FCAR and acrodermatitis enteropathica: GC B cells in ME patients were not as clonal as in AE patients, however, the plasma cell responses are predominantly via IGHA1 and IGHA2. Indeed, the IgA isotype can engage with the inhibitory Fc receptor FCAR on myeloid cells, and can mediate inhibitory effects on many immune cell subsets via activation of FcαRI receptors and induction of IL10 production51.