Clinical characteristics and molecular analysis of three Chinese children with Omenn syndrome.

[omenn syndrome]

Omenn syndrome (OS ) is a rare autosomal recessive genetic disorder and presents symptoms of severe combined immunodeficiency characterized by erythrodermia , eosinophilia , hepatosplenomegaly , lymphadenopathy , and elevated serum IgE levels . OS has been found to be caused by mutations in RAG 1 or RAG 2 gene that result in partial V (D )J recombination activity . No study on OS has been reported in Chinese children so far . In this study , the genotype and phenotypes of three infants with OS from three unrelated Chinese families were investigated . All the three children had most of the characteristics of OS except normal serum IgE level . Compound heterozygosity mutations in RAG 1 gene (1983 G >A ; 2444 C >T and 2219 C >T ; 3127 C >G ) were identified in two cases , and a homozygous deletion mutation with a premature stop codon was found at residue 2302 of RAG 1 gene (2302 delT , I 729 X ) in the remaining case , including three novel mutations (2302 delT , I 729 X ; 2219 C >T , R 699 W ; and 3127 C >G , Y 1001 X ). Spectratyping analysis of T -cell receptor β-chain variable region (TCRVβ ) gene rearrangement was performed in case 1 and case 2 . All the 25 TCRVβ subfamilies presented monoclonal or oligoclonal peaks in case 1 and 11 TCRVβ subfamilies were very weak or even absent in case 2 . This was the first report about OS in Chinese children . Molecular genetic testing represents an important tool for early confirmed diagnosis and may allow accurate carrier detection and prenatal diagnosis .