Searching for mutations in the HNF1B gene in a Brazilian cohort with renal cysts and hyperglycemia

ABSTRACT Objective To verify the presence of variants in HNF1B in a sample of the Brazilian population selected according to the presence of renal cysts associated with hyperglycemia. Subjects and methods We evaluated 28 unrelated patients with clinical suspicion of HNF1B mutation because of the concomitant presence of diabetes mellitus (DM) or prediabetes and renal cysts. Genotyping was accomplished using Sanger sequencing or multiplex ligation-dependent probe amplification (MLPA). In positive cases, available relatives were recruited. Results We found two patients with HNF1B mutations. The first presented the variant p.Pro328Leufs*48(c.983delC) and had DM, renal cysts, and hypomagnesemia. The second presented a heterozygous whole gene deletion in HNF1B, DM, renal cysts, body and tail pancreatic agenesis, and hypomagnesemia; this alteration was also found in his two siblings and his father. Conclusion The recruitment of suspected cases of HNF1B gene mutations in Brazilians due to hyperglycemia and renal cysts presents two positive cases. Our cases contribute to the annotation of clinical and biochemical phenotypes of this rare form of maturity-onset diabetes of the young (MODY).

A pioneering RET genetic screening study in the State of Ceará, Brazil, evaluating patients with medullary thyroid cancer and at-risk relatives: experience with 247 individuals

ABSTRACT Objective: Initial diagnosis of medullary thyroid carcinoma (MTC) is frequently associated with advanced stages and a poor prognosis. Thus, the need for earlier diagnoses and detection in relatives at risk for the disease has led to increased use of RET genetic screening. Subjects and methods: We performed RET screening in 247 subjects who were referred to the Brazilian Research Consortium for Multiple Endocrine Neoplasia (BRASMEN) Center in the State of Ceará. Direct genetic sequencing was used to analyze exons 8, 10, 11, and 13-16 in MTC index cases and specific exons in at risk relatives. Afterward, clinical follow-up was offered to all the patients with MTC and their affected relatives. Results: RET screening was performed in 60 MTC index patients and 187 at-risk family members. At the initial clinical assessment of the index patients, 54 (90%) were diagnosed with apparently sporadic disease and 6 (10%) diagnosed with hereditary disease. After RET screening, we found that 31 (52%) index patients had sporadic disease, and 29 (48%) had hereditary disease. Regarding at-risk relatives, 73/187 were mutation carriers. Mutations in RET codon 804 and the rare p.M918V mutation were the most prevalent. Conclusions: Performing RET screening in Ceará allowed us to identify a different mutation profile in this region compared with other areas. RET screening also enabled the diagnosis of a significant number of hereditary MTC patients who were initially classified as sporadic disease patients and benefited their relatives, who were unaware of the risks and the consequences of bearing a RET mutation.

More than kin, less than kind: one family and the many faces of diabetes in youth

SUMMARY Identification of the correct etiology of diabetes brings important implications for clinical management. In this report, we describe a case of a 4-year old asymptomatic girl with diabetes since age 2, along with several individuals in her family with different etiologies for hyperglycemia identified in youth. Genetic analyses were made by Sanger sequencing, laboratory measurements included HbA1c, lipid profile, fasting C-peptide, pancreatic auto-antibodies (glutamic acid decarboxylase [GAD], Islet Antigen 2 [IA-2], and anti-insulin). We found a Gly178Ala substitution in exon 5 of GCK gene in three individuals co-segregating with diabetes, and type 1 diabetes was identified in two other individuals based on clinical and laboratory data. One individual with previous gestational diabetes and other with prediabetes were also described. We discuss difficulties in defining etiology of hyperglycemia in youth in clinical practice, especially monogenic forms of diabetes, in spite of the availability of several genetic, laboratory, and clinical tools.

