[Gonadotropin-dependent precocious puberty: genetic and clinical characteristics].

BACKGROUND: In 90% cases of girls and 25-60% cases of boys the cause of gonadotropin-dependent precocious puberty (PP) is unclear. Up to 25-27.5% of gonadotropin-dependent PP cases are monogenic and suggest autosomal-dominant inheritance with incomplete sex-dependent penetrance. To date, mutations in genes KISS1, KISS1R, MKRN3, DLK1 have been described as causal variants leading to precocious hypothalamic-pituitary axis activation in childhood. Genetic testing in patients with hereditary forms of PP can expand our knowledge of underlying molecular mechanisms of the disease and it  is also necessary for genetic counselling. AIM: To study clinical features and genetic characteristics of patients with idiopathic gonadotropin-dependent precocious puberty. MATERIALS AND METHODS: A group of patients with idiopathic gonadotropin-dependent precocious puberty and positive family history (early or precocious puberty) was examined. Laboratory and instrumental diagnostic tests, full-exome sequencing (NGS, next-generation sequencing) were provided for all patients. RESULTS: The study included 30 patients (29 girls, 1 boy) with idiopathic gonadotropin-dependent precocious puberty. The median of patients age at the time of the examination was 7,2 years [6,5; 7,7]. Positive family history presented in all cases: in 40% of patients on father's side, in 37% - on mother's side, in 23% of patients PP was diagnosed in siblings. The fullexome sequencing was conducted to 21 patients: in 61,9% of cases (95% CI [40;79]) nucleotide variants were identified   in genes, associated with gonadotropin-dependent precocious puberty. MKRN3 gene defect was detected in most cases (77% cases (95% CI [49; 92]), which consistent with international data on its highest prevalence in the monogenic forms of PP. In 23% of cases (95% CI [7; 50]) nucleotide variants were identified in other candidate genes associated with neuroontogenesis and neuroendocrine regulation mechanisms of hypothalamic-pituitary axis. CONCLUSION: Our study confirms that detailed family history data in children with PP provides a rational approach to molecular-genetic testing. Data of inheritance pattern and clinical manifestations will simplify the diagnosis of hereditary forms of disease and enhance genetic counselling of families, followed by timely examination and administration of pathogenetic therapy.

[The clinical case of IgG4-related thyroid disease in a 6-year-old child].

IgG4-related disease is a rare chronic pathology manifested by lymphoplasmacytic infiltration of one or more organs, the formation of storiform fibrosis, tissue edema, and an increase of IgG4 in the blood. This disease was singled out as an independent nosological unit only in 2001. The incidence is less than 1 in 100,000 people per year. Almost any organ can be affected in IgG4-related disease. The association of Riedel's thyroiditis with IgG4 was established in 2010. Riedel's thyroiditis is an extremely rare inflammatory disease of the thyroid gland, which diagnosis is complicated by an atypical course and the absence of characteristic symptoms. Less than 300 clinical cases of the disease have been described in the world, only two from them were in children. This article presents a clinical case of a 6-year-old boy with Riedel's thyroiditis.

[Clinical guidelines «Precocious puberty¼].

The precocious puberty is an urgent problem of pediatric endocrinology characterized by clinical and pathogenetic heterogeneity. The appearance of secondary sex characteristics before the age of 8 years in girls and 9 years in boys requires timely diagnosis and the appointment of pathogenetically justified treatment in order to achieve the target indicators of final growth and prevent social deprivation. The developed clinical guidelines are the main working tool of the practitioner. They briefly and structurally present the main information about the epidemiology and modern classification of рrecocious puberty, methods of its diagnosis and treatment based on the principles of evidence-based medicine.

[Clinical and molecular genetic features of 3 family cases of the central precocious puberty, due to MKRN3 gene defects].

Gonadotropin-dependent precocious puberty (central) is a condition resulting from the early (up to 8 years in girls and 9 years in boys) reactivation of the hypothalamic-pituitary-gonadal axis. An increase in the secretion of sex steroids by the gonads in this form is a consequence of the stimulation of the sex glands by gonadotropic hormones of the pituitary gland. In the absence of central nervous system abnormalities, CPP is classified as idiopathic and as familial in some cases, emphasizing the genetic origin of this disorder. Loss-of-function mutations in Makorin Ring Finger Protein 3 (MKRN3) are the most common identified genetic cause of central precocious puberty compared to sporadic cases. In the present study we performed the first descrition of 3 family cases of central precocious puberty duo to novel MKRN3 gene mutation detected by NGS in the Russian Federation.

[Clinical and molecular genetic features of cases of isolated hypogonadotropic hypogonadism, associated with defects in GNRHR genes].

Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder characterised by lack of pubertal development and infertility, due to deficient production, secretion or action of gonadotropin-releasing hormone (GnRH). Clinically, there are variants of CHH with hypo-/anosmia (Kalman syndrome) and normosmic hypogonadotropic hypogonadism. Given a  growing list of gene mutations accounting for CHH, the application of next generation sequencing (NGS) comprises an excellent molecular diagnostic approach because it enables the simultaneous evaluation of many genes. Biallelic mutations in GNRHR gene lead to the development of hypogonadotropic hypogonadism with normosmia. In this paper, we describe 16 patients with proven GnRH resistance and estimate the frequency of pathogenic variants in the GNRHR gene in the Russian population.

[Nodular toxic goiter in children: clinical features, morphological variants].

BACKGROUND: Toxic nodular goiter (TNG) is a rare disease in which the cause of hyperthyroidism is the presence of a node or nodes that autonomously secrete thyroid hormones. With children and adolescents this condition is extremely rare - in 5-7.5% of all cases of nodular goiter. Therapy of toxic nodular goiter is aimed at relieving the symptoms of hyperthyroidism taking into account the malignant potential of the nodular formation. In the available literature, there are no data on the clinical course, comparative results of cytological and histological data in patients with toxic nodular goiter, which debuted in their childhood. AIM: Analysis of the features of the clinical course, comparison of the results of cytological and histological studies of toxic nodular goiter in children and adolescents. MATERIALS AND METHODS: A retrospective, single-center study of 21 patients with single-nodular toxic goiter, hospitalized at the Endocrinology Research Centre in the period from January 2016 to December 2019. RESULTS: The mean age at the time of the survey was 13.9 years. Thirteen patients (65%) had manifest thyrotoxicosis, and seven (35%) had subclinical hyperthyroidism. More than half of children - 57.1% (n = 12) did not receive thyreostatic therapy. The cytological picture in 11 patients (61.1%) corresponded to benign changes (nodular colloid goiter or adenomatous goiter) - Bethesda II, in 4 patients - follicular tumor - Bethesda IV, in 4 children the study was not informative. 19 patients (90.5%) underwent surgical treatment (hemithyroidectomy). According to the results of histological examination, follicular adenoma was found in 44.4% of children with nodular toxic goiter with benign results of TAB (Bethesda II) and was found in 50% with revealing follicular neoplasia (Bethesda IV). CONCLUSION: For the first time in the Russian Federation was carried out a comparative analysis of the characteristics of cytological and histological studies in children with toxic nodular goiter. It is significant that only in 10.5% (n=2) cytological and morphological results were consistent. The choice of radical treatment tactics should take into account the high frequency of mismatches between histological and morphological studies.

[Alternative Variants of Pax4 Human Transcription Factor: Comparative Transcriptional Activity].

MODY is a group of genetically and clinically heterogeneous forms of diabetes characterized by auto-somal dominant inheritance and is subdivided in 13 subtypes dependent on the gene involved. The subtype MODY9 is a very rare form caused by mutations in the gene encoding the PAX4 transcription factor which is engaged in differentiation of pancreatic beta-cells. PAX4 contains two DNA-binding domains-Paired and Homeo. Expression of the human PAX4 gene is tissue-specific. The alternatively spliced mRNA variants encode for protein isoforms which differ within their N- and C-terminal regions. In this study, the transcriptional activities of the human PAX4 variants, both known and new ones, were determined. The full-length PAX4 containing intact DNA-binding domains was found to have maximal activity in transient expression system of the firefly luciferase reporter gene under control of the insulin promoter in HEK293 cells. The transcriptional activity is significantly reduced in the variants lacking eight N-terminal amino acid residues and/or variants whose Homeo domain is truncated from the C-terminus. Similar data were obtained with the glucagon promoter reporter system. The aberrant PAX4 variants were shown to retain stability and nuclear localization.

[MODY2: Clinical and molecular genetic characteristics of 13 cases of the disease. The first description of MODY in Russia].

Maturity-onset diabetes of the young (MODY) is a clinically heterogenic group of diseases, with an autosomal dominant mode of inheritance and gene mutations resulting in dysfunction of pancreatic ß cells. The type of diabetes and further treatment policy can be reliably determined on the basis of the data of a molecular genetic study that confirms gene mutations. Today there are known mutations of 8 genes, of which glucokinase (GCK) gene mutation that leads to the development of MODY2 and occurs most frequently. The spread of this mutation among DM patients in our country has not been studied. The diagnosis of MODY2 was established in 13 members of 5 families with the clinical picture typical of this type. The molecular genetic study revealed 4 new and 1 earlier described mutations. The findings extend ideas on the molecular bases of MODY, which creates conditions for improving the diagnosis of this disease, genetic counseling and the development of pathogenetically founded approaches to treatment.

[Molecular genetic verification of isolated mineralocorticoid deficiency due to aldosterone synthase deficiency].

