ERCC8 and Cockayne syndrome: In this manuscript, for the first time in the Russian Federation, we present the results of a clinical and genetic study and follow-up of a Russian cohort of patients.<h4>Materials and methods</h4> During 2 years, from 2023 to 2025, 7 patients with Cockayne syndrome (4 girls and 3 boys) aged from 3 years 11 months to 16 years 3 months were under clinical observation, of whom 3 patients were diagnosed with Cockayne syndrome type A (causative variants in ERCC8 gene) and 4 patients with type B (causative variants in ERCC6 gene).