Clinical and genetic heterogeneity in Omenn syndrome and severe combined immune deficiency.

[omenn syndrome]

OS has been described as a clinical phenotype in infants characterized by SCID , diffuse erythroderma , and other distinct features . The pathogenesis is secondary to autologous , auto-reactive T cells produced as rare escapees from the SCID blockade . Mutations in either the RAG 1 or RAG 2 gene that lead to partial recombinase activity are responsible for many of the patients with these clinical features . We report on two patients , one with an atypical phenotype of OS (absence of rash but presence of other typical features ) who harbored a previously undescribed mutation in RAG 1 , and a second who had many of the classic features of OS but was found to have a mutation in the common gamma chain (gamma (c )) cytokine receptor gene . These cases highlight the clinical and genetic heterogeneity of OS .