Molecular Characteristics, Clinical and Immunologic Manifestations of 11 Children with Omenn Syndrome in East Slavs (Russia, Belarus, Ukraine)

Background Omenn syndrome [Mendelian Inheritance (OMIM 603554)] is a genetic disease of the immune system, characterized by the presence of fatal generalized severe erythroderma, lymphoadenopathy, eosinophilia and profound immunodeficiency. Objective We studied clinical and immunologic presentation of the disease manifestation among East Slavs population with genetically confirmed Omenn syndrome. Results We collected clinical and immunologic data of 11 patients (1 from Belarus, 5 – Ukraine, 5 – Russia): 6 females, 5 males. The age of Omenn syndrome manifestation varied from the 1st day of life to 1 year and 1 month, the age of diagnosis – 20 days to 1 year and 10 months. Nine out of 11 patients had classic immunologic phenotype T(+/−)B-NK+, 1 pt had TlowB + NK+ with CD3 + TCRgd + expansion and 1 had TlowB+/−NK+ phenotype. Eight out of 11 pts had mutation in RAG1 gene, 4 out of 8 had c.368-369delAA (p.K86fsX118) in homozygous state or heterozygous compound. In our cohort of patients, we also described two new mutations in RAG genes (p.E722Q in RAG1 and p.M459R in RAG2 ). At present, 7/11 were transplanted and 5 out of the transplanted are alive. Conclusion This study demonstrates that the most popular genetic abnormality in East Slavs children with Omenn syndrome is c.368-369delAA (p.K86fs118) in RAG1 gene, which may be connected with more favorable prognosis because 4/4 patients survived after hematopoietic stem cells transplantation.