SUMMARY
Although the hallmark of PIDs is increased susceptibility to infection, many are associated with and initially present with GI diseases, making routine evaluation of the gut necessary. A history of recurrent infections, clinical and/or histologic features atypical of the usual pattern of GI disease, or a poor response to conventional therapy should prompt further immunologic evaluation. Early diagnosis and treatment may prevent irreversible tissue damage and mortality. In most cases, treatment with replacement immunoglobulin and antibiotics does not reverse or prevent the development of GI disease; therefore, additional immunomodulatory therapies, including, in some cases, organ transplantation, are indicated.