. 88% presentó una función tiroidea normal. 88/106 nódulos fueron benignos. El carcinoma papilar de tiroides (CPT) fue la única lesión maligna hallada (17%). El análisis estadístico mostró una asociación significativa de CPT con TSH >2,5mU/l, nódulo sólido, márgenes irregulares, microcalcificaciones y adenopatías cervicales patológicas. Un resultado citológico Bethesda V/VI tuvo un valor predictivo (VP) positivo de 87,5% y VP negativo de 96,4%. Conclusiones: El nódulo tiroideo en pediatría es más frecuentemente maligno. La evaluación sistemática permitió identificar ciertos hallazgos clínicos, bioquímicos, ecográficos y citológicos predictores de malignidad que deben ser considerados al decidir el enfoque diagnóstico

Introduction: Published data on pediatric thyroid nodule´s characterization is scarce. With higher risk of malignancy than in adults, they require an exhaustive diagnostic work-up. Objective: To characterize a pediatric cohort with thyroid nodules to identify predictors of malignancy. Patients and methods: Demographic, clinical, biochemical, ultrasonographical and cytological data were analyzed prospectively in 106 patients <19 years that consulted with a thyroid nodule to our center (2008-2017). 89 patients reached final diagnosis (benign or malignant nodule) after surgery and 17 after a minimum follow-up of 2years. Differences between benign and malignant nodules were analyzed retrospectively. Results: median age was 13.9 years, with predominant pubertal females. 88% was euthyroid. 88/106 nodules were benign. Thyroid papillary carcinoma (TPC) was the only malignancy found (17%). Statistical analysis showed significant association of TPC with TSH levels >2.5mU/l, solid nodules, irregular margins, microcalcifications and pathologic adenopathies. Cytological results Bethesda V/VI showed positive and negative predictive values of 87.5% and 96.4% respectively. Conclusions: Pediatric thyroid nodules are more frequently malignant. The systematic evaluation of our cohort allowed the identification of clinical, biochemical ultrasonographical and cytological predictors of malignancy that have to be considered when deciding the diagnostic approach

New insights into thyroglobulin gene: molecular analysis of seven novel mutations associated with goiter and hypothyroidism.

The thyroglobulin (TG) gene is organized in 48 exons, spanning over 270 kb on human chromosome 8q24. Up to now, 62 inactivating mutations in the TG gene have been identified in patients with congenital goiter and endemic or non-endemic simple goiter. The purpose of the present study was to identify and characterize new mutations in the TG gene. We report 13 patients from seven unrelated families with goiter, hypothyroidism and low levels of serum TG. All patients underwent clinical, biochemical and imaging evaluation. Single-strand conformation polymorphism (SSCP) analysis, endonuclease restriction analysis, sequencing of DNA, genotyping, population screening, and bioinformatics studies were performed. Molecular analyses revealed seven novel inactivating TG mutations: c.378C>A [p.Y107X], c.2359C>T [p.R768X], c.2736delG [p.R893fsX946], c.3842G>A [p.C1262Y], c.5466delA [p.K1803fsX1833], c.6000C>G [p.C1981W] and c.6605C>G [p.P2183R] and three previously reported mutations: c.886C>T [p.R277X], c.6701C>A [p.A2215D] and c.7006C>T [p.R2317X]. Six patients from two families were homozygous for p.R277X mutation, four were compound heterozygous mutations (p.Y107X/p.C1262Y, p.R893fsX946/p.A2215D, p.K1803fsX1832/p.R2317X), one carried three identified mutations (p.R277X/p.C1981W-p.P2183R) together with a hypothetical micro deletion and the remaining two siblings from another family with typical phenotype had a single p.R768X mutated allele. In conclusion, our results confirm the genetic heterogeneity of TG defects and the pathophysiological importance of altered TG folding as a consequency of truncated TG proteins and missense mutations located in ACHE-like domain or that replace cysteine.

Severe congenital non-autoimmune hyperthyroidism associated to a mutation in the extracellular domain of thyrotropin receptor gene.

Activating mutations in the TSH Receptor (TSHR) gene have been identified as the molecular basis for congenital non-autoimmune hyperthyroidism. We describe the clinical findings and molecular characterization in a girl who presented severe non-autoimmune hyperthyroidism since birth, born to a mother with autoimmune thyroid disease. She was treated with methylmercaptoimidazol and ß-blockers, but remained hyperthyroid and required total thyroidectomy. To characterize the presence of an activating mutation, the whole coding sequence and intron-exon boundaries of TSHR gene were analyzed. The patient was heterozygous for p.Ser281Asn mutation and p.Asp727Glu polymorphism. This recurrent mutation, p.Ser281Asn, characterized in vitro by increased basal production of cAMP, is the unique germline activating gene variant described so far in the extracellular domain of TSH receptor. Interestingly, the patient's mother presented hyperthyroidism but without any TSHR gene activating mutation. Although congenital non-autoimmune hyperthyroidism is a rare condition, it should be investigated when severe disease persists, even in a newborn from an autoimmune hyperthyroid mother, in order to differentiate it from the more common congenital autoimmune disease.

