Cochlear dysfunction evidenced by reduction of amplitude of otoacoustic responses in patients with congenital hypothyroidism.

INTRODUCTION: The investigation of amplitudes of otoacoustic emissions in congenital hypothyroidism can provide information on cochlear function with more sensibility, when compared to other methods of auditory evaluation. AIM: To investigate cochlear function through the amplitude of distortion product otoacoustic emissions in individuals with congenital hypothyroidism and to correlate with clinical aspects. METHODS: An exploratory, analytical, cross-sectional study with a convenience sample, composed of 50 individuals with congenital hypothyroidism and a group of 42 individuals without the disease, mean age of 8.4 (±3.1) years. The subjects of the research were evaluated by means of tonal and speech audiometry, immittance and distortion product otoacoustic emissions (DPOAEs). Continuous variables were described as mean or median and standard deviation. The Spearman test evaluated the correlations between the variables. RESULTS: Otoacoustic emission amplitudes were significantly reduced in the exposed group, with congenital hypothyroidism, when compared to the group of individuals without the disease, especially in the medium frequencies. The Spearman test showed a slight correlation between the amplitude values of the otoacoustic emissions of some frequencies and the variables: disease time, diagnostic age, irregular serum free thyroxine hormone levels and thyroid stimulating hormone, especially in the condition of less treatment, whose correlation was negative. CONCLUSION: There was a correlation between the levels of signal amplitudes of otoacoustic emissions with clinical conditions and hormonal follow-up, suggesting probable subclinical auditory impairment in this population, as well as influence of some clinical aspects of congenital hypothyroidism on auditory function.

Association between BRAF (V600E) mutation and clinicopathological features of papillary thyroid carcinoma: a Brazilian single-centre case series.

OBJECTIVES: We aimed to investigate the prevalence of the BRAF (V600E) mutation in consecutive cases of papillary thyroid carcinoma (PTC) in patients diagnosed and treated at the Hospital Sao Rafael (Salvador, BA, Brazil) and evaluate its association with clinical and pathological characteristics of PTC. SUBJECTS AND METHODS: We retrospectively enrolled in the study a total of 43 consecutive PTC patients who underwent total thyroidectomy. We performed DNA extraction from formalin-fixed paraffin-embedded (FFPE) tumour tissue samples. Polymerase chain reaction (PCR) and direct sequencing were used to determine BRAF (V600E) mutation status. Univariate and multivariate logistic regression analyses were employed to identify independent associations. RESULTS: The prevalence of BRAF (V600E) mutation was 65.1% (28/43). A high frequency of older patients (p value: 0.004) was observed among the BRAF-mutated PTC group and, in contrast, a low frequency of concurrent Hashimoto's thyroiditis (HT) (p value: 0.011) was noted. Multivariate analysis confirmed that older age (OR: 1.15; 95% CI: 1.00 - 1.33; p value: 0.047) and HT (OR: 0.05; 95% CI: 0.006-0.40; p value: 0.005) were independent factors associated with BRAF (V600E) mutation. CONCLUSION: We found a high prevalence of BRAF (V600E) mutation in PTC cases. Older age and no concurrent HT were independently associated with BRAF (V600E) mutation.

Mutation screening in the genes PAX-8, NKX2-5, TSH-R, HES-1 in cohort of 63 Brazilian children with thyroid dysgenesis.

OBJECTIVE: To evaluate the candidate genes PAX-8, NKX2-5, TSH-R and HES-1 in 63 confirmed cases of thyroid dysgenesis. SUBJECTS AND METHODS: Characterization of patients with congenital hypothyroidism into specific subtypes of thyroid dysgenesis with hormone levels (TT4 and TSH), thyroid ultrasound and scintigraphy. DNA was extracted from peripheral blood leukocytes and the genetic analysis was realized by investigating the presence of mutations in the transcription factor genes involved in thyroid development. RESULTS: No mutations were detected in any of the candidate genes. In situ thyroid gland represented 71.1% of all cases of permanent primary congenital hypothyroidism, followed by hypoplasia (9.6%), ectopia (78%), hemiagenesis (6.0%) and agenesis (5.5%). The highest neonatal screening TSH levels were in the agenesis group (p < 0.001). CONCLUSIONS: Thyroid dysgenesis is possibly a polygenic disorder and epigenetic factors could to be implicated in these pathogeneses.

The c.63A>G polymorphism in the NKX2.5 gene is associated with thyroid hypoplasia in children with thyroid dysgenesis.