Isolated mineralocorticoid deficiency is a rare hereditary autosomal recessive disorder that is characterized by salt wasting and that has the severest manifestations in infants. This paper is the first in the Russian literature to describe cases of isolated aldosterone deficiency. In both cases, the patients were monitored and treated for misdiagnosed congenital adrenal hyperplasia; however, the permanently low level of 17-hydroxyprogesterone could put in doubt the diagnosis and suspect isolated mineralocorticoid deficiency, by keeping in mind a history of salt wasting. By using the presented cases as an example, the authors give an algorithm for the examination and differential diagnosis of this condition and other diseases that have the similar clinical picture. Aldosterone synthase deficiency in patients was verified by molecular genetic studies - there were mutations in the CYP112 gene.

Participation of the lateral geniculate body in mechanisms of brain activation.

The significance of the lateral geniculate body for nonspecific activation of the brain was elucidated in experiments on cats. It was established that when the connections of the lateral geniculate body remain intact, its stimulation elicits the usual activation of the EEG, but at higher threshold values of the current (120-190 microA) than when the mesencephalic reticular formation of the medial center of the thalamus is stimulated (50-80 microA). If only direct connections with the cortex remain, however, and the others are disrupted, the threshold for activation increases to 220-400 microA. When the lateral geniculate body is coagulated, cortical activity occurs only in response to very bright light flashes (250-1000 1x). All of this indicates that, in addition to carrying out its principal function of processing and sending the basic flow of visual impulsation to higher optical centers, the lateral geniculate body may be the source of activating transmissions sent to the cortex. Nonspecific stimulation that develops in the cortex is subsequently regulated by the cortex itself; the cortex plays a leading role in these processes.

[Participation of the lateral geniculate body in the mechanisms of brain activation]. / Uchastie naruzhnogo kolenchatogo tela v mekhanizmakh aktivatsii mozga.

In chronic experiments on cats with intact LGB, electrical stimulation of the latter (120-190 microA) caused brain activation with the same threshold as the stimulation of the mesencephalic RF or of the thalamic CM with 50-80 microA. With all but the geniculo-cortical connections of the LGB disrupted, the threshold for brain activation increased to 220-400 microA. After LGB coagulation leaving intact all optical tract connections to the superior colliculi and to the brain stem, the adequate cortical activation was only possible with very strong light flashes (250-1000 l). This suggests that the LGB participates in unspecific brain mechanisms and can induce cortical activation regulated afterwards by the cortex itself.

[Activation response to photic stimulation in normal cats and after transection of the afferent pathways of the mesencephalic reticular formation]. / Reaktsiia aktivatsii pri svetovom razdrazhenii v norme i posle pererezki afferentnykh putei mezéntsefal 'noi retikuliarnoi formatsii u koshki.

In chronic experiments on waking unrestrained cats with implanted electrodes the reaction of EEG activation to light stimulation was recorded in two sets of experiments in normal cats and in animals with transsection of brachia colliculi superioris that separated mesencephalic reticular system. The intensity of the activating reaction in the intact cats increased ith a rise in the light stimulus intensity. In the cats with brachia-colliculi superioris transsected there was no definite dependence on the stimuli intensity and the intensity of the activating reaction changed randomly. It is suggested that this irregularity is accounted for by blocking of the excitating afferent flow usually coming to the mesencephalic reticular formation through brachia and colliculi both from the visual pathways (ascending flow) and from the cortex (descending activation regulating flow).

[Analysis of photic signals by cats according to their intensity following transection of the superior quadrigeminal brachii]. / Analiz koshkoi svetovykh signalov po intensivnosti posle peresecheniia ruchek verkhnikh bugrov chetverokholmiia.

In experiments on cats trained by the motor alimentary conditioned method to discriminate photic stimuli by intensity, EEG changes were studied when differentiating signals of different biological significance before and after transection of the brachii of the superior colliculi. The normal direct proportional dependence of pronouncedness of brain electrical reactions on the complexity of stimuli analysis was disturbed after transection. The operated animals retained only the capacity for a rough differentiation by brightness, the fine gradation of EEG responses to negative signals of different fineness being lost. The disturbance of interaction between the analysing and activating brain systems after transection of the brachii may be due to both the lack of non-specific ascending tonic influences of the midbrain reticular formation on the cortex, and to the destruction of many pathways for corticofugal control of the activity of the brainstem non-specific apparatus.

[Electrical reactions in the cat brain during differentiation of photic stimuli]. / Elektricheskie reaktsii mozga koshki pri differentsirovanii svetovykh stimulov

Study of EEG responses to photic conditioned stimuli in cats has shown that the extent of brain activation depends not on the physical strength of the stimulus, but on its biological significance. The longest activation is recorded to a positive signal, even if it is the weakest flash of light. The intensity of EEG responses to negative stimuli is determined by the nearness of their physical parameters to those of the positive signal. Repeated presentation of a non-reinforced flash leads to a gradual extinction of EEG reactions. Brain activation in response to a reinforced positive signal persists unchanged even after a large number of its repetitions. The revealed properties of brain electrical reactions to stimuli of different significance accord with those previously recorded in response to acoustic stimuli. In both cases the data are in agreement with hypothesis of a central system of signal analysis, which performs the estimation of stimuli according to their biological quality.