This paper presents a clinical case of the mixed connective tissue disease in a girl, including in debut the symptoms of juvenile rheumatoid arthritis, in the future expanded clinic of systemic lupus erythematosus and dermatomyositis, with high activity of the autoimmune process till the development of macrophage activation syndrome. The purpose of the authors to draw attention of colleagues to the complexity of the diagnosis in the absence of mandatory laboratory markers of disease antibodies to ribonucleoprotein.

The aim of the research. To study the frequency of polymorphic allelic variants of the gene connexin 40 (CX40) in children with idiopathic sick sinus syndrome. Materials and Methods. A molecular genetic study of 50 children with idiopathic sick sinus syndrome (SSS) and in 102 healthy children of the control group was conducted. Results. Association SSS with Cx40 gene polymorphisms was established. In children with idiopathic SSS was revealed statistically the significant predominance of homozygous genotype -44AA. Conclusion. The genotype -44AA gene Cx40 defines a high relative risk of developing the disorders of impulse conduction in the formation of the combined pathology of the cardiac conducting system.

In this paper is presented an algorithm of differential diagnosis for causes of four-year-old girl’s long fever. Infectious diseases, debut of autoinflammation, neoplastic, lymphoproliferation illnesses, hemoblastosis were excluded by diagnostic search. Computer tomography and immunofermental analysis played a determinant role in diagnosis of helminthiasis.

The data of studies of lipid metabolism, endothelial function and hemostasis in 129 children with different various activity of chronic juvenile arthritis (CJA) have been presented. The rise of the degree of activity of the process was established to be accompanied with an increase in the severity of endothelial dysfunction, thrombogenic potential, the number of blebbing leukocytes in the peripheral blood, vascular endothelial growth factor (VEGF). In cases with the high activity of the process and continuously progressing CJA unfavorable factors of the endothelial condition are highdensity lipoprotein level and VEGF decrease, characterizing the disturbance of the endothelial repair processes.

The girl with severe pulmonary arterial hypertension and necrosis of the distal phalanx of the second finger of right hand on the background of periarteritis nodosa is described. The peculiarity of this case is the presence of a carriership of the methylenetetrahydrofolate reductase gene mutation and coagulant factors that determine susceptibility to thrombosis in the child. A stepped course of differential diagnosis and results of pathogenetic therapy with bosentan an inhibitor of endothelin-1 receptor, which defined the stabilization process, have been considered.