| Objective : To identify clinical features,genetic mechanisms and immunological characteristics of disease in a infant,who presented with Omenn syndrome and to review the literature.Methods:A 22 days of female infant was admitted into NICU with umbilical cord effusion for 6 days.Physical examination showed severe generalized erythroderma,edema on both eyelids,and yellow effusion in both external auditory canals.Even under broad-spectrum antibiotics,the patient developed otitis media,hepatomegaly,diarrhea and an episode of enterococcus faecium meningitis,prompting laboratory investigation for possible immunodeficiency.Low level of serum Ig G,slightly low level of Ig A and Ig M.Peripheral eosinophilia and total white blood cell was present.Flow cytometic analysis demonstrated the percentage of expansion of both CD4+/CD8+ ratio and CD19+.Inborn metabolic disease screening(IMD)demonstrated a normal level in blood sample,but glutaric acid,pyruvate and 3-hydroxyglutaric acid at higher level in urine sample.Normal expression in chromosome karyotype analysis.However,sequencing of the RAG1 gene of patient’s whole blood genomic(My Genostics Medical Laboratory)revealed heterozygous of two known RAG1 polymorphisms(c.2867T>C(p.I956T),c.2686T> G(p.W896G)),which both parents were found to be heterozygous.The patient was confirmed the diagnosis of Omenn syndrome and inherited through autosomal recessive.Results: At one month of age,two heterozygous mutations were found in RAG1 gene(My Genostics Medical Laboratory).Though Whole exome DNA sequencing,the c.2867 T > C(p.I956T)variation came from mother,and c.2686 T > G(p.W896G)mutation came from father,which cause Omenn syndrome and was inherited though autosomal recessive.Conclusions:Recognition of an underlying severe immunodeficiency in patient was frequently missed by primary caregivers,including neonatologist,pediatricians,and dermatologist.Gene sequencing was necessary to diagnose Omenn syndrome earlier and starting management and treatment. |
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