OBJECTIVE: To search for genetic alteration in NKX2.5 gene in patients presenting both congenital heart disease (CHD) and TD. SUBJECTS AND METHODS: Individual phenotypes were carefully analyzed in 86 children with thyroid dysgenesis (TD) using thyroid function tests, scintigraphy, ultrasound and echocardiography. DNA was extracted and NKX2.5 gene coding region was amplified by polymerase chain reaction (PCR) and sequenced. RESULTS: CHD were found in 8.1% of patients with TD. The mutation screening revealed two known polymorphisms in patients with isolated TD or TD associated with CHD. None of them are predicted to result in codon change in conserved domain. The c.63A>G polymorphism was detected in 54/86 patients (49 with isolated TD and 5 with TD combined with CHD). There was a significant association of c.63A>G polymorphism with hypoplasia (p < 0.036). The c.541G>A polymorphism was observed in only one patient with isolated thyroid hypoplasia. CONCLUSION: NKX2.5 mutations were not found. The c.63A>G polymorphism might be associated with thyroid hypoplasia.

Iodine nutritional status in Brazil: a meta-analysis of all studies performed in the country pinpoints to an insufficient evaluation and heterogeneity.

OBJECTIVES: Iodine deficiency disorder (IDD) is the result of an inadequate dietary intake of iodine, which physiological consequences are endemic goiter and thyroid dysfunction. The objective of this study was to a analyze studies that assessed the status of Brazil's population iodine nutrition and IDD prevalence. MATERIALS AND METHODS: Systematic review using PRISMA statement. Electronic database: PubMed, Medline, SciELO and Lilacs. Quality of studies: Newcastle-Ottawa Scale. Meta-analysis was carried out with R Core Team Statistical Software, version 3.1.0 (2014). The summary measure (WMD) and its confidence interval (CI) of 95% were calculated. The "Funnel plot" graph assessed publication bias and heterogeneity. RESULTS: Seventeen papers were eligible: pregnant women (2), school children (9), adults/elderly (4) and preschool children/infants (2). Geographic distribution: North (1), Northeast (1), Midwest (2), Southeast (13), South (3). Twenty-three thousand two hundred seventy-two subjects were evaluated between 1997 and 2013 and all have use urinary iodine (UI) measurement. However, only 7 studies could be included in meta-analysis, all from Southeast region. The overall prevalence of IDD in school children in southeast region was 15.3% (95% CI, 13-35%), however this data had an important heterogeneity, expressed by the I2 Statistic of 99.5%. CONCLUSION: Only few studies have been performed and enrolled populations from south/southeast region of Brazil. The actual IDD prevalence analysis is complex because it was detected bias due influence of individual studies and very high heterogeneity. IDD might still be high in some areas but this remained unknown even after this meta-analysis evaluation. The generation of a national program for analysis of iodine status in all regions is urgently required.

An international survey of screening and management of hypothyroidism during pregnancy in Latin America.

OBJECTIVE: To determine how endocrinologists in Latin America deal with clinical case scenarios related to hypothyroidism and pregnancy. MATERIALS AND METHODS: In January 2013, we sent an electronic questionnaire on current practice relating to management of hypothyroidism in pregnancy to 856 members of the Latin American Thyroid Society (LATS) who manage pregnant patients with thyroid disease. Subsequently, we have analyzed responses from physician members. RESULTS: Two hundred and ninety-three responders represent clinicians from 13 countries. All were directly involved in the management of maternal hypothyroidism and 90.7% were endocrinologists. The recommendation of a starting dose of L-thyoxine for a woman diagnosed with overt hypothyroidism in pregnancy, preconception management of euthyroid women with known thyroid autoimmunity and approach related to ovarian hyperstimulation in women with thyroid peroxidase antibodies were widely variable. For women with known hypothyroidism, 34.6% of responders would increase L-thyroxine dose by 30-50% as soon as pregnancy is confirmed. With regard to screening, 42.7% of responders perform universal evaluation and 70% recommend TSH < 2.5 mUI/L in the first trimester and TSH < 3 mUI/L in the second and third trimester as target results in known hypothyroid pregnant women. CONCLUSION: Deficiencies in diagnosis and management of hypothyroidism during pregnancy were observed in our survey, highlighting the need for improvement of specialist education and quality of care offered to patients with thyroid disease during pregnancy in Latin America.