Novel immunoassay for TSH measurement in rats

ABSTRACT Measuring thyroid hormones is an important aspect for the study of metabolism and for monitoring diseases in both human and animal models. The traditional method for hormone measurement in rats is the radioimmunoassay (RIA). However, the RIA is associated with some practical disadvantages, including the use of radioactive material, the need for specialized equipment and expert staff, the short shelf-life of kits according to the half-life of the radioisotope and high costs. The objective of this study was to develop a new cost-effective method for measuring TSH levels in rats that avoids the use of radioactive material. We developed an in-house competitive immunoassay using a reference standard, polyclonal antibody produced in rabbits and biotinylated antigen. This method was tested in 64 Wistar rats that were divided into a control group (n = 41) and a group with hypothyroidism (n = 23). Our assay demonstrated an analytical sensitivity of 0.24 ng/mL (n = 12) and an intra-assay coefficient of variation (CV) of 8.9% for sera with TSH levels of 1.5 ng/mL and 13.2% for sera with TSH levels of 17.5 ng/mL (n = 14). The inter-assay CV was 13.5% for sera with TSH levels of 1.4 ng/mL and 14.5% for TSH levels of 18.2 ng/mL (n = 5). The analysis of mean TSH levels in control rats (5.06 ± 0.5701) and hypothyroid rats (51.09 ± 5.136) revealed a statistically significant difference (p < 0.001) between the groups. This method showed good sensitivity, can be automated and is low-cost compared with RIA. Our method offers a viable alternative for TSH measurement in rats.

Insights into the posttranslational structural heterogeneity of thyroglobulin and its role in the development, diagnosis, and management of benign and malignant thyroid diseases

ABSTRACT Thyroglobulin (Tg) is the major glycoprotein produced by the thyroid gland, where it serves as a template for thyroid hormone synthesis and as an intraglandular store of iodine. Measurement of Tg levels in serum is of great practical importance in the follow-up of differentiated thyroid carcinoma (DTC), a setting in which elevated levels after total thyroidectomy are indicative of residual or recurrent disease. The most recent methods for serum Tg measurement are monoclonal antibody-based and are highly sensitive. However, major challenges remain regarding the interpretation of the results obtained with these immunometric methods, particularly in patients with endogenous antithyroglobulin antibodies or in the presence of heterophile antibodies, which may produce falsely low or high Tg values, respectively. The increased prevalence of antithyroglobulin antibodies in patients with DTC, as compared with the general population, raises the very pertinent possibility that tumor Tg may be more immunogenic. This inference makes sense, as the tumor microenvironment (tumor cells plus normal host cells) is characterized by several changes that could induce posttranslational modification of many proteins, including Tg. Attempts to understand the structure of Tg have been made for several decades, but findings have generally been incomplete due to technical hindrances to analysis of such a large protein (660 kDa). This review article will explore the complex structure of Tg and the potential role of its marked heterogeneity in our understanding of normal thyroid biology and neoplastic processes.

Low iodine diet does not improve the efficacy of radioiodine for the treatment of Graves’ disease

Objective Consuming a low-iodine diet (LID) is a widely accepted practice before administering radioiodine (131I) to evaluate and to treat thyroid disease. Although this procedure is well established for the management of patients with differentiated thyroid cancer, its use in patients with benign disease is unclear. So, we aimed to evaluate the influence of a LID on the outcome in patients with Graves’ disease (GD) treated with131I. Subjects and methods We evaluated 67 patients with GD who were divided into 2 groups: one group (n = 31) consumed a LID for 1-2 weeks, and the second group (n = 36) was instructed to maintain a regular diet (RD). Results The LID group experienced a 23% decrease in urinary iodine after 1 week on the diet and a significant 42% decrease after 2 weeks on the diet. The majority (53%) of the patients in the LID group had urinary iodine levels that were consistent with deficient iodine intake. However, there was no difference in the rate of hyperthyroidism’s cure between the LID and the RD groups 6 months after 131I therapy. Furthermore, the therapeutic efficacy did not differ in patients with varying degrees of sufficient iodine intake (corresponding urinary iodine levels: < 10 μg/dL is deficient; 10-29.9 μg/dL is sufficient; and > 30 μg/dL is excessive). Conclusion In the present study, we demonstrated that although a LID decreased urinary iodine levels, those levels corresponding with sufficient or a mild excess in iodine intake did not compromise the therapeutic efficacy of131I for the treatment of GD.