Variable clinical presentation and outcome in pediatric patients with resistance to thyroid hormone (RTH).

Resistance to thyroid hormone (RTH) is characterized by elevated levels of thyroid hormones, normal or slightly increased TSH levels respondent to TRH, resistance to thyroid hormone administration, and variable clinical expression. To describe the diverse clinical and biochemical findings of six children from five unrelated families with molecular diagnosis of RTH (0.5-12.7 years) and their follow-up (3-20 years). All RTH patients and 4 affected parents' harbored mutations in exons 9 or 10 of the thyroid receptor ß gene: p.M313T (de novo), pN331D, p.L341P, p.L346F, and p.P453L. At consultation 5/6 had goiter, 4/6 tachycardia, and 3/5 learning disabilities. Median hormone levels were: T(4) 257.4 nmol/l (NR: 77.2-180.2); FreeT(4) 39.9 pmol/(NR:10.3-28.3); T(3) 4.28 nmol/l (NR:1.23-3.39) TSH 2.8 mUI/l (NR: 0.5-5) always responsive to TRH. TSH levels remained detectable after supraphysiologic T(3) administration while SHBG levels showed a paradoxical decrease in 4/6. Thyroid antibodies, initially present in two subjects, became positive in other two during follow-up. All patients grew normally and presented variable symptoms that were treated according to need. Two patients developed psychiatric disorders. Only one of the four affected parents exhibited clinical signs of RTH (tachycardia and depression). Parent's thyroid profile showed similar TSH and T(3) levels but lower T(4) and FT(4) than their children. RTH has a distinctive biochemical profile with highly variable clinical manifestations and outcomes. Its recognition and molecular characterization avoid misleading diagnosis. Treatment has to be instituted according to each subject's own clinical requirements.

Hipotiroidismo congénito transitorio por defectos bialélicos del genDUOX2. Dos casos clínicos / Transient congenital hypothyroidism due to biallelic defects of DUOX2 gene. Two clinical cases

El hipotiroidismo congénito afecta a 1:2000-3000 recién nacidos detectados por pesquisa neonatal. Las oxidasas duales, DUOX1 y 2, generan agua oxigenada, lo que constituye un paso crítico en la síntesis hormonal. Se han comunicado mutaciones en el gen DUOX2 en casos de hipotiroidismo congénito transitorio y permanente. Se describen dos hermanos con hipotiroidismo congénito detectados por pesquisa neonatal, con glándula tiroides eutópica y tiroglobulina elevada. Recibieron levotiroxina hasta su reevaluación en la infancia con suspensión del tratamiento. Su función tiroidea fue normal y se consideró el cuadro como transitorio por un posible defecto de organificación. Ambos pacientes eran heterocigotos compuestos para una mutación en el exón 9 del alelo paterno (c.1057_1058delTT, p.F353PfsX36 o p.F353fsX388) y otra en el exón 11 del alelo materno (c.1271T>G, p.Y425X) del gen DUOX2. Nuestro hallazgo confirma que la magnitud del defecto de DUOX2 no se relaciona con el número de alelos afectados, lo que sugiere mecanismos compensadores en la generación de peróxido.

Congenital hypothyroidism affects 1:2000-3000 newborns detected by neonatal screening programs. Dual oxidases, DUOX1 and 2, generate hydrogen peroxide needed for the thyroid hormone synthesis. Mutations in the DUOX2 gene have been described in transient and permanent congenital hypothyroidism. Two brothers with congenital hypothyroidism detected by neonatal screening with eutopic gland and elevated thyroglobulin are described. They were treated with levothyroxine until it could be suspended in both during childhood, assuming the picture as transient. Organification disorder was confirmed. Both patients were compounds heterozygous for a mutation in exon 9 of the paternal allele (c.1057_1058delTT, p.F353PfsX36 or p.F353fsX388) and in exon 11 of the maternal allele (c.1271T > G, p.Y425X) of DUOX2 gene. Our finding confirms that the magnitude of the defect of DUOX2 is not related to the number of inactivated alleles, suggesting compensatory mechanisms in the peroxide supply