Association between BRAF (V600E) mutation and clinicopathological features of papillary thyroid carcinoma: a Brazilian single-centre case series

ABSTRACT Objectives: We aimed to investigate the prevalence of the BRAF (V600E) mutation in consecutive cases of papillary thyroid carcinoma (PTC) in patients diagnosed and treated at the Hospital Sao Rafael (Salvador, BA, Brazil) and evaluate its association with clinical and pathological characteristics of PTC. Subjects and methods: We retrospectively enrolled in the study a total of 43 consecutive PTC patients who underwent total thyroidectomy. We performed DNA extraction from formalin-fixed paraffin-embedded (FFPE) tumour tissue samples. Polymerase chain reaction (PCR) and direct sequencing were used to determine BRAF (V600E) mutation status. Univariate and multivariate logistic regression analyses were employed to identify independent associations. Results: The prevalence of BRAF (V600E) mutation was 65.1% (28/43). A high frequency of older patients (p value: 0.004) was observed among the BRAF-mutated PTC group and, in contrast, a low frequency of concurrent Hashimoto's thyroiditis (HT) (p value: 0.011) was noted. Multivariate analysis confirmed that older age (OR: 1.15; 95% CI: 1.00 - 1.33; p value: 0.047) and HT (OR: 0.05; 95% CI: 0.006-0.40; p value: 0.005) were independent factors associated with BRAF (V600E) mutation. Conclusion: We found a high prevalence of BRAF (V600E) mutation in PTC cases. Older age and no concurrent HT were independently associated with BRAF (V600E) mutation.

Mutation screening in the genes PAX-8, NKX2-5, TSH-R, HES-1 in cohort of 63 Brazilian children with thyroid dysgenesis

ABSTRACT Objective: To evaluate the candidate genes PAX-8, NKX2-5, TSH-R and HES-1 in 63 confirmed cases of thyroid dysgenesis. Subjects and methods: Characterization of patients with congenital hypothyroidism into specific subtypes of thyroid dysgenesis with hormone levels (TT4 and TSH), thyroid ultrasound and scintigraphy. DNA was extracted from peripheral blood leukocytes and the genetic analysis was realized by investigating the presence of mutations in the transcription factor genes involved in thyroid development. Results: No mutations were detected in any of the candidate genes. In situ thyroid gland represented 71.1% of all cases of permanent primary congenital hypothyroidism, followed by hypoplasia (9.6%), ectopia (78%), hemiagenesis (6.0%) and agenesis (5.5%). The highest neonatal screening TSH levels were in the agenesis group (p < 0.001). Conclusions: Thyroid dysgenesis is possibly a polygenic disorder and epigenetic factors could to be implicated in these pathogeneses.

The c.63A>G polymorphism in the NKX2.5 gene is associated with thyroid hypoplasia in children with thyroid dysgenesis

Objective To search for genetic alteration in NKX2.5 gene in patients presenting both congenital heart disease (CHD) and TD. Subjects and methods Individual phenotypes were carefully analyzed in 86 children with thyroid dysgenesis (TD) using thyroid function tests, scintigraphy, ultrasound and echocardiography. DNA was extracted and NKX2.5 gene coding region was amplified by polymerase chain reaction (PCR) and sequenced. Results CHD were found in 8.1% of patients with TD. The mutation screening revealed two known polymorphisms in patients with isolated TD or TD associated with CHD. None of them are predicted to result in codon change in conserved domain. The c.63A>G polymorphism was detected in 54/86 patients (49 with isolated TD and 5 with TD combined with CHD). There was a significant association of c.63A>G polymorphism with hypoplasia (p < 0.036). The c.541G>A polymorphism was observed in only one patient with isolated thyroid hypoplasia. Conclusion NKX2.5 mutations were not found. The c.63A>G polymorphism might be associated with thyroid hypoplasia.

Iodine nutritional status in Brazil: a meta-analysis of all studies performed in the country pinpoints to an insufficient evaluation and heterogeneity

