Purpose: to analyze the mutation frequency of the GNAQ/GNA11 gene in circulating tumor DNA and genotypes of the polymorphic marker C3435T of the ABCB1 gene in a large sample of patients with intraocular melanocytic neoplasms (IMN).Material and methods. In an open prospective study performed in 2015–2022, 272 IMN patients with intraocular melanocytic neoplasms aged 28 to 87 (ave. 58.3 ± 12.6), including 187 females (68.8 %) and 85 males (31.2 %), were divided into three groups depending on the nature of the tumor focus: Group I, n = 141, progressing choroidal melanomas; Group II, n = 67, stationary melanomas, and Group III, n = 64, choroidal nevi.Results. In Group I, at least one mutation in the GNAQ/GNA11 gene was detected in 134 patients (95.0 %). Of these, 35 patients (24.8 %) revealed two mutations, and 16 patients (11.3 %) had 3 mutations. In Group II, one mutation was detected in 49 patients (73.1 %), of which three patients (4.5 %) had two mutations. In Group III, one mutation in the GNAQ/GNA11 gene was detected in 13 patients (20.3 %). When comparing the overall frequency of mutations in the GNAQ/GNA11 genes in Groups I and II, significant differences were obtained (OR = 7.03 (2.77 to 17.86), F = 0.000015, ξ2 = 20.6), with Group I having mutations identified in 95 % of cases and Group II, in 73.1 %. Significant differences were also obtained when comparing the frequency of the studied mutations in Groups I and III (OR = 75.1 (28.36 to 198.86), F = 0.0000001, ξ2 = 121.15) with a frequency of 20.3 % in Group III. The frequency of mutations in the GNAQ/GNA11 genes was significantly higher in Group II than in Group III (OR = 10.68 (4.73 to 24.1), F = 0.0000001, ξ2 = 36.64). The frequencies of heterozygous mutations in all 4 exons were significantly higher in Group I than in Groups II and III, except for the GNAQ183 gene when comparing Groups I and II. Heterozygous mutations in all 4 exons were significantly more frequent in Group II than in Group III. Homozygous mutations were found only in Group I patients, but, in spite of this, no significant differences were detected when comparing them with other groups. The frequency of genotype CC of the polymorphic marker C3435T of ABCB1 gene was significantly lower in Group I as compared to Group II, whilst the frequency of genotype CT was significantly higher than in group II.Conclusion. The general analysis of molecular genetic studies of 272 patients with intraocular melanocytic neoplasms showed a direct correlation between the frequency of detection of mutations in genes and the size and source of the tumor. The obtained results substantiate both screening of patients from risk groups and differentiation of patients depending on the size and source of the tumor.
