The immunodeficiency is defined by deleterious mutations in TNFRSF13C encoding for B cell-activating factor receptor (Baff-R).
So far only two patients with deleterious mutations in TNFRSF13C have been published encoding for Baff-R (Warnatz et al. 2009). However, several patients have been identified carrying point mutations which may contribute to the manifestation of antibody deficiency, but the evidence is less strict, since these variants are also found in healthy people and the immunological presentation doesn’t reflect the expected phenotype of an absent BAFF-R function.
Deleterious mutations. The index patient had upper airway infections since childhood, the first pneumonia at age 37 and was diagnosed at age 57 after his third pneumonia. His older sister never presented with a remarkable susceptibility to infections until old age. Neither BAFF-R deficient person developed autoimmunity, abnormal...