Objectives Iodine deficiency disorder (IDD) is the result of an inadequate dietary intake of iodine, which physiological consequences are endemic goiter and thyroid dysfunction. The objective of this study was to a analyze studies that assessed the status of Brazil’s population iodine nutrition and IDD prevalence. Materials and methods Systematic review using PRISMA statement. Electronic database: PubMed, Medline, SciELO and Lilacs. Quality of studies: Newcastle-Ottawa Scale. Meta-analysis was carried out with R Core Team Statistical Software, version 3.1.0 (2014). The summary measure (WMD) and its confidence interval (CI) of 95% were calculated. The “Funnel plot” graph assessed publication bias and heterogeneity. Results Seventeen papers were eligible: pregnant women (2), school children (9), adults/elderly (4) and preschool children/infants (2). Geographic distribution: North (1), Northeast (1), Midwest (2), Southeast (13), South (3). Twenty-three thousand two hundred seventy-two subjects were evaluated between 1997 and 2013 and all have use urinary iodine (UI) measurement. However, only 7 studies could be included in meta-analysis, all from Southeast region. The overall prevalence of IDD in school children in southeast region was 15.3% (95% CI, 13-35%), however this data had an important heterogeneity, expressed by the I2 Statistic of 99.5%. Conclusion Only few studies have been performed and enrolled populations from south/southeast region of Brazil. The actual IDD prevalence analysis is complex because it was detected bias due influence of individual studies and very high heterogeneity. IDD might still be high in some areas but this remained unknown even after this meta-analysis evaluation. The generation of a national program for analysis of iodine status in all regions is urgently required. Arch Endocrinol Metab. 2015;59(1):13-22 .

An international survey of screening and management of hypothyroidism during pregnancy in Latin America / Uma avaliação internacional do rastreio e manejo do hipotireoidismo durante a gestação na América Latina

Objective To determine how endocrinologists in Latin America deal with clinical case scenarios related to hypothyroidism and pregnancy. Materials and methods In January 2013, we sent an electronic questionnaire on current practice relating to management of hypothyroidism in pregnancy to 856 members of the Latin American Thyroid Society (LATS) who manage pregnant patients with thyroid disease. Subsequently, we have analyzed responses from physician members. Results Two hundred and ninety-three responders represent clinicians from 13 countries. All were directly involved in the management of maternal hypothyroidism and 90.7% were endocrinologists. The recommendation of a starting dose of L-thyoxine for a woman diagnosed with overt hypothyroidism in pregnancy, preconception management of euthyroid women with known thyroid autoimmunity and approach related to ovarian hyperstimulation in women with thyroid peroxidase antibodies were widely variable. For women with known hypothyroidism, 34.6% of responders would increase L-thyroxine dose by 30-50% as soon as pregnancy is confirmed. With regard to screening, 42.7% of responders perform universal evaluation and 70% recommend TSH < 2.5 mUI/L in the first trimester and TSH < 3 mUI/L in the second and third trimester as target results in known hypothyroid pregnant women. Conclusion Deficiencies in diagnosis and management of hypothyroidism during pregnancy were observed in our survey, highlighting the need for improvement of specialist education and quality of care offered to patients with thyroid disease during pregnancy in Latin America. Arq Bras Endocrinol ...

Objetivo Determinar, na América Latina, como os endocrinologistas lidam com cenários clínicos relacionados ao hipotireoidismo durante a gravidez. Materiais e métodos Em Janeiro de 2013, foi enviado, para 856 membros da Sociedade Latino-Americana de Tireoide (LATS), um questionário eletrônico sobre práticas relacionadas ao manejo do hipotireoidismo durante a gestação. Subsequentemente, as respostas foram analisadas. Resultados Duzentos e noventa e três médicos, de 13 países, responderam ao questionário. Todos estavam diretamente envolvidos no manejo de hipotireoidismo materno e 90,7% eram endocrinologistas. As recomendações de iniciar terapia com levotiroxina para uma mulher com hipotireoidismo franco durante a gravidez e o manejo na fase de pré-concepção de pacientes eutireoidianas com conhecida autoimunidade em hiperestimulação ovariana variaram amplamente. Para mulheres com hipotireoidismo conhecido, apenas 34,6% dos respondedores aumentariam a dose de levotiroxina em 30-50% assim que a gravidez fosse confirmada. Em relação ao rastreamento, 42,7% dos respondedores realizam avaliação universal. Setenta por cento recomendam TSH < 2,5 mUI/L no primeiro trimestre e TSH < 3 mUI/L no terceiro trimestre como alvos. Conclusão Observamos problemas no diagnóstico e manejo do hipotireoidismo durante a gestação, enfatizando a necessidade, na América Latina, de melhoria na educação médica continuada em áreas como tireoiodopatias na gestação. Arq Bras Endocrinol Metab. ...

