The melanocortin 1 receptor is a Gs protein-coupled receptor implicated in melanogenesis regulation. The receptor gene is highly polymorphic, which accounts for the association of several of its single-nucleotide polymorphisms (SNPs) with an increased risk of melanoma. The present study aimed to evaluate the distribution of melanocortin 1 receptor gene variants R151C, R160W, and D294H within the Russian population of Eastern Siberia and its association with melanoma development. Melanoma patients (n=95) admitted to Krasnoyarsk Territorial Oncological Center and healthy controls (n=334) were enrolled in the study. A clinical examination of patients was performed to evaluate the phenotypic features of melanoma patients. SNPs were analyzed by real-time PCR. Clinical examination indicated a more frequent occurrence of fair skin type, blue eyes, blonde and red hair, and more frequent localization of freckles on the neck, trunk, and extremities in the melanoma group of patients. The R151C melanocortin 1 receptor gene variant was found in 18% of melanoma patients and associated with an increased likelihood of melanoma development (odds ratio=6.4; 95% confidence interval: 2.8–14.3; P=0.0001). The two remaining variant alleles of the melanocortin 1 receptor gene occurred with low frequency both in controls and in the melanoma group. The R160W SNP was identified neither in controls nor in melanoma patients. The D294H heterozygous variant was observed in 0.3% of individuals in the control group and in 1.1% of the patients in the melanoma group. Such an asymmetric distribution of the melanocortin 1 receptor within red hair color genotypes in the population under study compared with other populations may be because of Russian genetic homogeneity. Carriers of the mutant R151C allele should exercise caution in terms of exposure to the sun to avoid the risk of melanoma development.

Yellow nail syndrome is an extremely rare syndrome, mainly in people over 50 years of age, occurring both systemically and in isolation and requiring the most careful collection of anamnesis, since this condition has a close relationship with respiratory diseases, malignant neoplasms of internal organs and rheumatoid arthritis. Moreover, this rare disease is not sufficiently studied to fully understand its pathogenesis and effective treatment. Patients pay attention to the yellow color of the nails, associated with the deposition of melanin, bile pigments and hemosiderin in the submarginal space, slowing down the growth and thickening of the nail. It should be noted that the change in the nail plates can be observed long before the other clinical manifestations of this syndrome are detected, and probably this can in some cases serve as a harbinger of incipient changes in the lung tissue, neoplasms and changes in the lymphatic vessels. In this regard, it is extremely important to clearly differentiate this condition and refer patients to related specialists for verification of the diagnosis and further treatment.

Linear IgA-dependent bullous dermatosis is a rare subepidermal bladderworm disease that occurs in both adults and children. The pathogenesis of the disease, regardless of age, is the same, where the basis is the autoimmune response to antigens of the basal membrane zones of the skin, the clinical picture in childhood differs from the manifestations at an older age, having a clear picture and localization of manifestations. The causes of the onset of the disease in older people are most often associated with taking medications, manifested as a side effect of the therapy being taken, cancer, and in children, both an acquired character and a genetic predisposition are responsible for the manifestation of linear IgA-dependent bullous dermatosis. The diagnosis can be confirmed by histological and immunofluorescence analysis.

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