Seborrheic dermatitis (SD) is a chronic, relapsing skin disease manifested by inflammation and desquamation in areas where sebaceous glands accumulate. SD is characterized by changes in the qualitative composition and quantity of sebum produced, disruption of the epidermal barrier, and a defective immune response to skin colonization by Malassezia spp. It is important to note that SD is a multifactorial disease. By understanding the genetics of the disease, personal approach to selecting an individual treatment plan based on its key aspects of development and course can be made, thereby increasing the patient’s quality of life and minimizing drug exposure. The genetics of SD and other inflammatory diseases with a chronic relapsing course have not been sufficiently studied and are currently of particular interest to scientists. The materials presented in this review suggest that one of the reasons for the development of SD in adults may be carriage of the genotype C/C variant of the nucleotide sequence at position -13910 of the MCM6 gene (rs4988235). However, there are no studies that show a direct association of SD with the rs4988235 C/C genotype of the MCM6 gene. The article shows a direct association between chronic relapsing SD in a patient with poor response to standard treatment methods with the C/C genotype of the nucleotide sequence of the MCM6 gene at position -13910. To confirm the connection between the variant of the C/C nucleotide sequence at position -13910 of the gene and SD, additional studies of patients with a newly diagnosed SD are required.
A clinical case of a patient with a prolonged course of SD, with a minimal response to standard therapy against the background of a variant of the C/C nucleotide sequence at position -13910 of the MSM6 gene (rs4988235), who achieved stable remission of the disease with nutritional correction is described.

Keywords: MSM6, personalized nutrition, adult nutrition, rs4988235, seborrheic dermatitis, lactase, lactose