Estudo clínico, genético e molecular de pacientes com Disgenesia Tireoidiana

INTRODUÇÃO: Hipotireoidismo Congênito (HC), é uma das doenças metabólicas mais comuns na infância com incidência de 1:3.000 a 1:4.000 recém-nascidos. Um grupo de doenças relacionadas às alterações no desenvolvimento da tireoide, denominadas disgenesias tireoidianas (DT), responsabiliza-se por aproximadamente 85% de todos os casos de HC, sendo sua patogênese pouco conhecida. OBJETIVOS: Geral: Caracterização clínica e genética de pacientes com HC diagnosticados com disgenesia tireoidiana. Específicos: 1. Caracterizar clínica dos indivíduos com HC em acompanhamento na APAE/Salvador (Associação de Pais e Amigos dos Excepcionais); 2. Avaliar a existência de associação entre malformações tireoidianas e malformações cardiacos; 3. Pesquisar polimorfismos e mutações nos genes candidatos: PAX8, TSH-R, NKX2.5 e HES1, em pacientes diagnosticados com disgenesia tireoidiana; 4. Pesquisar o gene TSH-R numa coorte de pacientes com HC diagnosticados no programa de triagem neonatal da França. METODOLOGIA: Até o ano de 2016, 1.188 crianças foram diagnosticadas com HC e 773 estão em acompanhamento. Duzentos e dezoito crianças confirmadas com HC foram caracterizadas clinicamente através de testes de função da tireoide (TT4 e TSH), ultrassonografia e cintilografia, seguidas de dosagem de tireoglobulina. Toda a região codificantes dos genes PAX8, TSH-R, NKX2.5 e HES1 incluindo íntrons e éxons foram amplificados a partir do DNA genômico através da PCR (Reação em cadeia da Polimerase) utilizando-se técnicas padrão seguida de Sequenciamento direto. RESULTADOS: Sessenta e três pacientes foram diagnosticados com DT e 155 com glândula tópica normal. Hipoplasia representou 33,4% dos casos de DT, agenesia 19%, ectopia 27% e hemiagenesia 20,6%. Altos concentrações de TSH no teste do pezinho foram detectados no grupo das agenesias seguido das hipoplasias. Na análise genética/molecular, 31 (49,2%) dos pacientes foram identificados com o polimorfismo p.D727E em heterozigose e 4 (6,4%) em homozigose, no gene TSH-R; 4/63 pacientes tiveram o polimorfismo p.P52T em heterozigose; 14/63 apresentaram a variante polimórfica p.N181N e 2/63 apresentaram a substituição sinônima conhecida p.L645L, todos no gene TSH-R. o polimorfismo p.Glu21 foi encontrado em 54% dos pacientes e p.Gln181 encontrado em 1 paciente no gene NKX2.5. Nenhuma alteração foi encontrada no gene HES1, bem como em PAX8. CONCLUSÕES: Este é o primeiro estudo realizado na população de HC no Estado da Bahia. Análises clínicas revelaram um padrão distinto entre os subgrupos da DT quando comparados com glândula normal; 6 polimorfismos já descritos foram encontrados em dois genes candidatos. Nenhuma mutação patogênica foi encontrada. A descrição fenotípica é essencial para a correta avaliação genética e os mecanismos nela implicados, além de utilizados para predição da gravidade do HC. A identificação de novos genes ou eventos moleculares que controlam a função tireoidiana pós-natal seria de grande utilidade no esclarecimento das DT

INTRODUCTION: Congenital hypothyroidism (CH), is the most common metabolic diseases in childhood with incidence of 1: 3000-1: 4000 newborns. A group of diseases related to alterations in the development of the thyroid, called thyroid dysgenesis (TD), is responsible for approximated 85% of all HC cases, and the majority has unknown pathogenesis. OBJECTIVES: General: clinical and genetic characterization of CH patients diagnosed with TD. Specific: 1. CH clinical characterization in individuals followed at APAE/Salvador; 2. evaluating the association between thyroid abnormalities and other abnormalities or syndromes; 3. search polymorphisms and mutations in known candidate genes for TD: PAX8, TSH-R, NKX2.5 and HES1; 4. XX METHODS: Until the year 2016, 1.188 children were diagnosed for CH and 773 were actually follow in APAE-Salvador. A continuous series of 218 children with confirmed HC were characterized clinically through thyroid function tests (TT4 and TSH), thyroid ultrasound and scintigraphy, followed by serum thyroglobulin measurement. The entire coding region of the candidate genes (PAX8, TSH-R, NKX2.5 and HES1), including exon/intron boundaries, was amplified from genomic DNA by polymerase chain reaction (PCR) using standard techniques, followed by direct sequencing. Results: Sixty-three patients were diagnosed with DT and 155 with in situ thyroid gland (ISTG). Hypoplasia represented 33,4% of all cases of DT, agenesis (19%), ectopy (27%) and hemiagenesis (20,6%). The higher screening TSH levels was in the agenetic group followed by hypoplasia. In the genetic/molecular analysis, 31 (49,2%) patients were identified with a polymorphism of TSH-R gene (p.D727E); 4/63 patients had a heterozygous p.P52T; 14/63 patients showed p.N187N polymorphic variants of the gene; and 2/63 patients presented a known p.L645L synonimous substitution. The polymorphism p.Glu21was found in 54% of patients, and p.Gln181 found in only one patient in the NKX2.5 gene. None alteration was detected in HES1 gene. CONCLUSIONS: This is the first CH population-based study in State of Bahia, Brazil. Clinical analysis revealed distinct hormonal patterns in DT subgroup when compared with ISTG, with only 6 known polymorphisms identified in few cases of TD in TSH-R, PAX8, NKX2.5 and HES1 genes. No mutation was found in a candidate genes studied. A detailed description of phenotype might be essential to target the correct genetic and mechanism implicated, and useful to predict CH severity. The identification of additional genes or molecular events controlling early postnatal thyroid function would be helpful.

