Maria Beatriz da Fonte Kohek

No evidence of the inactivating mutation (C566T) in the follicle-stimulating hormone receptor gene in Brazilian women with premature ovarian failure

OBJECTIVE To investigate the presence of FSH receptor gene mutations in women with premature ovarian failure (POF). DESIGN Clinical and molecular studies. SETTING Research laboratory in a university setting. PATIENT(S) Fifteen 46,XX women with POF and 42 normal fertile controls. INTERVENTION(S) Exon 7 was amplified and digested with BsmI to screen for the previously described inactivating mutation C566T. Exon 10 was screened for mutations by denaturing gradient gel electrophoresis and direct sequencing. MAIN OUTCOME MEASURE(S) Polymerase chain reaction followed by restriction enzyme analysis, denaturing gradient gel electrophoresis, and direct sequencing. RESULT(S) No inactivating mutations were identified in exons 7 and 10 of the FSH receptor gene in women with familial or sporadic POF. Exon 10 had two polymorphisms, G919A and G2039A, whose allelic frequencies were 46.7% and 56.6%, respectively, in women with POF. The allelic frequency of both polymorphisms was 59.5% in normal fertile controls. CONCLUSION(S) No inactivating mutations in exons 7 and 10 of the FSH receptor gene were identified in Brazilian women with POF. A high frequency of two polymorphisms that are in linkage disequilibrium was found in exon 10 of this gene.

No evidence of somatic activating mutations on gonadotropin receptor genes in sex cord stromal tumors

OBJECTIVE To search for somatic activating mutations of gonadotropin receptor (FSH-R and LH/chorionic gonadotropin receptor [CG-R]) genes as a cause of sex cord stromal tumors. DESIGN Molecular studies in human tissue. SETTING University hospital. SPECIMEN(S): Eight granulosa cell tumors collected from paraffin-embedded tissue, eight Leydig cell tumors, and three thecomas collected from fresh-frozen or paraffin-embedded tissue. INTERVENTION(S) Tumor samples were used for DNA extraction. The entire exon 11 of the LH/CG-R gene and a hot spot for gonadotropin receptor activating mutations on exon 10 of the FSH-R gene were amplified by polymerase chain reaction. The former was analyzed by denaturing gradient gel electrophoresis and automatic direct sequencing, and the latter by automatic direct sequencing. MAIN OUTCOME MEASURE(S) Results of denaturing gradient gel electrophoresis and automatic direct sequencing. RESULT(S) No somatic activating mutation was detected in exon 11 of the LH/CG-R gene in eight Leydig cell tumors and three thecomas. In addition, no mutations were detected in eight granulosa cell tumors in the hot spot for activating mutations in exon 10 of the FSH-R gene. CONCLUSION(S) Somatic activating mutations of gonadotropin receptors seem to play no relevant role in the development of sex cord stromal tumors.

Mutation analysis of the follicle-stimulating hormone receptor gene in girls with gonadotropin-independent precocious puberty resulting from autonomous cystic ovaries.

OBJECTIVE To search for germline activating mutations of the FSH receptor in girls with gonadotropin-independent precocious puberty. DESIGN Molecular studies in human tissue. SETTING Four girls with polycystic ovaries and gonadotropin-independent isosexual precocious puberty without clinical and molecular features of McCune-Albright syndrome. INTERVENTION(S) Peripheral blood was used for DNA extraction. The alpha-subunit of the Gs gene and the entire exon 10 of FSH receptor gene were amplified by polymerase chain reaction (PCR). Gs-alpha mutations characteristic of McCune-Albright syndrome were excluded by denaturating gradient gel electrophoresis (DGGE) and allele-specific PCR. Exon 10 of the FSH receptor gene was analyzed by DGGE and direct sequencing. MAIN OUTCOME MEASURE(S) Results of DGGE and direct sequencing. RESULT(S) No germline activating mutations were detected in exon 10 of our patients. Instead, two previously described polymorphisms were found, leading to the substitution of alanine for threonine at position 307 and of serine for asparagine at position 680 of the FSH receptor molecule. CONCLUSION(S) Germline activating mutations were not found in exon 10 of the FSHR gene in any of our patients. Further studies, preferably in ovarian tissue, will be required to exclude the presence of somatic activating mutations of the FSH receptor in these patients.

