Background. The main component of the dermis is collagen, an organic compound of a group of fibrillar proteins. The papillary dermis is formed by smaller bundles of collagen fibers with predominance of fibroblasts, fibrocytes, mast cells, T-lymphocytes, while the reticular dermis is characterized by larger bundles that form a characteristic network providing strength to the skin, hence the name of the layer – reticular. In young skin, collagen type I (80%) and III (15%) fibers with ratio 6:1 predominate. With age, there is a decrease in the content of type I collagen, which leads to a thickening and disruption of the bonds between the fibers. Most cosmetic procedures are aimed at collagen stimulation; before stimulating collagen production, however, it is necessary to provide cells with essential amino acids for the synthesis of collagen types I and III and direct inflammation in a controlled way. Amino acid replacement therapy (AART) is a fundamental step in preparing patients for invasive procedures. In this article, for the first time, for the diagnosis of undifferentiated connective tissue dysplasia (UCTD) of patients, the «UCTD diagnostic genetic panel» developed by the authors and the questionnaire for UCTD screening in cosmetology practice were used.
Objective. Improvement of the effectiveness of skin correction protocols during collagen-stimulating procedures, development of screening questionnaire for the detection of UCTD in cosmetology practice, testing of a genetic panel to identify signs of UCTD during collagen stimulation, development of correction protocols based on the data obtained.
Methods. The study included three patients who received a complex correction protocol based on polylactic acid and AART.
Results. Due to the combined use of the UCTD screening questionnaire in cosmetology practice and genetic panels, the authors managed to achieve pronounced results when using collagen-stimulating methods in patients and prevent possible complications.
Conclusion. General approaches to the diagnosis of UCTD should be based on a comprehensive analysis of the results of clinical and laboratory tests. The capabilities of genetic panels in combination with a screening questionnaire make it possible to achieve pronounced results and avoid possible complications.

Keywords: amino acid replacement therapy, polylactic acid, AestheFill, undifferentiated connective tissue dysplasia, collagen