IGHG3 and leishmaniasis: Therefore, it appears that FcγRIIIB-NA1/NA2 genotype is associated with VL and may be considered as a risk factor for developing VL in Iranian patients infected with Leishmania. Based on the fact that the FcγRIIIB-NA1 isoform for human IgG2 and IgG3 has a higher affinity than the FcγRIIIB-NA2 isoform (9) and our results which revealed that the FcγRIIIB-NA2/NA2 genotype was more frequent in group 2, it may be concluded that the rate of FcγRIIIB expression but not its affinity to IgG2 and IgG3 can determine the outcome of leishmaniasis.