Optimizing nucleic acid extraction from thyroid fine-needle aspiration cells in stained slides, formalin-fixed/paraffin-embedded tissues, and long-term stored blood samples / Otimização da extração de ácidos nucleicos de material de punção aspirativa por agulha fina de tiroide obtido de lâminas coradas, tecidos fixados em formalina e emblocados em parafina e amostras de sangue estocadas por longo período

OBJECTIVE: Adequate isolation of nucleic acids from peripheral blood, fine-needle aspiration cells in stained slides, and fresh and formalin-fixed/paraffin-embedded tissues is crucial to ensure the success of molecular endocrinology techniques, especially when samples are stored for long periods, or when no other samples can be collected from patients who are lost to follow-up. Here, we evaluate several procedures to improve current methodologies for DNA (salting-out) and RNA isolation. MATERIALS AND METHODS: We used proteinase K treatment, heat shock, and other adaptations to increase the amount and quality of the material retrieved from the samples. RESULTS: We successfully isolated DNA and RNA from the samples described above, and this material was suitable for PCR, methylation profiling, real-time PCR and DNA sequencing. CONCLUSION: The techniques herein applied to isolate nucleic acids allowed further reliable molecular analyses. Arq Bras Endocrinol Metab. 2012;56(9):618-26.

OBJETIVO: O isolamento adequado de ácidos nucleicos a partir de sangue periférico, lâmina corada de punção aspirativa por agulha fina, tecido fixado em formalina e emblocado em parafina e tecido fresco é fundamental para assegurar o sucesso de técnicas aplicadas em endocrinologia molecular, principalmente quando lidamos com amostras estocadas por longos períodos ou quando há impossibilidade de nova coleta de amostra de pacientes que perderam o seguimento. Neste trabalho, objetivamos otimizar as metodologias clássicas para a extração de DNA (salting-out) e RNA. MATERIAIS E MÉTODOS: Utilizamos proteinase K, choque térmico, dentre outras modificações, com o objetivo de aumentar a quantidade e a qualidade do material recuperado a partir das amostras descritas acima. RESULTADOS: Isolamos com sucesso DNA e RNA de tais amostras e o material obtido foi adequado para a realização de PCR, perfil de metilação, PCR em tempo real e sequenciamento de DNA. CONCLUSÃO: As técnicas aplicadas neste estudo para isolar ácidos nucleicos permitiram a realização posterior de análises moleculares consistentes e confiáveis. Arq Bras Endocrinol Metab. 2012;56(9):618-26.

Autoimmune polyendocrine syndrome type 1: case report and review of literature / Síndrome poliglandular autoimune tipo 1: descrição de caso e revisão da literatura

Autoimmune polyendocrine syndrome type 1 (APECED) is a rare autosomal recessive disorder characterized by autoimmune multiorgan attack. The disease is caused by mutations in the autoimmune regulator gene (AIRE), resulting in defective AIRE protein, which is essential for selftolerance. Clinical manifestations are widely variable. Although the classic triad is composed by mucocutaneous candidiasis, hypoparathyroidism and adrenal failure, many other components may develop. Treatment is based on supplementation of the various deficiencies, and patients require regular follow-up throughout their lifespan. This article describes the case of a patient with the disease, and reviews literature data on the epidemiology, clinical course, immunogenetic aspects, diagnosis and treatment of the syndrome.

Síndrome poliglandular autoimune tipo 1 é uma rara desordem autossômica recessiva caracterizada por ataque autoimune a diversos órgãos. A doença é causada por mutações no gene AIRE (autoimmune regulator), resultando em uma proteína AIRE defeituosa, proteína esta essencial para a manutenção da autotolerância. As manifestações clínicas são extremamente variáveis. A tríade clássica é composta por candidíase mucocutânea crônica, hipoparatiroidismo e insuficiência adrenal, porém diversos outros componentes podem estar presentes. A base do tratamento é a reposição das diversas deficiências, e os pacientes devem ser acompanhados por toda a vida. Este artigo descreve o caso de uma paciente com a síndrome e apresenta uma revisão sobre a epidemiologia, quadro clínico, aspectos imunogenéticos, diagnóstico e tratamento da desordem, de acordo com a literatura publicada.