First case of CD40LG deficiency in Ecuador, diagnosed after whole exome sequencing in a patient with Severe Cutaneous Histoplasmosis

Severe infections with Histoplasma capsulatumare commonly observed in patient with secondary immunodeficiency disorders. We report a two and a half years old boy previously healthy with disseminated cutaneous histoplasmosis. Using whole exome sequencing, we found an indelmutation at the CD40LGgene, suggesting a diagnosis of hyper-IgM (HIGM) syndrome, even in the absence of the usual features for the disease. Interestingly, the patient lives in a region endemic for histoplasmosis. The unusual infections in our case suggest that in children with severe histoplasmosis and resident in endemic areas, HIGM syndrome should be considered as a diagnosis.