[Clinical phenotype and gene diagnostic analysis of Omenn syndrome].

[omenn syndrome]

Omenn syndrome is a rare autosomal recessive hereditary severe combined immunodeficiency . The purpose of this study was to understand clinical characteristics and genetic mutation type of Omenn syndrome and to improve the recognition of Omenn syndrome among pediatric clinicians .One suspected case of severe combined immunodeficiency was found to have pneumonia repeatedly , intractable diarrhea , poor antibiotic treatment effect , lymphadenopathy , hepatosplenomegaly and erythroderma . The patient was diagnosed as having Omenn syndrome by RT-PCR , and the expression of RAG 1 /RAG 2 and gene analysis of RAG 1 /RAG 2 were performed .The classification of lymphocyte was CD 3 (+) cells (35 .3 %), CD 19 (+) cells (0 .4 %), CD 16 (+) cells (57 .6 %). After stimulation with phytohemagglutinin (PHA ), lymphocyte proliferation of the child was extremely low . Genetic studies showed RAG 1 homozygous deletion mutation (2302 del T ). He had detectable activated T -lymphocytes with low circulating B-lymphocytes and no evidence of maternal T -cell engrafment as indicated by the short tandem repeat (STR ) analysis .Omenn syndrome is a severe combined immunodeficiency disease caused by mutations in the RAG 1 /RAG 2 gene . The disease has been reported rarely in China . The clinical manifestations of the disease is early postnatal repeated infections and erythroderma . Mutation analysis of RAG 1 /RAG 2 gene may help to confirm the diagnosis and may be useful in early immune reconstitution and genetic counseling .