Monogenic forms of inherited disorders of connective tissue and multifactorial connective tissue dysplasia are quite common in the population. Despite the high level of modern molecular techniques, clarification of their nosology of today, still remains a distant prospect. These difficulties are due to a large variety of mutations expressed their phenotypic polymorphism clinical manifestations, the considerable size of the genes encoding the proteins of the connective tissue, a rarity major mutations and low availability of molecular genetic research methods to verify the diagnosis. Clarification of the incidence of connective tissue displasia hindered by the lack of common terminology, standardized diagnostic criteria, as well as the practical inaccessibility of modern molecular genetic techniques to identify this heterogeneous pathology. The first part is devoted to the recommendations of the pediatric aspects of diagnosis of hereditary disorders of connective tissue with agreed international diagnostic criteria, and connective tissue displasia. Details covered principles of tactics and treatment of patients with this pathology. The attention of researchers aimed at studying the problems of the modifying effect of this disease on the nature of the flow of almost all diseases. This proves the feasibility of making additions to the standards of inspection and management of these patients with the mandatory inclusion of a comprehensive treatment of the underlying disease additional treatment and rehabilitation, correcting disorders caused by comorbidities.

In October 2014 in Moscow at the XIII Russian Congress “Innovative Technologies in Pediatrics and Pediatric Surgery” was adopted the first part of the Russian recommendations “Congenital and multifactorial hereditary connective tissue disorders in children. Diagnostic algorithms. Tactics of treatment”. Multifactorial connective tissue dysplasia have a high prevalence in the population. We present the second part of the draft Guidelines dealing with multiple organ disorders in the connective tissue dysplasia. Despite the high level of modern molecular techniques, clarification of their nosology remains a distant prospect. Figuring out the incidence of connective tissue dysplasia hindered by the lack of common terminology, standardized diagnostic criteria, as well as the practical inaccessibility of modern molecular genetic techniques to identify the disease. In the first part of the Guidelines we could not find a place for all aspects of this complex issue, which bears an interdisciplinary approach. Later it was planned to develop recommendations for doctors of various specialties. During writing the second part it was taken into account the specialists and research teams from St Petersburg, Moscow, Tver, Omsk, Novosibirsk, Ivanovo, Chelyabinsk, Izhevsk, Orenburg, Smolensk, Petrozavodsk, Nalchik, Barnaul, Saratov, Rostov-on-Don, Voronezh, Stavropol, Yaroslavl. The core of the group works in active collaboration since 2008. The draft of the second part of the recommendation characterized especially multifactorial connective tissue dysplasia in infants, multiple organ disorders of the cardiovascular, respiratory, urinary system, gastrointestinal tract, hemostasis, nervous, musculoskeletal, upper respiratory tract and maxillodental apparatus. It sets out the course and tactics of various diseases with concurrent connective tissue dysplasia.

Ehlers-Danlos syndrome (EDS) is a heterogeneous group of monogenic diseases caused by a violation of collagen metabolism, the structure and function of myomatrix and the synthesis of proteoglycans. This pathology is characteri zed by hyperelasticity of the skin, subcutaneous globules, overextension of the joints, tissue vulnerability and hemorrhagic syndrome. EDS is one of the seven hereditary connective tissue disorders for which international diagnostic criteria are met. More than 30 years ago, the so-called Berlin nosology of hereditary connective tissue disorders was first compiled and approved (1986). For a long time, doctors used the “Villefranche Nosology” classification of EDS, adopted in 1998 and divided the disease into 6 types. The new criteria were published by the International Committee of Experts in 2017. In the clinical classification of EDS, 13 types with different inheritance, clinical features and biochemical defects are described. In most cases, it is inherited by an autosomal dominant type. True prevalence is unknown due to the complexity of verification and a large number of light forms, the frequency of diagnosed cases is 1 : 5000 births, severe forms are rare (1 : 100 000). Diagnosis of this syndromeis also based on the diagnostic criteria of the international classification. The lecture presents new data on classification diagnostic criteria of EDS, polymorphism of the clinical picture, genetic heterogeneity, the main principles of treatment of the disease. The new classification criteria take into account, in the main, the features of the clinical picture, they did not simplify the diagnosis, but they increased the specificity and increased the significance of the clinical and anamnestic features. The scope of the examination is determined by the presence of leading clinical signs. The genealogical examination and molecular genetic methods of diagnostics are of great importance.

Во второй части проекта Российских рекомендаций, принятых на Х Национальном форуме с международным участием «Здоровье детей: профилактика и терапия социально значимых заболеваний» 11 мая 2016 года в Санкт-Петербурге, представлены данные об особенностях диагностики и лечения проявлений дисплазии соединительной ткани в детской кардиологии, нефрологии, гастроэнтерологии, пульмонологии, гематологии, ортопедии и в других разделах педиатрии. Ключевые слова: соединительная ткань, наследственные нарушения, дети The second part of the draft of the Russian Recommendations adopted at X National Forum with international participation «Children's health: prevention and treatment of socially significant diseases», May 11, 2016 in St. Petersburg, presents the data on the diagnostic features and treatment of the manifestations of connective tissue dysplasia in pediatric cardiology, nephrology, gastroenterology, pulmonology, hematology, orthopedics and in other sections of pediatrics.

The morbidity of the new coronavirus infection (COVID-19) in the Russian Armed Forces is decreasing thanks to the sanitary and preventive anti-epidemic measures, the most effective of which is mass vaccination. The purpose of this research was to study the peculiarities of the formation of herd immunity among adolescent students of the Russian Ministry of Defense (MoD) colleges against the background of the COVID-19 epidemic. Materials and methods of the research: according to the epidemic indications, a two-stage seroepidemiological multicenter prospective study of herd immunity to SARS-CoV-2 was carried out in Dec. 2021 - May 2022, against the background of vaccination, among adolescent students of the Russian Defense Ministry colleges. 515 adolescents aged 11 to 17 years old (median age 13 [12; 15] years old) from the two Russian MoD schools located in the city of Saint Petersburg, of which 292 (57%) girls and 223 (43%) boys, were involved in the study. The adolescents were divided into groups based on gender and previous COVID-19 illness e.g., those who already had COVID-19 and those who had not prior to the study. In the second stage of the study the number of samples from boys and girls decreased by 74.3% and 34.4%, respectively, due to the lack of parents’ consent to the vaccination. The assessment of the immunity intensity was carried out using the Anti‐SARS‐CoV‐2 IgG levels in blood serum by enzyme-linked immunosorbent assay (ELISA). Results: the initially high levels of seroprevalence to SARS-CoV-2 were established among both girls and boys (90.4% and 91.5%, respectively, p=0.09) that indicated a latent course of the epidemic process in the studied groups of teenagers. In adolescent girls and boys vaccinated against the background of a previous COVID-19 illness, the combined immunity is formed in 62.3% and 68.1%, respectively (p=0.11). Conclusion: the epidemic process of COVID-19 tends to be latent in organized adolescent groups, being realized in inapparent forms of the infection. Those adolescents who’ve been vaccinated after COVID-19 illness develop the immunity with positive seroconversion dynamics.