Endemic infections in Southeast Asia provide new insights to the phenotypic spectrum of primary immunodeficiency disorders.

Primary immunodeficiency disorders (PIDs) are rare genetic diseases of the immune system. With improving awareness of PIDs among clinicians, the number of patients diagnosed with PIDs is rising rapidly in Southeast Asia. However, delayed diagnosis remains common and adversely affects the prognosis of these patients. In this review, we provide simple phenotypic approach to the diagnosis of PIDs based on pattern recognition. Through multi-centered collaborative studies in the Asian Primary Immunodeficiency Network (APID), we present unique patterns of infectious diseases associated with PIDs in Southeast Asia, including BCG disease, tuberculosis, melioidosis, Penicillium marneffei and Chromobacterium violaceum infections. These initial observations suggest the possibility of utilizing these infections that rarely affect normal healthy children as 'indicators' for PIDs, which is of particular relevance for clinicians working in Southeast Asia.