Aim of the study was identification of genes and their polymorphisms associated with pathological tortuosity (PT) of internal carotid arteries (ICA) for elucidation of etiological causes of this anomaly taking into consideration its high prevalence and clinical significance. We invited for examination 61 families of children with previously diagnosed PT ICA and used color Doppler duplex scanning of brachiocephalic zone in examination of close relatives of a proband. Samples of venous blood were taken from a family member in whom PT ICA had been detected and the affected child. The group of patients for genotyping comprised 100 individuals with PT ICA. Control group (n=245) was formed from DNA bank on the basis of population approach. The following genetic methods of diagnosis were applied: clinico-genealogical, allele specific polymerase chain reaction, search in available data bases of PT ICA candidate genes and their polymorphisms. According to data of genealogy analysis in most cases inheritance of pathological sign of tortuous ICA was autosomal dominant (37.7%) or autosomal-recessive (39.3%). Association of A80807T polymorphism of the transcriptional factor Sp4 gene with PT ICA was established. Probability of PT ICA in A80807/A80807 homozygotes was 1.64 times higher than in carriers of 2 other genotypes (A80807/T80807 and T80807/T80807).