Active spread of ß-thalassemia beyond the thalassemia belt: A study on a Russian population.

ß-Thalassemia is a disease traditionally associated with thalassemia belt countries. Nonetheless, as global migration intensifies, ß-thalassemia-causing variants spread far from their origin. We investigated this process to detect some patterns underlying its course. We analyzed ß-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 ß0 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 ß-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.

Molecular Genetic Analysis of Russian Patients with Coagulation Factor FVII Deficiency.

Coagulation factor VII (proconvertin) is one of the proteins starting the blood coagulation cascade. Plasma FVII concentration is regulated by different factors. A low level of FVII could also be a result of FVII deficiency (MIM# 227500), the rare autosomal recessive inherited disease caused by pathogenic variants in the F7 gene. The aim of this study was to describe a mutation spectrum of the F7 gene and genotype-phenotype relationship in patients with FVII deficiency in Russia for the first time. We studied the primary structure of the F7 gene of 54 unrelated patients with FVII deficiency by direct Sanger sequencing. Pathogenic variants in the F7 gene were detected in 37 (68.5%) of them. We identified 24 different mutations located mostly in the serine protease domain. Five pathogenic variants had never been reported before. A major mutation in the Russian population was c.1391delC (p. Pro464Hisfs*32), linked with rs36209567 and rs6046 functional polymorphisms, that is widely distributed in East Europe. As in other countries, the F7 genotypes poorly correlated with the severity of clinical manifestations but were quite well associated with FVII levels. Minor alleles of functional polymorphisms rs510335, rs5742910, rs561241, rs36209567, and rs6046 could also participate in the F7 genotype and influence FVII levels.