Active spread of β‐thalassemia beyond the thalassemia belt: A study on a Russian population

• Published in: Clinical genetics 2025-01, Vol.107 (1), p.23-33
• Main Authors: Shchemeleva, Ekaterina, Salomashkina, Valentina V., Selivanova, Daria, Tsvetaeva, Nina, Melikyan, Anait, Doronina, Liliya, Surin, Vadim L.
• Format: Article
• Language: English
• Subjects: beta-Globins - genetics; beta-Thalassemia - diagnosis; beta-Thalassemia - epidemiology; beta-Thalassemia - genetics; Blood diseases; Caucasus; Ethnicity - genetics; Female; Genetic Variation; Genetics, Population; Human Migration; Humans; Male; migration; Minority & ethnic groups; mutation spectrum; novel mutation; Population studies; Russia - epidemiology; Thalassemia; thalassemia belt; β‐thalassemia
• ISSN: 0009-9163; 1399-0004; 1399-0004
• DOI: 10.1111/cge.14606

β‐Thalassemia is a disease traditionally associated with thalassemia belt countries. Nonetheless, as global migration intensifies, β‐thalassemia–causing variants spread far from their origin. We investigated this process to detect some patterns underlying its course. We analyzed β‐thalassemia–causing variants and the origin of 676 unrelated participants in Moscow, the largest city of Russia, far away from the thalassemia belt. Our analyses revealed that modern Russia has one of the broadest spectra of thalassemia‐causing variants: 46 different variants, including two novel β0 variants. Only a small proportion of the reported pathogenic variants likely originated in the resident subpopulation. Almost half of the variants that supposedly had emerged outside the Russian borders have already been assimilated by (were found in) the resident subpopulation. The primary modern source of immigration transferring thalassemia to a nonthalassemic part of Russia is the Caucasus region. We also found traces of ancient migration flows from non‐Caucasus countries. Our data indicate that β‐thalassemia–causing variants are actively spilling over into resident populations of countries outside thalassemia belt regions. Therefore, viewing thalassemia as a disease exclusive to specific ethnic groups creates a mind trap that can complicate the diagnosis. Our study represents the first comprehensive 20‐year investigation of the spectrum of pathogenic β‐thalassemia variants in a Russian population and the influence of modern and historical migration processes on this spectrum.