Effects of EDTA and Sodium Citrate on hormone measurements by fluorometric (FIA) and immunofluorometric (IFMA) methods

BackgroundMeasurements of hormonal concentrations by immunoassays using fluorescent tracer substance (Eu3+) are susceptible to the action of chemical agents that may cause alterations in its original structure. Our goal was to verify the effect of two types of anticoagulants in the hormone assays performed by fluorometric (FIA) or immunofluorometric (IFMA) methods.MethodsBlood samples were obtained from 30 outpatients and were drawn in EDTA, sodium citrate, and serum separation Vacutainer®Blood Collection Tubes. Samples were analyzed in automatized equipment AutoDelfia™ (Perkin Elmer Brazil, Wallac, Finland) for the following hormones: Luteinizing hormone (LH), Follicle stimulating homone (FSH), prolactin (PRL), growth hormone (GH), Sex hormone binding globulin (SHBG), thyroid stimulating hormone (TSH), insulin, C peptide, total T3, total T4, free T4, estradiol, progesterone, testosterone, and cortisol. Statistical analysis was carried out by Kruskal-Wallis method and Dunns test.ResultsNo significant differences were seen between samples for LH, FSH, PRL and free T4. Results from GH, TSH, insulin, C peptide, SHBG, total T3, total T4, estradiol, testosterone, cortisol, and progesterone were significant different between serum and EDTA-treated samples groups. Differences were also identified between serum and sodium citrate-treated samples in the analysis for TSH, insulin, total T3, estradiol, testosterone and progesterone.ConclusionsWe conclude that the hormonal analysis carried through by FIA or IFMA are susceptible to the effects of anticoagulants in the biological material collected that vary depending on the type of assay.

An Inhibin B and Estrogen-Secreting Adrenocortical Carcinoma Leading to Selective FSH Suppression

Objective: Hormone-secreting adrenocortical tumors are frequently associated with endocrine syndromes. We describe a 30-year-old man who had abdominal pain, a nodule in the right breast and loss of libido. Abdominal magnetic resonance imaging revealed a very large tumor in the right adrenal gland. Methods: Hormonal profile disclosed increased levels of estradiol and slightly low testosterone levels. The basal and stimulated LH levels were normal, whereas basal and stimulated FSH levels were totally suppressed. Cortisol and adrenal androgen levels were normal. The unusual finding of selective FSH suppression suggested secretion of inhibin B by the adrenocortical tumor. A very high level of serum inhibin B (405 pg/ml) was demonstrated by ELISA assay. Right adrenalectomy and nephrectomy were performed and the tumor was classified as a malignant tumor (Weiss score: 7.0) and unilateral mastectomy disclosed a lipoma. Results: One week after surgery, a GnRH-stimulation test disclosed normal basal and stimulated FSH levels and low levels of inhibin B and estradiol. Immunohistochemical analysis with anti-B-inhibin antibody revealed intense staining in the adrenocortical tumor cells. One month after surgery, an abdominal magnetic resonance imaging revealed a local recurrence of the tumor and a second surgery was performed with partial resection of the tumor and the patient died 1 year after the first surgery. Conclusion: We herein report the first inhibin B and estradiol-secreting adrenocortical carcinoma. The unusual selective inhibition of FSH secretion should be considered a valuable hormonal finding for the diagnosis of inhibin B-secreting adrenocortical tumors.

Clinical and molecular analysis of human reproductive disorders in Brazilian patients

Several genes that influence the development and function of the hypothalamic-pituitary-gonadal-axis (HPG) have been identified. These genes encode an array of transcription factors, matrix proteins, hormones, receptors, and enzymes that are expressed at multiple levels of the HPG. We report the experience of a single Endocrinology Unit in the identification and characterization of naturally occurring mutations in families affected by HPG disorders, including forms of precocious puberty, hypogonadism and abnormal sexual development due to impaired gonadotropin function. Eight distinct genes implicated in HPG function were studied: KAL, SF1, DAX1, GnRH, GnRHR, FSHbeta, FSHR, and LHR. Most mutations identified in our cohort are described for the first time in literature. New mutations in SF1, DAX1 and GnRHR genes were identified in three Brazilian patients with hypogonadism. Eight boys with luteinizing hormone- (LH) independent precocious puberty due to testotoxicosis were studied, and all have their LH receptor (LHR) defects elucidated. Among the identified LHR molecular defects, three were new activating mutations. In addition, these mutations were frequently associated with new clinical and hormonal aspects, contributing significantly to the knowledge of the molecular basis of reproductive disorders. In conclusion, the naturally occurring genetic mutations described in the Brazilian families studied provide important insights into the regulation of the HPG.

O papel dos receptores das gonadotrofinas na reprodução feminina

The critical actions of the pituitary gonadotropins in the sexual reproductive life in both sexes depend on the structural and functional integrity of their respective receptors. Gonadotropin receptors located within the cytoplasmic membrane are members of the G-protein coupled receptor superfamily which displays a common structure composed by a large extracellular region and seven-transmembrane helices. The recent identification of natural-occurring inactivating and activating mutations in the LH and FSH receptor genes has contributed to our better understanding of gonadal disorders. In the present study, we reviewed the molecular aspects of the defects of these genes and their phenotypic implications in females. In women with homozygous inactivating mutations in these genes, frequent symptoms, such as menstrual irregularities (secondary amenorrhea or oligoamenorrhea) and infertility can drive the endocrinologist to establish the final diagnosis of LH or FSH ovarian resistance.