Estudo clínico, genético e molecular de pacientes com Disgenesia Tireoidiana

INTRODUÇÃO: Hipotireoidismo Congênito (HC), é uma das doenças metabólicas mais comuns na infância com incidência de 1:3.000 a 1:4.000 recém-nascidos. Um grupo de doenças relacionadas às alterações no desenvolvimento da tireoide, denominadas disgenesias tireoidianas (DT), responsabiliza-se por aproximadamente 85% de todos os casos de HC, sendo sua patogênese pouco conhecida. OBJETIVOS: Geral: Caracterização clínica e genética de pacientes com HC diagnosticados com disgenesia tireoidiana. Específicos: 1. Caracterizar clínica dos indivíduos com HC em acompanhamento na APAE/Salvador (Associação de Pais e Amigos dos Excepcionais); 2. Avaliar a existência de associação entre malformações tireoidianas e malformações cardiacos; 3. Pesquisar polimorfismos e mutações nos genes candidatos: PAX8, TSH-R, NKX2.5 e HES1, em pacientes diagnosticados com disgenesia tireoidiana; 4. Pesquisar o gene TSH-R numa coorte de pacientes com HC diagnosticados no programa de triagem neonatal da França. METODOLOGIA: Até o ano de 2016, 1.188 crianças foram diagnosticadas com HC e 773 estão em acompanhamento. Duzentos e dezoito crianças confirmadas com HC foram caracterizadas clinicamente através de testes de função da tireoide (TT4 e TSH), ultrassonografia e cintilografia, seguidas de dosagem de tireoglobulina. Toda a região codificantes dos genes PAX8, TSH-R, NKX2.5 e HES1 incluindo íntrons e éxons foram amplificados a partir do DNA genômico através da PCR (Reação em cadeia da Polimerase) utilizando-se técnicas padrão seguida de Sequenciamento direto. RESULTADOS: Sessenta e três pacientes foram diagnosticados com DT e 155 com glândula tópica normal. Hipoplasia representou 33,4% dos casos de DT, agenesia 19%, ectopia 27% e hemiagenesia 20,6%. Altos concentrações de TSH no teste do pezinho foram detectados no grupo das agenesias seguido das hipoplasias. Na análise genética/molecular, 31 (49,2%) dos pacientes foram identificados com o polimorfismo p.D727E em heterozigose e 4 (6,4%) em homozigose, no gene TSH-R; 4/63 pacientes tiveram o polimorfismo p.P52T em heterozigose; 14/63 apresentaram a variante polimórfica p.N181N e 2/63 apresentaram a substituição sinônima conhecida p.L645L, todos no gene TSH-R. o polimorfismo p.Glu21 foi encontrado em 54% dos pacientes e p.Gln181 encontrado em 1 paciente no gene NKX2.5. Nenhuma alteração foi encontrada no gene HES1, bem como em PAX8. CONCLUSÕES: Este é o primeiro estudo realizado na população de HC no Estado da Bahia. Análises clínicas revelaram um padrão distinto entre os subgrupos da DT quando comparados com glândula normal; 6 polimorfismos já descritos foram encontrados em dois genes candidatos. Nenhuma mutação patogênica foi encontrada. A descrição fenotípica é essencial para a correta avaliação genética e os mecanismos nela implicados, além de utilizados para predição da gravidade do HC. A identificação de novos genes ou eventos moleculares que controlam a função tireoidiana pós-natal seria de grande utilidade no esclarecimento das DT. Palavras-chave: